喷孔数调控活性分层对乙醇-柴油双燃料燃烧的影响

基于1台自然吸气的单缸柴油机,结合缸内三维燃烧仿真计算,研究了不同直喷正时、不同预混比例条件下,直喷喷油器的喷孔数对乙醇-柴油双燃料发动机燃烧和排放特性的影响。结果表明,优化直喷喷油器的喷孔数,能影响直喷柴油的缸内分布,调控乙醇-柴油双燃料发动机燃烧过程。减少喷孔数,可以有效降低缸内高活性柴油的分布区域,减少初始着火的位置,从而降低缸内最高燃烧压力和压力升高率,并且可以在炭烟排放保持较低水平的基础上,降低氮氧化物(NO_x)排放。随着乙醇预混比例的增大,喷孔数对燃烧和排放的影响先增大后减小。随着喷油提前角的增大,由于直喷燃油在缸内混合较为均匀,喷孔数的影响作用逐渐减小。

Effects of Reactivity Stratification on Ethanol-Diesel Dual Fuel Combustion Based on Nozzle Hole Number

Based on a naturally aspirated single-cylinder diesel engine ,the effects of nozzle hole number for direct injector on ethanol-diesel dual fuel combustion and emission were researched under different injection timings and pre-mixing ratios by uti-lizing the in-cylinder 3D simulation and calculation .The results show that optimization of nozzle hole number can affect fuel in-cylinder distribution and regulate the combustion process of ethanol-diesel dual fuel engine.The reduction of nozzle hole number can lower the distribution area of high reactivity fuel ,which will reduce the initial ignition positions .The maximum combustion pressure and pressure rise rate further decrease .In addition ,NO xemission reduces and soot emission can keep within a low level .With the increase of ethanol proportion ,the effects of nozzle hole number on combustion and emission first increase and then decrease .With the increase of fuel supply advance angle ,the nozzle hole number has little influence due to the injected fuel in-cylinder uniform mixing .