Numerical and Empirical Studies of Heat Transfer in High-Enthalpy Argon–Air Mixtures

Abstract

The present work uses numerical simulations to examine the effect of added argon on stagnation heat flux in high-enthalpy airflow in arc-heated wind tunnels. An in-house solver is used to compute laminar high-enthalpy flow of argon–air mixtures over a cylinder under the assumption of local thermochemical equilibrium. The study considers a range of stagnation enthalpies, over which chemical reactions in the stagnation region are increasingly more significant. Considering a range of wall temperatures between 294.4 and 2000 K, the existing correlations for stagnation heat flux with the current numerical results are compared. It was found that the correlation by Kemp and Riddell (“Heat Transfer to Satellite Vehicles Re-Entering the Atmosphere,” Jet Propulsion, Vol. 27, No. 2, 1957, pp. 132–137) performs better than the others. Computations were also performed to study the effect of argon, where it was found that the available correlations do not agree well with the computed heat fluxes. Based on the current simulations, a modification is proposed to the generalized Chapman form to capture the effect of argon on the stagnation heat flux.