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University of Kansas
1.
Lee, Ken Thye.
An Analytical and Experimental Investigation of Potential Mechanical Work Extraction from Supersonic Jet Flow on High Speed Mini Turbines.
Degree: MS, Aerospace Engineering, 2010, University of Kansas
URL: http://hdl.handle.net/1808/6019 
► In the present study, an inexpensive method of mechanical power extraction from supersonic jets was investigated. Detailed experiments were carried out to measure the mechanical…
(more)
▼ In the present study, an inexpensive method of mechanical power extraction from supersonic jets was investigated. Detailed experiments were carried out to measure the mechanical torque generated by a 45o planar bladed mini-turbine with a radius of 12.8 mm. The mini-turbine was exposed to supersonic flow of air exhausting from the exit of a sonic nozzle (diameter of 0.711 mm) into still air. Experiments were carried out by placement of the mini-turbine in various configurations with respect to the supersonic jet flow centerline. These experiments were conducted in the Adaptive Aerostructures Laboratory at the
University of
Kansas using compressed air with a supply pressure of around 6.12 to 6.80 atm. The mini-turbine was tested up to speeds of 50,000 RPM. In addition, the experiments were carried out to determine the mechanical shaft power of the mini-turbine and the overall efficiency of the power conversion from fluid aerodynamic power of the supersonic jet flow to the mechanical shaft power measured. Ten different configurations were tested by positioning the mini-turbine at x/Dturbine = 0.5 and x/Dturbine = 0.25 (x/Dturbine defined as the lateral distance of the supersonic jet from the mini-turbine centerline axis normalized by mini-turbine diameter), +/- 3o and +/- 1.5o inclination angle, and +/- 2.5o and +/- 1.0o directional angle offset relative to the nozzle exit supersonic jet centerline axis, respectively. The effect of nozzle exit area variation on mechanical shaft power extraction and aero-mechanical efficiency of power conversion in each of the test configurations was tested for three different areas; Ae = 0.397 μm2, 0.75Ae = 0.298 μm2 and 0.5Ae = 0.199 μm2. Additional studies were performed to determine the effect of varying the axial location (y/De) of the mini-turbine along the supersonic jet centerline axis measured downstream from the ejector nozzle exit. These experiments were conducted for the three nozzle exit area cases mentioned above. Shadowgraph images were captured for the supersonic jet shock structure and jet spread at the three different nozzle exit areas specified. Results obtained from the experimental runs showed that the mechanical shaft power of the mini-turbine was in the range of 1-2 W and the aero-mechanical efficiency of power conversion achieved were approximately 25% to 40% for the mini-turbine operating at speeds of approximately 35,000 to 50,000 RPM. The aero-mechanical efficiency of power conversion increased when the nozzle exit area was reduced and as the mini-turbine was placed further downstream of the nozzle exit, respectively. These results were attributed to the fact that the jet spread and shear layer growth rate increased at the far-field locations downstream of the nozzle exit. The flow images captured showed visible diamond shock structures in the near-field region for the underexpanded nozzle exit flow and the degree of underexpansion decreased as the nozzle exit area was decreased. Reasonable values of the mini-turbine shaft power extracted from supersonic jet…
Advisors/Committee Members: Barrett, Ronald (advisor), Farokhi, Saeed (cmtemember), Taghavi, Ray (cmtemember).
Subjects/Keywords: Aerospace engineering; Mechanical engineering; Kinetic energy; Mechanical work extraction; Microjets; Mini turbines; Sonic underexpanded nozzle; Supersonic flow
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APA (6th Edition):
Lee, K. T. (2010). An Analytical and Experimental Investigation of Potential Mechanical Work Extraction from Supersonic Jet Flow on High Speed Mini Turbines. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/6019
Chicago Manual of Style (16th Edition):
Lee, Ken Thye. “An Analytical and Experimental Investigation of Potential Mechanical Work Extraction from Supersonic Jet Flow on High Speed Mini Turbines.” 2010. Masters Thesis, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/6019.
MLA Handbook (7th Edition):
Lee, Ken Thye. “An Analytical and Experimental Investigation of Potential Mechanical Work Extraction from Supersonic Jet Flow on High Speed Mini Turbines.” 2010. Web. 15 Jul 2019.
Vancouver:
Lee KT. An Analytical and Experimental Investigation of Potential Mechanical Work Extraction from Supersonic Jet Flow on High Speed Mini Turbines. [Internet] [Masters thesis]. University of Kansas; 2010. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/6019.
Council of Science Editors:
Lee KT. An Analytical and Experimental Investigation of Potential Mechanical Work Extraction from Supersonic Jet Flow on High Speed Mini Turbines. [Masters Thesis]. University of Kansas; 2010. Available from: http://hdl.handle.net/1808/6019
University of Kansas
2.
Vatti, Kranthi.
Damping Estimation of Plates for Statistical Energy Analysis.
Degree: MS, Aerospace Engineering, 2011, University of Kansas
URL: http://hdl.handle.net/1808/7876
► The Power Input Method (P.I.M.) and the Impulse Response Decay Method (I.R.D.M.) are used to evaluate how the accuracy of damping loss factor estimation for…
(more)
▼ The Power Input Method (P.I.M.) and the Impulse Response Decay Method (I.R.D.M.) are used to evaluate how the accuracy of damping loss factor estimation for plates is affected with respect to various processing parameters, such as the frequency resolution, the frequency bandwidth, the number of measurement locations, and the signal to noise ratio. In several computational experiments, accuracy is assessed for a wide range of damping loss factors from low (0.1%) to moderate (1%) to high (10%). A wide range of frequency is considered, including "low frequencies" for which modal density is less than one per band. The Power Input Method (P.I.M.) is first validated with computational studies of an analytical single degree of freedom oscillator. Experimental loss factor estimates for plates (multiple degree of freedom systems) are also computed using the P.I.M. algorithm. The P.I.M. is shown to estimate loss factors with reasonable accuracy for highly damped plates in the 300 Hz - 4000 Hz, wherein modal density exceeds unit value. In this case "reasonable accuracy" means the estimated loss factors are within 10% of those predicted by the impulse response decay method. For lower damping levels the method fails. The analytical Impulse Response Decay Method (I.R.D.M.) is validated by the use of two computational models: a single degree of freedom oscillator and a uniform rectangular panel. The panel computational model is a finite element model of a rectangular plate mechanically excited at a single point. The computational model is used to systematically evaluate the effect of frequency resolution, frequency bandwidth, the number of measurement points used in the computations, and noise level for all the three levels of damping. The "optimized" I.R.D.M. is shown to accurately estimate damping in plate simulations with low to moderate levels of damping with a deviation of no more than 2% from the known damping value. For highly damped plates the I.R.D.M. tends to under-estimate loss factors at high frequency. Experimental loss factor estimation for an aluminum plate with full constrained layer damping treatment, classified as a highly damped plate, and an undamped steel plate, classified as a lightly damped plate are computed using the "optimized" I.R.D.M. algorithm. Statistical Energy Analysis (S.E.A.), which is a natural extension of the Power Input Method, is used to evaluate coupling loss factors for two sets of plates, one set joined along a line and the other set joined at a point. Two alternative coupling loss factor estimation algorithms are studied, one using individual plate loss factor estimations, and the other using the loss factors of the plates estimated when the plates are coupled. The modal parameters (modal density and coupling loss factors) for both sets of plates are estimated experimentally and are compared with theoretical results. The estimations show reasonable agreement between agreement and theory that is, within 5 % for the damped system of plates. For the undamped system of plates the results are…
Advisors/Committee Members: Ewing, Mark (advisor), Hale, Richard (cmtemember), Farokhi, Saeed (cmtemember).
Subjects/Keywords: Aerospace engineering; Mechanics; Acoustics; Frequency response analysis; High frequency analysis; Plate vibration; Statistical energy analysis; Vibration
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APA (6th Edition):
Vatti, K. (2011). Damping Estimation of Plates for Statistical Energy Analysis. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/7876
Chicago Manual of Style (16th Edition):
Vatti, Kranthi. “Damping Estimation of Plates for Statistical Energy Analysis.” 2011. Masters Thesis, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/7876.
MLA Handbook (7th Edition):
Vatti, Kranthi. “Damping Estimation of Plates for Statistical Energy Analysis.” 2011. Web. 15 Jul 2019.
Vancouver:
Vatti K. Damping Estimation of Plates for Statistical Energy Analysis. [Internet] [Masters thesis]. University of Kansas; 2011. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/7876.
Council of Science Editors:
Vatti K. Damping Estimation of Plates for Statistical Energy Analysis. [Masters Thesis]. University of Kansas; 2011. Available from: http://hdl.handle.net/1808/7876
University of Kansas
3.
Tourani, Chandraprakash Chandra.
COMPUTATIONAL SIMULATION OF SCRAMJET COMBUSTORS - A COMPARISON BETWEEN QUASI-ONE DIMENSIONAL AND 2-D NUMERICAL SIMULATIONS.
Degree: MS, Aerospace Engineering, 2011, University of Kansas
URL: http://hdl.handle.net/1808/7635
► 1-D simulations based on the quasi-one-dimensional equations of fluid motion plus an ignition delay model and 2-D numerical simulations based on Reynolds-Averaged Navier-Stokes (RANS) equations…
(more)
▼ 1-D simulations based on the quasi-one-dimensional equations of fluid motion plus an ignition delay model and 2-D numerical simulations based on Reynolds-Averaged Navier-Stokes (RANS) equations have been performed for two different scramjet combustors. The combustor configurations at DLR and NASA's SCHOLAR Supersonic Combustor have been used as test cases for the 1-D and 2-D simulations. Comparisons between the published 3-D computational and experimental results and quasi-one-dimensional and 2-D simulations have been performed. The quasi-one dimensional modeling of NASA's SCHOLAR supersonic combustor captures the trends in Mach number, static pressure and static temperature for both cold flow and combustion case. The comparison with experimental result for combustion case reveals a close agreement with the pressure peak and the presence of an ignition delay. Thus, 1-D simulation very closely predicts the flow evolution within the combustor. On the other hand, for DLR supersonic combustor, due to the lack of oblique wave (i.e. shock waves and expansion waves) and shear dominated viscous flow simulation, 1-D model severely fails to predict the trend followed by the experimental result along the centerline of the combustor. However, the 1-D model is able to match the overall flow velocity achieved within the combustor downstream of the wedge at approximately six wedge chord lengths.
Advisors/Committee Members: Farokhi, Saeed (advisor), Taghavi, Ray (cmtemember), Keshmiri, Shahriar (cmtemember).
Subjects/Keywords: Aerospace engineering; Air-breathing propulsion; Combustor; Hypersonic; Quasi one-dimensional; Scramjet
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APA (6th Edition):
Tourani, C. C. (2011). COMPUTATIONAL SIMULATION OF SCRAMJET COMBUSTORS - A COMPARISON BETWEEN QUASI-ONE DIMENSIONAL AND 2-D NUMERICAL SIMULATIONS. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/7635
Chicago Manual of Style (16th Edition):
Tourani, Chandraprakash Chandra. “COMPUTATIONAL SIMULATION OF SCRAMJET COMBUSTORS - A COMPARISON BETWEEN QUASI-ONE DIMENSIONAL AND 2-D NUMERICAL SIMULATIONS.” 2011. Masters Thesis, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/7635.
MLA Handbook (7th Edition):
Tourani, Chandraprakash Chandra. “COMPUTATIONAL SIMULATION OF SCRAMJET COMBUSTORS - A COMPARISON BETWEEN QUASI-ONE DIMENSIONAL AND 2-D NUMERICAL SIMULATIONS.” 2011. Web. 15 Jul 2019.
Vancouver:
Tourani CC. COMPUTATIONAL SIMULATION OF SCRAMJET COMBUSTORS - A COMPARISON BETWEEN QUASI-ONE DIMENSIONAL AND 2-D NUMERICAL SIMULATIONS. [Internet] [Masters thesis]. University of Kansas; 2011. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/7635.
Council of Science Editors:
Tourani CC. COMPUTATIONAL SIMULATION OF SCRAMJET COMBUSTORS - A COMPARISON BETWEEN QUASI-ONE DIMENSIONAL AND 2-D NUMERICAL SIMULATIONS. [Masters Thesis]. University of Kansas; 2011. Available from: http://hdl.handle.net/1808/7635
University of Kansas
4.
Carroll, Jonathan.
Diffuser Augmented Wind Turbine Analysis Code.
Degree: MS, Aerospace Engineering, 2014, University of Kansas
URL: http://hdl.handle.net/1808/14597
► Wind Energy is becoming a significant source of energy throughout the world. This ever increasing field will potentially reach the limit of availability and practicality…
(more)
▼ Wind Energy is becoming a significant source of energy throughout the world. This ever increasing field will potentially reach the limit of availability and practicality with the wind farm sites and size of the turbine itself. Therefore, it is necessary to develop innovative wind capturing devices that can produce energy in the locations where large conventional horizontal axis wind turbines (HAWTs) are too impractical to install and operate. A diffuser augmented wind turbine (DAWT) is one such innovation. DAWTs increase the power output of the rotor by increasing the wind speed into the rotor using a duct. Currently, developing these turbines is an involved process using time consuming Computational Fluid Dynamics codes. A simple and quick design tool is necessary for designers to develop efficient energy capturing devices. This work lays out the theory for a quick analysis tool for DAWTs using an axisymmetric surface vorticity method. This method allows for quick analysis of duct, hubs and rotors giving designers a general idea of the power output of the proposed hub, blade and duct geometry. The method would be similar to the way blade element momentum theory is used to design conventional HAWTs. It is determined that the presented method is viable for preliminary design of DAWTs.
