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1.
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…
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▼ 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 (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 April 22, 2021.
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. 22 Apr 2021.
Vancouver:
Li Y. Large-eddy simulations of turbulent flows using the high-order FR/CPR method. [Internet] [Doctoral dissertation]. University of Kansas; 2016. [cited 2021 Apr 22].
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
2.
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…
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▼ 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 April 22, 2021.
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. 22 Apr 2021.
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 2021 Apr 22].
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
3.
LIiu, Yangliu.
Vortical Flow Effects on Flow Separation Control.
Degree: MS, Aerospace Engineering, 2016, University of Kansas
URL: http://hdl.handle.net/1808/23991
► The effect of Reynolds number, oscillation frequency, amplitude, and the incident angle on flow separation control is studied numerically in this thesis. Two configurations are…
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▼ The effect of Reynolds number, oscillation frequency, amplitude, and the incident angle on flow separation control is studied numerically in this thesis. Two configurations are investigated, cylinders in tandem and the cylinder-airfoil arrangement. The upstream cylinder changes locations, size, and oscillating frequencies and amplitudes, which necessitates investigating its effect on separation control of the downstream cylinder or airfoil. A validation simulation based on an airfoil in the wake of a stationary cylinder is carried out to verify the numerical method that will be used in this study. The results show that high-Reynolds-number, high-frequency low-amplitude oscillation motion of the upstream cylinder reduces the flow separation on the downstream airfoil. By placing an oscillating cylinder in the upstream, the flow separation point moves slightly further downstream even at zero angles of attack.
Advisors/Committee Members: Zheng, Zhongquan Charlie (advisor), Taghavi, Ray (cmtemember), Wang, Zhijian (cmtemember).
Subjects/Keywords: Aerospace engineering; Engineering; Flow over cylinder and airfoil; Flow over tandem cylinders; Flow separation control; Vortical flow effct
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APA (6th Edition):
LIiu, Y. (2016). Vortical Flow Effects on Flow Separation Control. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/23991
Chicago Manual of Style (16th Edition):
LIiu, Yangliu. “Vortical Flow Effects on Flow Separation Control.” 2016. Masters Thesis, University of Kansas. Accessed April 22, 2021.
http://hdl.handle.net/1808/23991.
MLA Handbook (7th Edition):
LIiu, Yangliu. “Vortical Flow Effects on Flow Separation Control.” 2016. Web. 22 Apr 2021.
Vancouver:
LIiu Y. Vortical Flow Effects on Flow Separation Control. [Internet] [Masters thesis]. University of Kansas; 2016. [cited 2021 Apr 22].
Available from: http://hdl.handle.net/1808/23991.
Council of Science Editors:
LIiu Y. Vortical Flow Effects on Flow Separation Control. [Masters Thesis]. University of Kansas; 2016. Available from: http://hdl.handle.net/1808/23991
University of Kansas
4.
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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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 April 22, 2021.
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. 22 Apr 2021.
Vancouver:
Shi L. Adaptive High-Order Differential Formulation for the Compressible Navier-Stokes Equations. [Internet] [Doctoral dissertation]. University of Kansas; 2014. [cited 2021 Apr 22].
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
University of Kansas
5.
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 April 22, 2021.
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. 22 Apr 2021.
Vancouver:
Raina AA. IMPACT ON WIND TURBINE BLADE DESIGN AND AERODYNAMIC PERFORMANCE USING INTEGRAL VORTEX GENERATORS. [Internet] [Doctoral dissertation]. University of Kansas; 2016. [cited 2021 Apr 22].
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
6.
Weingart, Robert.
On-Track Testing as a Validation Method of Computational Fluid Dynamic Simulations of a Formula SAE Vehicle.
Degree: M.E., Mechanical Engineering, 2015, University of Kansas
URL: http://hdl.handle.net/1808/19383
► This thesis is about the validation of a computational fluid dynamics simulation of a ground vehicle by means of a low-budget coast-down test. The vehicle…
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▼ This thesis is about the validation of a computational fluid dynamics simulation of a ground vehicle by means of a low-budget coast-down test. The vehicle is built to the standards of the 2014 Formula SAE rules. It is equipped with large wings in the front and rear of the car; the vertical loads on the tires are measured by specifically calibrated shock potentiometers. The coast-down test was performed on a runway of a local airport and is used to determine vehicle specific coefficients such as drag, downforce, aerodynamic balance, and rolling resistance for different aerodynamic setups. The test results are then compared to the respective simulated results. The drag deviates about 5% from the simulated to the measured results. The downforce numbers show a deviation up to 18% respectively. Moreover, a sensitivity analysis of inlet velocities, ride heights, and pitch angles was performed with the help of the computational simulation.
