A Prediction Method for the Performance of a Low-recoil Gun with Front Nozzle

Abstract

With the increasing muzzle velocity of guns, heavier mount is required to absorb the recoil during firing cycle. One of the greatest challenges in the design of a gun is to balance the muzzle velocity and the recoil, especially for guns on aircrafts and deployable vehicles. To resolve the conflict between gun power and maneuvering characteristics, lots of new low-recoil weapons and devices have been developed in recent years. A concept of rarefaction wave gun (RAVEN) was proposed by Dr. Kathe to meet the demand above. The RAVEN is based on rarefaction wave theory and has a similar structure to the recoilless gun. It can significantly reduce the weapon recoil and the heat in barrel, while minimally reducing the projectile velocity. The main principle of the RAVEN is that the rarefaction wave will not reach the projectile base until the muzzle by delaying the venting time of an expansion nozzle at the breech. Studies over the past two decades have provided important results on the RAVEN by experiments and theories. Recently, investigators have examined the effects of the open time and the positions of vents for the RAVEN. The performances of low-recoil guns such as muzzle velocity and recoil are very corresponding to both effects above, particularly for the RAVEN with front nozzle. The purpose of this paper is to provide an engineering method for predicting the performance of a low-recoil gun with front nozzle. Numerical simulations in the RAVEN with front nozzle were carried out by using the transient two-dimensional two-fluid theory. The propellant combustion, interphase drag, intergranular stress, and heat transfer between two phases were considered in all regions of the RAVEN with front nozzle. To reduce the computational cost and improve the simulation accuracy, the arbitrary Lagrangian-Eulerian approach was used to describe the motions of the projectile. And the second-order finite volume method was implemented efficiently to describe both gas and solid phases. The main conclusions of the study are as follows: (1) The simulation method was validated by a commonly used the AGARD gun. Comparisons of the predicted results of the AGARD gun by our code and other different codes in references demonstrate the accuracy and reliability of our present numerical method. (2) Based on the condition of the AGARD gun, a RAVEN with front nozzle was proposed and numerical simulations were provided to describe and understand the physical phenomenon of the interior ballistic process in the RAVEN with front nozzle. (3) The lower muzzle velocity and the lower recoil impulse are formed by shorter vent opening time. The rarefaction wave will reach the projectile base faster. The shorter distance between vent location and breech can increase the propagation length of the rarefaction wave. The muzzle velocity will increase and the recoil impulse will decrease.