Coupling relationship between the overpressure and the flame propagation speed (δ = 1.7%)

Coupling relationship between the overpressure and the flame propagation speed (δ = 1.7%)

Source: BAM, Division Explosion Protection Gases and Dusts

Fuel safety has drawn increasing attention during the production, transportation, storage and utilization processes. Many studies have been conducted to investigate the influence of initial conditions (pressure, temperature, vessel volume, etc.) on fuel explosion characteristics in a semi-/confined pipe. Generally, the gasoline-air mixture explosion usually happens in a space containing obstacles in many cases, resulting in the acceleration of the flame and the rapid growth of overpressure due to the generation of turbulences near the obstacle. However, only few attentions have been paid to the external explosion (or secondary explosion) out of the pipe. This paper aims to study the impact of the obstacle location and gas concentration on the occurrence of an external explosion and the relationship between the external overpressures and flame propagation process.

As part of a scientific collaboration with China Aerodynamics Research and Development Center and State Key Laboratory of NBC Protection for Civilian in Beijing, studies were carried out in a semi-confined pipe to investigate the effects of obstacle location and gasoline vapor concentration on gasoline-air fuel explosions. The variations of internal overpressure, external overpressure, flame propagation and flame-overpressure coupling relationship were analyzed. More than two positive overpressure peaks were observed in the external overpressure histories. Moreover, a coupling relationship between overpressure and flame propagation was found. It could be deduced that the formation of the positive overpressure peak of the external overpressure might be directly related to the gas explosion inside the pipe and the flow jet caused by the high-speed flame propagation, rather than the external explosion out of the pipe. These results improve our understanding on gas explosion dynamics in a semi-confined space, thus providing a theoretical basis for gas explosion preventions and controls.

Effects of gas concentration and obstacle location on overpressure and Flame propagation characteristics of hydrocarbon fuel-air explosion in a semi-confined pipe
Dejian Wu, Li Guoqing, W. Jun, J. B. Shimao, Q. Sheng
published in Fuel, Vol. 285, page 119268, 2021
BAM, Division Explosion Protection Gases and Dusts