Numerical Simulation And Aerodynamic Calculation Of Supersonic Warhead In The Rarefied Atmosphere

The ruthless property of the modern war forced missiles to be flying much higher, which has to be more prominent gas rarefaction effect on those missiles fly in the high altitude. In that high altitude environment, it is no long applicable for the Navier-Stokes equation based on the assumption of continuity, while using the Boltzmann equation to solve is very difficult, so it is necessary to adopt a new method which can solve the rarefaction gas flow issue. The method of DSMC simulated flow field through computer calculation, which avoided complex mathematical, it’s also been quite successfully applied to lots of various industries. This article is aimed to study and write a general Aerodynamic parameter obtain program base on DSMC technique method with rectangular grid simulation for researching of hypersonic gas flow. Then compare with engineering calculation for further digging out the possibility of combining DSMC and engineering calculation.First of all, this article studied some basic theoretical knowledge of gas molecular dynamics, which describe the structure progress of velocity distribution function, made the basic assumption of the rarefaction gas flow, and the graph representation for gas macroscopic quantity. Through analyzing elastic collision to derive the formula for calculating the velocity of the molecule. It studied molecular interaction potential and several common molecular patterns.Secondly, this article discussed general method of the Cartesian grid, to extend the object boundary to be intersect of the grid. We also studied the case of the cutting process and the reflection of the molecules on the surface of the object, the cutting process of the intersecting grid. The method is proved to be correct after analyzing the change regulars of the parameters through simulating flow under variety of different conditions of wedge.Next one, more efficient proposal for searching the molecular position is raised after a depth discussion on the implementation and application of the DSMC method in the 2 dimensional thin air flow. However, some details of the DSMC program are studied, and the model is built up and realized by the simulation of the interaction between the molecules and the object surface. The sampling and the change of the molecular energy are studied. The calculation procedure of the DSMC program is given. Using FORTRAN90 software to develop DSMC program for arbitrary shaped warhead at any height. The numerical simulation of hypersonic flow in two dimensional case is carried out.Finally, we study the parameters after the shock wave.Compared the two kinds of physical parameters of different regions. Obtained the parameters after the shock wave in rarefied gas by DSMC methods. We developed a new type of engineering calculation methods witch is based on the shock-expansion wave methods and compare the simulation result with the DSMC methods in the same condition.At last we discussed how to promote the new method and the study points in the future.