Impact of Shape Change on Capsule Aerodynamics and Shock-wave Boundary Layer Interaction

Blunt capsule shapes have proven to be suitable for atmospheric entry flights on numerous missions. Some concepts like MarcoPolo-R focus on fully passive entry systems without a parachute, demanding for aerodynamic stability of the shape throughout the complete entry flight. These probes are commonly equipped with a Thermal Protection System (TPS) consisting of an ablative material. The recession of the TPS in the early entry flight phase may lead to a significant shape change. The capsule needs to remain aerodynamically stable for a successful mission completion despite these shape changes. Within ESA’s Modshape TRP the aerodynamic impact of the recession on the MarcoPolo-R capsule is investigated experimentally and numerically. Static force and moment measurements in the TMK wind tunnel are a major part of this TRP. The experimental simulations are conducted on the nominal or baseline configuration and two configurations representing the aero shape with the recessed TPS after the hot entry flight phase of different entry scenarios. The flow structure around the capsule is visualised at supersonic Mach numbers by means of schlieren imaging. Under certain conditions, development of a complex shock system on the leeward side of the inclined capsule is observed. Numerical simulations with the DLR TAU code are performed to support the interpretation of the flow phenomena in these cases