Numerical investigation on combustion in muzzle flows using an inert gas labeling method

The influence of the precursor flow on combustion in muzzle flows is investigated. The fourth-order Runge-Kutta method is employed to solve the classical interior ballistics model, providing velocity for the projectile when it accelerates along the barrel. An inert gas labeling method is proposed. An additional species, helium, is chosen as the label to tracing the precursor gas which fills the barrel before the projectile starts. A high-resolution upwind scheme, AUSM+ (Advection Upstream Splitting Method), and detailed reaction kinetics model are employed to solve the multispecies Navier-Stokes equations with finite rate chemistry. The precursor flow generated by the precursor gas driven out of the barrel ahead of the projectile is simulated. The development of muzzle flow with chemical reaction is simulated. It is demonstrated from the results that the secondary temperature rise in the intermediate region behind the Mach disk is attributed to combustion in this area. It is found that the core of the precursor gas supplies oxygen for combustion at 150μs after the projectile base leaves the muzzle. Furthermore, despite the disrupted precursor flow, the precursor gas is still united and gradually diffuses into the propellant gas.