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You searched for +publisher:"University of New South Wales" +contributor:("Gai, Sudhir, Engineering & Information Technology, UNSW Canberra, UNSW"). Showing records 1 – 3 of 3 total matches.

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University of New South Wales

1. Sridhar, Vikram. Computational and Experimental Investigation of Supersonic Two-dimensional and Axi-symmetric Shallow Open Cavities.

Degree: Engineering & Information Technology Canberra, 2014, University of New South Wales

Time-accurate numerical simulations and experiments were carried out on two-dimensional/planar and axi-symmetric open cavities with length-to-depth ratios of 3, 5, 6 and 8 in a Mach 2 freestream. The study focusses on turbulent boundary layer at entry to cavity. The effect of entry boundary layer thickness on cavity flow dynamics was investigated using two-dimensional models. The axi-symmetric configuration was used mainly to eliminate possible three-dimensional effects that may have been present in two-dimensional cavity configurations and compare the results. The numerical investigation used an in-house code Eilmer-3 developed by Dr. Peter Jacobs and his associates at the University of Queensland. Eilmer-3 basically solves time accurate compressible Navier-Stokes equations using the advection upwind splitting method combining difference and vector splitting flux scheme and incorporates Wilcox k-w turbulence modelling. The experiments involved high speed time-resolved density sensitive flow visualisation such as schlieren, differential interferometry, streak schlieren technique and unsteady surface pressure measurements. The study on two-dimensional/planar configurations showed that beyond a certain length-to-depth ratio of the cavity, strong periodic oscillations become broadband and the flow is less unsteady. The cavity drag, which increased with length-to-depth ratio, however, increased at a faster rate once this threshold was crossed. For the two boundary layer thickness-to-cavity depth ratios considered here, this change in flow behaviour occurred when L/D ≈ 5. This was seen in both simulations and experiments. Use of differential interferometry on two−dimensional/planar cavities showed wave-fronts and closed loop structures (corresponding to vortices) in the shear layer. It also qualitatively confirmed the change in flow behaviour for L/D > 5. With the axi-symmetric cavities, the overall flow physics were similar to that of the planar cavities. Again the change in drag behaviour seemed to occurred when L/D ≥ 5. Experiments carried out in JAXA wind tunnel with a scaled up axi-symmetric model agreed with these observations. Both numerical and experimental data on axi-symmetric cavities showed that the assumption of two-dimensional flow in respect of planar cavities with large aspect ratios is a reasonable one to capture the essential flow physics of cavity flows. The experiments and numerical simulations showed that cavities with thin separating boundary layers are more unsteady than those with a thick separating boundary layer. For the two boundary layer thicknesses investigated, the threshold length-to-depth ratio, indicating change in flow behaviour, did not change and was L/D ≈ 5.The streak schlieren technique applied to time-resolved schlieren images revealed wave motions inside the cavity and enabled quantification of these motions for the first time. Finally, it has been shown that, incorporating the cavity floor in the boundary condition using the linear inviscid flow stability… Advisors/Committee Members: Kleine, Harald, Engineering & Information Technology, UNSW Canberra, UNSW, Gai, Sudhir, Engineering & Information Technology, UNSW Canberra, UNSW.

Subjects/Keywords: turbulent; Supersonic; Cavity

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APA (6th Edition):

Sridhar, V. (2014). Computational and Experimental Investigation of Supersonic Two-dimensional and Axi-symmetric Shallow Open Cavities. (Doctoral Dissertation). University of New South Wales. Retrieved from http://handle.unsw.edu.au/1959.4/53981 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12692/SOURCE02?view=true

Chicago Manual of Style (16th Edition):

Sridhar, Vikram. “Computational and Experimental Investigation of Supersonic Two-dimensional and Axi-symmetric Shallow Open Cavities.” 2014. Doctoral Dissertation, University of New South Wales. Accessed November 18, 2019. http://handle.unsw.edu.au/1959.4/53981 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12692/SOURCE02?view=true.

MLA Handbook (7th Edition):

Sridhar, Vikram. “Computational and Experimental Investigation of Supersonic Two-dimensional and Axi-symmetric Shallow Open Cavities.” 2014. Web. 18 Nov 2019.

