基于变海拔功率恢复的增压系统匹配计算研究

针对柴油机的变海拔功率恢复目标,进行了以增压压力恢复为目标的废气放气式增压系统匹配计算,确定了压气机和涡轮特性。在该匹配方案的基础上进行了柴油机变海拔运行范围的性能计算,得到了不同海拔高度的增压压力MAP图,并以目标增压压力为基准,根据放气阀的切换边界线确定了放气阀变海拔控制策略。研究结果表明:采用该匹配方案可以在海拔3 000m和平原工况实现增压压力恢复,但在高海拔高转速工况下可能超速;随着海拔高度的降低,柴油机外特性扭矩值逐渐减小,而废气放气阀关闭状态的运行区域逐渐减小,废气放气阀调节状态的运行区域逐渐增大。

Matching Calculation of Turbocharging System Based on Power Recovery at Different Altitudes

For the power recovery of diesel engine,the matching calculation of waste-gate turbocharging system was carried out with the purpose of boost pressure recovery and the compressor and turbine characteristic were determined.The performance calculation was carried out within the operating range of diesel engine at different altitudes and the boost pressure MAP diagrams were achieved.The control strategies of waste-gate valve were determined according to the switching boundary linesbased on the target boost pressure.The research result show that the matching scheme can recover the boost pressure at 3 000 m and 0 m,but may overspeed at high altitude and high speed conditions.With the decrease of altitude,the full torque value of diesel engine for every speed decreases.In addition,the operating zone of waste-gate valve closing state reduces and that of waste-gate adjusting state increases with the increase of altitude.