A study on a surface ablation of the jet vane system in a rocket nozzle

During the rocket propulsion process, the jet vane which is installed in the rear side of rocket nozzle part is ablated chemically or mechanically due to the interaction of vane with a combusted gas. In this study, the simulation for the chemical ablation phenomenon of jet vane is tried out as a basic research on the jet vane performance test. Also, distributions of thermal boundary conditions such as heat transfer coefficient and recovery temperature are calculated and used as the input values for the acquisition of surface ablation rate. The thermal boundary layer integral method is applied to the calculation of these boundary conditions. User defined functions are inserted into a numerical code (FLUENT) for calculation of thermal boundary conditions and surface ablation rate. Leading edge on a jet vane is heated heavily compared with the side surfaces and therefore the ablation occurs primarily on that part. When the jet vane is rotated, the windward surface is heated and ablated more than the leeward surface. However, the ablation rate on a side surface is much lower than that on a leading edge of vane, so ablation of jet vane side surface can be ignored during the jet vane ablation simulation. In about 10 seconds of vane operation time, total ablation area is calculated not to be over 4% of the vane side surface area.