Diaphragm opening processes with a finite time affect the generated shock waves and shock tube flows. This effect is dominant in short and low-pressure shock tubes. In this research, a high-speed visualization of the opening process of a cellophane diaphragm, which is a suitable material for operation in a low-pressure shock tube, is conducted. The self-shaping opening morphology of cellophane diaphragms is observed at the initial stage with an approximate crack propagation speed of 807 m/s, which is greater than the speed of sound of the test gas. The initial opening motion of the petals, which are formed by cracks, is successfully modeled by the rotational equation of motion. Through analysis of the generation and coalescence of compression waves, whose characteristic velocities are calculated from the measured pressure histories, the shock formation distance is reasonably estimated. From the visualized diaphragm opening processes and analysis of coalescence of compression waves, we revealed that the initial stage of the diaphragm opening process plays a dominant role in shock wave formation rather than the entire process.

中文翻译：

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玻璃纸隔膜破裂过程对激波管中激波形成的影响

具有有限时间的隔膜打开过程会影响产生的激波和激波管流动。这种效应在短的和低压的激波管中占主导地位。在这项研究中，对玻璃纸隔膜的打开过程进行了高速可视化，这是一种适合在低压冲击管中操作的材料。在初始阶段观察到玻璃纸隔膜的自成型开口形态，裂纹扩展速度约为807 m/s，大于测试气体的声速。由裂纹形成的花瓣的初始张开运动通过旋转运动方程成功建模。通过分析压缩波的产生和合并，压缩波的特征速度是从测量的压力历史中计算出来的，合理估计激波形成距离。从可视化的隔膜张开过程和对压缩波合并的分析，我们发现隔膜张开过程的初始阶段在冲击波的形成中起主导作用，而不是整个过程。