Research On Numerical Simulation Of DME Engine Based On KIVA Code

The development of China's automotive industry is facing two major constraints: energy security and environment protection.The decrease of the energy and the pollution of the environment have been the two serious problems in the world. It has become a highlight to researching the operation process especially combustion process for IC-engine. The method of numerical simulation can effectively forecast the complete performance of IC-engines and partly replace some engine experiment, and carry on various parameter researches in different operational modes without the time and space limit, guide the designs of engines with the new combustion system, optimize the performance of original engines. It can also forecast the power and exhaust emissions of the engine fired with various fuels. Therefore the method of numerical simulation has very powerful vitality and many advantages.Dimethyl ether(DME)is one kind of the new type and the clean alternative fuels for diesel engine. It is an imperative task for China to develop alternative fuels for automobiles with due consideration to the country's structure of energy supply. DME, with high thermal efficiency and low emission due to its special properties, has in recent years attracted increasingly wide attention and has been considered as an alternative fuel which will contribute to the rationalization of China's energy structure and the improvement of the environment. The research about DME is universal used on diesel engine is processing. So studying the burning characteristics of DME is propitious to manufacture and optimize DME engine.At present, two first research of DME engine have sets of shelf experimental study and artificial simulation study mainly. Experimental study of main shelves is all through some transformation of the fuel system on the traditional diesel engine both at home and abroad, carry on the substitution of the DME fuel. And DME study history to be very much short as diesel engine artificial simulation.KIVA, a multidimensional simulation program developed by U.S. Los Alamos National Laboratory, is introduced in this thesis. KTVA procedure has not DME fuel depot, relevant parameter and relevant subprogram of model of ether, KIVA procedure can not make DME combustion process operation directly. In order to make KIVA procedure have the ability to operate DME burning simulation, this text should build DME combustion numerical platform.In order to build DME combustion numerical platform, this text has added various kinds of thing properties of liquid DME to the fuelib of KIVA source program, Revising DATA and recompiling and producing EXE executable file and make it has computing capability of liquid DME combustion process. According to DME fuel, this text has built oil bunch models and burning models t, and has coupled it into KIVA , and has transformed subprograms inject, pmovtv, break, colidenn, evapd, Chem, chempm, Pmom, pcoupl,etc.Utilize above-mentioned built DME engine calculation simulation platformt, this text has calculated the emulation of the following several respect: DME, diesel oil combustion process average pressure, contrast of temperature in cylinder; DME, diesel oil combustion process NO_X emission, PM emission in cylinder; DME, contrast of the heat release rate of combustion process of diesel oil; DME, diesel oil combustion process contrast of temperature field in cylinder; Change of the content of every component part in DME combustion process; DME engine power and discharge performance under different load.Through the numerical emulation of DME combustion process ,draw the following conclusion: (l)Under the circumstances that the same fuel sprays angle ahead of time and amount of oil gushed out of the same equivalent circulation, DME engine has higher pressure and average temperature than diesel oil engine, the DME engine working state is softer; (2)Under above-mentioned condition, DME engine has lower NO_X,PM emission than diesel oil engine, its numerical result s is identical at experimental results, reaching EuropeIII discharge demand of regulation, reaching our studying DME purpose;(3)burning time for DME engine is advanced than diesel oil engine. (4)Corresponding different crank angel , DME engine cylinder maximum temperature is lower than Diesel engine, and DME engine cylinder high temperature distribution range is lighter than Diesel engine, this will reduce the formulation of NO_X. (5)DME engine has less component part O₂, CO, CO₂ amount than diesel oil engine in cylinder.