Research On Numerical Simulation Of Attitude Control Rocket Engine Plume

The flight attitude and orbit changes of the spacecraft in space are made by the attitude control engine. The plume generated from the running thrusters may have an impact on the antenna, sensitive apparatus or the surface of the solar panel in aerodynamic force,aerodynamic heat or plume contamination, the worst cases resulting in damage of the components or the reduction of the service of the spacecraft. Therefore, an accurate prediction of the impact produced by the engine plume is of vital significance particularly in the design of spacecrafts.The attitude control engine woks in an environment where the air density is extremely low. When the Knudsen number (the ratio of the mean free path of gas molecules to the characteristic scale) is greater than one, the continuum medium assumption is consequently no longer proper and the gas dynamics method no longer applicable, and the flow of air is influenced apparently by the rarefied gas effect.In this paper, the numerical value of the attitude control thruster plume flow under the effect of rarefied gas is simulated by the Direct Simulation Monte Carlo method (DSMC) .The impact of the plume impingement effects on the surface of the relevant components of the spacecraft is studied via the numerical simulation of the impingement effect between the plume and the baffle.In order to realize the combination of the internal and the external flow field of the engine nozzle, the simulation on the flow field inside the nozzle is conducted through applying "Fluent", and afterwards, the calculated results of simulation programs serve as the initial conditions for the exterior flow field of the nozzle.The simulation program for the external three-dimensional plume field is compiled based on the core program of "bird" by means of DSMC method according to the rarified gas dynamics theory, studying the change laws of the plume flow field in different working environments to analyze the plume impingement effects generated by the plume flow.Through the simulated analysis of the engine plume, we can study distribution of the flow field outside the nozzle to describe the degree of rarefied gas, which confirms the necessity of applying the DSMC method in the study of the high altitude engine plume field.First, the parameters of the change laws of the flow field under the unimpeded condition are analyzed. After that, the thruster plume effects of the baffles impinged in different positions(including vertical board, horizontal board and sideling board) are studied to analyze the impact of position modification of the baffles on the impingement effects. Now, we can obtain the change laws of the density, pressure, temperature and velocity of the engine plume in different working environments, from which we can analyze the compact of the plume on the impingement effects such as aerodynamic force and aerodynamic heat produced by the baffles in different positions.