Chemical Reactions In Hypersonic Rarefied Flow Dsmc Numerical Simulation Study

On the basis of molecule gas dynamics, the direct simulation Monte-Carlo (DSMC) method for the simulation of chemical reaction of hypersonic rarefied gas flow is studied through the combination of the existing DSMC numerical theory in this thesis. The DSMC program for reacting rarefied gas flow is developed to analyze the aerodynamic and aerothermdynamic characteristics around the hypersonic aero-vehicles.The present work apples the Larsen-Borgnakke phenomenological theory to describe the energy exchange between the kinetic and internal modes of collision molecules. On this basis, the DSMC phenomenological chemical reaction model is developed using the steric factor method. This model employs Larsen-Borgnakke theory for vibrational excitation to treat dissociation. While for combination reaction, the equilibrium collision theory is used in order to avoid the error caused by the difference equilibrium temperature in mixture gas. Additionally, a new method that combines the Maximum Entropy and DSMC method is presented without the assumption of local equilibrium distributions, and is more efficient for non-equilibrium condition.The numerical procedure of the present work adopts VHS molecular model, and according the grid principles in DSMC, a composite molecular kinetic tracking method which deals with the tracing of simulated molecules efficiently is developed based on the structured body-fitted grids. NTC method is used to select collision molecules and diffuse reflection model is used for the collision between molecules and body surface. Some cases employ finitely catalyzed method to the disposal of wall boundary, and useful results are obtained.Finally with the work above, the numerical simulation of chemical reaction in closed high temperature area, and hypersonic flows with high altitude around cylinder and blunted cone are carried out. The parameters of flow field and body surface are analyzed. By comparing the present results with the theory, experimental data and the reference numerical results, it is proved that the phenomenological reacting model developed in this thesis is reliable.