Research on the base cavity of a sub-launched projectile

The finite volume method based on a multiphase model is adopted to solve the Reynolds-Averaged Navier-Stokes (RANS) equations, which takes into account the effects of fluid compressibility, viscosity, gravity, medium mixture and energy transfer of water and combustion gas. The program Fluent User Define Function (UDF) module combined with the dynamic mesh method is employed to simulate the coupling flow field of combustion gas, water field and trajectory of projectile. The results show that the volume of gas cavity at the bottom of projectile and tail pressure will fluctuate after bottom of the projectile leaving the launch tube. The cause of the fluctuation is analyzed and its effects on the trajectory of projectile are presented. The numerical and experimental results agree well with each other.