Structural response for vented hydrogen-air deflagrations: Effects of volumetric blockage ratio

The explosion venting experiments of hydrogen-air premixed gas were carried out in a 1-m³ cuboid container. The effects of the obstacles parallel to the vent on the structural response of the container during the explosion venting were investigated. The internal overpressure and acceleration of the vessel wall were captured by acceleration and pressure sensors, respectively. The time–frequency distributions of pressure and acceleration were obtained by a Short-Time Fast Fourier Transform. The effects of obstacles on the dynamic structure response were studied by analyzing the internal overpressure, vibration acceleration, and high-speed videos. With the increase of obstacles, the maximum overpressure and vessel vibration increased, and the maximum overpressure and maximum vibration acceleration appeared earlier. The vibration signals had two dominant frequencies, 300-600 Hz and 900-1200 Hz. The low-frequency vibration (300–600 Hz) was induced by acoustic oscillation of the internal pressure. The high-frequency vibration (900–1200 Hz) was a container resonance triggered by the coupling of the flame and the acoustic wave. As VBR increased, the duration of high-frequency oscillations decreased gradually; the increase of obstacles would weaken the high-frequency structural response of the container. The results can guide the design of hydrogen explosion protection and mitigation measures.