Study on deflagration process of LPG/DME blended combustible gas cloud in open space

In order to reveal the deflagration characteristics and evolution law of LPG (liquefied petroleum gas)/DME (dimethyl ether) blended gas cloud under normal temperature and pressure in open space under different equivalence ratios and DME contents (0%、30%、50%、70%、100%), experiments and numerical simulations were conducted to study the deflagration overpressure, flame speed, gas velocity and their interactions, and the sensitivity analysis of key elementary reactions of LPG/DME blended gas was carried out. The results showed that the addition of DME can elevate the deflagration intensity of LPG, and in the same equivalent ratio the more of DME was blended into LPG, the greater the peak overpressure was, and so as to the maximum flame speed and the peak gas velocity. What's more, within certain limits the peak overpressure generated by gas deflagration showed a linear increase with the increase of the maximum flame speed. During the gas cloud deflagration, the flame speed went through three stages, including flame formation, acceleration and attenuation, and the DME blended ratio (λ) showed significant effect on the flame acceleration process. Then, the formation mechanism of overpressure and the state field distribution during gas cloud deflagration were proposed. The chemical reaction rate has a decisive effect on the flame speed, and the maximum flame speed restricts the peak overpressure and the peak gas velocity. Finally, the effect of promoting reaction is dominant after the addition of DME according to the sensitivity analysis.