高压气体驱动二级轻气炮发射过程的数值模拟方法及应用

A two-stage light gas gun is a common hypervelocity launcher. Over the years, most researchers adopted simplified one-dimensional models and rarely used three-dimensional finite element models. This paper used the coupled Eulerian-Lagrangian algorithm to calculate the gas-driven hydrodynamic field in a 14-mm-caliber two-stage light gas gun. The two-stage light gas gun was decoupled into two three-dimensional numerical models according to whether the diaphragm was broken. A three-factor four-level orthogonal test was carried out to get the material friction coefficient and the broken diaphragm pressure, which were difficult to measure in experiments. The ordinary least square method was used to calculate the orthogonal test data. The friction coefficient between the piston and the pump tube was 0.82, the friction coefficient between the projectile and the launch tube was 0.30, and the broken diaphragm pressure was 11.73 MPa. The orthogonal test showed that the friction coefficient and the broken diaphragm pressure significantly influenced the calculation results. The friction could not be ignored in calculating the launch process of the two-stage light gas gun. So keeping the gun body clean was necessary to improve the projectile velocity. The numerical model for the two-stage light gas gun was established based on the method mentioned above, which completely reproduced the launch process of the gas gun, and visually represented the change of the flow field. The velocities of the projectile were numerically obtained by the established model, which were highly consistent with the experimental results. In addition, the verification condition was selected to analyze the change of the flow field, and the pressure nephograms at the critical moments were given. It should be noted that the velocity range of the projectile was 3－5 km/s. The method is fully applicable for the projectile velocity below 3 km/s and is generalizable for the higher projectile velocity. The gas gun simplification method, grading idea and key parameter confirmation method can be extended to other two/multi-stage light-gas guns, such as solid propellant driven and detonation driven.