Advisors/Committee Members: Taghavi, Ray (advisor), Farokhi, Saeed (cmtemember), Zheng, Charlie (cmtemember).
Subjects/Keywords: Aerospace engineering; Aerodynamic analysis; Dawt; Diffuser augmented wind turbine; Shrouded wind turbine; Wind turbine
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APA (6th Edition):
Carroll, J. (2014). Diffuser Augmented Wind Turbine Analysis Code. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/14597
Chicago Manual of Style (16th Edition):
Carroll, Jonathan. “Diffuser Augmented Wind Turbine Analysis Code.” 2014. Masters Thesis, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/14597.
MLA Handbook (7th Edition):
Carroll, Jonathan. “Diffuser Augmented Wind Turbine Analysis Code.” 2014. Web. 15 Jul 2019.
Vancouver:
Carroll J. Diffuser Augmented Wind Turbine Analysis Code. [Internet] [Masters thesis]. University of Kansas; 2014. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/14597.
Council of Science Editors:
Carroll J. Diffuser Augmented Wind Turbine Analysis Code. [Masters Thesis]. University of Kansas; 2014. Available from: http://hdl.handle.net/1808/14597
University of Kansas
5.
Burns, Aaron.
Turbine Tip Clearance Control Using Fluidic Oscillators.
Degree: MS, Aerospace Engineering, 2015, University of Kansas
URL: http://hdl.handle.net/1808/19426
► This study investigates the impact to power generation and efficiency by injecting flow into the tip clearance region of a gas turbine rotor. New to…
(more)
▼ This study investigates the impact to power generation and efficiency by injecting flow into the tip clearance region of a gas turbine rotor. New to this design is using a fluidic oscillator as the jet source for the injection instead of a circular jet. The fluidic oscillator in this study is a bistable, vent fed oscillator. It creates a sweeping jet at its exit with a primary frequency in the 1 kHz to10 kHz range dependent on the supply mass flow and internal geometry. In this study, rotor tip clearance in the range of 2% to 10% of blade span is investigated for the flowing rotor tip types: flat tip, 2 and 4 fluidic oscillators on a flat tip, circle jets on a flat tip, squealer tip, 4 fluidic oscillators on a squealer tip, and circle jets on a squealer tip. This study was performed using the commercial CFD package STAR-CCM+. A polyhedral mesh was used for enhanced accuracy and reduced compute times. The significant flow models used were implicit unsteady, k-e turbulence, and real air. Also the turbine rotor was rotated about the z-axis (cylindrical) to simulate a real rotor. Only two blades of the entire rotor were simulated using periodic boundary conditions to simulate the rest of the rotor wheel. The tips with 4 fluidics showed the largest efficiency gain of 2% to 3% over the flat tip, 0% to 1% over the squealer tip, and about 1% over the circle jet tips. The 4 fluidic tips produced nearly twice as power per orifice as compared to the circle jet tips. The 2 fluidic tip had an efficiency gain of about 1% over the flat tip, an efficiency loss compared to the squealer tip, and 0% to 0.5% gain over the circle jet tips. The 2 fluidic tip produced 12% to 40% more power than the circle jet tips. The two 4 fluidic tips and the 2 fluidic tip created more turbine power that in took the compressor to make the supply air. However, when compared to the power production of the squealer tip, almost all tip configurations did not produce more power than it took to make the supply air.
Advisors/Committee Members: Farokhi, Saeed (advisor), Taghavi, Ray (cmtemember), Zheng, Charlie (cmtemember).
Subjects/Keywords: Aerospace engineering; Fluidic Oscillator; Tip Clearance Control; Tip Clearance Loss; Turbine
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APA (6th Edition):
Burns, A. (2015). Turbine Tip Clearance Control Using Fluidic Oscillators. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/19426
Chicago Manual of Style (16th Edition):
Burns, Aaron. “Turbine Tip Clearance Control Using Fluidic Oscillators.” 2015. Masters Thesis, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/19426.
MLA Handbook (7th Edition):
Burns, Aaron. “Turbine Tip Clearance Control Using Fluidic Oscillators.” 2015. Web. 15 Jul 2019.
Vancouver:
Burns A. Turbine Tip Clearance Control Using Fluidic Oscillators. [Internet] [Masters thesis]. University of Kansas; 2015. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/19426.
Council of Science Editors:
Burns A. Turbine Tip Clearance Control Using Fluidic Oscillators. [Masters Thesis]. University of Kansas; 2015. Available from: http://hdl.handle.net/1808/19426
University of Kansas
6.
Homsrivaranon, Kanin.
Investigation of Active Flow Control on an Extremely Thick Wind Turbine Airfoil.
Degree: MS, Aerospace Engineering, 2016, University of Kansas
URL: http://hdl.handle.net/1808/21970
► Today, modern wind turbine size has become larger than ever. The conventional airfoil near rotor hub cannot provide the structure integrity for the rotor blades.…
(more)
▼ Today, modern wind turbine size has become larger than ever. The conventional airfoil near rotor hub cannot provide the structure integrity for the rotor blades. Large diameter wind turbine required for extremely thick airfoil, such as the FX77-W-343 34.4% wind turbine dedicated airfoil. The exceptionally thick airfoil has an unfavorable characteristic, such as sharp stalling and stalling at low angle of attack. To prevent undesired behavior, the FX77-W-343 airfoil with co-flow jet active flow control is simulated in 2-D CFD using STAR-CCM+ to investigate the enhancement in performance. The simulation is done at low Reynolds number of 1,000,000 with injection and suction momentum coefficient of 0.05. The simulation presents promising performance increase of maximum lift coefficient by 190% and improves lift-to-drag ratio by 94%. While sharp stalling behavior cannot be solved with co-flow jet flow control, the operating margin of the extremely thick airfoil is increased by 130% by delaying the stall angle of attack of 8deg.
Advisors/Committee Members: Farokhi, Saeed (advisor), Taghavi, Ray (cmtemember), Keshmiri, Shawn (cmtemember).
Subjects/Keywords: Aerospace engineering
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APA (6th Edition):
Homsrivaranon, K. (2016). Investigation of Active Flow Control on an Extremely Thick Wind Turbine Airfoil. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/21970
Chicago Manual of Style (16th Edition):
Homsrivaranon, Kanin. “Investigation of Active Flow Control on an Extremely Thick Wind Turbine Airfoil.” 2016. Masters Thesis, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/21970.
MLA Handbook (7th Edition):
Homsrivaranon, Kanin. “Investigation of Active Flow Control on an Extremely Thick Wind Turbine Airfoil.” 2016. Web. 15 Jul 2019.
Vancouver:
Homsrivaranon K. Investigation of Active Flow Control on an Extremely Thick Wind Turbine Airfoil. [Internet] [Masters thesis]. University of Kansas; 2016. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/21970.
Council of Science Editors:
Homsrivaranon K. Investigation of Active Flow Control on an Extremely Thick Wind Turbine Airfoil. [Masters Thesis]. University of Kansas; 2016. Available from: http://hdl.handle.net/1808/21970
University of Kansas
7.
Lee, Adrian Kok Chiang.
Evaluation of Protruding Centerbody on the Novel Airdata Sensor.
Degree: MS, Aerospace Engineering, 2016, University of Kansas
URL: http://hdl.handle.net/1808/22341
► A novel airdata sensor was developed at the University of Kansas1. The Bio-Inspired probe was designed for high angles of attack and sideslip use, suitable…
(more)
▼ A novel airdata sensor was developed at the
University of Kansas1. The Bio-Inspired probe was designed for high angles of attack and sideslip use, suitable for Unmanned Aerial Vehicle (UAV) flight control system and other highly maneuverable aircraft applications. The probe displayed excellent speed measurement of up to angle of attack and sideslip of ±40°, compared to ±25° exhibited by a conventional pitot tube at the same accuracy. With the goal of evaluating the novel probe’s protruding centerbody and effects on angular sensitivity, two new sets of probe were developed, featuring elongated (L/D 1.5) and shortened (L/D 0.5) protruding centerbodies to gain deeper understanding of the Coanda effect on the blunt protruding centerbody featured on the Bio-inspired probe. The protruding centerbody uses the Coanda effect to turn air flow streamline and attach to the centerbody surface. The analysis included pressure and velocity measurement at high angle of attack wind tunnel tests and Computational Fluid Dynamic simulations on the new and original (L/D 1.0) prototypes. As expected, the elongated ellipsoid centerbody (L/D 1.5) probe exhibited an improved flow capture. Design improvements such as centerbody optimization and direct drag measurement are suggested to improve the novel probe capabilities. Further research will be concentrated on a flight testing on a UAV with the novel airdata sensor and a conventional Pitot-static tube.
Advisors/Committee Members: Taghavi, Ray (advisor), Farokhi, Saeed (cmtemember), Keshmiri, Shawn (cmtemember).
Subjects/Keywords: Aerospace engineering; Engineering; airdata sensor; Bio-Inspired; Coanda effect; flow capture; protruding centerbody
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APA (6th Edition):
Lee, A. K. C. (2016). Evaluation of Protruding Centerbody on the Novel Airdata Sensor. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/22341
Chicago Manual of Style (16th Edition):
Lee, Adrian Kok Chiang. “Evaluation of Protruding Centerbody on the Novel Airdata Sensor.” 2016. Masters Thesis, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/22341.
MLA Handbook (7th Edition):
Lee, Adrian Kok Chiang. “Evaluation of Protruding Centerbody on the Novel Airdata Sensor.” 2016. Web. 15 Jul 2019.
Vancouver:
Lee AKC. Evaluation of Protruding Centerbody on the Novel Airdata Sensor. [Internet] [Masters thesis]. University of Kansas; 2016. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/22341.
Council of Science Editors:
Lee AKC. Evaluation of Protruding Centerbody on the Novel Airdata Sensor. [Masters Thesis]. University of Kansas; 2016. Available from: http://hdl.handle.net/1808/22341
University of Kansas
8.
Mullick, Sunayan.
IMPACT OF NEW CHEVRON CONFIGURATIONS ON MIXING ENHANCEMENT IN SUBSONIC JETS.
Degree: MS, Aerospace Engineering, 2017, University of Kansas
URL: http://hdl.handle.net/1808/25896
► A major contributor to the overall noise of an aircraft is jet noise – the noise generated by the gases exiting the exhaust nozzle of…
(more)
▼ A major
contributor to the overall noise of an aircraft is jet noise – the noise generated by the gases exiting the exhaust nozzle of a jet engine. One approach to mitigate jet noise is through the implementation of chevron nozzles. In the present context, first, a baseline axisymmetric separate-flow nozzle, termed the 3BB model, with an external plug having a bypass ratio of 5 is analyzed. The specifications of this nozzle are taken from an acoustic study carried out at the NASA John H. Glenn Research Center. Then, various chevron configurations are added to the core and fan nozzles to produce three chevron nozzles. Of these, two are presented as modified versions of the conventional chevron nozzle and form the essence of this work. The third chevron nozzle represents the conventional chevron nozzle in use today. For all the nozzles considered in this study, the flow conditions used represent the takeoff environment of a contemporary subsonic aircraft. The fan nozzle total pressure is set to 1.8 atm while the core nozzle total pressure is 1.65 atm. The total temperature inside the fan nozzle is set to 333.3 K while the core nozzle has a total temperature of 833.3 K. The freestream conditions are given as: static pressure = 0.98 atm, total pressure = 1.04 atm, total temperature = 298.8 K and Mach number = 0.28. For the three chevron nozzles, the core and fan nozzles have 12 chevrons each. Each chevron extends over a sector of 30 degrees of the circumference. To carry out the study presented herein, first, computer-aided design (CAD) models of the four nozzles are created. These models are then used to carry out computational fluid dynamics (CFD) simulations with the conditions stated above. The CFD simulations are performed on STAR-CCM+. The results of the simulations carried out for the baseline nozzle are compared with existing experimental and numerical data to validate the use of STAR-CCM+ as a tool for studying jet flows. Once this step is complete, numerical simulations are carried out for the three chevron nozzles. The results from these are compared with those obtained for the baseline nozzle. The turbulent kinetic energy (TKE) and the mean axial velocity are the two main parameters that represent mixing enhancement and are focused on in this work. Since the TKE levels for a given nozzle are directly linked to the jet noise generated, the TKE is an important indication of the jet noise produced by a given nozzle. Other jet mixing parameters such as the centerline total temperature decay and the centerline velocity of the jet flow exiting each nozzle are also analyzed. A 2-D axisymmetric grid is produced for the 3BB nozzle while a 3-D mesh is generated for each of the chevron nozzles. To reduce the computation cost, only a 30° sector of the chevron nozzles is modeled. Since the Shear Stress Transport (SST) k-ω turbulence model has been widely used in several aerospace applications, it is chosen for all simulations here as well. The numerical analysis shows that STAR-CCM+ can successfully be used for the study…
Advisors/Committee Members: Taghavi, Ray (advisor), Farokhi, Saeed (cmtemember), Keshmiri, Shawn (cmtemember).
