重型柴油机二级增压系统匹配仿真研究

为了降低重型柴油机的燃油消耗率，采用GT-POWER软件建立仿真模型，在一台单级可变截面涡轮增压器（variable geometry turbocharger, VGT）柴油机上开展了二级增压匹配与增压系统参数优化工作。仿真结果表明，所提出的二级增压系统在匹配点能够以最高效率运行，在全工况都能提供足够的进气流量；完全关闭低压级废气旁通阀，正交优化高压级废气旁通阀开度和米勒循环度，能够进一步降低二级增压发动机的燃油消耗率；降低级间中冷温度能够降低泵气损失，提高增压压力，温度由100℃降至50℃在标定点能够使燃油消耗率降低约3 g/（kW·h）。对二级增压及参数优化工作的燃油消耗率改善效果进行了试验验证，低速工况燃油消耗率整体有所下降，高效点燃油消耗率下降4.1%。

Simulation Study on Two-Stage Turbocharger Matching for Heavy-Duty Diesel Engines

In order to reduce the fuel consumption rate of a heavy-duty diesel engine， the matching of a two-stage turbocharger using GT-POWER software was carried out on a single stage variable geometry turbocharger（VGT） diesel engine. Simulation results show the proposed two-stage turbocharging system can operate at peak efficiency at the matching point and provide sufficient intake airflow across all operating conditions. Fully closing the wastegate valve in the low-pressure stage and synergistically optimizing the wastegate valve opening in the high-pressure stage along with Miller cycle valve closing angle can further reduce the fuel consumption rate of the two-stage turbocharged engine. Furthermore， reducing the intercooler temperature between stages can reduce pumping losses and enhance boost pressures. Specifically， a temperature reduction from 100 ℃ to 50 ℃ at the rated point can result in an approximate improvement of 3 g/（kW·h） in fuel consumption rate. Experimental validation of the improvement in fuel efficiency from the two-stage turbocharging system was conducted， revealing reduction in fuel consumption rates during low-speed operating conditions and reduction of 4.1% in fuel consumption rate at the high-efficiency operating point.