水下航行器-发射筒间隙流动仿真

Simulation of Gap Flow of an Underwater Vehicle-Launch Tube

针对水下航行器发射尾部经过气密环时发射筒底与气密腔连通过程,采用动边界非定常数值仿真,研究了不同初始压比与航行器运动速度下航行器-发射筒间隙内的流场演化与压力脉动特性。结果表明,尾部连通初期筒底高温高压气体进入间隙腔的瞬时速度可达音速以上,气流在冲击远离筒底的气密环后反射并产生剧烈的流动振荡和压力脉动。随着航行器运动,连通区增加压力脉动幅值下降;当初始压比增加时,压力脉动峰值和谷值线性变化,在初始压比p_(t)/p_(0)=3.0时相对峰值和谷值分别可达1.4倍和0.5倍间隙初始压力;航行器运动速度增加时泄漏速度增大,压力脉动峰值增大且出现时间提前;以上参数下压力脉动周期不变。

When the tail of an undersea vehicle passes through the seal ring, complex characteristics—such as high speed and separation flow—arise during the connection process of the bottom of the launch tube and the seal cavity. Considering these characteristics and using the dynamic boundary unsteady value simulation, the flow field evolution and pressure fluctuation characteristics in the vehicle-tube gap were studied under different initial pressure ratios and vehicle speeds. The results show that the instantaneous speed of the high-temperature and high-pressure gas at the bottom of the tube can exceed the speed of sound when entering the gap cavity in the initial stage of the tail connection. The airflow is reflected after hitting the seal ring away from the bottom of the tube and produces violent flow oscillations and pressure fluctuations. Owing to the movement of the vehicle, the connection area increases and the impact peak amplitude gradually decreases. The amplitude of pressure fluctuation increases linearly with the initial pressure ratio. When the initial pressure ratio is 3.0, the relative peak and valley values of the pressure fluctuation can reach 1.4 times and 0.5 times of the initial pressure, respectively. When the speed of the vehicle increases, the leakage rate and peak pressure increase and the time of occurrence is advanced;meanwhile, the pressure fluctuation period remains unchanged under the above parameters.