A Simulation Study On Jet Breakup Of Dimethyl Ether At High Pressure

DME (dimethyl ether) is a high-quality alternative fuel for compression-ignition engine. Injection quality of the fuel is the critical factor of the formation of the gas mixture for compression-ignition engine, which influences the combustion performance of combustion engine, and determine the power and the economy of the engine. Therefore, the deep research of DME spray characteristics are helpful for understanding the combustion of DME, which has a important theoretical significance and useful value for optimizing the injection and combustion system of DME engine.Based on the comprehensive analysis of the mechanism and process of the engine fuel sprays, The characteristics of DME jet breakup are simulated, which are adopted by the CDM mode, the k-εdouble equation model and the VOF track method, the simulation results are in accord with the tests by comparison, and the spray modes are proved correct.The program of DME physicochemical parameter is established based on the predecessor's research of DME physicochemical characteristics. The variable parameter process of the DME injection is investigated. The simulation results show that the better quality of the jet breakup can be realized by increasing the ambient pressure, nozzle hole diameter and inject pressure.The cavitation flow of the DME in a nozzle is numerical simulated using mixed multiphase flow model coupled with cavitation model. The reasons of the cavitation generation and the effects on the DME breakup are studied, the pressure in the spray hole which is below the saturated vapor pressure of the DME result in the cavitation generation, the main causes which influence on the DME breakup of the high speed are the turbulence interference, the air-power compact and the cavitation flow.