Mohammad-Reza Heidari - Associate Professor of Department of Aerospace Engineering, Islamic Azad University,Parand Tehran, IRAN P.O.B 6673637673
Seyed Mohammad-Hosein Mousavi-Sajad - Aerospace graduate student of Islamic Azad University

In this paper, the transient simulation of hypersonic flow is performed inside a typical blowdown-indraft wind tunnel along, with the standard model inside the test section. This study aims to investigate the sample hypersonic wind tunnel start procedure as well as its transient flow physics and aerodynamics. Due to lack ofpossibility of accurate comparison between the experimental and numerical results in transient condition, the selected turbulence models are investigated first and the SST/k-ω model is chosen for the numerical solution among them. After that, the steady flow solution is performed for the HB2 standard model and the acquiredresults are compared with the experimental ones. After turbulence model validation, specifying the assumptions,and studying the grid in steady flow, the transient flow is numerically simulated across the entire wind tunnel domain including the nozzle, the test section and the diffuser. The acquired results from the transient numerical solution show that a shock wave is formed after the nozzle throat and it moves toward downstream of the tunnel internal flow. The results of the performed analyzes present the required time intervals for the tunnel start, shockwave motion as well as its passage over the model, and finally, development of the steady state flow across theentire tunnel both, quantitatively and qualitatively. This study facilitates reaching improved understanding and correct perception of the aerodynamic procedure of the tunnel start and possible obstacles along the way of extracting design conditions and applications of hypersonic wind tunnels. Both, steady and transient numerical solutions are performed using finite volume method and the flow is assumed to be axisymmetric

numerical simulation, transient flow, hypersonic wind tunnel, standard test model, turbulence model