Research On Dimethyl Ether(DME) Fuel Spray Characteristics Under High Temperature And High Pressure Condition

DME (is short for Dimethyl Ether) is oxygen fuel and has been widespreadknown as an alternative to diesel fuel since it has the following good points: extensiveraw material source, mature preparation method, high octane, no soot emissionsetcetera. It’s known to all that there are great differences of theoretical air requirementand evaporation characteristics between DME and diesel. Since spray characteristics isfundaments of combustion, it is necessary to get detailed understanding of spraycharacteristics under high temperature and high pressure.Turbocharged engine-like environment and naturally aspirated engine-likeenvironment are selected as the experimental conditions. Spray experiment is carriedout in a constant volume vessel.The development process of DME spray under8.8MPa-920K and4.5MPa-800K conditions are discussed in this paper. Effects ofinjection pressure and injector diameter on spray development process are alsoinvestigated. At the same time, KH-RT split model is improved and splitting constantsare adjusted. Numerical simulation analysis on spray characteristics is carried out withKIVA-3V software. Compared with diesel under different injection rate while the sameheat conditions, discussed the influences of injection pressures on distribution of DMEspray average equivalent.The results showed that, there was no significant difference in DME sprayappearance and spray development process under selected conditions of hightemperature and high pressure. Spray penetration increases as nozzle hole diameterincreases. Because of the increasing of environment density, spray penetrationdecreases under high temperature and high pressure conditions. DME spray evaporatesmore quickly as ambient air temperature goes higher. Numerical simulation resultsshow that, improved spray breakup model is similar to experimental results. For DME,by increasing the diameter of nozzle hole, at low injection pressure such as60MPa condition, the same spray effect as diesel spray under high injection pressure such as200MPa can be realized.