Flame dynamics and flammability limit of DME(30%)/LPG blended clean fuel in elongated closed pipeline under multi-factors

DME(30%)/LPG blended clean fuel has been increasingly used worldwide for home cooking, heating and car driving. In order to figure out its explosion characteristics, an explosion and propagation experimental platform of multi-component gases was built, and the explosion pattern classification, flammability limit and flame dynamics under equivalence ratio and initial pressure were studied, also a new method for predicting the flammability limit of multi-component blended gas based on the ratio of ultimate-to-initial pressure was proposed. The results show that in initial acceleration area with obstacles, the chemical reactivity and explosion hazards of DME(30%)/LPG blended fuel in rich fuel condition is obviously higher than that in lean fuel condition. In stable acceleration area, the flame front velocity shows obvious fluctuation before entering the stable deflagration stage, and both the tearing of flame front structure and flame velocity fluctuation weaken gradually as the initial pressure increases. The growth rates of flame acceleration and explosion hazards are higher in the process of fuel concentration approaching the optimum concentration (Φ = 1.2) than that the initial pressure increasing from 101 kPa to 201 kPa. The evolution characteristics of the ratio of ultimate-to-initial pressure obeys the sinusoidal wave function, and the predicted flammability limit by this function is of acceptable error with Le Chatelier method and experimental mid-point fitting method, which provides a new idea and method for solving the flammability limits of complex multi-component gas fuel.