Study On Characteristics Of Atomic Oxygen To Solid Surface In Leo

In this thesis, the direct simulation Monte Carlo(DSMC) method and its models are studied. On this basis, the DSMC program is developed to investigate and analyze the aerodynamic and thermal characteristics around the supersonic and hypersonic vehicles .In this thesis, the binary elastic collision theory has been detailedly analyzed, and at the same time, the simple hard sphere (HS) model, the variable hard sphere (VHS) model, the variable soft sphere (VSS) model for the inverse-power-law have all been introduced. As to the nonelastic collision energy exchange model, the Larsen-Borgnakke model, which is compatible with VHS and the statistical nonelastic collision cross-section model, which is compatible with VSS, also have been proposed.With the structured rectangular grids, the movement of simulative molecules are traced and the collision molecules are selected.The internal energy exciting and relaxation probability is established to simulate energy exchange based on Larsen-Bergnakke model. No time counter method is used to simulate the collision molecules sampled and diffuse reflection model is used to simulate the collision between molecules and body surface. In addition, the cell width and step time of DSMC method are studied and some useful results are obtained.The flow chart of the DSMC program for the gas flow program without nonequilibrium reaction has been proposed and some important details have also been explained.With the program above, flows in transitional region around cylinder, rectangle and arrow are simulated. The aerodynamic and flow characteristics and flow phenomena are analyzed. By comparing the present results with the reference results and experimental data, it is proved that the method developed in this thesis is reliable, and it can provide numerical value for spaceflight aerocraft.