可变喷嘴涡轮增压器喷嘴环叶片位置对柴油机性能的影响

Effect of Nozzle Ring Vane Position of VNT on Diesel Engine Performance

针对普通废气涡轮增压器低速响应和高速功率不能同时兼顾的特点,对可变喷嘴涡轮增压器(VNT)进行了试验研究。通过试验分析了喷嘴环叶片位置对柴油机性能的影响,并得到了VNT的优化脉谱。同时进行了VNT的瞬态响应研究。研究结果表明:VNT通过改变涡轮喷嘴环面积可与柴油机各工况实现最佳匹配,燃油消耗率在全工况范围内明显改善,在高速低负荷时燃油消耗率降低最多,达到了10%;通过增加低速的进气量,VNT对柴油机低速高负荷工况性能有明显改善,扭矩约增加15N·m,油耗率降低2%,烟度从原机4.5 BSU降低到2.5 BSU;通过与原机外特性的对比,在中高速的NO_x和烟度排放与原机相差不大,在低速区NO_x增加约100×10^(-6),烟度降低2 BSU,在整个转速范围内油耗率降低2%～3%。

Due to the fact that low-speed response and high-speed power characteristics can not be considered simultaneously for normal turbochargers, the experimental research on the variable nozzle turbocharger （VNT） was conducted, analyzing mainly the effect of the nozzle ring position of VNT on engine performance and transient response capability of the VNT, and achieving the optimized VNT map. The results indicate that the matching of VNT with diesel engine can be optimized at every operating condition by varying the area of nozzle ring. The SFC can be improved obviously at all the operating conditions, especially at high speed and low load conditions the SFC decreases by about 10%. By increasing the mass flux of inflow, the performance of diesel engine at low Speed and high load conditions is improved, torque increases by 15 N·m, SFC decreases by 2 % and smoke decreases from 4.5 BSU to 2.5 BSU. In comparing to the original engine, the engine with VNT has little difference in NOx and smoke emissions at middle and high speed ranges, but the NOx emission increases by 100×10^-6 and the smoke decreases by 2 BSU at low speed range, the SFC decreases by 2%-3% at the whole speed range