ENDGAME - Laboratory Experiment 2024-01-17 Exp. 003 - High Speed Camera data

Shock-tube experiments in combination with high speed Schlieren shadow photography. The shocktube setup consists of a high-pressure reservoir connected with a cylindrical tube through a diaphragm pulse valve which allows a fast release of pressurized gas into the ambient pressure tube. The high-pressure reservoir is filled with compressed air at a given overpressure with respect to ambient pressure (up to 8 bar). The pipe was either empty (i.e. with air at ambient conditions) or filled with a given amount of small particles. We adopted pipes an inner diameter of 4 cm and different lengths (20, 30 and 80 cm). We also considered different volumes of pressurized gas (~650 cm3 and ~1550 cm3). A pressure sensor has been placed at the vent of the conduit to record pressure variations during experiments. Images from the high speed camera were collected at a frame rate of 30000 fps. When the valve is open, a jet flow is produced, with shock and acoustic waves propagating in the atmosphere, which become visible due to the high speed Schlieren shadow photography.激波管（Shock-tube）实验结合高速纹影阴影摄影（high speed Schlieren shadow photography）开展。 本实验所用激波管装置由高压储气罐与圆柱形管段组成，二者通过膜片脉冲阀连接，该阀可将高压气体快速释放至常压管段内。高压储气罐内充装的压缩空气相对于环境压力存在设定过压，最大过压可达8 bar。实验管段可为空管（即内部为环境条件下的空气），或装填定量的细小颗粒。本次实验采用内径为4 cm的管段，管长分别为20 cm、30 cm与80 cm；同时还设置了两种不同容积的高压气体充装量（约650 cm³与1550 cm³）。实验中于管道排气口处安装压力传感器，用于记录实验过程中的压力变化。高速相机以30000帧每秒（fps）的帧率采集图像。 当膜片脉冲阀开启时，会产生射流，同时伴随激波与声波在大气中传播，借助高速纹影阴影摄影技术可清晰观测到上述波动现象。