Effect of DME addition on flame dynamics of LPG/DME blended fuel in tail space of closed pipeline

In order to recognize and reveal the explosion characteristics and hazards of LPG blended fuel with active fuel additions, flame dynamics of liquefied petroleum (LPG)/dimethyl ether (DME) blended fuel in the tail space of a closed pipeline was experimentally investigated. A high-speed camera and a pressure transducer were used to acquire the flame structure and explosion overpressure, and the displacement and speed were further calculated by MATLAB programming. The research results show that the flame under the conditions of stoichiometric and lean-fuel concentration presents a more remarkable local suppressive propagation compared with the rich-fuel condition. In the vicinity of stoichiometric concentration, the increase of equivalence ratio leads to the increase of flame front temperature, meanwhile, the process also improves the molecular diffusion coefficient and heat transfer efficiency. The reverse propagation of flame brings obvious temperature loss to fuel system. The existence of reflected reverse flow makes it difficult for the flame to propagate to the end of the closed space. The increase of equivalence ratio and DME blended ratio is helpful for the improvement of flame suppressive mechanism and flame acceleration mechanism, and the effect of the latter is more obvious. The knowledge obtained about flame dynamic characteristics can improve the assessment and recognition of explosion hazards of blended fuel.