可调二级增压柴油机旁通阀特性和调节规律的试验

对柴油机应用可调二级增压系统进行了全工况的试验研究.结果表明,涡轮旁通阀可以对增压压力进行调节进而影响柴油机的性能.可调二级增压系统可以增大柴油机中低转速的增压压力,改善碳烟排放;当循环供油量增加后还可以提高中低速时的外特性转矩.中低转速中高负荷时,两级增压会提高进气量改善燃烧,明显地提高了燃油经济性.中高速时,进气量的提高没有明显地改善燃烧的效果,反而造成泵气损失增大,基于经济性考虑应开启涡轮旁通阀,与此同时为避免节流效应压气机旁通阀也应开启将高压级增压器完全旁通,旁通后由于复杂的进排气管增加了流动损失使得油耗略有升高.

Experiment on Characteristic of Bypass Valves and Regulating MAP of a Regulated Two-Stage Turbocharged Diesel Engine

Experimental study was conducted on a regulated two-stage turbocharged(R2S)diesel engine.The bypass valve of turbine is parallel which locates with the high pressure stage turbine,through which the boost pressure is regulated and engine performance varies.At low to middle engine speed,the R2S system improves boost level and reduces smoke emission.Torque at full load is increased when fuel rate is increased.Compared to base engine,fuel consumption reduces obviously due to combustion improvement at low to middle engine speed and middle to high load by two stages turbocharging.At middle to high engine speed,higher boost pressure does not improve combustion,on the contrary,deteriorates the pump loss.Therefore,from the economy aspect,bypass valve of turbine should be full opening at those operating points.Accordingly,the compressor bypass valve should also be opened to reduce the flow loss.Fuel consumption slightly increases due to non-optimized complex intake and exhaust system due to bypass.