Generating High Speed Earth Re-entry Test Conditions in an Expansion Tube for Interplanetary Return Missions

Future space missions, such as return from Mars, will require entry speeds of the order of 15 km/s. These harsh conditions are dominated by radiative heat flux, coupling of surface ablation with the flow radiation, have never actually been tested in a flight scenario, and have scarce and limited ground testing data available. This paper investigates the feasibility of generating these conditions in the X2 expansion tube at the University of Queensland so that these flows can be tested over scaled test models for the study of shock relaxation, heat flux, shock standoff, or ablation. This paper presents a theoretical performance map of the X2 facility for the generation of these conditions, before it presents some of the unique issues which may be encountered when generating and investigating them. Some preliminary experimental data is then presented, showing that these 15 km/s equivalent flight speed test conditions can be generated in X2 within the current performance limits of the facility