Experimental and Numerical Study on the Explosion Dynamics of the Non-Uniform Liquefied Petroleum Gas and Air Mixture in a Channel with Mixed Obstacles

Abstract

Mixed obstacles have a great influence on the deflagration process of liquefied petroleum gas (LPG)-air premixed combustible gas with concentration gradient. The arrangement of mixed obstacles may further stimulate overpressure and flame propagation. In this work, based on experimental and numerical simulations, this paper analyzes the flame and overpressure, and mainly studies the coupling relationship among the explosion overpressure characteristics, the structure of flame and the speed of flame propagation. The result shows that when the rectangular obstacle is 100 mm away from the ignition source, not only the speed of flame is the fastest, but also the time required to reach the maximum over-pressure is the shortest. In this configuration, an elongated flame is formed between a rectangular obstacle and a flat obstacle, and an obvious backflow structure appears. In addition, the average growth rate of overpressure has a minimum value, reaching at −35 MPa/s. The existence of rectangular obstacles further stimulates the overpressure. When the rectangular obstacle is 400 mm away from the ignition source, the maximum overpressure value is the highest among the four configurations. Besides, the time when the maximum area of flame appears in the simulation is almost the same as the time when the maximum overpressure is obtained. In addition, the average growth rate of overpressure increases significantly after touching the rectangular obstacle, which coincides with the mutation time of the front tip of the flame, overpressure and area of flame after the flame encounters the rectangular obstacle. This research has an important theoretical guiding significance for preventing LPG leakage and explosion accidents in a long and narrow space.