CAJ | 학술논문

在进行增压器与柴油机匹配及柴油机系统动态仿真时,需要准确计算柴油机进气流量.为确定最佳的进气流量计算模型,对进气流量平均值模型进行比较分析,综合考虑增压中冷、废气再循环率、充量系数及工况变化的影响并建立相应的修正模型,利用 Matlab/Simulink 对所有模型进行了仿真验证.仿真和试验结果表明:修正后的进气流量模型计算结果与试验数据相吻合,最优模型的平均相对误差为2.96%,模型设计合理准确.研究结果可为准确计算涡轮增压柴油机进气流量及其模型的选择提供指导和依据.
재진행증압기여시유궤필배급시유궤계통동태방진시,수요준학계산시유궤진기류량.위학정최가적진기류량계산모형,대진기류량평균치모형진행비교분석,종합고필증압중랭、폐기재순배솔、충량계수급공황변화적영향병건립상응적수정모형,이용 Matlab/Simulink 대소유모형진행료방진험증.방진화시험결과표명:수정후적진기류량모형계산결과여시험수거상문합,최우모형적평균상대오차위2.96%,모형설계합리준학.연구결과가위준학계산와륜증압시유궤진기류량급기모형적선택제공지도화의거.
Air mass flow determination is a major issue for matching of turbocharger and dynamic simulation of diesel engine system. Generally speaking, there are two kinds of mean value models of air mass flow. One is based on the amount of air for fuel combustion, which involves engine power, fuel consumption rate, instantaneous excess air ratio and coefficient of scavenging; and the other is on the basis of the definition of volumetric efficiency, which relates to piston swept volume, air density and coefficient of scavenging. However, different purpose and conditions of research form various mathematical models of air mass flow, and the results of calculation varied wildly. In order to get the optimum simulation model, different mean value models of air mass flow were comprehensively compared and further analyzed in this paper. Furthermore, the influence of turbocharger, intercooler, exhaust gas recirculation rate, volumetric efficiency and operation condition were particularly taken fully into account. Firstly, relative condition correction was carried out for the first type of original models to make them can be applied to any operating condition beyond the rated condition. The precision of models were remarkably improved through multiplying the original models by the ratio of engine speed under any operating condition to rated speed. Secondly, by considering the effect of exhaust gas, the mass conservation equation was rebuilt, and then the correctional formula of air mass flow for turbocharged diesel engines which were equipped with exhaust gas recirculation system were derived. Finally, part of the above models were modified via taking account of the influence of combustion chamber geometry, compression ratio, cooling efficiency and scavenging efficiency on volumetric efficiency. Meanwhile, all the mathematical models were simulated with Matlab/Simulink and verified through comparing the simulation results with experimental values. Eventually, the simulation and experimental results show that the air mass flow model after revising fit well with the actual situation. In addition, the average relative error of the optimal model is 2.96% and therefore the design of model is reasonable and accurate. Consequently, the results of this study will be helpful to accurately calculate the air mass flow of turbocharged diesel engine, and provide useful reference for its model selection.