柱形充液室内多股燃气射流流场的气体与液体两相流场演化特性

基于水下枪炮发射的工程背景，对火药燃烧形成的多股高压燃气射流从模拟弹头头部喷入柱形充液室的过程进行了实验观测和数值模拟研究。实验观测采用高速录像记录，数值模型采用流体体积函数模型来描述液体环境中多个燃气泡的扩展，数值模拟结果与实验观测结果相符。数值仿真结果表明：喷孔轴线上的燃气压力经历下降和上升的过程后达到稳定值，空腔附近的水流场由于燃气作用出现压力峰，随后逐渐衰减；在燃气空腔扩展的过程中，离喷孔距离越远的截面上燃气-水流场的压力分布越均匀，截面平均压力随着空腔扩展逐渐下降；随着时间的增长，截面上气体组分分数可达70%.

The Evolution of Gas-liquid Flow of Multiple Combustion Gas Jets in a Cylindrical Water-filled Chamber

The injection process of multiple high-pressure combustion gas jets is observed experimentally and simulated numerically during gun firing underwater. The gas is generated by gunpowder burning and injected into a cylindrical water-filled chamber through simulated bullet. In experiment, a high-speed camera system is used to record the injecting process of air. The volume-of-fluid method is used to describe the expansion of the gas cavities in water. The numerical results show a good agreement with experimental observations. Numerical simulations show that the gas pressure along the axis of orifice reaches a steady value after declining and rising. A pressure peak appears in the water near the gas cavity under the effect of combustion gas, and then is gradually attenuated. During the expansion of the gas cavities, the pressure distribution of gas-water flow field on a cross section away from nozzle is relatively uniform, and the average pressure on the section decreases with the expansion in the cavity. The area fraction of gas on the section could be up to 70% over time.