Study On LPG Deflagration Characteristics And Flow Field Of Different Gas Components In Pipeline

In recent years,gas explosions have occurred from time to time,causing serious casualties and property damage,affecting people’s sense of security and well-being,and hindering socio-economic development.Among them,according to the classification of gas sources,LPG(liquefied petroleum gas)has the highest percentage of explosive accidents.Therefore,to effectively prevent and control the explosion of LPG,this paper studied the deflagration characteristics of LPG,through the visual pipeline gas and dust explosion integrated experimental system,combined with a high-speed camera and PIV particle image test system to obtain the explosion pressure,flame propagation images and flow field of LPG in different composition ratios,different equivalence ratios,and different obstacle blockage rate conditions.Through theoretical analysis,the main conclusions are as follows:The flame propagation speed showed a trend of increasing first and then decreasing with time,and the flame propagation speed was the smallest at the moment of "tulip" flame appearance.The larger the proportion of C3H8 in LPG,the faster the flame propagation speed.The closer the equivalent ratio was to 1.0,the shorter the time it took for the flame to fill the whole pipe,the more the flame front was affected by the bouncing shock wave,the more the"tulip" flame structure was destroyed,and the flame front appeared obvious folds.In the pipeline arrangement of obstacles,flame propagation speed with the change of time appeared first increased and then decreased,and then increased abruptly,and finally oscillating changed in the trend.Before the flame crossed the obstacle,the shock wave bounced off the obstacle and the flame structure appeared "flat",and when the flame crossed the obstacle,the flame propagation speed increased sharply.The gas composition ratio of LPG had little effect on the maximum explosion pressure but had a significant effect on the maximum explosion pressure rise rate,the time to reach the maximum explosion pressure,and the time to reach the maximum explosion pressure rise rate.The maximum explosion pressure rise rate gradually increased with the increase in the proportion of C3H8,while the time to reach the maximum explosion pressure,the time to reach the maximum explosion pressure rise rate decreased with the increase of C3H8 proportion.In the same proportional ratio conditions,the maximum explosion pressure and the maximum explosion pressure rise rate increased first and then decreased with the increase of the equivalence ratio.As the obstruction rate increased,the maximum explosion pressure gradually increased,and the time to reach the maximum explosion pressure gradually decreased.The larger the proportion of C3H8 in LPG,the more uniform the flow field distribution,but,overall,the gas composition ratio had little effect on the flow field.The variation of the LPG equivalent ratio had a significant effect on the flow field,the closer the equivalent ratio was to 1.0,the larger the area of localized high vorticity region appeared.The obstacle could significantly change the structure of the explosive flow field,and the number of vortex structures increased as the obstruction rate of the obstacle increased.There was a high coupling between flame structure,flame propagation,explosion pressure,and flow field.The larger the area of the high vortex region in the flow field,the faster the flame propagation and the higher the explosion pressure.The results of this study are intended to achieve the purpose of strengthening the understanding of the deflagration characteristics of LPG and enriching and improving the theory of gas explosion and providing a theoretical reference for the explosion prevention and control of LPG.