Subjects/Keywords: Aerospace engineering
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APA ·
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APA (6th Edition):
Mullick, S. (2017). IMPACT OF NEW CHEVRON CONFIGURATIONS ON MIXING ENHANCEMENT IN SUBSONIC JETS. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/25896
Chicago Manual of Style (16th Edition):
Mullick, Sunayan. “IMPACT OF NEW CHEVRON CONFIGURATIONS ON MIXING ENHANCEMENT IN SUBSONIC JETS.” 2017. Masters Thesis, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/25896.
MLA Handbook (7th Edition):
Mullick, Sunayan. “IMPACT OF NEW CHEVRON CONFIGURATIONS ON MIXING ENHANCEMENT IN SUBSONIC JETS.” 2017. Web. 15 Jul 2019.
Vancouver:
Mullick S. IMPACT OF NEW CHEVRON CONFIGURATIONS ON MIXING ENHANCEMENT IN SUBSONIC JETS. [Internet] [Masters thesis]. University of Kansas; 2017. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/25896.
Council of Science Editors:
Mullick S. IMPACT OF NEW CHEVRON CONFIGURATIONS ON MIXING ENHANCEMENT IN SUBSONIC JETS. [Masters Thesis]. University of Kansas; 2017. Available from: http://hdl.handle.net/1808/25896
University of Kansas
9.
Brown, Matthew Alan.
A Computational Method for Determining Distributed Aerodynamic Loads on Planforms of Arbitrary Shape in Compressible Subsonic Flow.
Degree: MS, Aerospace Engineering, 2013, University of Kansas
URL: http://hdl.handle.net/1808/14195
► The methods presented in this work are intended to provided an easy to understand and easy to apply method for determining the distributed aerodynamic loads…
(more)
▼ The methods presented in this work are intended to provided an easy to understand and easy to apply method for determining the distributed aerodynamic loads and aerodynamic characteristics of planforms of nearly arbitrary shape. Through application of the cranked wing approach, most planforms can be modeled including nearly all practical lifting surfaces with some notable exceptions. The methods are extremely accurate for elliptic wings and rectangular wings with some notable difficulty attributed to swept wings and wings with control surface deflection. A method for accounting for the shift in the locus of aerodynamic centers is also presented and applied to the lifting line theory to mitigate singularities inherent in its formulation. Comparisons to other numerical methods as well as theoretical equations and experimental data suggest that the method is reasonably accurate, but limited by some of its contributing theories. Its biggest benefit is its ability to estimate viscous effects which normally require more sophisticated models.
Advisors/Committee Members: Taghavi, Ray (advisor), Farokhi, Saeed (cmtemember), Keshmiri, Shawn (cmtemember).
Subjects/Keywords: Aerospace engineering; Aerodyanmic loads; Cranked wing; Wing aerodyanmics; Wing loads
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APA (6th Edition):
Brown, M. A. (2013). A Computational Method for Determining Distributed Aerodynamic Loads on Planforms of Arbitrary Shape in Compressible Subsonic Flow. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/14195
Chicago Manual of Style (16th Edition):
Brown, Matthew Alan. “A Computational Method for Determining Distributed Aerodynamic Loads on Planforms of Arbitrary Shape in Compressible Subsonic Flow.” 2013. Masters Thesis, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/14195.
MLA Handbook (7th Edition):
Brown, Matthew Alan. “A Computational Method for Determining Distributed Aerodynamic Loads on Planforms of Arbitrary Shape in Compressible Subsonic Flow.” 2013. Web. 15 Jul 2019.
Vancouver:
Brown MA. A Computational Method for Determining Distributed Aerodynamic Loads on Planforms of Arbitrary Shape in Compressible Subsonic Flow. [Internet] [Masters thesis]. University of Kansas; 2013. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/14195.
Council of Science Editors:
Brown MA. A Computational Method for Determining Distributed Aerodynamic Loads on Planforms of Arbitrary Shape in Compressible Subsonic Flow. [Masters Thesis]. University of Kansas; 2013. Available from: http://hdl.handle.net/1808/14195
University of Kansas
10.
Chandra, Yatish.
Investigation of the Aerodynamic Performance of a DG808s UAS in Propeller Slipstream using Computational Fluid Dynamics.
Degree: MS, Aerospace Engineering, 2017, University of Kansas
URL: http://hdl.handle.net/1808/25935
► Unmanned Aerial Systems (UASs) are relatively affordable and immediately available compared to commercial aircraft. Hence, their aerodynamics and design accuracies are often based on extrapolating…
(more)
▼ Unmanned Aerial Systems (UASs) are relatively affordable and immediately available compared to commercial aircraft. Hence, their aerodynamics and design accuracies are often based on extrapolating from design standards and procedures widely used in the aerospace industry for commercial aircraft with most often, acceptable results. Engineering level software such as Advanced Aircraft Analysis (AAA) use general aviation aircraft data and later extrapolate them onto UASs for aerodynamic and flight dynamics modeling but are limited by their platform repository and relatively high Reynolds number evaluations. UASs however, are aircraft which fly at comparatively low speeds and low Reynolds number with close proximities between the components wherein such standards may not hold good. This thesis focuses on evaluating the accuracy and impact of such industry standards on the aerodynamics and flight dynamics of UASs. A DG808s UAS is chosen for the study which was previously modeled using the AAA software at The
University of
Kansas by the Flight Systems Team. Using the STAR-CCM+ code, performance data were compared and assessed with AAA. Aerodynamic simulations were carried out for two different configurations viz., aircraft with and without propeller slipstream effects. Data obtained for the non-powered simulations were found to be in good agreement with the AAA model. For the powered flight however, discrepancies between the AAA model and CFD data were observed with large values for the vertical tail side-force coefficient. A comparison with the system identification data from the flight tests was made to confirm and validate this vertical tail behavior with the help of rudder deflection inputs. A relationship between the propeller RPM and the aerodynamic model was established by simulating two different propeller speeds. Based on the STAR-CCM+ data and the resulting comparisons with AAA, updates necessary to the UAS aerodynamic and flight dynamics models currently used in the industry were discussed and concluded with a stress on dependency on higher fidelity methods such as Computational Fluid Dynamics.
Advisors/Committee Members: Taghavi, Ray (advisor), Keshmiri, Shawn (cmtemember), Farokhi, Saeed (cmtemember).
Subjects/Keywords: Aerospace engineering; Aerodynamics; CFD; DG808s; Downwash; Sidewash; UAS
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APA (6th Edition):
Chandra, Y. (2017). Investigation of the Aerodynamic Performance of a DG808s UAS in Propeller Slipstream using Computational Fluid Dynamics. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/25935
Chicago Manual of Style (16th Edition):
Chandra, Yatish. “Investigation of the Aerodynamic Performance of a DG808s UAS in Propeller Slipstream using Computational Fluid Dynamics.” 2017. Masters Thesis, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/25935.
MLA Handbook (7th Edition):
Chandra, Yatish. “Investigation of the Aerodynamic Performance of a DG808s UAS in Propeller Slipstream using Computational Fluid Dynamics.” 2017. Web. 15 Jul 2019.
Vancouver:
Chandra Y. Investigation of the Aerodynamic Performance of a DG808s UAS in Propeller Slipstream using Computational Fluid Dynamics. [Internet] [Masters thesis]. University of Kansas; 2017. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/25935.
Council of Science Editors:
Chandra Y. Investigation of the Aerodynamic Performance of a DG808s UAS in Propeller Slipstream using Computational Fluid Dynamics. [Masters Thesis]. University of Kansas; 2017. Available from: http://hdl.handle.net/1808/25935
University of Kansas
11.
D'Silva, Adam.
Investigation on Entropy Signature of Objects.
Degree: MS, Aerospace Engineering, 2017, University of Kansas
URL: http://hdl.handle.net/1808/24146
► With the use of modern configuration and advanced stealth technologies, aircraft have the ability to minimize their signatures significantly. The three main signatures being infrared,…
(more)
▼ With the use of modern configuration and advanced stealth technologies, aircraft have the ability to minimize their signatures significantly. The three main signatures being infrared, radar, and noise. A new observable, not taken into consideration, is entropy trail. This is a new and exciting area of research, to detect an object in motion, based on its entropy trail. The objective is to investigate two objects, a sphere and wing, generate an entropy trail regardless of shape, size, or implemented low observable technologies. Literature review established that the sphere and wing had negligible IR, radar, and noise signatures. IR signature was 0.18% and 0.07% off ambient temperature, radar signature was −19.9 dBm2 and −10.6dBm2, and noise signature was negligible since the incoming flow was M ≤ 0.1. The entropy trail of a sphere and wing were investigated using the 2nd Law of Thermodynamics and Gibbs equation. The trails were determined with CFD analysis at non-dimensionalized distances, away from the trailing edge, of the models. Wind tunnel measurements validated CFD results by measuring total pressure at arbitrary positions in the wake. Temperature measurements were not considered since the process is adiabatic. The results were in agreement between CFD and wind tunnel expect for the wing at 16 degrees angle of attack. This was due to the presence of a vortex and separated flow, which is difficult to capture with pitot tubes.
Advisors/Committee Members: Farokhi, Saeed (advisor), Taghavi, Ray (cmtemember), Keshmiri, Shawn (cmtemember).
Subjects/Keywords: Aerospace engineering; Entropy Signature; Low Observable
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APA (6th Edition):
D'Silva, A. (2017). Investigation on Entropy Signature of Objects. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/24146
Chicago Manual of Style (16th Edition):
D'Silva, Adam. “Investigation on Entropy Signature of Objects.” 2017. Masters Thesis, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/24146.
MLA Handbook (7th Edition):
D'Silva, Adam. “Investigation on Entropy Signature of Objects.” 2017. Web. 15 Jul 2019.
Vancouver:
D'Silva A. Investigation on Entropy Signature of Objects. [Internet] [Masters thesis]. University of Kansas; 2017. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/24146.
Council of Science Editors:
D'Silva A. Investigation on Entropy Signature of Objects. [Masters Thesis]. University of Kansas; 2017. Available from: http://hdl.handle.net/1808/24146
University of Kansas
12.
Valleru, Vinay.
Aeroacoustic Analysis of a Wind Turbine with Sinusoidal Leading-Edge Blade.
Degree: MS, Aerospace Engineering, 2018, University of Kansas
URL: http://hdl.handle.net/1808/27762
► Wind turbines are a major source of renewable power generation in the U.S with a share of 4.7% in total electricity produced and is a…
(more)
▼ Wind turbines are a major source of renewable power generation in the U.S with a share of 4.7% in total electricity produced and is a clean energy source. While wind energy has its advantages, it also has room for improvement and few drawbacks. One of the drawbacks is the noise associated with the operation of the wind turbine and its impact on nearby communities. The noise generated from wind turbines is known to cause annoyance and sleep disturbance to the people living nearby and few countries have acted to regulate the installation of wind turbines near communities. The primary aim of this research is to design a wind turbine blade with tubercles and evaluate it's aerodynamic and noise performance. A preliminary step in achieving this goal is to perform 3D steady flow analysis and noise analysis on a base model, namely the NREL Phase VI blade using commercial CFD software, STAR CCM+. Three-dimensional steady RANS equations with SST k-ω turbulence model with all y+ wall treatment is used to perform numerical analysis of the blade at five different wind speeds from 7m/s to 25m/s, by keeping the wind turbine angular speed constant at 72RPM. To reduce computational cost and time, only one blade is analyzed instead of two, and a periodic boundary condition is used with 1800 symmetry. The pressure data from the CFD results are used as an input to Curle Broadband Noise source model to estimate the sound Pressure level (SPL). This process aids in validating the prediction that the bionic wind turbine blade can be more efficient and generate less noise than a conventional wind turbine at the same wind speeds.
Advisors/Committee Members: Taghavi, Ray (advisor), Farokhi, Saeed (advisor), Wu, Huixuan (cmtemember).
Subjects/Keywords: Aerospace engineering; Aeroacoustics; Bio-mimicry; CFD; NREL Phase VI; STAR CCM+; Wind Turbines
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Export
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Manager
APA (6th Edition):
Valleru, V. (2018). Aeroacoustic Analysis of a Wind Turbine with Sinusoidal Leading-Edge Blade. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/27762
Chicago Manual of Style (16th Edition):
Valleru, Vinay. “Aeroacoustic Analysis of a Wind Turbine with Sinusoidal Leading-Edge Blade.” 2018. Masters Thesis, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/27762.
MLA Handbook (7th Edition):
Valleru, Vinay. “Aeroacoustic Analysis of a Wind Turbine with Sinusoidal Leading-Edge Blade.” 2018. Web. 15 Jul 2019.
Vancouver:
Valleru V. Aeroacoustic Analysis of a Wind Turbine with Sinusoidal Leading-Edge Blade. [Internet] [Masters thesis]. University of Kansas; 2018. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/27762.
Council of Science Editors:
Valleru V. Aeroacoustic Analysis of a Wind Turbine with Sinusoidal Leading-Edge Blade. [Masters Thesis]. University of Kansas; 2018. Available from: http://hdl.handle.net/1808/27762
University of Kansas
13.
Flesberg, Sonja.
Mixing Enhancement in a Scramjet Combustor Using Fuel Jet Injection Swirl.
