Aerothermal analysis of plume interaction with deployed landing legs of the CALLISTO vehicle

Kurzfassung

The current European long term strategy aims at moving towards reusable launch vehicles (RLV) for the first stages of launchers. In accordance with this strategy the German Aerospace Center (DLR) has entered into a collaboration with the Japan Aerospace Exploration Agency (JAXA) and the French Space Agency (CNES) for the development of RLV relevant technologies. A part of this collaboration is a vertical take off and vertical landing (VTVL) reusable subscale launcher first stage demonstrator - the Cooperative Action Leading to Launcher Innovation in Stage Toss back Operations (CALLISTO). The mission of the CALLISTO vehicle is to return to the launch pad using retro propulsion and an Approach and Landing System (ALS) with extendable landing legs. This development leads to additional aerothermal design questions compared to traditional launchers. In the case of CALLISTO the highest heat fluxes are caused by heating from hot exhaust gases of the aft bay section. This especially affects the unfolded ALS during the final phase of the landing approach. The arising heat fluxes, therefore, influence the structural design and the thermal protection system (TPS) of the ALS. In this study we conduct computational fluid dynamics (CFD) investigations using Reynolds averaged Navier Stokes (RANS) methods of the aerothermal loads on the ALS during the landing phase. We use the Spalart-Allmaras turbulence model and frozen chemistry for the simulations. We analyse the flow field as well as the surface distributions. We investigate the necessity of simulations including the plume for these analyses. We use analyses of the flow fields as well as the surface distributions to investigate the influence of angle of attack, angle of roll, atmospheric conditions, flight speed and thrust level.