Estimation of Effective Specific Heat Ratio Based on Shock Stand-Off Distance Measurement of a Blunt Body in Hypersonic Air and CO2 Flows

초록

The objective of this study is to find effective specific heat ratio through experiments and related CFD simulations. To this end, the shock stand-off distance was measured using a detonation-driven shock tunnel under both Earth and Mars atmospheric conditions. Further, the thermochemical non-equilibrium characteristics of high-enthalpy hypersonic flow were simulated using the 2-T model, and the Mach number of the flow was calculated. The experimental and simulation results showed that the shock stand-off distance decreased with increasing total enthalpy in both air and CO2. The measured shock stand-off distance and the calculated Mach number were substituted into the equation proposed by DeChant of Sandia National Laboratories to derive the effective specific heat ratio. Using the estimated effective specific heat ratio, the predictability of flow characteristics before and after the shock wave was confirmed. As a result, it was possible to estimate the flow characteristics from the Mach number and total enthalpy conditions for the aerodynamic design of hypersonic vehicles.

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