Degree: PhD, Aerospace Engineering, 2015, University of Kansas
URL: http://hdl.handle.net/1808/19380
► The scramjet engine has proven to be a viable means of powering a hypersonic vehicle, especially after successful flights of the X-51 WaveRider and various…
(more)
▼ The scramjet engine has proven to be a viable means of powering a hypersonic vehicle, especially after successful flights of the X-51 WaveRider and various Hy-SHOT test vehicles. The major challenge associated with operating a scramjet engine is the short residence time of the fuel and oxidizer in the combustor. The fuel and oxidizer have only milliseconds to mix, ignite and combust in the combustion chamber. Combustion cannot occur until the fuel and oxidizer are mixed on a molecular level. Therefore the improvement of mixing is of utmost interest since this can increase combustion efficiency. This study investigated mixing enhancement of fuel and oxidizer within the combustion chamber of a scramjet by introducing swirl to the fuel jet. The investigation was accomplished with numerical simulations using STAR-CCM+ computational fluid dynamic software. The geometry of the
University of Virginia Supersonic Combustion Facility was used to model the isolator, combustor and nozzle of a scramjet engine for simulation purposes. Experimental data from previous research at the facility was used to verify the simulation model before investigating the effect of fuel jet swirl on mixing. The model used coaxial fuel jet with a swirling annular jet. Single coaxial fuel jet and dual coaxial fuel jet configurations were simulated for the investigation. The coaxial fuel jets were modelled with a swirling annular jet and non-swirling core jet. Numerical analysis showed that fuel jet swirl not only increased mixing and entrainment of the fuel with the oxidizer but the mixing occurred further upstream than without fuel jet swirl. The burning efficiency was calculated for the all the configurations. An increase in burning efficiency indicated an increase in the mixing of H2 with O2. In the case of the single fuel jet models, the maximum burning efficiency increase due to fuel injection jet swirl was 23.3%. The research also investigated the possibility that interaction between two swirling jets would produce increased mixing and to study how the distance between the two fuel injector exits would affect mixing. Three swirl patterns were investigated: 1) the first swirl pattern as viewed by an observer looking downstream had the right fuel annular jet swirling counter clockwise and the left fuel annular jet swirling clockwise, 2) the second swirl pattern as viewed by an observer looking downstream had the right fuel jet swirling clockwise and the left fuel jet swirling counter clockwise, 3) the third swirl pattern as viewed by an observer looking downstream had both the right and left fuel jet swirling in the same clockwise direction. Each one of the swirl patterns were simulated with the distances between the center points of the fuel jets modelled 3, 4, and 5 times the fuel injector radius. The swirl pattern that produced the greatest increase in burning efficiency differed according to the fuel injector spacing. The maximum increase in burning efficiency compared to the corresponding non-swirling two jet baseline case was 24.6% and was…
Advisors/Committee Members: Taghavi, Ray (advisor), Farokhi, Saeed (advisor), Taghavi, Ray (cmtemember), Farokhi, Saeed (cmtemember), Hale, Richard (cmtemember), Barrett, Ronald (cmtemember), Yimer, Bedru (cmtemember).
Subjects/Keywords: Aerospace engineering; fuel jet injection swirl; mixing enhancement; scramjet combustion
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APA (6th Edition):
Flesberg, S. (2015). Mixing Enhancement in a Scramjet Combustor Using Fuel Jet Injection Swirl. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/19380
Chicago Manual of Style (16th Edition):
Flesberg, Sonja. “Mixing Enhancement in a Scramjet Combustor Using Fuel Jet Injection Swirl.” 2015. Doctoral Dissertation, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/19380.
MLA Handbook (7th Edition):
Flesberg, Sonja. “Mixing Enhancement in a Scramjet Combustor Using Fuel Jet Injection Swirl.” 2015. Web. 15 Jul 2019.
Vancouver:
Flesberg S. Mixing Enhancement in a Scramjet Combustor Using Fuel Jet Injection Swirl. [Internet] [Doctoral dissertation]. University of Kansas; 2015. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/19380.
Council of Science Editors:
Flesberg S. Mixing Enhancement in a Scramjet Combustor Using Fuel Jet Injection Swirl. [Doctoral Dissertation]. University of Kansas; 2015. Available from: http://hdl.handle.net/1808/19380
University of Kansas
14.
Lechtenberg, Travis Francis.
DERIVATION AND OBSERVABILITY OF UPPER ATMOSPHERIC DENSITY VARIATIONS UTILIZING PRECISION ORBIT EPHEMERIDES.
Degree: MS, Aerospace Engineering, 2010, University of Kansas
URL: http://hdl.handle.net/1808/6295
► Several models of atmospheric density exist in today's world, yet most possess significant errors when compared to data determined from actual satellite measurements. This research…
(more)
▼ Several models of atmospheric density exist in today's world, yet most possess significant errors when compared to data determined from actual satellite measurements. This research utilizes precision orbit ephemerides (POE) in an optimal orbit determination scheme to generate corrections to existing density models to better characterize observations of satellites in low earth orbit (LEO). These corrections are compared against accelerometer derived densities that are available for a few select satellites, notably, the CHAMP and GRACE satellites. These corrections are analyzed by determining the cross correlation coefficients and root-mean-squared values of the estimated corrected densities as compared to the accelerometer derived densities for these satellites. The POE derived densities showed marked improvement using these methods of comparison over the existing empirical density models for all examined time periods and solar and geomagnetic activity levels. The cross correlation values for the POE derived densities also consistently out-performed the High Accuracy Satellite Drag Model (HASDM). This research examines the ability of POE derived densities to characterize short term variations in atmospheric density that occur on short time scales. The specific phenomena examined were travelling atmospheric disturbances (TAD) and geomagnetic cusps, which had temporal spans of less than half the period of the satellite's orbit, more specifically spans of between four and ten minutes, and less than three minutes respectively. Density variations of shorter duration are more difficult to observe even in accelerometer data due to diurnal variations that arise from cyclical increases due to the satellite passing from the darkened side of the earth to the lit side. This research also examines the effects of a vertically propagating atmospheric densities by looking at periods of time during which both the GRACE and CHAMP satellites have coplanar orbits, during which perturbations can be examined for their capability to extend vertically through the atmosphere, as well as their observability in POE derived densities. Additionally, this research extends the application of optimal orbit determination techniques to an additional satellite, the TerraSAR-X, which lacks an accelerometer. For LEO, one of the greatest uncertainties in orbit determination is drag, which is largely influenced by atmospheric density. There are many factors which affect the variability of atmospheric densities, and some of these factors are well modeled, such as atmospheric heating and to some degree, the solar and geomagnetic activity levels, though some variations are not modeled at all. The orbit determination scheme parameters found to perform best for most cases were a baseline model of one of the three Jacchia based baseline models, a density correlation half-life of 18 or 180 minutes, and a ballistic coefficient correlation half life of 1.8 minutes. All three Jacchia based models performed very similarly, with the CIRA-1972 model edging out the…
Advisors/Committee Members: McLaughlin, Craig A. (advisor), Farokhi, Saeed (cmtemember), Keshmiri, Shahriar (cmtemember).
Subjects/Keywords: Aerospace engineering; Atmospheric density; Orbit determination; Precision orbit ephemerides; Satellite drag
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APA (6th Edition):
Lechtenberg, T. F. (2010). DERIVATION AND OBSERVABILITY OF UPPER ATMOSPHERIC DENSITY VARIATIONS UTILIZING PRECISION ORBIT EPHEMERIDES. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/6295
Chicago Manual of Style (16th Edition):
Lechtenberg, Travis Francis. “DERIVATION AND OBSERVABILITY OF UPPER ATMOSPHERIC DENSITY VARIATIONS UTILIZING PRECISION ORBIT EPHEMERIDES.” 2010. Masters Thesis, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/6295.
MLA Handbook (7th Edition):
Lechtenberg, Travis Francis. “DERIVATION AND OBSERVABILITY OF UPPER ATMOSPHERIC DENSITY VARIATIONS UTILIZING PRECISION ORBIT EPHEMERIDES.” 2010. Web. 15 Jul 2019.
Vancouver:
Lechtenberg TF. DERIVATION AND OBSERVABILITY OF UPPER ATMOSPHERIC DENSITY VARIATIONS UTILIZING PRECISION ORBIT EPHEMERIDES. [Internet] [Masters thesis]. University of Kansas; 2010. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/6295.
Council of Science Editors:
Lechtenberg TF. DERIVATION AND OBSERVABILITY OF UPPER ATMOSPHERIC DENSITY VARIATIONS UTILIZING PRECISION ORBIT EPHEMERIDES. [Masters Thesis]. University of Kansas; 2010. Available from: http://hdl.handle.net/1808/6295
University of Kansas
15.
Fattig, Eric.
Comparison of Precision Orbit Derived Density Estimates for CHAMP and GRACE Satellites.
Degree: MS, Aerospace Engineering, 2011, University of Kansas
URL: http://hdl.handle.net/1808/7653
► Current atmospheric density models cannot adequately represent the density variations observed by satellites in Low Earth Orbit (LEO). Using an optimal orbit determination process, precision…
(more)
▼ Current atmospheric density models cannot adequately represent the density variations observed by satellites in Low Earth Orbit (LEO). Using an optimal orbit determination process, precision orbit ephemerides (POE) are used as measurement data to generate corrections to density values obtained from existing atmospheric models. Densities obtained using these corrections are then compared to density data derived from the onboard accelerometers of satellites, specifically the CHAMP and GRACE satellites. This comparison takes two forms, cross correlation analysis and root mean square analysis. The densities obtained from the POE method are nearly always superior to the empirical models, both in matching the trends observed by the accelerometer (cross correlation), and the magnitudes of the accelerometer derived density (root mean square). In addition, this method consistently produces better results than those achieved by the High Accuracy Satellite Drag Model (HASDM). For satellites orbiting Earth that pass through Earth's upper atmosphere, drag is the primary source of uncertainty in orbit determination and prediction. Variations in density, which are often not modeled or are inaccurately modeled, cause difficulty in properly calculating the drag acting on a satellite. These density variations are the result of many factors; however, the Sun is the main driver in upper atmospheric density changes. The Sun influences the densities in Earth's atmosphere through solar heating of the atmosphere, as well as through geomagnetic heating resulting from the solar wind. Data are examined for fourteen hour time spans between November 2004 and July 2009 for both the CHAMP and GRACE satellites. This data spans all available levels of solar and geomagnetic activity, which does not include data in the elevated and high solar activity bins due to the nature of the solar cycle. Density solutions are generated from corrections to five different baseline atmospheric models, as well as nine combinations of density and ballistic coefficient correlated half-lives. These half-lives are varied among values of 1.8, 18, and 180 minutes. A total of forty-five sets of results emerge from the orbit determination process for all combinations of baseline density model and half-lives. Each time period is examined for both CHAMP and GRACE-A, and the results are analyzed. Results are averaged from all solutions periods for 2004-2007. In addition, results are averaged after binning according to solar and geomagnetic activity levels. For any given day in this period, a ballistic coefficient correlated half-life of 1.8 minutes yields the best correlation and root mean square values for both CHAMP and GRACE. For CHAMP, a density correlated half-life of 18 minutes is best for higher levels of solar and geomagnetic activity, while for lower levels 180 minutes is usually superior. For GRACE, 180 minutes is nearly always best. The three Jacchia-based atmospheric models yield very similar results. The CIRA 1972 or Jacchia 1971 models as baseline consistently…
Advisors/Committee Members: McLaughlin, Craig A. (advisor), Farokhi, Saeed (cmtemember), Keshmiri, Shahriar (cmtemember).
Subjects/Keywords: Aerospace engineering; Atmospheric density; Champ satellite; Grace satellites; Orbit determination; Precision orbit data; Solar and geomagnetic activity
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APA ·
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MLA ·
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APA (6th Edition):
Fattig, E. (2011). Comparison of Precision Orbit Derived Density Estimates for CHAMP and GRACE Satellites. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/7653
Chicago Manual of Style (16th Edition):
Fattig, Eric. “Comparison of Precision Orbit Derived Density Estimates for CHAMP and GRACE Satellites.” 2011. Masters Thesis, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/7653.
MLA Handbook (7th Edition):
Fattig, Eric. “Comparison of Precision Orbit Derived Density Estimates for CHAMP and GRACE Satellites.” 2011. Web. 15 Jul 2019.
Vancouver:
Fattig E. Comparison of Precision Orbit Derived Density Estimates for CHAMP and GRACE Satellites. [Internet] [Masters thesis]. University of Kansas; 2011. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/7653.
Council of Science Editors:
Fattig E. Comparison of Precision Orbit Derived Density Estimates for CHAMP and GRACE Satellites. [Masters Thesis]. University of Kansas; 2011. Available from: http://hdl.handle.net/1808/7653
University of Kansas
16.
Li, Wen.
TIME DOMAIN SIMULATION FOR SOUND PROPAGATION OVER VARIOUS OBJECTS AND UNDER VORTICAL BACKGROUND CONDITIONS.
