Numerical Simulation on Muzzle Flow Field of Deflection Device of Cannon Pod

Abstract

In order to reduce the harm to the airfoil caused by the flow field at the bore port of pod cannon installed under the airfoil,a cannon pod deflection-device was designed according to the foreign advanced cannon-pod deflection-device structure. Based on the three-dimensional Euler equation and the hydrodynamic calculation software,the flow fields of the bore port with and without deflection device were numerically simulated respectively by applying the overlapping grid technology. The bore port flow-fields with deflection device of 0°,30° and 60° miter angles were simulated and analyzed respectively. The harm caused by asymmetric flow-field structure of deflection device with different miter angle bores on airfoil was studied. The results show that this deflection-device changes the symmetrical flow-field into an asymmetric one,which can effectively reduce the impact and burn of gunpowder gas on the airfoil. In addition,with the increase of the deflection device miter angle, the reduction is more obvious, which contributes to reducing the harm of gunpowder gas to the airfoil. Through the calculation of the lateral velocity of the projectile, the lateral velocity increment of the projectile can be obtained. The lateral velocity of the projectile is mainly caused by the eccentric structure and the miter angle of the deflection device. With the increase of the miter angle,the lateral velocity increment of the projectile has a tendency to decrease first and then increase. It can minimize the lateral velocity increment and ensure the shooting accuracy to select the appropriate miter-angle.