基于FIRE的二甲醚-空气预混特性的模拟

Simulation on Premixed Characteristic of Dimethyl Ether-air Mixtures Based on FIRE

为研究内燃机代用燃料的燃烧特性,在一台压燃式发动机上对二甲醚-空气在进气道内的预混特性进行了模拟.在选定初始条件的情况下,运用FIRE软件对GW4D20发动机进气道内气体流动进行了三维数值模拟,对相应的进气道速度流场进行了分析.结果表明:二甲醚在传统压燃式发动机上应用时,需要对其进气道进行结构优化,以改善混合气均匀性,并减少死区数量;其次,对进气歧管位置进行调整和对流体流动引导可以形成滚流,加速混合气的混合;此外,流量增加20%时,速度接近为0的区域减少,因此在进气前端加装增压装置,有利于混合气的预混.

In order to study the combustion characteristics of the internal combustion engine alternative fuel,the premixed characteristic of dimethyl ether-air mixtures in the inlet on a compression ignition engine is simulated.Under the specified initial conditions,a 3D numerical simulation is applied to the GW4D20 engine inlet gas flow through using the FIRE software,and the inlet velocity flow field is analyzed.The results show that it is necessary to optimize the structure of the inlet to improve the gas mixture homogeneity and reduce the number of dead zone when dimethyl ether is used in conventional compression ignition engines.In addition,it is also essential to adjust the position of the intake manifold,and guide the fluid flow to accelerate the mixing of the mixed gas.Lastly,when the flow rate is increased by 20%,the number of dead zone is reduced.Therefore,it is beneficial for premixed to retrofit supercharging device in the front of the air intake.