Degree: MS, Aerospace Engineering, 2015, University of Kansas
URL: http://hdl.handle.net/1808/23960
► Acoustic wave propagations have been studied for a long time with both experimental and numerical methods. Most of the analytical solutions for wave propagations are…
(more)
▼ Acoustic wave propagations have been studied for a long time with both experimental and numerical methods. Most of the analytical solutions for wave propagations are considered for simple environments such as a homogeneous atmospheres. As a result, the analytical solutions are unable to be applied for complicated environments. Numerical methods have become more and more important in acoustics studies after decades of development. The finite difference time-domain method (FDTD) is one of the most commonly used numerical methods in wave propagation studies. Compared with the other methods, the FDTD method is able to include many aspects of sound wave behaviors such as reflection, refraction, and diffraction in the physical problems. In this thesis, the linearized acoustic Euler equations coupled with the immersed boundary method are applied to investigate the sound wave propagation over complex environments. For the three-dimensional simulations of sound wave propagation in long distance, the moving domain method and parallel computing techniques are applied. Based on these approaches, the computational costs are significantly reduced and the simulation efficiency is greatly improved. When looking into the effects of high subsonic vortical flow, a high order WENO scheme is applied for the simulation. In this way the simulation stability can be achieved and the sound scattering of vortical flow can be studied. Then, the numerical scheme is applied to simulate an ultrasonic plane wave propagating through biological tissue. The linearized Euler acoustic equations coupled with the spatial fractional Laplacian operators are used for numerical simulations. The absorption and attenuation effects of the biological lossy media are successfully observed from the simulation results. Throughout this thesis, the simulation results are compared with either experimental measurements or analytical solutions so that the accuracy of the implemented numerical scheme is validated.
Advisors/Committee Members: Zheng, Zhongquan Charlie (advisor), Farokhi, Saeed (cmtemember), Taghavi, Ray (cmtemember).
Subjects/Keywords: Aerospace engineering
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APA (6th Edition):
Li, W. (2015). TIME DOMAIN SIMULATION FOR SOUND PROPAGATION OVER VARIOUS OBJECTS AND UNDER VORTICAL BACKGROUND CONDITIONS. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/23960
Chicago Manual of Style (16th Edition):
Li, Wen. “TIME DOMAIN SIMULATION FOR SOUND PROPAGATION OVER VARIOUS OBJECTS AND UNDER VORTICAL BACKGROUND CONDITIONS.” 2015. Masters Thesis, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/23960.
MLA Handbook (7th Edition):
Li, Wen. “TIME DOMAIN SIMULATION FOR SOUND PROPAGATION OVER VARIOUS OBJECTS AND UNDER VORTICAL BACKGROUND CONDITIONS.” 2015. Web. 15 Jul 2019.
Vancouver:
Li W. TIME DOMAIN SIMULATION FOR SOUND PROPAGATION OVER VARIOUS OBJECTS AND UNDER VORTICAL BACKGROUND CONDITIONS. [Internet] [Masters thesis]. University of Kansas; 2015. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/23960.
Council of Science Editors:
Li W. TIME DOMAIN SIMULATION FOR SOUND PROPAGATION OVER VARIOUS OBJECTS AND UNDER VORTICAL BACKGROUND CONDITIONS. [Masters Thesis]. University of Kansas; 2015. Available from: http://hdl.handle.net/1808/23960
University of Kansas
17.
Sweeten, Benjamin Casey.
CFD Analysis of UAVs using VORSTAB, FLUENT, and Advanced Aircraft Analysis Software.
Degree: MS, Aerospace Engineering, 2010, University of Kansas
URL: http://hdl.handle.net/1808/6292
► Aerodynamic analysis of three different UAVs was completed using multiple software programs. Two of the software programs were high fidelity CFD programs, and the other…
(more)
▼ Aerodynamic analysis of three different UAVs was completed using multiple software programs. Two of the software programs were high fidelity CFD programs, and the other one was an engineering level code. Advanced Aircraft Analysis was the first program used to determine the stability and control derivatives for each vehicle. These results were then compared to the higher fidelity CFD program, VORSTAB, stability and control derivatives. From the comparison conclusions were drawn about the programs and the vehicles themselves. Next, FLUENT was used to determine if there was a possibility of downwash over the top of the vehicle. Recommendations were then made for was to help prevent the downwash and flow separation from occurring. Also, recommendations were made for ways to continue upon this research.
Advisors/Committee Members: Keshmiri, Shahriar (advisor), Farokhi, Saeed (advisor), Hale, Richard (cmtemember), Taghavi, Ray (cmtemember).
Subjects/Keywords: Aerospace engineering
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APA (6th Edition):
Sweeten, B. C. (2010). CFD Analysis of UAVs using VORSTAB, FLUENT, and Advanced Aircraft Analysis Software. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/6292
Chicago Manual of Style (16th Edition):
Sweeten, Benjamin Casey. “CFD Analysis of UAVs using VORSTAB, FLUENT, and Advanced Aircraft Analysis Software.” 2010. Masters Thesis, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/6292.
MLA Handbook (7th Edition):
Sweeten, Benjamin Casey. “CFD Analysis of UAVs using VORSTAB, FLUENT, and Advanced Aircraft Analysis Software.” 2010. Web. 15 Jul 2019.
Vancouver:
Sweeten BC. CFD Analysis of UAVs using VORSTAB, FLUENT, and Advanced Aircraft Analysis Software. [Internet] [Masters thesis]. University of Kansas; 2010. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/6292.
Council of Science Editors:
Sweeten BC. CFD Analysis of UAVs using VORSTAB, FLUENT, and Advanced Aircraft Analysis Software. [Masters Thesis]. University of Kansas; 2010. Available from: http://hdl.handle.net/1808/6292
University of Kansas
18.
Hwang, Seung-Jae.
Numerical Simulation of Enhanced Mixing in Scramjet Combustor Using Ramp, Tabs and Suction Collar.
Degree: PhD, Aerospace Engineering, 2011, University of Kansas
URL: http://hdl.handle.net/1808/8080
► Numerical simulations of the scramjet combustor by using the commercial CFD code Fluent with the coupled implicit method with second-order accurate discretization have been obtained…
(more)
▼ Numerical simulations of the scramjet combustor by using the commercial CFD code Fluent with the coupled implicit method with second-order accurate discretization have been obtained for the reacting flows with the parallel fuel injection (ramp injection) and normal fuel injection (wall injection) schemes. Incorporated in the scramjet combustors are delta tabs and suction collars of two types as means of mixing enhancement. The main mechanism of the tabs and suction collars for mixing enhancement is the generation of streamwise vorticity and providing outstanding flameholding capability along with the induced global instability of the shear layer. The idea has been previously recommended for mixing enhancement of the scramjet combustor, but no experimental or computational data on the combustor performance has been reported, yet. The finite rate reaction model is used for the species transport model that only considers four species, H2, O2, H2O and N2. Vitiated air (mass fraction of O2, H2O, and N2 being 0.198, 0.139, and 0.663, respectively) enters the combustor at Mach number of 2.5 at a stagnation temperature and pressure of 1500 K and 101,325 Pa, respectively. The equivalence ratio is fixed at 0.45 in the present study. An optimization study of the combinations of the tabs and suction collars has been performed. Uninstalled thrust force for the optimal combination which was composed of the relieved ramp, 4 delta tabs, suction collar type I and 4 delta tabs in the fuel inlet scheme produced an additional 73% increase in thrust with only an additional 3.37% loss of the total pressure compared to the ramp injection alone, i.e., the baseline case. The numerical results clearly indicate that the fuel injection schemes investigated in the present study are more efficient than a strut or multi-staged strut and wall injection scheme.
Advisors/Committee Members: Farokhi, Saeed (advisor), Taghavi, Ray (cmtemember), Barrett-Gonzalez, Ron (cmtemember), Keshmiri, Shahriar (cmtemember), Huang, Weizhang (cmtemember).
Subjects/Keywords: Aerospace engineering; Combustor; Enhanced; Mixing; Scramjet; Suction collar; Tabs
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APA (6th Edition):
Hwang, S. (2011). Numerical Simulation of Enhanced Mixing in Scramjet Combustor Using Ramp, Tabs and Suction Collar. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/8080
Chicago Manual of Style (16th Edition):
Hwang, Seung-Jae. “Numerical Simulation of Enhanced Mixing in Scramjet Combustor Using Ramp, Tabs and Suction Collar.” 2011. Doctoral Dissertation, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/8080.
MLA Handbook (7th Edition):
Hwang, Seung-Jae. “Numerical Simulation of Enhanced Mixing in Scramjet Combustor Using Ramp, Tabs and Suction Collar.” 2011. Web. 15 Jul 2019.
Vancouver:
Hwang S. Numerical Simulation of Enhanced Mixing in Scramjet Combustor Using Ramp, Tabs and Suction Collar. [Internet] [Doctoral dissertation]. University of Kansas; 2011. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/8080.
Council of Science Editors:
Hwang S. Numerical Simulation of Enhanced Mixing in Scramjet Combustor Using Ramp, Tabs and Suction Collar. [Doctoral Dissertation]. University of Kansas; 2011. Available from: http://hdl.handle.net/1808/8080
University of Kansas
19.
Wei, Zhenglun.
Numerical and theoretical study of flapping airfoil aerodynamics using a parallelized immersed-boundary method.
Degree: PhD, Aerospace Engineering, 2014, University of Kansas
URL: http://hdl.handle.net/1808/19600
► Flight has fascinated humans for centuries. Human inventions such as missiles, aircraft , unmanned aerial vehicles (UAV), and micro air vehicle (MAV) are inspired by…
(more)
▼ Flight has fascinated humans for centuries. Human inventions such as missiles, aircraft , unmanned aerial vehicles (UAV), and micro air vehicle (MAV) are inspired by natural flying expertise. As natural flyers usually operate in a vortex-dominated environment, interactions between their wings and the vortices have significant influences on force generation and flying efficiency. Some interesting phenomena induced from such vortex-body interactions have gotten a lot of attention in the past few decades. A good example is that birds and insects are credited with extracting energy from ambient vortices. In a simpler form, bio-inspired airfoils with either passive or active flapping motions are found to have the potential to harvest energy from incoming vortices generated from an upstream object, i.e. a cylinder. The current study identified the interaction modes of the leading edge vortex (LEV) and trailing edge vortex (TEV) between the active flapping airfoil and the incoming vortices. The relation between the interaction modes and the energy extraction capacity of an active harvester is investigated guided by a potential theory. The interaction modes induced by a passive energy harvester always benefit the energy extraction efficiency. However, the dynamic response of the passive harvester was found to vary corresponding to the properties of the incoming vortical wake. A profound appreciation of energy extracting mechanisms can provide a solution for the energy consumption issue of MAV and UAV. However, difficulties are encountered in practical applications of energy harvesting on how to detect the locations of generated vortices and what the trajectory of the vortex downstream of the moving body is. Some observations are realized and the fluid dynamics of the phenomena is beyond the fundamentals described in the textbook. One well-known instance is the asymmetric wake formed downstream of a symmetric sinusoidal heaving airfoil. In this study, factors that influence the formation of the asymmetric wakes on both the near wake and far wake regions are demonstrated. Novel vortex models are developed to explore the vortex dynamic mechanisms of the asymmetric wake and its development from the near wake region to the far wake region. In order to analyze the flow fields for the bio-inspired problems, Computational Fluid Dynamics (CFD) provides powerful and convenient tools. The shape of bio-inspired wings/airfoils and their maneuvers are usually very complicated. In CFD, the immersed-boundary (IB) method is an advantageous approach to simulate such problems. In this study, an immersed-boundary method is implemented in a parallel fashion in order to speed up the computational rate.. A variety of numerical schemes have been applied to the IB method, including different spatial schemes and temporal schemes; their performances are investigated. In addition, the IB method has been successfully implemented with the fluid-structure interaction models for studying passive mobile objectives, i.e. the energy harvester. The possibility…
Advisors/Committee Members: Zheng, Zhongquan (advisor), Farokhi, Saeed (cmtemember), Huang, Weizhang (cmtemember), Keshmiri, Shawn (cmtemember), Taghavi, Ray (cmtemember).
Subjects/Keywords: Aerospace engineering; Mechanical engineering
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APA (6th Edition):
Wei, Z. (2014). Numerical and theoretical study of flapping airfoil aerodynamics using a parallelized immersed-boundary method. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/19600
Chicago Manual of Style (16th Edition):
Wei, Zhenglun. “Numerical and theoretical study of flapping airfoil aerodynamics using a parallelized immersed-boundary method.” 2014. Doctoral Dissertation, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/19600.
MLA Handbook (7th Edition):
Wei, Zhenglun. “Numerical and theoretical study of flapping airfoil aerodynamics using a parallelized immersed-boundary method.” 2014. Web. 15 Jul 2019.
Vancouver:
Wei Z. Numerical and theoretical study of flapping airfoil aerodynamics using a parallelized immersed-boundary method. [Internet] [Doctoral dissertation]. University of Kansas; 2014. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/19600.
Council of Science Editors:
Wei Z. Numerical and theoretical study of flapping airfoil aerodynamics using a parallelized immersed-boundary method. [Doctoral Dissertation]. University of Kansas; 2014. Available from: http://hdl.handle.net/1808/19600
University of Kansas
20.
Smith, Leslie Ann.
The Effect of Pulsed Injection on Shear Layer Dynamics in a Scramjet Combustion Chamber.
