Numerical Simulation Of Muzzle Flow Field Using Modified AUSM Scheme

The muzzle blast wave is an important factor which affects the firing precision, so muzzle flow field is simulated by developing program. Initial muzzle flow field caused by the movement of projectile in barrel and the interaction between projective and flow field are considered. The development of muzzle flow field is analyzed. Main points are as follows:The mathematic model of muzzle flow field is established using Euler formulation of ALE form as governing equation. To solve the model, Finite Volume Method is used to process spatial discretization; AUSM~+-up sheme is chosen to calculate surface convection flux of control volume; different kinds of mesh are dealt with limiters and solution reconstuction; time discretization is processed using four-order Runge-Kutta method; dummy cell is used to process boundary condition. The complex shape of projectile is dealt with unstructured mesh. The movement of projectile is handled using hybrid moving mesh to avoid the reconstuction of mesh and to reduce the error of interpolation as far as possible. Object-oriented, unit test, version control and other software engineering methods are used to develop program, which can run in different operating systems. The numerical examples of shock tube, flow over circular cylinder and circular cylinder moving in flow field are calculated to inspect and verify the program.The muzzle flow filed of 7.62mm rifle is calculated and analyzed. Internal ballistics is coupled, the movement of projectile in and out of barrel are calculated together to avoid the loss of accuracy caused by splitting them. The pressure in front of projectile is considered to modify the calculation. The phenomena are analyzed using the result, such as the movement of projectile in barrel, the development of muzzle flow field, etc.