Numerical and experimental study of plume impingement effects

Plume impingement effects would affect the attitude control and the keeping of spacecrafts, which mainly include aerodynamics forces and heat load. The heat load would put the spacecraft into a hot environment, which could result in damage to some parts or the whole spacecraft. In order to study the plume impingement effects of the attitude control thruster, experimental studies were carried out in a supersonic low density wind tunnel which could simulate the 80km altitude environment. Firstly, the plume impingement forces were measured by experiment which used cold nitrogen as the test gas with three conical model thruster nozzles. Secondly, based on the experimental research on plume impingement effects of model nozzles, the experimental studies were carried out for both the plume impingement forces and heat load with two attitude control thrusters. During the experiment, the heated nitrogen was used to simulate the real working process of the attitude control thrusters. The data of plume impingement forces and heat load were obtained. Thirdly, in order to judge whether the backflow was formed or not, a project was designed to test the heat flux of baffle in the backflow specially. Results of the measurement provided the reference judgment for backflow analysis. To compare with the plume impingement experimental data, calculations were carried out with both engineering method and Navier-Stokes (N-S) equations coupled with the Direct Simulation Monte Carlo method (DSMC). The comparison between numerical results and experimental measurements showed that the engineering method could effectively estimate the plume impingement forces and heat load in the current experiment conditions. The distribution of plume impingement forces and heat load were obtained with DSMC method simulating 3D plume field. The calculated plume impingement forces and heat load on the centerline coincide with measurement results. And the position of both the peak forces and heat load of the calculations also coincide with measurement results. Considering the calculation efficiency, both engineering method and Navier-Stokes (N-S) equations coupled with DSMC method should be used together in plume impingement effects calculations. The work in this paper gives plume impingement forces and heat load data of attitude control thrusters at 80km altitude, which provides valuable reference for engineering applications.