Shock wave evolution and overpressure hazards in partly premixed gas deflagration of DME/LPG blended multi-clean fuel

In order to reveal the shock wave propagation and overpressure hazards of DME (dimethyl ether)/LPG (liquefied petroleum gas) blended fuel in the process of partly premixed gas deflagration, both experimental apparatus and numerical model for multiple-gas explosion and propagation are established. The results show that the overpressure in the sharp-dropping overpressure hazards zone are generally more than 200 kPa, and the distribution range was 5.75–6.75 times of the maximum overpressure hazards zone. The overpressure in the gentle-dropping overpressure hazards zone is the smallest, but its propagation and influence distance is the largest, which can cause certain damage to people and buildings in the far field. The participation of DME at lean-fuel concentration had the greatest effect on the increase of overpressure hazards in the original premixed zone, which could reach 306.6%. The increase of equivalence ratio and the addition of DME fuel both accelerate the superposition of multiple pressure waves. High overpressure risk is always accompanied by high overpressure evolution speed. As equivalence ratio increases, the relationship between the average shock wave velocity and the DME blended ratio was linear, quadratic and cubic, also the flame acceleration mechanism by high burning rate and the flame deceleration mechanism by low combustion heat successively dominates.