Advisors/Committee Members: Sorem, Robert M (advisor), Tenpas, Peter W (cmtemember), Zheng, Zhongquan (Charlie) (cmtemember).
Subjects/Keywords: Mechanical engineering; Aerospace engineering; Analysis; CFD-Simulation; Coast-Down Test; External Aerodynamics; FSAE; Validation
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APA (6th Edition):
Weingart, R. (2015). On-Track Testing as a Validation Method of Computational Fluid Dynamic Simulations of a Formula SAE Vehicle. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/19383
Chicago Manual of Style (16th Edition):
Weingart, Robert. “On-Track Testing as a Validation Method of Computational Fluid Dynamic Simulations of a Formula SAE Vehicle.” 2015. Masters Thesis, University of Kansas. Accessed April 22, 2021.
http://hdl.handle.net/1808/19383.
MLA Handbook (7th Edition):
Weingart, Robert. “On-Track Testing as a Validation Method of Computational Fluid Dynamic Simulations of a Formula SAE Vehicle.” 2015. Web. 22 Apr 2021.
Vancouver:
Weingart R. On-Track Testing as a Validation Method of Computational Fluid Dynamic Simulations of a Formula SAE Vehicle. [Internet] [Masters thesis]. University of Kansas; 2015. [cited 2021 Apr 22].
Available from: http://hdl.handle.net/1808/19383.
Council of Science Editors:
Weingart R. On-Track Testing as a Validation Method of Computational Fluid Dynamic Simulations of a Formula SAE Vehicle. [Masters Thesis]. University of Kansas; 2015. Available from: http://hdl.handle.net/1808/19383
University of Kansas
7.
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 ·
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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 April 22, 2021.
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. 22 Apr 2021.
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 2021 Apr 22].
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
8.
Karwas, Alex A.
An Unconditionally Stable Method for Numerically Solving Solar Sail Spacecraft Equations of Motion.
Degree: PhD, Aerospace Engineering, 2015, University of Kansas
URL: http://hdl.handle.net/1808/19374
► Solar sails use the endless supply of the Sun's radiation to propel spacecraft through space. The sails use the momentum transfer from the impinging solar…
(more)
▼ Solar sails use the endless supply of the Sun's radiation to propel spacecraft through space. The sails use the momentum transfer from the impinging solar radiation to provide thrust to the spacecraft while expending zero fuel. Recently, the first solar sail spacecraft, or sailcraft, named IKAROS completed a successful mission to Venus and proved the concept of solar sail propulsion. Sailcraft experimental data is difficult to gather due to the large expenses of space travel, therefore, a reliable and accurate computational method is needed to make the process more efficient. Presented in this document is a new approach to simulating solar sail spacecraft trajectories. The new method provides unconditionally stable numerical solutions for trajectory propagation and includes an improved physical description over other methods. The unconditional stability of the new method means that a unique numerical solution is always determined. The improved physical description of the trajectory provides a numerical solution and time derivatives that are continuous throughout the entire trajectory. The error of the continuous numerical solution is also known for the entire trajectory. Optimal control for maximizing thrust is also provided within the framework of the new method. Verification of the new approach is presented through a mathematical description and through numerical simulations. The mathematical description provides details of the sailcraft equations of motion, the numerical method used to solve the equations, and the formulation for implementing the equations of motion into the numerical solver. Previous work in the field is summarized to show that the new approach can act as a replacement to previous trajectory propagation methods. A code was developed to perform the simulations and it is also described in this document. Results of the simulations are compared to the flight data from the IKAROS mission. Comparison of the two sets of data show that the new approach is capable of accurately simulating sailcraft motion. Sailcraft and spacecraft simulations are compared to flight data and to other numerical solution techniques. The new formulation shows an increase in accuracy over a widely used trajectory propagation technique. Simulations for two-dimensional, three-dimensional, and variable attitude trajectories are presented to show the multiple capabilities of the new technique. An element of optimal control is also part of the new technique. An additional equation is added to the sailcraft equations of motion that maximizes thrust in a specific direction. A technical description and results of an example optimization problem are presented. The spacecraft attitude dynamics equations take the simulation a step further by providing control torques using the angular rate and acceleration outputs of the numerical formulation.
