喷管对水下爆轰气泡形态和压力特征影响的实验研究

针对具有不同类型喷管的爆轰管在水下爆轰中形成的燃气射流问题,搭建了爆轰实验平台,研究了单次爆轰过程中尾部喷管对水下气泡形态与压力特征的影响。采用数字粒子图像测速技术对高速摄影机拍摄得到的气泡脉动图片进行流场可视化分析,得到各喷管工况下的气泡速度场。为了确认爆轰管内是否形成稳定爆轰波,并观察爆轰波在气液两相界面上的透反射特性,爆轰管尾部安装有2个动态压力传感器,同时在距离喷管一定距离处设置一个水下爆炸传感器,以监测水中传播的压力波。结果表明：扩张喷管工况下的气泡脉动过程与直喷管工况基本一致,但扩张喷管提高了燃气射流速度,气泡膨胀体积更大;因为燃气射流的持续性,收敛喷管工况下的气泡脉动过程具有明显差异,气泡膨胀体积较小,但气泡二次脉动时长相较于一次脉动时长衰减更小;扩张喷管提高了气泡脉动强度,扩张喷管工况下的气泡脉动压力与透射冲击波压力远大于直喷管工况下的气泡脉动压力与透射冲击波压力;收敛喷管工况下的气泡脉动压力与透射冲击波压力都较小,但收敛喷管燃气射流的持续性减缓了气泡脉动压力的衰减速度。相比于直喷管,扩张喷管工况下的气泡脉动时间、气泡脉动压力与透射冲击波压力都更大。收敛喷管工况下的气泡...

Experimental study on effects of nozzles on gas bubble shapes and pressure characteristics of underwater detonation

A detonation experimental system was established to explore the characteristics of underwater detonation gas jets from the detonation tubes with different types of nozzles. The effects of different types of nozzles on underwater bubble shapes and pressure characteristics during detonation were experimentally studied. The digital particle image velocimetry was used to visualize the bubble pulsation pictures captured by a high-speed camera, and the bubble velocity fields in the different nozzle cases were obtained. Two dynamic pressure sensors were installed at the end of the detonation tube to confirm whether the stable detonation wave was formed, and to observe the transmission and reflection characteristics of the detonation wave on the gas-liquid two-phase interface, respectively. An underwater explosion sensor was installed at a certain distance from the nozzle to measure the underwater pressure wave. The results show that the bubble pulsation process in the divergent nozzle case is basically the same as that in the case of the straight nozzle, but the divergent nozzle improves the gas jet velocity and increases the bubble volume of the first bubble pulsation. The combined effect of the convergent nozzle and its reflected shock wave reduces the injection speed of the detonation gas. Because of the continuity of the gas jet, the bubble pulsation process in the convergent nozzle case is obviously different. The maximum bubble volume in the convergent nozzle case is smaller, but the attenuation of the second bubble pulsation duration is smaller than that of the first pulsation duration. The divergent nozzle increases the gas velocity and kinetic energy, which enhances the bubble pulsation intensity, the bubble pulsation pressure and transmitted shock wave pressure in the divergent nozzle case are much higher than those in the straight nozzle case. The bubble pulsation pressure and the transmitted shock wave pressure in the convergent nozzle case are both low, but the continuity of the convergent nozzle gas jet retards the attenuation speed of the bubble pulsation pressure. Compared with the straight nozzle, the bubble pulsation time in the divergent nozzle case is longer, the bubble pulsation pressure and transmitted shock wave pressure are higher. The duration of the bubble pulsation in the convergent nozzle case is shorter, and the convergent nozzle can obviously inhibit the transmitted shock wave pressure and the bubble pulsation pressure.