Vancouver:

Sridhar V. Computational and Experimental Investigation of Supersonic Two-dimensional and Axi-symmetric Shallow Open Cavities. [Internet] [Doctoral dissertation]. University of New South Wales; 2014. [cited 2019 Nov 18]. Available from: http://handle.unsw.edu.au/1959.4/53981 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12692/SOURCE02?view=true.

Council of Science Editors:

Sridhar V. Computational and Experimental Investigation of Supersonic Two-dimensional and Axi-symmetric Shallow Open Cavities. [Doctoral Dissertation]. University of New South Wales; 2014. Available from: http://handle.unsw.edu.au/1959.4/53981 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12692/SOURCE02?view=true


University of New South Wales

2. Khraibut, Amna. Laminar Hypersonic Leading Edge Separation.

Degree: Engineering & Information Technology, 2018, University of New South Wales

A numerical and analytical investigation of hypersonic leading edge separation has been conducted. This particular configuration was first analyzed by Chapman in the 1950s for supersonic flows. This study will look at this configuration under hypersonic flow conditions, numerically, analytically, and also with basic surface pressure measurements taken in T-ADFA. Effects of wall temperature and leading edge bluntness have been considered in the study, including perfect and real gas simulations to examine their effects on separation. Slip corrections have also been implemented. A compressible Navier-Stokes solver, US3D, specifically developed for hypersonic flows has been used to carry out the numerical simulations. The simulations revealed many interesting features caused by wall temperature and bluntness effects. Firstly, while the size of separation has been shown to increase with the increase in wall temperature, wall cooling seems to give rise to secondary vortices within the separated region. An explanation for the existence of these secondary vortices has been presented in terms of gradients, characteristic angle, and the Reynolds number on the dividing streamline. The numerical results have also been analyzed in the context of the triple-deck theory, Chapman's isentropic recompression theory, and analytical work of Oswatitisch and Inger with particular emphasis on the streamline angles and curvatures at separation and reattachment. The most interesting finding has been in characterizing the separation in terms of the triple-deck scaled angle, which delineates stable and unstable secondary vortices. It is shown that a unique relationship exists between this angle and the size of separation and that it is independent of the agency provoking separation. Bluntness studies, on the other hand, showed a very complex interplay between bluntness which delays separation, viscous interactions which promote separation, and the incidence angle. In bluntness studies, map of pressure gradients revealed a complex mechanism in which disturbances can provoke secondary vortices. Analysis of streamline angles and curvatures revealed a very complex separation process on the microscale as a result of separation. Three-dimensional nozzle simulations using the same CFD solver have been carried-out to verify the freestream conditions. These simulations have been validated by performing a pitot pressure survey in T-ADFA. Both laminar and turbulent flow simulations were considered. Comparison with the experimental measurements showed that the laminar flow assumption overpredicts the size of the core flow, while the turbulent boundary layer assumption showed very good agreement with experiments. Limited surface pressure data were also obtained and overall showed good agreement with the numerical results. Advisors/Committee Members: gai, sudhir, Engineering & Information Technology, UNSW Canberra, UNSW, neely, andrew, Engineering & Information Technology, UNSW Canberra, UNSW.

Subjects/Keywords: flow separation; hypersonic flows; aerothermodynamics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Khraibut, A. (2018). Laminar Hypersonic Leading Edge Separation. (Doctoral Dissertation). University of New South Wales. Retrieved from http://handle.unsw.edu.au/1959.4/59808 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:49842/SOURCE01?view=true

Chicago Manual of Style (16th Edition):

Khraibut, Amna. “Laminar Hypersonic Leading Edge Separation.” 2018. Doctoral Dissertation, University of New South Wales. Accessed November 18, 2019. http://handle.unsw.edu.au/1959.4/59808 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:49842/SOURCE01?view=true.

MLA Handbook (7th Edition):

Khraibut, Amna. “Laminar Hypersonic Leading Edge Separation.” 2018. Web. 18 Nov 2019.

Vancouver:

Khraibut A. Laminar Hypersonic Leading Edge Separation. [Internet] [Doctoral dissertation]. University of New South Wales; 2018. [cited 2019 Nov 18]. Available from: http://handle.unsw.edu.au/1959.4/59808 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:49842/SOURCE01?view=true.