Advisors/Committee Members: Taghavi, Ray (advisor), Farokhi, Saeed (cmtemember), Keshmiri, Shawn (cmtemember), Zheng, Zhongquan Charlie (cmtemember), Yimer, Bedru (cmtemember).
Subjects/Keywords: Aerospace engineering; Finite Element Method; Propagation; Sailcraft; Solar Sail; Spacecraft; Trajectory
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APA (6th Edition):
Karwas, A. A. (2015). An Unconditionally Stable Method for Numerically Solving Solar Sail Spacecraft Equations of Motion. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/19374
Chicago Manual of Style (16th Edition):
Karwas, Alex A. “An Unconditionally Stable Method for Numerically Solving Solar Sail Spacecraft Equations of Motion.” 2015. Doctoral Dissertation, University of Kansas. Accessed April 22, 2021.
http://hdl.handle.net/1808/19374.
MLA Handbook (7th Edition):
Karwas, Alex A. “An Unconditionally Stable Method for Numerically Solving Solar Sail Spacecraft Equations of Motion.” 2015. Web. 22 Apr 2021.
Vancouver:
Karwas AA. An Unconditionally Stable Method for Numerically Solving Solar Sail Spacecraft Equations of Motion. [Internet] [Doctoral dissertation]. University of Kansas; 2015. [cited 2021 Apr 22].
Available from: http://hdl.handle.net/1808/19374.
Council of Science Editors:
Karwas AA. An Unconditionally Stable Method for Numerically Solving Solar Sail Spacecraft Equations of Motion. [Doctoral Dissertation]. University of Kansas; 2015. Available from: http://hdl.handle.net/1808/19374
9.
Flanagan, Harold Patrick.
Improved Atmospheric Density Estimation for ANDE-2 Satellites using Drag Coefficients Obtained from Gas-Surface Interaction Equations.
Degree: MS, Aerospace Engineering, 2015, University of Kansas
URL: http://hdl.handle.net/1808/19392
► A major issue in the process of predicting the future position of satellites in low earth orbit (LEO) is that the drag coefficient of a…
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▼ A major issue in the process of predicting the future position of satellites in low earth orbit (LEO) is that the drag coefficient of a satellite is generally not precisely known throughout the satellite’s lifespan. One reason for this problem is that as a satellite travels through the Earth’s thermosphere, variations in the composition of the thermosphere directly affect the drag coefficient of the satellite. The greatest amount of uncertainty in the drag coefficient from these variations in the thermosphere comes from the amount of atomic oxygen that covers the satellites surface as the satellite descends to lower altitudes. This percent surface coverage of atomic oxygen directly affects the interaction between the surface of the satellite and the gas through which it is passing. The work performed in this thesis determines the drag coefficients of the ANDE-2 satellites over their life spans by using satellite laser ranging (SLR) data of the ANDE-2 satellites in unison with gas-surface interaction equations. The fractional coverage of atomic oxygen is determined by using empirically determined data and semi-empirical models that attempt to predict the fractional coverage of oxygen relative to the composition of the atmosphere. These drag coefficients are then used to determine the atmospheric densities experienced by these satellites over various days, so that inaccuracies in the atmospheric models can be observed. The drag coefficients of the ANDE-2 satellites decrease throughout the satellites’ life, and vary most due to changes in the temperature and density of the atmosphere. The greatest uncertainty in the atmosphere’s composition occurs at lower altitudes at the end of ANDE-2’s life.
Advisors/Committee Members: McLaughlin, Craig A (advisor), Chao, Haiyang (cmtemember), Zheng, Zhongquan C (cmtemember).
Subjects/Keywords: Aerospace engineering; ANDE-2; Atmospheric Density; Gas-Surface Interaction Equations; Satellite Drag Coefficients
…was done in collaboration with the Los Alamos National
Laboratory and the University of… …Kansas in Mehta (2013) with simulations performed by Dr. Andrew
Walker from the Los…
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APA (6th Edition):
Flanagan, H. P. (2015). Improved Atmospheric Density Estimation for ANDE-2 Satellites using Drag Coefficients Obtained from Gas-Surface Interaction Equations. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/19392
Chicago Manual of Style (16th Edition):
Flanagan, Harold Patrick. “Improved Atmospheric Density Estimation for ANDE-2 Satellites using Drag Coefficients Obtained from Gas-Surface Interaction Equations.” 2015. Masters Thesis, University of Kansas. Accessed April 22, 2021.
http://hdl.handle.net/1808/19392.
