Numerical Study on Influence of Wall Thermal Effect on Thermal Impact of Gas Explosion

Abstract

A gas explosion can impact the roadway and cause serious damage. The thermal effect of the roadway wall is an important factor affecting the gas explosion and its impact. In view of the shortcomings of existing research studies, a basic numerical model of a pipe is established under the thermal impact effect of a gas explosion based on LS-DYNA software. The thermal conductivity coefficients of the pipe wall are set as 15, 30, 45 and 60 W/(m·K), respectively. Five measuring points A–E are set on the inner wall of the pipe, and four measuring points F-I are set in the air region. The equivalent stress distribution of the pipe wall, the pressure and displacement of each measuring point and the time history curve of shock wave velocity at the measuring point in the air region are numerically simulated under the impact of a gas explosion with different thermal effects. The research results show that the stress concentration phenomenon is more obvious and the equivalent stress distribution is more uneven, and the gas explosion intensity is greater when the pipe wall is approximately adiabatic. With an increase in the thermal conductivity coefficient, the amount of thermal dissipation through the pipe wall increases, the pressure peak value of each measuring point of the pipe wall decreases as a whole, and the radial displacement value of the arranged measuring points presents a smaller trend. With an increase in the thermal conductivity coefficient of the pipe wall, the thermal dissipation of the pipe wall increases, so the subsequent energy that drives the shock wave decreases, the impact degree on the pipe wall also decreases, and at the same time, in the pipe with a high thermal conductivity coefficient, the gas explosion energy involved in expansion work is lower, and thus the explosion intensity reduces. The shock wave velocity at a location farther away from the explosion source after a gas explosion also decreases. The research results have important practical significance for improving the theory of the wall thermal effect and the level of gas explosion prevention in confined spaces.