Computational Studies of the Virginia Tech Hypersonic Wind Tunnel

This paper presents steady-state (viscous) and timeaccurate (inviscid) numerical solutions of the flowfield inside the Virginia Tech Hypersonic Wind Tunnel (VTHST) with a Mach 4 nozzle. The numerical solutions are obtained using a computational fluid dynamics (CFD) solver named GASP. Comparisons between the steady-state CFD solutions and available experimental data are also presented in this paper. The first objective of my research is to study the steadystate flowfield characteristics of the VTHST. The second objective of my research is to simulate the supersonic wind tunnel starting process, which has seldom been simulated using CFD. I was able to obtain reasonable Mach contours with my steady-state CFD calculations. However, I determined that steady-state CFD calculations cannot accurately predict the flowfield inside the VTHST because much higher pressure ratios (the total pressure in the settling chamber divided by the back pressure at the diffuser exit) are required to start the VTHST in steady-state CFD calculations than those required to start the actual tunnel. Currently, I am running time-accurate calculations for the VTHST with a Mach 4 nozzle. Although the calculations are still in progress, it seems that the VTHST can start at the correct pressure ratio in the time-accurate calculations.