Degree: PhD, Aerospace Engineering, 2015, University of Kansas
URL: http://hdl.handle.net/1808/19415
► One of the greatest problems that scramjet research faces is fuel air mixing. The residence time for a scramjet engine, or the time it takes…
(more)
▼ One of the greatest problems that scramjet research faces is fuel air mixing. The residence time for a scramjet engine, or the time it takes for a volume of air to completely pass through the engine, is on the order of 0.1 ms. In that extremely short period of time fuel must be injected and fully mirco-mixed at stoichiometric ratios with the combustion chamber airflow. The fuel-air mixture must then be combusted and expanded through the nozzle to produce thrust. The goal of this research is to develop a new more efficient method of fuel air mixing within a scramjet combustion chamber. A possible way to speed up the mixing process of parallel injection without incurring the total pressure losses that would occur in normal injection is to inject the fuel from the rear side of a backward facing step. Backward facing steps in supersonic flow produce a Prandtl-Meyer expansion fan followed by a shear layer. The instabilities in this shear layer have dominant resonant frequencies. It is believed that if fuel is injected in pulses that impinge on the shear layer at these dominant resonant frequencies that the shear layer will resonate. When the shear layer resonates the vortices that form in the shear layer will grow in magnitude, thus mixing the injected fuel with the air. To test this hypothesis a new test section was designed and built that features a one inch step under which an injector can be housed. This new test section was installed in the supersonic facility at the
University of
Kansas. Two injectors were also designed that each feature a face plate, one with eight injection ports arranged in a ring and one with 5 injection ports. Between the face plate and a back plate there is a cavity that houses a rotating valve that is powered by a pneumatic motor. Five valves were built: one with 8 teeth, one with 16 teeth, one with 5 teeth that are the same size as the gaps between the teeth, one with 5 teeth where the teeth are 50% larger than the gaps, and one with 5 teeth where the teeth are 50% smaller than the gaps. The 8 tooth valve and 16 tooth valve where used with the 8 port injector face plate. The 5 tooth valves were used with the 5 port injector face plate. As the valve rotates the teeth block and unblock the injection ports injecting carbon dioxide gas into the test section. The 8 port injector was tested over a range of frequencies from 1.6 kHz to 10.0 kHz. The 5 port injector was tested for each valve over a range of frequencies from 1.0 kHz to 4.0 kHz. Static pressure data was taken along the upper and lower walls of the test section by means of an array of pressure sensors. The pressure data from the test section was compared to results generated using a three dimensional CFD simulation of the test section. Overall the pressure data on the lower wall agreed reasonably well with the CFD simulation. The vorticity and turbulence contours generated by the STAR-CCM+ simulation suggest that as a pulse is injected into the test section from the step it causes the shear layer to curve outward near the point of…
Advisors/Committee Members: Farokhi, Saeed (advisor), Barrett, Ron (cmtemember), Taghavi, Ray (cmtemember), Yimer, Bedru (cmtemember), Keshmiri, Shawn (cmtemember).
Subjects/Keywords: Aerospace engineering; Injector; Micro-mixing; Pulsed Injection; Scramjet; Shear Layer
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APA (6th Edition):
Smith, L. A. (2015). The Effect of Pulsed Injection on Shear Layer Dynamics in a Scramjet Combustion Chamber. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/19415
Chicago Manual of Style (16th Edition):
Smith, Leslie Ann. “The Effect of Pulsed Injection on Shear Layer Dynamics in a Scramjet Combustion Chamber.” 2015. Doctoral Dissertation, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/19415.
MLA Handbook (7th Edition):
Smith, Leslie Ann. “The Effect of Pulsed Injection on Shear Layer Dynamics in a Scramjet Combustion Chamber.” 2015. Web. 15 Jul 2019.
Vancouver:
Smith LA. The Effect of Pulsed Injection on Shear Layer Dynamics in a Scramjet Combustion Chamber. [Internet] [Doctoral dissertation]. University of Kansas; 2015. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/19415.
Council of Science Editors:
Smith LA. The Effect of Pulsed Injection on Shear Layer Dynamics in a Scramjet Combustion Chamber. [Doctoral Dissertation]. University of Kansas; 2015. Available from: http://hdl.handle.net/1808/19415
University of Kansas
21.
Li, Yanan.
Large-eddy simulations of turbulent flows using the high-order FR/CPR method.
Degree: D.Eng., Aerospace Engineering, 2016, University of Kansas
URL: http://hdl.handle.net/1808/24138
► Large eddy simulation (LES) was originally proposed for simulating atmospheric flows and then has become one of the most successful methodologies for turbulence simulation for…
(more)
▼ Large eddy simulation (LES) was originally proposed for simulating atmospheric flows and then has become one of the most successful methodologies for turbulence simulation for its good balance between accuracy and cost. In LES, energetic scales are resolved while the small equilibrium scales are modeled by the sub-grid scale(SGS) stress models. The resolution of the wide spectrum of the energetic scales is a big challenge for numerical methods. High-order methods are very promising in LES for its low dissipation and dispersion errors. For smooth turbulent flow, high-order methods have the potential to achieve high accuracy at lower cost than lower order methods. This thesis presents the investigation of the performance of different LES sub-grid scale stress (SGS) models with the high-order flux reconstruction or the correction procedure via reconstruction( FR/CPR) method. A mathematical analysis of scale similarity is conducted and presented as well. In addition, numerical schemes’ behavior in nonlinear wave propagation is studied and presented. The computationa of discontinuities, such as shocks, is another challenge to the numerical methods. In the simulation of shocks, non-physical oscillations can occur at the discontinuities and lead to divergence. The situation is worse for high-order methods. This thesis also presents a new flux limiter for the FR/CPR method. The new technique shows good properties, convergence for steady problems and accuracy preserving for vortex dominated flows. It is very promising in handling shock and turbulence interaction problems.
Advisors/Committee Members: Wang, Z. J. (advisor), Farokhi, Saeed (cmtemember), Taghavi, Ray (cmtemember), Tu, Xuemin (cmtemember), Zheng, Zhongquan (cmtemember).
Subjects/Keywords: Aerospace engineering; computational fluid dynamics; high-order numerical schemes; large-eddy simulation; shock capturing; turbulence
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APA ·
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APA (6th Edition):
Li, Y. (2016). Large-eddy simulations of turbulent flows using the high-order FR/CPR method. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/24138
Chicago Manual of Style (16th Edition):
Li, Yanan. “Large-eddy simulations of turbulent flows using the high-order FR/CPR method.” 2016. Doctoral Dissertation, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/24138.
MLA Handbook (7th Edition):
Li, Yanan. “Large-eddy simulations of turbulent flows using the high-order FR/CPR method.” 2016. Web. 15 Jul 2019.
Vancouver:
Li Y. Large-eddy simulations of turbulent flows using the high-order FR/CPR method. [Internet] [Doctoral dissertation]. University of Kansas; 2016. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/24138.
Council of Science Editors:
Li Y. Large-eddy simulations of turbulent flows using the high-order FR/CPR method. [Doctoral Dissertation]. University of Kansas; 2016. Available from: http://hdl.handle.net/1808/24138
University of Kansas
22.
Bramlette, Richard.
Development, Modeling, Simulation, and Testing of a Novel Propane-Fueled Brayton-Gluhareff Cycle Acoustically-Pressurized Ramjet Engine.
Degree: PhD, Mechanical Engineering, 2016, University of Kansas
URL: http://hdl.handle.net/1808/23515
► In the 1950s, Eugene Gluhareff built the first working “pressure jet” engine, a variation on the classical ramjet engine with a pressurized inlet system relying…
(more)
▼ In the 1950s, Eugene Gluhareff built the first working “pressure jet” engine, a variation on the classical ramjet engine with a pressurized inlet system relying on sonic tuning which allowed operation at subsonic speeds. The engine was an unqualified success. Unfortunately, after decades of sales and research, Gluhareff passed away leaving behind no significant published studies of the engine or detailed analysis of its operation. The design was at serious risk of being lost to history. This dissertation is intended to address that risk by studying a novel subscale modification of Gluhareff’s original design operating on the same principles. Included is a background of related engine and how the pressure jet is distinct. The preliminary sizing of a pressure jet using closed-form expressions is then discussed followed by a review of propane oxidation modeling, how it integrates into the Computational Fluid Dynamics (CFD) solver, and the modeling of the pressure jet engine cycle with CFD. The simulation was matched to experimental data recorded on a purpose-built test stand recording chamber pressure, exhaust speed (via a Pitot/static system), temperatures, and thrust force. The engine CFD simulation produced a wide range of qualitative results that matched the experimental data well and suggested strong recirculation flows through the engine confirming suspicions about how the engine operates. Engine operating frequency between CFD and experiment also showed good agreement and appeared to be driven by the “Kadenacy Effect.” The research effort lastly opens the door for further study of the engine cycle, the use of pressurized intakes to produce static thrust in a ramjet engine, the Gluhareff pressure jet’s original geometry, and a wide array of potential applications. A roadmap of further study and applications is detailed including a modeling and testing of larger engines.
Advisors/Committee Members: Depcik, Christopher (advisor), Tenpas, Peter (cmtemember), Li, Xianglin (cmtemember), Taghavi, Ray (cmtemember), Farokhi, Saeed (cmtemember).
Subjects/Keywords: Aerospace engineering; Mechanical engineering; Chemistry; Chemical Kinetics; Computational Fluid Dynamics; Jet Propulsion; Pressure Jet; Propane Oxidation; Ramjet
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APA (6th Edition):
Bramlette, R. (2016). Development, Modeling, Simulation, and Testing of a Novel Propane-Fueled Brayton-Gluhareff Cycle Acoustically-Pressurized Ramjet Engine. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/23515
Chicago Manual of Style (16th Edition):
Bramlette, Richard. “Development, Modeling, Simulation, and Testing of a Novel Propane-Fueled Brayton-Gluhareff Cycle Acoustically-Pressurized Ramjet Engine.” 2016. Doctoral Dissertation, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/23515.
MLA Handbook (7th Edition):
Bramlette, Richard. “Development, Modeling, Simulation, and Testing of a Novel Propane-Fueled Brayton-Gluhareff Cycle Acoustically-Pressurized Ramjet Engine.” 2016. Web. 15 Jul 2019.
Vancouver:
Bramlette R. Development, Modeling, Simulation, and Testing of a Novel Propane-Fueled Brayton-Gluhareff Cycle Acoustically-Pressurized Ramjet Engine. [Internet] [Doctoral dissertation]. University of Kansas; 2016. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/23515.
Council of Science Editors:
Bramlette R. Development, Modeling, Simulation, and Testing of a Novel Propane-Fueled Brayton-Gluhareff Cycle Acoustically-Pressurized Ramjet Engine. [Doctoral Dissertation]. University of Kansas; 2016. Available from: http://hdl.handle.net/1808/23515
University of Kansas
23.
Dande, Himanshu Amol.
Panel Damping Loss Factor Estimation Using The Random Decrement Technique.
Degree: MS, Aerospace Engineering, 2010, University of Kansas
URL: http://hdl.handle.net/1808/7752
► The use of the Random Decrement Technique (RDT) for estimating panel damping loss factors ranging from 1% to 10% is examined in a systematic way,…
(more)
▼ The use of the Random Decrement Technique (RDT) for estimating panel damping loss factors ranging from 1% to 10% is examined in a systematic way, with a focus on establishing the various parameters one must specify to use the technique to the best advantage. Throughout, loss factors are estimated in full or 1/3rd octave frequency bands with standard 1/3rd octave center frequencies. The full octave filters, which are more computationally efficient than the 1/3rd octave filters, are chosen in the experimental analysis of the damped plates with varied loss factor levels. Two computational models are examined: a single degree of freedom oscillator and a computational model of a uniform rectangular panel. The panel computational model is a finite element model of a rectangular plate mechanically exited at a single point. These models are used to establish a systematic process for evaluating: the appropriate narrow band filter selection; trigger conditions; record length required as a function of frequency and damping level; the averaging scheme; and, the curve-fitting scheme for assigning loss factors in narrow frequency bands. Loss factor estimates for three damped plates are computed using the "optimized" Random Decrement estimation algorithm and compared with estimates from the Impulse Response Decay Method. For the highly damped plates, RDT out-performed IRDM because the loss factors from IRDM are underestimated. For lightly damped plates, RDT and IRDM are consistent in most frequency bands.
Advisors/Committee Members: Ewing, Mark (advisor), Hale, Richard (cmtemember), Farokhi, Saeed (cmtemember), Matamoros, Adolfo (cmtemember).
Subjects/Keywords: Aerospace engineering; Frequency domain filtering; Impulse response decay method irdm; Random decrement technique; Time domain filtering; Triggering scheme
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APA (6th Edition):
Dande, H. A. (2010). Panel Damping Loss Factor Estimation Using The Random Decrement Technique. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/7752
Chicago Manual of Style (16th Edition):
Dande, Himanshu Amol. “Panel Damping Loss Factor Estimation Using The Random Decrement Technique.” 2010. Masters Thesis, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/7752.
MLA Handbook (7th Edition):
Dande, Himanshu Amol. “Panel Damping Loss Factor Estimation Using The Random Decrement Technique.” 2010. Web. 15 Jul 2019.
Vancouver:
Dande HA. Panel Damping Loss Factor Estimation Using The Random Decrement Technique. [Internet] [Masters thesis]. University of Kansas; 2010. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/7752.
Council of Science Editors:
Dande HA. Panel Damping Loss Factor Estimation Using The Random Decrement Technique. [Masters Thesis]. University of Kansas; 2010. Available from: http://hdl.handle.net/1808/7752
University of Kansas
24.
Raina, Amool A.
