Numerical Simulation on the Influence of Elbow Structure on Hydrogen Flame Propagation Process in Pipes

Abstract

Combustible gas accounts for an increasing proportion of energy in countries. As the main transportation tool of combustible gas, the safety of pipeline has always been the focus of researchers. When the gas explodes, the accident consequences are greatly affected by the pipeline structure. The study on the hydrogen explosion characteristics of a typical pipe structure (elbow structure) is carried out in the paper. The results show that in pipes with large elbow angles, the flame front can form local cavity regions as flame passes through the elbows. The influence of elbow structure on flame propagation is mainly concentrated in the middle and late stages. In the middle stage, the elbow structure creates a relatively closed space in advance, so that the speed peak-2 occurs earlier than the straight pipe. In the later stage, the acceleration effect produced by the outer wall (concave wall) plays a leading role, and the flame accelerates for the third time after passing through the elbow. There is an interactive relationship between the development of the explosion overpressure and the flame propagation in the elbow.