A Numerical Study on the Thermal Loads During a Supersonic Rocket Retro-Propulsion Maneuver

Abstract

Return and vertical landing oft the first launch stage is a concept enabling reusable launch systems and has been successfully applied by SpaceX with the Falcon 9. The Falcon 9 first stage descends by two or three phases of retro-propulsion. Especially the supersonic retro-propulsion phase, using three of its nine engines, is of interest as it exhibits conditions close to Mars reentry. During retro-Propulsion the first stage is partially submerged in the hot exhaust plume. In this study a generic model based on the Falcon9's features and dimensions is used to perform a numerical Investigation of the plume-vehicleinteraction. Using Large eddy Simulation (LES) and Reynolds-A veraged-Navier-Stokes equations (RANS) based computation al methods the flow field is characterized at different trajectory points during retro-propulsion. Based on several steady RANS calculations, an aerothermal data base is created and coupled into a simple finite element structural heating model of the casing. Results show, that despite the high gas temperatures, the low gas density leads to amanageable heat flux and only moderate temperature increase on the cylindrical walls when using conventional Aluminum materials.