Modeling the Complete Operation of a Free-Piston Shock Tunnel for a Low Enthalpy Condition

Introduction

Accurate analysis of experimental data from hypersonic impulse facilities is difficult due to the limited amount of free-stream flow property data that can be measured at the nozzle exit. Reflected shock tunnels (RSTs) are particularly difficult due to short test periods and high total pressures. To over come the lack of knowledge at nozzle exit in RSTs, experimenters typically calculate the quasi-steady gas properties at nozzle exit based on assumption that the test gas is processed, in stages, by idealized waves that are essentially decoupled. Such a simplified calculation uses shock tube initial fill conditions, experimental incident shock speed, stagnation pressure and Pitot pressure as inputs.