IMPACT ON WIND TURBINE BLADE DESIGN AND AERODYNAMIC PERFORMANCE USING INTEGRAL VORTEX GENERATORS.
Degree: PhD, Aerospace Engineering, 2016, University of Kansas
URL: http://hdl.handle.net/1808/23513
► This dissertation is aimed at understanding the impact on performance, loads and cost using integral vortex generators on wind turbine blade designs. In order to…
(more)
▼ This dissertation is aimed at understanding the impact on performance, loads and cost using integral vortex generators on wind turbine blade designs. In order to investigate the possibility of this new design space, an optimization analysis is carried out. Three configurations are designed as a part of this dissertation. The current phase of work consists of creating a baseline blade that spans 56m in length. In order to determine the effectiveness of vortex generators on airfoils used on the 56m blade design, a verification and validation study of CFD tools is carried out. For this exercise, the LS(1)-0417MOD airfoil is used. STAR CCM+ software is used for performing the CFD analysis on the clean and vortex generator configurations of the LS(1)-0417MOD airfoil. Satisfactory results are obtained from the CFD analysis. A CFD analysis of a 47% thick airfoil is performed as well. This data has been used in the design of the 56m blade. Further, finite span airfoils incorporating vortex generators for the FB47 and NACA63621 airfoils are analyzed. This data is then used to evaluate the improvement of aerodynamic performance of the add-on 56m blade configuration. Vortex generators are incorporated in the post design phase of the clean 56m blade design and the improvement in performance in recorded. It is observed that a 0.4% improvement in AEP along with a 1.2% increase in loads and 2.13% increase in cost of energy is seen. Thereafter, the optimization and design of the 56m blade with integral vortex generators is carried out. Finally a full blade design of the 56m blade with integral vortex generators is carried out and the key performance metrics are recorded. A 1.7% increase in aerodynamic performance is recorded for the integral vortex generator case. This increase in performance also results in a 15.3% increase in blade root bending moment. However, a reduction in the total cost of energy is obtained as compared to the baseline blade design.
Advisors/Committee Members: Farokhi, Saeed (advisor), Taghavi, Ray (cmtemember), Keshmiri, Shawn (cmtemember), Zheng, Zhongquan (cmtemember), Medina, Mario (cmtemember).
Subjects/Keywords: Aerospace engineering; Vortex generators; Wind Energy; Wind Turbines
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APA (6th Edition):
Raina, A. A. (2016). IMPACT ON WIND TURBINE BLADE DESIGN AND AERODYNAMIC PERFORMANCE USING INTEGRAL VORTEX GENERATORS. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/23513
Chicago Manual of Style (16th Edition):
Raina, Amool A. “IMPACT ON WIND TURBINE BLADE DESIGN AND AERODYNAMIC PERFORMANCE USING INTEGRAL VORTEX GENERATORS.” 2016. Doctoral Dissertation, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/23513.
MLA Handbook (7th Edition):
Raina, Amool A. “IMPACT ON WIND TURBINE BLADE DESIGN AND AERODYNAMIC PERFORMANCE USING INTEGRAL VORTEX GENERATORS.” 2016. Web. 15 Jul 2019.
Vancouver:
Raina AA. IMPACT ON WIND TURBINE BLADE DESIGN AND AERODYNAMIC PERFORMANCE USING INTEGRAL VORTEX GENERATORS. [Internet] [Doctoral dissertation]. University of Kansas; 2016. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/23513.
Council of Science Editors:
Raina AA. IMPACT ON WIND TURBINE BLADE DESIGN AND AERODYNAMIC PERFORMANCE USING INTEGRAL VORTEX GENERATORS. [Doctoral Dissertation]. University of Kansas; 2016. Available from: http://hdl.handle.net/1808/23513
University of Kansas
25.
Underwood, Sean Christopher.
Aerothermodynamics of Impingement and Film Cooling in a Gas Turbine Blade.
Degree: PhD, Aerospace Engineering, 2018, University of Kansas
URL: http://hdl.handle.net/1808/27605
► The service life of gas turbine engine turbine blades depends on the blade’s material, service temperature and total stress. In high-performance gas turbines, film cooling…
(more)
▼ The service life of gas turbine engine turbine blades depends on the blade’s material, service temperature and total stress. In high-performance gas turbines, film cooling is widely used to reduce the blade service temperature. Often impingement cooling is also employed to target the stagnation point heat transfer for internally-cooled gas turbine blades. A novel thermal wind tunnel was designed to study the combined effect of the impingement and film cooling on blunt airfoils. The hot exhaust plume of a micro-jet is used as the source of high-temperature gas flow in the thermal wind tunnel. An ejector nozzle was designed and integrated with the hot jet to provide a thermally controlled test section environment in the research facility. Measurements of freestream parameters such as gas speed, turbulence intensity and gas temperature were made. An airfoil that utilizes leading-edge (internal) impingement as well as film cooling holes on its suction surface was designed and fabricated. A cooling sleeve is used inside the airfoil to guide the impingement jets on the leading edge and to supply the coolant to the film holes. The surface temperature distribution is measured by an array of eight thermocouples flush-mounted on the airfoil surface downstream of the film holes. The initial ranges of blowing parameters (Mb) investigated were between 5 and 6. Numerical simulation using a commercially available Reynolds-Averaged Navier-Stokes (RANS) software was used and validated by the experimental measurements. The numerical simulations for the airfoil consisted of two thermal wall boundary conditions, the adiabatic and conjugate heat transfer (CHT) models. The adiabatic model focuses on the effect of film cooling on an adiabatic wall. The conjugate heat transfer model represents the solid and fluid heat transfer exchange, conduction and convection. Verification and validation was completed to ensure accurate aerothermodynamic simulations. The experimental and numerical data showed a close comparison for the suction surface temperatures and cooling effectiveness. A broader range of characteristic parameters (blowing parameter, turbulence intensity (Tu) and density ratio) were studied to show their impact on film cooling effectiveness parameter. The effects from the blowing parameter are reported for different Mb of 0.53 to 5.95 with two turbulent intensities, 5% and 20%. The adiabatic film effectiveness parameter showed two unique trends: low Mb with low Tu or high Mb with high Tu both exhibited improved film cooling effectiveness. Jet detachment is also detected at Mb ~ 1.5 for the current film cooling set up. The study of turbulence intensity effects was completed in the range of 5% to 25 % for two density ratios of 1.65 and 1.99. The turbulence intensity study showed that higher Tu caused the adiabatic film effectiveness to decrease by an average 18%. The density ratio (DR) in the film cooling is studied to explore the real turbine environment. The velocity ratio and turbulence intensity is held at a constant of 0.64 and…
Advisors/Committee Members: Taghavi, Ray (advisor), Farokhi, Saeed (advisor), Wu, Huixuan (cmtemember), Keshmiri, Shawn (cmtemember), Medina, Mario (cmtemember).
Subjects/Keywords: Aerospace engineering; Mechanical engineering; Aerothermodynamics; Film Cooling; Gas Turbine; Impingement Cooling; Propulsion; Turbine Blade Cooling
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APA (6th Edition):
Underwood, S. C. (2018). Aerothermodynamics of Impingement and Film Cooling in a Gas Turbine Blade. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/27605
Chicago Manual of Style (16th Edition):
Underwood, Sean Christopher. “Aerothermodynamics of Impingement and Film Cooling in a Gas Turbine Blade.” 2018. Doctoral Dissertation, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/27605.
MLA Handbook (7th Edition):
Underwood, Sean Christopher. “Aerothermodynamics of Impingement and Film Cooling in a Gas Turbine Blade.” 2018. Web. 15 Jul 2019.
Vancouver:
Underwood SC. Aerothermodynamics of Impingement and Film Cooling in a Gas Turbine Blade. [Internet] [Doctoral dissertation]. University of Kansas; 2018. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/27605.
Council of Science Editors:
Underwood SC. Aerothermodynamics of Impingement and Film Cooling in a Gas Turbine Blade. [Doctoral Dissertation]. University of Kansas; 2018. Available from: http://hdl.handle.net/1808/27605
University of Kansas
26.
Kim, A Ram.
Intelligent Guidance, Navigation and Control of Multi-Agent UASs with Validation and Verification.
Degree: PhD, Aerospace Engineering, 2018, University of Kansas
URL: http://hdl.handle.net/1808/27816
► Following the exponential growth in the usage of unmanned aerial systems (UASs) across the Aerospace Industry, more intelligent and robust guidance, navigation, and control algorithms…
(more)
▼ Following the exponential growth in the usage of unmanned aerial systems (UASs) across the Aerospace Industry, more intelligent and robust guidance, navigation, and control algorithms are vital to cope with increasing levels of mission complexity. Additionally, many unmanned aerial operations require large payloads and long endurance such as extended reconnaissance, large-scale search and rescue and fine resolution terrain mapping. However, the stringent payload of a single agent or small UASs reduces their overall practicality and effectiveness. My research aims to address these inherent limitations of small UASs with a swarm by holding the required formation in order to distribute tasks and payload among multiple UASs. The goal of this research is to overcome the challenges of operating multi-agent systems by developing phasic navigation and guidance algorithms. Aircraft dynamics and their interactions with surrounding agents are highly nonlinear, which makes autonomous formation flight very sensitive to aircraft initial conditions. The phasic navigation algorithms are proposed and consist of hybrid mathematical approaches: Frenet-Serret curvature control, Hungarian algorithm and moving mesh methods. At the first phase, the curvature control allieviates the sensitivity to initial conditions of multi-agent UASs in unstructured environments by matching agents’ heading angle to the united direction. A variation of Hungarian algorithm is implemented with a moving virtual terminal to assign each agent to the formation position. In the second phase of navigation, the moving mesh methods are applied for holding the formation by defining the outer agents’ position for the boundary condition. The significance of the moving mesh methods is a scalability and a inherent intercollision avoidance. Due to the profound difference between the longitudinal and lateral-directional motion of a fixed-wing aircraft, a multi-scale moving point guidance algorithm has been designed to create the separate virtual reference points in the longitudinal and lateral-direction planes for the first time. This method has been shown to greatly reduce tracking oscillations and improve the overall tracking quality and coherency of the formation. Monte Carlo simulations are performed to ensure the stability and robustness of implementing proposed algorithms through an essentially exhaustive search. A broad range of random initial conditions have been used to validate the effectiveness of guidance, navigation, and control algorithms. Another unique contribution of this work is the validation and verification of proposed algorithms by the hardware-in-the-loop testbed and the numerous flight tests. The hardware-in-the-loop testbed is designed to test the avionics and communication before the flight test by simulating onboard 6-degrees of freedom nonlinear equations of motion. Over one hundred flight tests have been conducted using three distinct aircraft platforms between 2016 and 2018 to validate the fundamental building blocks of this architecture. In…
Advisors/Committee Members: Keshmiri, Shawn (advisor), Ewing, Mark (cmtemember), Hale, Richard (cmtemember), Farokhi, Saeed (cmtemember), Huang, Weizheng (cmtemember).
Subjects/Keywords: Aerospace engineering; Guidance; Multi-agent; Navigation; Validation; Verification
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APA (6th Edition):
Kim, A. R. (2018). Intelligent Guidance, Navigation and Control of Multi-Agent UASs with Validation and Verification. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/27816
Chicago Manual of Style (16th Edition):
Kim, A Ram. “Intelligent Guidance, Navigation and Control of Multi-Agent UASs with Validation and Verification.” 2018. Doctoral Dissertation, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/27816.
MLA Handbook (7th Edition):
Kim, A Ram. “Intelligent Guidance, Navigation and Control of Multi-Agent UASs with Validation and Verification.” 2018. Web. 15 Jul 2019.
Vancouver:
Kim AR. Intelligent Guidance, Navigation and Control of Multi-Agent UASs with Validation and Verification. [Internet] [Doctoral dissertation]. University of Kansas; 2018. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/27816.
Council of Science Editors:
Kim AR. Intelligent Guidance, Navigation and Control of Multi-Agent UASs with Validation and Verification. [Doctoral Dissertation]. University of Kansas; 2018. Available from: http://hdl.handle.net/1808/27816
University of Kansas
27.
Jin, Wonjin.
A Computational Study of Icing Effects on the Performance of an S-Duct Inlet.
