柴油机燃油喷射系统参数优化匹配对NO_X排放的影响

Influence of Optimal Matching of Fuel Injection System's Parameters on NO_X Emission Performance of Diesel Engine

基于某船用柴油机燃油喷射系统的电控化改造,利用AMESim和AVL_FIRE仿真软件分别建立燃油喷射系统仿真模型与柴油机缸内燃烧模型,采用一次回归正交试验设计方法对燃油喷射系统参数进行优化,再运用二次回归正交试验设计方法将优化结果与喷油提前角(16°CA^24°CA)匹配优化。研究结果表明,初步优化得到的三组参数组合匹配下的喷油压力均高于105 MPa,经过再次优化的8×0.26 mm-15.0 mm-0.46 mm/°CA-900 mm-20.02°CA(喷孔数×孔径—柱塞直径—凸轮型线速度—油管长度—喷油提前角)参数组合下NO_X排放量最低,生成的NO_X质量分数为0.089 6‰;通过回归分析建立NO_X排放量数学预测模型精确度较高,测量最优点(以NO_X排放量为优化目标)误差低于3%,可以用于参数优化匹配研究。

Based on the electronically-controlled modification of a diesel engine＇s fuel injection system, the simulation model of the fuel injection system and high pressure circulation in diesel engine cylinder are established separately by using AMEsim and AVLFIRE simulation software. The parameters of the fuel injection system is optimized by means of the regression orthogonal experiment design method, and the optimized results are matched with the injection advance angle（16°CA^24°CA） by the quadratic regression orthogonal design method. The research results show that the pressure of fuel injection is higher than 105 MPa under the three sets of parameters combination matching in Preliminary optimization, and the best NOX emission（the mass fraction is 0.896‰） is reached when the parameters is 8-0.26 mm-15.0 mm-0.46 mm/°CA-900 mm-20.02°CA（number of nozzle-diameter of orifice-diameter of plunger-cam velocity-length of high pressure fuel pipe–spray advance angle）. The mathematical prediction model of NOX emission with high accuracy is established by regression analysis, and the error of the measurement at the optimum point（NOX emissions is the optimization goal） is less than 3%, so it can be used for parameter optimization matching.