Deflagration shock wave dynamics of DME/LPG blended clean fuel under the coupling effect of initial pressure and equivalence ratio in elongated closed space

The deflagration shock wave evolution regimes and explosion hazards of DME (dimethyl ether)/LPG (liquefied petroleum gas) blended clean fuel under equivalence ratio of Φ = 0.8–1.6 and initial pressure of P₀ = 101–201 kPa were investigated systematically. The results indicate that the DME/LPG blended fuel under rich-fuel condition is of higher chemical reactivity, greater explosion hazard and is more vulnerable to the enhancement effect of P₀. For the explosion overpressure, the change of equivalence ratio can make the overpressure increase to 1.5–2.0 times of the original value to the maximum extent, while the increase of initial pressure contributes 112%∼181% to the growth rate of overpressure, and the effect is more obvious when the equivalence ratio is closer to the flammability limits. However, as for shock wave propagation speed, these two parameters are reduced to 1.04–1.07 and 4.35%∼19.30% respectively. The significance analysis results of Φ (A), P₀ (B) and their interaction (A×B) on explosion overpressure are as follows: B>A>A×B. The reflected overpressure can reach 2.8 times of the incident overpressure. The coupling relationships between the overpressure/shock wave propagation velocity and the initial pressure, equivalence ratio show “uplifted ridge” shape, in which Φ = 1.2 is the “ridge line”, and the whole “ridge” rises continuously with the initial pressure. The research results are of great significance for revealing the explosion hazards of DME/LPG blended fuel, formulating relevant industry standards, and formulating scientific and effective explosion-proof measures.