Degree: PhD, Aerospace Engineering, 2009, University of Kansas
URL: http://hdl.handle.net/1808/5242
► The performance of a diffusing S-duct inlet (M2129) is computationally studied for the effects of inlet icing. Different ice accretion shapes, predicted by numerical analysis…
(more)
▼ The performance of a diffusing S-duct inlet (M2129) is computationally studied for the effects of inlet icing. Different ice accretion shapes, predicted by numerical analysis in the literature reviewed, are simulated on the inlet lip. Two commercial codes, FLUENT and STAR-CCM+ are used for the steady- and unsteady-state computations. The shear-stress transport (SST) k-e turbulence model and large eddy simulation (LES) turbulence model are applied in the computations. The glaze ice shape, which is characterized by intrusive horns, degrades inlet performance, while the effect of the streamlined rime ice shape is negligible. At the free-stream Mach number of M=0.23, the glaze ice causes a 3.2 percent decrease in the total pressure recovery and a 26 percent reduction in the inlet mass flow rate. This result comes from the massive flow separation and flow blockage from the glaze ice horns. The total pressure recovery is further decreased by 22.8 percent, as the free-stream Mach number increases to M=0.85, due to the increased internal blockage and formation of internal shocks in the S-duct inlet. Also, the glaze iced inlet induces 6.6 percent increase in the engine thrust loss and the specific fuel consumption at M=0.25. The level of the ice-induced flow blockage by the ice accretion is also important for the inlet performance. The symmetrical glaze ice that covers the entire inlet lip portion causes a nearly 11.8 percent decrease in the total pressure recovery at M=0.475, whereas the top- or bottom-asymmetrical glaze ice that accretes on a ¼ portion of the inlet lip leads to just a 2.5 percent decrease. Also, the dynamic inlet distortion level, which is represented by the total pressure fluctuation at the engine face, is almost doubled with the symmetrical glaze ice when compared to the asymmetrical glaze ice. Therefore, the dynamic inlet distortion is proportional to the total pressure recovery that corresponds to the steady-state inlet distortion. Furthermore, the application of local angles of attack and local sideslip angles for the iced S-duct inlet contributes to the further degradation of the inlet performance, regardless of the ice shapes. However, the angles that provide the most distortion for each ice shape all differ due to the combined effects of the angle of attack or sideslip angle, icing location, and downward duct curvature. In addition, both the steady-state inlet distortion and dynamic inlet distortion become most severe at the highest angles tested: symmetrical (angle of attack=+20º), top-asymmetrical (angle of attack=-20º), bottom-asymmetrical (angle of attack=+20º), and side-asymmetrical glaze (sideslip angle=-20º). Finally, a strongly coupled temperature-total pressure distortion is created at the engine face under the icing condition. This coupling, as measured by the total pressure distortion parameter, increases the engine face distortion by 6.97 percent in the glaze iced inlet at M=0.85 when the inlet wall is heated to 350 K.
Advisors/Committee Members: Taghavi, Ray (advisor), Lan, Chuan-Tau (cmtemember), Farokhi, Saeed (cmtemember), Barrett, Ronald M (cmtemember), Medina, Mario A (cmtemember).
Subjects/Keywords: Aerospace engineering; Mechanical engineering; Diffusing s-duct; Dynamic distortion; Icing; Inlet; Temperature distortion; Total pressure distortion
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APA (6th Edition):
Jin, W. (2009). A Computational Study of Icing Effects on the Performance of an S-Duct Inlet. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/5242
Chicago Manual of Style (16th Edition):
Jin, Wonjin. “A Computational Study of Icing Effects on the Performance of an S-Duct Inlet.” 2009. Doctoral Dissertation, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/5242.
MLA Handbook (7th Edition):
Jin, Wonjin. “A Computational Study of Icing Effects on the Performance of an S-Duct Inlet.” 2009. Web. 15 Jul 2019.
Vancouver:
Jin W. A Computational Study of Icing Effects on the Performance of an S-Duct Inlet. [Internet] [Doctoral dissertation]. University of Kansas; 2009. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/5242.
Council of Science Editors:
Jin W. A Computational Study of Icing Effects on the Performance of an S-Duct Inlet. [Doctoral Dissertation]. University of Kansas; 2009. Available from: http://hdl.handle.net/1808/5242
University of Kansas
28.
Shi, Lei.
Adaptive High-Order Differential Formulation for the Compressible Navier-Stokes Equations.
Degree: PhD, Aerospace Engineering, 2014, University of Kansas
URL: http://hdl.handle.net/1808/27533
► High-order methods have the potential to achieve higher accuracy at lower cost than lower order methods. This potential has been demonstrated conclusively for smooth problems…
(more)
▼ High-order methods have the potential to achieve higher accuracy at lower cost than lower order methods. This potential has been demonstrated conclusively for smooth problems in the 1st International Workshop on High-Order Methods. For non-smooth problems, solution based hp-adaptations offer the best promise. Adjoint-based adaptive methods have the capability of dynamically distributing computing resources to areas which are important for predicting engineering performance parameters, such as lift or drag. This thesis presents a robust and efficient adjoint-based adaptive high-order differential formulation for the compressible Navier-Stokes equations, which can rapidly determine an accurate estimate of an engineering output within a prescribed error threshold. The flux reconstruction (FR) or the correction procedure via reconstruction (CPR) method used in this work is a high-order differential formulation. We develop a parallel adjoint-based adaptive CPR solver which can work with any element-based error estimate and handle arbitrary discretization orders for mixed elements. First, a dual-consistent discrete form of the CPR method is derived. Then, an efficient and accurate adjoint-based error estimation method for the CPR method is developed and its accuracy and effectiveness are verified for the linear and non-linear partial differential equations (PDE). For anisotropic h-adaptations, we use a local output error sampling procedure to find the optimal refinement option. The current method has been applied to aerodynamic problems. Numerical tests show that significant savings in the number of DOFs can be achieved through the adjoint-based adaptation.
Advisors/Committee Members: Wang, Z.J. (advisor), Farokhi, Saeed (cmtemember), Huang, Weizhang (cmtemember), Taghavi, Ray (cmtemember), Tu, Xuemin (cmtemember), Zheng, Zhongquan (cmtemember).
Subjects/Keywords: Aerospace engineering; Adaptive Method; Adjoint-based Adaptation; Computational Fluid Dynamics; High-order Method; Navier-Stokes Equations
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APA ·
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MLA ·
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Export
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APA (6th Edition):
Shi, L. (2014). Adaptive High-Order Differential Formulation for the Compressible Navier-Stokes Equations. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/27533
Chicago Manual of Style (16th Edition):
Shi, Lei. “Adaptive High-Order Differential Formulation for the Compressible Navier-Stokes Equations.” 2014. Doctoral Dissertation, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/27533.
MLA Handbook (7th Edition):
Shi, Lei. “Adaptive High-Order Differential Formulation for the Compressible Navier-Stokes Equations.” 2014. Web. 15 Jul 2019.
Vancouver:
Shi L. Adaptive High-Order Differential Formulation for the Compressible Navier-Stokes Equations. [Internet] [Doctoral dissertation]. University of Kansas; 2014. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/27533.
Council of Science Editors:
Shi L. Adaptive High-Order Differential Formulation for the Compressible Navier-Stokes Equations. [Doctoral Dissertation]. University of Kansas; 2014. Available from: http://hdl.handle.net/1808/27533
29.
Kulhanek, Sarah Logan.
Design, Analysis, and Simulation of Rocket Propulsion System.
Degree: MS, Aerospace Engineering, 2012, University of Kansas
URL: http://hdl.handle.net/1808/10198
► This document details the functionality of a software program used to streamline a rocket propulsion system design, analysis and simulation effort. The program aids in…
(more)
▼ This document details the functionality of a software program used to streamline a rocket propulsion system design, analysis and simulation effort. The program aids in unifying the nozzle, chamber and injector portions of a rocket propulsion system design effort quickly and efficiently using a streamlined graphical user interface (GUI). The program also allows for the selection of common nozzle profiles including 80% rao, conical, a user selected percentage bell, and a minimum length nozzle (MLN) using method of characteristics (MOC). Chamber dimensions, propellant selections, and injector selection between doublet or triplet allow for further refinement of the desired rocket system design. The program takes the available selections and specifications made by the user and outputs key design parameters calculated from the input variables. A 2-D graphical representation of the nozzle and/or chamber is plotted and coordinates of the plotted line are displayed. Additional design calculations are determined and displayed within the program such as specific impulse, exhaust velocity, propellant weight flow, fundamental instability frequencies, etc. The rocket propulsion system design coordinates are saved to a *dat file which can be used in a CAD program to plot a 3-D model of the rocket propulsion system. The *dat file is compatible for creating splines in Unigraphics NX, Catia, and SolidWorks. Coordinates of the injectors are saved to a *dat file to be modeled in a CAD program as well. The program currently provides a symbolic link in the form of a button on the output page which will open Unigraphics NX CAD program. The post-processing simulation of the rocket propulsion system is done in a computational fluid dynamics (CFD) program such as ANSYS ICEM CFD mesh generation software and ANSYS FLUENT CFD. The program provides a button on the output page which will open the ANSYS ICEM CFD mesh program and the ANSYS FLUENT CFD program. The user inputs the parasolid or IGES/STEP file of the CAD 3-D modeling of the rocket propulsion system into the ANSYS ICEM CFD meshing software. The geometry tolerant mesher program produces a volume or surface mesh to be read into the ANSYS FLUENT CFD software. Using ANSYS FLUENT CFD software, the user can choose to model the flow, turbulence, heat transfer, air flow over the rocket, combustion in the chamber, or various other options of the rocket propulsion system. The rocket propulsion system is a graphical user interface (GUI) which is run through Matlab and is compatible for 2009-2011 Matlab versions.
Advisors/Committee Members: Taghavi, Ray (advisor), Farokhi, Saeed (advisor), Taghavi, Ray (cmtemember), Farokhi, Saeed (cmtemember), Keshmiri, Shahriar (cmtemember).
Subjects/Keywords: Aerospace engineering; Design; Program; Propulsion system; Rocket
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APA (6th Edition):
Kulhanek, S. L. (2012). Design, Analysis, and Simulation of Rocket Propulsion System. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/10198
Chicago Manual of Style (16th Edition):
Kulhanek, Sarah Logan. “Design, Analysis, and Simulation of Rocket Propulsion System.” 2012. Masters Thesis, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/10198.
MLA Handbook (7th Edition):
Kulhanek, Sarah Logan. “Design, Analysis, and Simulation of Rocket Propulsion System.” 2012. Web. 15 Jul 2019.
Vancouver:
Kulhanek SL. Design, Analysis, and Simulation of Rocket Propulsion System. [Internet] [Masters thesis]. University of Kansas; 2012. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/10198.
Council of Science Editors:
Kulhanek SL. Design, Analysis, and Simulation of Rocket Propulsion System. [Masters Thesis]. University of Kansas; 2012. Available from: http://hdl.handle.net/1808/10198
30.
Giridhar, Rohith.
Prediction of Aerodynamic Noise Generated By Wind Turbine Blades.
Degree: MS, Aerospace Engineering, 2016, University of Kansas
URL: http://hdl.handle.net/1808/21976
► The preliminary step in the computational study of mitigating the aerodynamic noise generated by wind turbine blades involves accurate prediction of aerodynamic noise generated by…
(more)
▼ The preliminary step in the computational study of mitigating the aerodynamic noise generated by wind turbine blades involves accurate prediction of aerodynamic noise generated by a wind turbine rotor which can be used a basis for comparison. The NREL Phase VI HAWT rotor has been chosen to perform this study. This is achieved by first predicting the three dimensional flow field around the rotor through CFD analysis using SST k-ω turbulence model for wind speeds of 7m/s, 10m/s, 13m/s and 15m/s. CFD analysis has been performed using the rotating reference frame method at steady state conditions which resulted in predicting the flow field accurately with less computational time. The rotational periodic boundary condition with 1800 symmetry has been used with which one blade has been simulated instead of two. This reduced the mesh size and thus computational costs to perform the CFD analysis. To validate the prediction of flow field obtained through CFD analysis, performance characteristics and aerodynamic characteristics such as torque generated and trends of pressure coefficients at different span locations are validated against the time averaged experimental results and other results pertaining to the same published in previous computational study. The results obtained through CFD analysis show good agreement with both experimental results and previous computational results. Based on the trends of pressure coefficients predicted for different wind speeds we see that it is most accurate at a wind speed of 7m/s and this accuracy gradually decreases with increase in wind speed. Once the flow field was accurately predicted, this was used to predict both the location and magnitude of aerodynamic noise generated by the blade using the Curle broadband noise source model. Aeroacoustic analysis indicates that major noise sources are located near the tip of the blade and it gradually decreases as we move towards its root. This trend is observed at all four wind speed conditions. It is also observed that with increase in wind speeds, there is increase in the intensity of noise generated by the blades and thus increase in Sound Power Level across the blade.
Advisors/Committee Members: Farokhi, Saeed (advisor), Farokhi, Saeed (cmtemember), Taghavi, Ray (cmtemember), Keshmiri, Shawn (cmtemember).
Subjects/Keywords: Aerospace engineering; Aero acoustics; Aerodynamic Noise; Curle; NREL Phase VI; SST k-omega; Wind Turbine Noise
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APA ·
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Export
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APA (6th Edition):
Giridhar, R. (2016). Prediction of Aerodynamic Noise Generated By Wind Turbine Blades. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/21976
Chicago Manual of Style (16th Edition):
Giridhar, Rohith. “Prediction of Aerodynamic Noise Generated By Wind Turbine Blades.” 2016. Masters Thesis, University of Kansas. Accessed July 15, 2019.
http://hdl.handle.net/1808/21976.
MLA Handbook (7th Edition):
Giridhar, Rohith. “Prediction of Aerodynamic Noise Generated By Wind Turbine Blades.” 2016. Web. 15 Jul 2019.
Vancouver:
Giridhar R. Prediction of Aerodynamic Noise Generated By Wind Turbine Blades. [Internet] [Masters thesis]. University of Kansas; 2016. [cited 2019 Jul 15].
Available from: http://hdl.handle.net/1808/21976.
Council of Science Editors:
Giridhar R. Prediction of Aerodynamic Noise Generated By Wind Turbine Blades. [Masters Thesis]. University of Kansas; 2016. Available from: http://hdl.handle.net/1808/21976
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Open Access Theses and Dissertations
