Dsmc Method In The Transition Region Supersonic And Hypersonic Flow

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.With the structured body-fitted grids, the movement of simulate molecular is traced and the collision molecules is selected. Based on the structured grids, the molecules' tracing and locating method, which is called grid face vertical vector tracing method, is developed. Using this method, the molecular movement, molecular indexing and the collision between molecules and body surface are finished in a cycle. Moreover, molecules are located by computing the dot product of the six grid faces' vertical vector. The computational efficiency is improved greatly.For the VSS molecular model, the internal energy exciting and relaxation probability is established to simulate energy exchange involving translational, rotational and vibrational modes based on Larsen-Bergnakke model. No time counter method is used to select collision molecules 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.With the above method, flows in transitional region around cylinder, sphere double cone and Apollo capsule are simulated. The aerodynamic and flow characteristics 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.