Research on the Process of Dispersing the Bullet by a Large-Size Gasbag with Multiple Inlet Nozzles Based on the Fluid–Structure Interaction Method

Abstract To meet the needs of the airborne dispenser to disperse large-mass bullets, the dispersal system of large-size gasbag with multiple inlet nozzles was designed and built. The rationality and feasibility of the dispersal system were verified by the experimental study of the interior ballistic process. On this basis, the fluid–structure interaction method was used to simulate and analyze the process of the gasbag propelling the bullet when the number of inlet nozzles is different. The calculation results show that the final shape of the expanded gasbag is pillow shaped, and wrinkles appear at the ends of the long side and in the middle of the short side of the gasbag. The stress at the wrinkles is relatively large, and the stress on the wall of the gasbag with three inlet nozzles is greater than that on the wall of the gasbag with two inlet nozzles. Affected by the changes of flow field in the gasbag and the deformation of the gasbag, the process of the gasbag propelling the bullet is divided into two stages, and there are also two large fluctuation peaks during the change of the acceleration of the bullet. Moreover, the expansion process of gasbag with two inlet nozzles lags behind that of the gasbag with three inlet nozzles, and the maximum acceleration and separation velocity of the bullet are also relatively reduced by 2% and 3%, respectively.