MLA Handbook (7th Edition):
Flanagan, Harold Patrick. “Improved Atmospheric Density Estimation for ANDE-2 Satellites using Drag Coefficients Obtained from Gas-Surface Interaction Equations.” 2015. Web. 22 Apr 2021.
Vancouver:
Flanagan HP. Improved Atmospheric Density Estimation for ANDE-2 Satellites using Drag Coefficients Obtained from Gas-Surface Interaction Equations. [Internet] [Masters thesis]. University of Kansas; 2015. [cited 2021 Apr 22].
Available from: http://hdl.handle.net/1808/19392.
Council of Science Editors:
Flanagan HP. Improved Atmospheric Density Estimation for ANDE-2 Satellites using Drag Coefficients Obtained from Gas-Surface Interaction Equations. [Masters Thesis]. University of Kansas; 2015. Available from: http://hdl.handle.net/1808/19392
10.
Zhou, Cheng.
Adaptive High-Order Discretization of the Reynolds-Averaged Navier-Stokes(RANS) Equations.
Degree: PhD, Aerospace Engineering, 2016, University of Kansas
URL: http://hdl.handle.net/1808/24139
► The use of high-order methods to compute turbulent flows governed by the Reynolds- averaged Navier-Stokes (RANS) equations is an active research topic in the compu-…
(more)
▼ The use of high-order methods to compute turbulent flows governed by the Reynolds- averaged Navier-Stokes (RANS) equations is an active research topic in the compu- tational fluid dynamics (CFD) community. However, it is well known that high-order methods for the non-smooth turbulence modeling equations are difficult to converge to the steady-state because of the numerical stiffness. The objective of this work is to de- velop a robust and efficient high-order discretization that can simulate turbulent flows governed by the Reynolds-Averaged Navier-Stokes equations, which involves the de- velopment of high-order space discretization of robust turbulence modeling equations, the improvement of time integration strategy, and the application of effective mesh adaptation methods. In the present study, correction procedure via reconstruction (CPR) high-order dis- cretization is developed to solve the Reynolds-averaged Navier-Stokes (RANS) equa- tions with the modified Spalart and Allmaras (SA) model. In this model, the non- dimensional length scale depends on the distance to the nearest wall. To compute the distance of each solution point in the domain to the nearest curved polynomial wall boundaries, the CPR high-order discretization is extended to solve the Eikonal equa- tion. On the other hand, to improve time integration strategy for the simulation of turbulent flows, the present work carried out a comparative study of several implicit time integration schemes to determine which is the most efficient, robust and general scheme. Additionally, an adjoint-based adaptive mesh refinement method is utilized to minimize the output error. Numerical results show that, to achieve a certain level of accuracy, the adaptive CPR discretization of the RANS equations with the SA model saves orders of magnitude in terms of number of degrees of freedom comparing to the numerical results of uniform mesh refinement, when applied to the simulations of turbulent flows.
Advisors/Committee Members: Wang, Z.J. (advisor), Farokhi, Saeed (cmtemember), Taghavi, Ray (cmtemember), Tu, Xuemin (cmtemember), Zheng, Zhongquan Charlie (cmtemember).
Subjects/Keywords: Aerospace engineering; Mathematics; Adaptive; CFD; CPR; High-order method; RANS
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APA ·
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APA (6th Edition):
Zhou, C. (2016). Adaptive High-Order Discretization of the Reynolds-Averaged Navier-Stokes(RANS) Equations. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/24139
Chicago Manual of Style (16th Edition):
Zhou, Cheng. “Adaptive High-Order Discretization of the Reynolds-Averaged Navier-Stokes(RANS) Equations.” 2016. Doctoral Dissertation, University of Kansas. Accessed April 22, 2021.
http://hdl.handle.net/1808/24139.
MLA Handbook (7th Edition):
Zhou, Cheng. “Adaptive High-Order Discretization of the Reynolds-Averaged Navier-Stokes(RANS) Equations.” 2016. Web. 22 Apr 2021.
