Influence of key-slot structure on interior ballistic performance of low-velocity aircraft

To investigate the interior ballistic performance of the cooperation of the guide slot and the guide key at a low velocity, a pressure-structure coupling method was put forward to obtain the effect of different structures. A lumped parameter model of an interior ballistic was utilized to govern the propellant combustion. The mechanical behaviors were predicted based on the engineering software ABAQUS. We coupled the interior ballistic parameters and the structures through moving boundaries by using a user subroutine interface VUAMP in ABAQUS. The results show that the coupling approach can accurately predict the movement process of the aircraft in the barrel, and different numbers of slots and different guide key structures were simulated. The fewer the slots, the smaller the resistance of the aircraft, but the corresponding guiding performance is poor. Inversely, more slots lead to the better guiding performance. Furthermore, different guide key structures have a greater impact on the exit velocity of the aircraft, but have little effect on the guiding performance. The guide key with edge rounding-off in side is a better structure case, which can obtain a stable rotational velocity and high launch speed on the premise of ensuring rigidity. The result can be applied to provide an important reference in determining reasonable numbers of slots and guide key structures for the application in engineering.