The Australian National University
Скачать 141.83 Kb.
|
 Faculty of Science Department of Physics PHYS 3020/27 - Computational Fluid Dynamics Case Studies Modelling of Laminar Hypersonic Flow over Axisymmetric and 2-Dimensional Compression Corner Geometries with the Computational Fluid Dynamics Packages FASTRAN and GASP By Guy Lynch 3069919 26 November 2001 Supervisor: Dr Frank Houwing Abstract Contents 1 Introduction 1 2 Theory 4 3 Simulation Setup and Procedure 15 4 Results and Discussion 23 5 Conclusions 36 References 37 Appendix 38 1 IntroductionThe extreme pressures and thermal stresses imparted to a body by a hypersonic flow moving over it are of critical concern in the design of high-speed aerospace vehicles. A comprehensive understanding of the behaviour and associated phenomena of hypersonic flows over conceivable body geometries is required to overcome the adverse effects on vehicle control and performance they might have. Viscous interactions, such as flow separation induced by a shock wave/boundary layer interaction and the thermal loading caused by subsequent flow reattachment, are an important phenomenon in hypersonic aerodynamics. Actual flight testing during the design and development of hypersonic aerospace vehicles is prohibitively expensive and, in most situations, physically unrealizable with current technology. Ground based facilities for generating high Mach number flows are limited in number with high demands on their use. As well as being expensive and time consuming to operate, the generated flow conditions are often not the same as those experienced in reality. Regions of thermal, chemical and vibrational non-equilibrium exist in the free stream of shock tunnel tests and in flight, but it is difficult to achieve direct dynamic similarity between the two. As a result it is necessary to test physical, chemical and numerical models in laboratory tests and use these models to predict actual flight conditions. It is important for laboratories to be able to test the validity of such models using Computational Fluid Dynamics (CFD) codes. CFD methods are desirable for predicting the effects of hypersonic flow over bodies, however they require comparison with established experimental methods to confirm their reliability as a prediction tool. The ability of CFD codes to accurately predict the effects of different flow conditions and their interactions when flowing over different geometries needs to be verified. To achieve this it is necessary to produce experimental results with known flow and boundary conditions and to compare them with CFD simulations produced using the same conditions. This study is concerned with CFD modelling of the laminar-separated flow that occurs during the passage of a hypersonic freestream over a concave (compression) corner. In particular, the study is concerned with the thermal loads that result from flow separation over the compression corner. Computational simulations of hypersonic flow over 2-dimensional (2D) and axisymmetric compression corner geometries are made using the GASP and FASTRAN CFD packages. A comparison is made between the relative performance of the two CFD packages, as well as their correlation with PLIF1 thermometry images obtained during previously undertaken experiments in the Australian National University's T2 and T3 Shock Tunnel facilities.
The aims of this study were to:
|