Vancouver:
Zhou C. Adaptive High-Order Discretization of the Reynolds-Averaged Navier-Stokes(RANS) Equations. [Internet] [Doctoral dissertation]. University of Kansas; 2016. [cited 2021 Apr 22].
Available from: http://hdl.handle.net/1808/24139.
Council of Science Editors:
Zhou C. Adaptive High-Order Discretization of the Reynolds-Averaged Navier-Stokes(RANS) Equations. [Doctoral Dissertation]. University of Kansas; 2016. Available from: http://hdl.handle.net/1808/24139
University of Kansas
11.
Jia, Feilin.
Towards industrial large eddy simulation using the FR/CPR method.
Degree: PhD, Aerospace Engineering, 2019, University of Kansas
URL: http://hdl.handle.net/1808/29660
► NASA’s 2030 CFD Vision calls for the development of accurate and efficient scale-resolving simulations for turbulent flow, such as large eddy simulation (LES) and direct…
(more)
▼ NASA’s 2030 CFD Vision calls for the development of accurate and efficient scale-resolving simulations for turbulent flow, such as large eddy simulation (LES) and direct numerical simulation (DNS). This is primarily because the Reynolds-averaged Navier-Stokes (RANS) approach has failed to predict vortex-dominated flow involving large flow separations, e.g., flow through a jet engine or over aircraft near the edge of the flight envelope, i.e., during take-off and landing at high angles of attack. Although the DNS approach resolves all turbulence scales, it is too expensive in the foreseeable future for real world flow problems because of the disparate length and time scales in the flow. LES resolves the energetic large scales while modeling the smaller scales, so it provides a good compromise between accuracy and cost. As a result, LES is widely considered to be the method of choice for next generation CFD design tool. The major obstacle for LES is its considerable computational cost since unsteady 3D simulations need to be performed to obtain the mean flow quantities such as the drag and lift coefficients. In order to resolve the dominant scales in a turbulent flow, numerical methods used for LES should have low dissipation and dispersion errors. This means standard second order finite-volume methods are usually not accurate or efficient enough for LES applications. High-order methods (order of accuracy 2) have demonstrated their potential for LES and DNS in the past decade because of their low embedded numerical dissipation and dispersion errors. In the present study, we develop and demonstrate a recently developed high-order method, called flux reconstruction (FR) or correction procedure via reconstruction (CPR), for industrial LES. A major advantage of the FR/CPR method is its capability to handle unstructured mixed meshes, and its compactness and scalability, which is particularly desired on modern super-computers. We therefore address the following major pacing items in industrial LES in the present study: High-order methods Geometric flexibility Efficient time integration Efficient implementation on modern super computers Demonstration for real world applications
Advisors/Committee Members: Taghavi, Ray (advisor), Wang, Z.J. (advisor), Taghavi, Ray (cmtemember), Wang, Z.J. (cmtemember), Farokhi, Saeed (cmtemember), Zheng, Zhongquan (cmtemember), Shontz, Suzanne M (cmtemember).
Subjects/Keywords: Aerospace engineering; computational fluid dynamics; correction procedure via reconstruction; flux reconstruction; high order method; implicit time scheme
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APA ·
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MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
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APA (6th Edition):
Jia, F. (2019). Towards industrial large eddy simulation using the FR/CPR method. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/29660
Chicago Manual of Style (16th Edition):
Jia, Feilin. “Towards industrial large eddy simulation using the FR/CPR method.” 2019. Doctoral Dissertation, University of Kansas. Accessed April 22, 2021.
http://hdl.handle.net/1808/29660.
MLA Handbook (7th Edition):
Jia, Feilin. “Towards industrial large eddy simulation using the FR/CPR method.” 2019. Web. 22 Apr 2021.
Vancouver:
Jia F. Towards industrial large eddy simulation using the FR/CPR method. [Internet] [Doctoral dissertation]. University of Kansas; 2019. [cited 2021 Apr 22].
Available from: http://hdl.handle.net/1808/29660.
Council of Science Editors:
Jia F. Towards industrial large eddy simulation using the FR/CPR method. [Doctoral Dissertation]. University of Kansas; 2019. Available from: http://hdl.handle.net/1808/29660
12.
Blanco, Rafael Rodriguez.
Performance Analysis of an Annular Diffuser Under the Influence of a Gas Turbine Stage Exit Flow.