Council of Science Editors:

Khraibut A. Laminar Hypersonic Leading Edge Separation. [Doctoral Dissertation]. University of New South Wales; 2018. Available from: http://handle.unsw.edu.au/1959.4/59808 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:49842/SOURCE01?view=true


University of New South Wales

3. Currao, Gaetano. Experimental Study of Hypersonic Fluid Structure Interaction with Shock Impingement on a Cantilevered Plate.

Degree: Engineering & Information Technology, 2018, University of New South Wales

This work investigates fundamental fluid-structure interaction (FSI) experiments performed in a short duration hypersonic wind tunnel at Mach 6. The thesis aims to discuss and quantify the relationship between structural deformations and viscous aspects such as transition, separated flow and shock wave – boundary layer interactions (SWBLI). Part of the findings will be used to describe the impact of deployment and deformation on the performance of control surfaces.The main experiment involves a shock impinging on cantilevered elastic plate. The pressure increase, determined by the shock reflection on the plate, causes the cantilevered plate to oscillate. The plate motion affects the salient feature of the SWBLI in terms of length of the separated region, transition, peak heating and peak pressure. The problem is broken down into its main features and driving phenomena. In fact, preliminary experiments involve a cantilevered plate without impinging shock and a shock impinging on a rigid plate, in order to separate the phenomena purely due to FSI or SWBLI.Measurements consist of time-resolved sparse pressure and temperature measurements as well as surface measurements. Pressure-sensitive paint (PSP) and IR thermography are used to investigate and quantify the impact of three-dimensional effects on pressure and thermal distributions. In this work, three-dimensional effects are the result of limited plate width and/or Görtler boundary layer instability. The experimental data is compared against transient fully laminar and fully turbulent numerical solutions.Among the major findings, the thesis demonstrates that the boundary layer displacement thickness cannot always be considered a point function of the local plate inclination and speed. The numerical solutions significantly underestimate peakheating and peak pressure when boundary layer transition takes place within the separated region. Gortler boundary layer instability triggers the transition resulting in peak hating fluctuations close to 10%. Concerning control surfaces, transition in the separated region can lead to levels of heating 100% higher than the laminar values. Finally, a 1 % control surf~ce deformation at the trailing edge due to fluid-structure interaction results in a 2 - 3% loss in efficiency. Advisors/Committee Members: Neely, Andrew, UNSW Canberra, UNSW, Gai, Sudhir, Engineering & Information Technology, UNSW Canberra, UNSW.

Subjects/Keywords: FSI; Hypersonic; Aeroelasticty; Shock wave - Boundary Layer interaction

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Currao, G. (2018). Experimental Study of Hypersonic Fluid Structure Interaction with Shock Impingement on a Cantilevered Plate. (Doctoral Dissertation). University of New South Wales. Retrieved from http://handle.unsw.edu.au/1959.4/60351 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:51888/SOURCE02?view=true

Chicago Manual of Style (16th Edition):

Currao, Gaetano. “Experimental Study of Hypersonic Fluid Structure Interaction with Shock Impingement on a Cantilevered Plate.” 2018. Doctoral Dissertation, University of New South Wales. Accessed November 18, 2019. http://handle.unsw.edu.au/1959.4/60351 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:51888/SOURCE02?view=true.

MLA Handbook (7th Edition):

Currao, Gaetano. “Experimental Study of Hypersonic Fluid Structure Interaction with Shock Impingement on a Cantilevered Plate.” 2018. Web. 18 Nov 2019.

Vancouver:

Currao G. Experimental Study of Hypersonic Fluid Structure Interaction with Shock Impingement on a Cantilevered Plate. [Internet] [Doctoral dissertation]. University of New South Wales; 2018. [cited 2019 Nov 18]. Available from: http://handle.unsw.edu.au/1959.4/60351 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:51888/SOURCE02?view=true.

Council of Science Editors:

Currao G. Experimental Study of Hypersonic Fluid Structure Interaction with Shock Impingement on a Cantilevered Plate. [Doctoral Dissertation]. University of New South Wales; 2018. Available from: http://handle.unsw.edu.au/1959.4/60351 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:51888/SOURCE02?view=true

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