In the present work, different modelling approaches are applied for the numerical simulation of high enthalpy flows with equilibrium air assumption. The first approach uses Srinivasan curve fits for estimating thermodynamic and transport properties of air at high temperature whereas the second method estimates the properties by computing the equilibrium air composition at a given density and temperature. Another approach of computing equilibrium flow by running perfect air simulation with equivalent specific heat ratio is also shown. Two-dimensional Navier-Stokes equations are solved using in-house finite volume solver capable of solving perfect gas and equilibrium air flows. Numerical results are presented for various invis-cid and viscous laminar flow cases. In the case of inviscid hypersonic flow over a cylinder, lower post shock stagnation temperature is obtained with equilibrium air assumption as compared to perfect air flow with constant specific heat ratio. For the viscous simulations, numerical results for 2 cases are presented : hypersonic laminar flow over a flatplate and shock wave-boundary layer interaction (SWBLI) over a compression corner. In the flatplate case, hydrodynamic and thermal boundary layer obtained with curve fits and composition approach match with the literature. This case is also run with different Argon concentrations. It is observed that increase in Argon concentration leads to increase in the peak temperature and wall heat flux. However, the increase is insignificant for moderate Argon concentration. In the SWBLI case, smaller separation bubble is obtained with equilibrium air assumption compared to perfect air, which is in accordance with the literature. Moreover, lower temperature is obtained in the boundary layer for equilibrium air.
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