Degree: MS, Aerospace Engineering, 2013, University of Kansas
URL: http://hdl.handle.net/1808/12960
► In this investigation the performance of a gas turbine exhaust diffuser subject to the outlet flow conditions of a turbine stage is evaluated. Towards that…
(more)
▼ In this investigation the performance of a gas turbine exhaust diffuser subject to the outlet flow conditions of a turbine stage is evaluated. Towards that goal, a fully three-dimensional computational analysis has been performed where several turbine stage-exhaust diffuser configurations have been studied: a turbine stage with a shrouded rotor coupled to a diffuser with increasing divergence angle in the diffuser, and a turbine stage with an unshrouded rotor was also considered for the exhaust diffuser performance analysis. The large load of this investigation was evaluated using a steady state numerical analysis utilizing the "mixing plane" algorithm between the rotating rotor and stationary stator and diffuser rows. Finally, an unsteady analysis is performed on a turbine stage with an unsrhouded rotor coupled to an annular exhaust diffuser with an outer wall opening angle of 18°. It has been found that the over the tip leakage flow in the unshrouded rotor emerges as a swirling wall jet at the upper wall of the diffuser. When using the turbine with the shrouded rotor no wall jet was observed, making the flow at the entrance to the diffuser "quasi-uniform". The maximum opening angle of the diffuser upper wall achieved before the diffuser stalls was 12° with a static pressure recovery coefficient of Cp = 0.293. When the wall jet was observed, diffuser opening angles of 18° were possible with a static pressure recovery of Cp = 0.365. Consequently the wall jet energizes the diffuser upper wall boundary layer flow, allows for higher static pressure recovery levels and postpones diffuser stall. By altering the speed of the rotor the effect of the swirl in the turbine exit plane on the performance of the diffuser was explored. In the case where the wall jet was absent the diffuser recovers more pressure when the inlet is swirl-free. In this case the performance of the diffuser is independent on whether the turbine exit flow has co or counter swirl. In the presence of the wall jet, higher static pressure recovery was achieved when the wall jet was in co-swirl and the core flow at a slightly counter-swirl direction. This observation was more pronounced when larger diffuser upper wall opening angles were considered. In the unsteady analysis it was found that the wall jet axial velocity and swirl intensities pulsate with the relative position of the rotor to the stator. The wall jet is always co-swirling while the core flow is counter-swirling. Moreover, the wall jet does not penetrate the diffuser boundary layer as deeply as was observed in the steady state case and flow separation occurs at the upper endwall corner of the diffuser. Furthermore the performance of the diffuser shows a periodic variation that seems to depend on the relative position of the rotor to the stator. The averaged pressure recovery coefficient is Cp = 0.321 which is 11.0 % less than predicted in the steady state case.
Advisors/Committee Members: Farokhi, Saeed (advisor), Taghavi, Ray (cmtemember), Zheng, Zhongquan Charlie (cmtemember).
Subjects/Keywords: Aerospace engineering; Mechanical engineering; Diffuser; Over the tip leakage; Swirl; Turbine; Wall jet
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APA ·
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MLA ·
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CSE |
Export
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APA (6th Edition):
Blanco, R. R. (2013). Performance Analysis of an Annular Diffuser Under the Influence of a Gas Turbine Stage Exit Flow. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/12960
Chicago Manual of Style (16th Edition):
Blanco, Rafael Rodriguez. “Performance Analysis of an Annular Diffuser Under the Influence of a Gas Turbine Stage Exit Flow.” 2013. Masters Thesis, University of Kansas. Accessed April 22, 2021.
http://hdl.handle.net/1808/12960.
MLA Handbook (7th Edition):
Blanco, Rafael Rodriguez. “Performance Analysis of an Annular Diffuser Under the Influence of a Gas Turbine Stage Exit Flow.” 2013. Web. 22 Apr 2021.
Vancouver:
Blanco RR. Performance Analysis of an Annular Diffuser Under the Influence of a Gas Turbine Stage Exit Flow. [Internet] [Masters thesis]. University of Kansas; 2013. [cited 2021 Apr 22].
Available from: http://hdl.handle.net/1808/12960.
Council of Science Editors:
Blanco RR. Performance Analysis of an Annular Diffuser Under the Influence of a Gas Turbine Stage Exit Flow. [Masters Thesis]. University of Kansas; 2013. Available from: http://hdl.handle.net/1808/12960
. 
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