Coupling Mechanism Between Turbine Stages in a Two-Stage Turbocharging System
The performance coupling mechanism between turbine stages in a two-stage turbocharging system for a heavy duty diesel engine were studied by means of bench experiments and 3D-computational fluid dynamics(CFD)calculation.The performance of low-pressure turbine in two-stage turbocharging system is sensitive to the coupling effect.When the bypass valve is closed,the efficiency of low-pressure turbine is increased by 2.8％at high load conditions(PR=2.40).When the bypass valve is opened,the performance of low-pressure turbine deteriorates drastically and the efficiency is reduced up to 7.5％.Further flow field analysis was carried out on the mechanism of the performance deterioration of the low-pressure turbine caused by the valve state.The results show that,when the bypass valve is closed,the tip leakage flow loss is suppressed due to the influence of swirling flow at the high-pressure turbine exit on the inlet of low-pressure turbine.On the other hand,when the bypass valve is opened,the flow from the bypass branch interacts strongly with the swirling flow,leading to a higher flow loss in the volute.
heavy duty diesel enginetwo-stage turbochargingturbineperformance coupling
万方数据
维普
