Abstract: In order to prevent or control hydrogen explosions in the confined vessels, experiments were carried out by using a 20 L confined spherical vessel, and parameters of hydrogen-air explosion were measured, such as the maximum explosion pressure and the maximum rate of pressure rise at different initial low-pressures conditions(0.025-0.1 MPa). The standard turbulence model (k-ε) and the probability density function (PDF) model, and Fluent software were used to simulate the explosion process of hydrogen-air mixture under different pressure. It was shown that the maximum explosion pressure and maximum rate of pressure rise are linear with the initial pressures when the hydrogen concentration is kept constant, that the maximum explosion pressure decreases by 75.1%-75.9% and the maximum maximum rate of pressure decreases by 77.1%-83.7%, when the initial pressure decreases from 0.1 MPa to 0.025 MPa, and that the time taken by the flame front reaching the wall of the apparatus is longer when the initial pressure is lower.

Key words: low-pressure effect, maximum explosion pressure, maximum rate of pressure rise, numerical simulation, flame propagation characteristics