A Computational Fluid Dynamic Study for Temperature Uniformity at a Wind Tunnel Outlet with Effects of Heat Transfer along Tunnel Walls

A Computational Fluid Dynamics (CFD) Modelling was carried out to investigate temperature uniformity at a wind tunnel outlet region to benefit its design and construction. Low temperate (110K) nitrogen entered the wind tunnel at inlet, passed through two turning area with 18 turning vanes and went into expansion session, stable session and congestion session, finally towards outlet discharge nozzle session. The model considered static nitrogen isolation layer in physical model and three more isolation layer outside the tunnel as well as possible heat transfer from ambient environment. Two case scenario for supersonic and subsonic at outlet (Mach Number 0.9 and 1.3) were conducted with a uniform temperature imposed at inlet, as well a 3rd case scenario (Mach Number 0.9) with a non-uniform temperature distribution at inlet. Existence of porous zone (to model honeycomb session) and porous interfaces (to model damping interfaces) at the stable session were also included. Contours of temperature and velocity on representative cross sections were presented, and effects of Mach number, total pressure and initial temperature distribution at inlet on temperature uniformity at outlet were discussed. Based on the numerical results, improvement of tunnel geometry for better flow uniformity at outlet regions were also suggested. (paper)