The present study focuses on the influence of the swirling flows on flow behaviors and performance of a radial-flow turbocharger turbine under pulsating inflow condition.To characterize the effects of swirling flow,th...The present study focuses on the influence of the swirling flows on flow behaviors and performance of a radial-flow turbocharger turbine under pulsating inflow condition.To characterize the effects of swirling flow,three sets of simulations of the turbine were carried out,which are an unsteady simulation under pulsating swirling inflow,an unsteady simulation under equivalent pulsating uniform inflow,and quasi-steady simulations under uniform inflow.Results proved that swirling flow has a considerable negative influence on turbine instantaneous performance and lead to 2.5%cycle-averaged efficiency reduction under pulsating flow condition.Swirling inflow would lead to significant losses in both the volute and the rotor,while the pulsating inflow leads to higher losses in the rotor and shows little influence on the losses in the volute.The instantaneous efficiency reduction of the turbine could be correlated with the time-varying inlet swirl strength.Under the influence of unsteady inlet swirls,the volute flow field is highly distorted and the free vortex relation is no longer valid.The swirling flow has strong interactions with the wake flow of the volute tongue,leading to additional losses.Relative flow angle at rotor inlet is remarkably reduced and its distribution is significantly distorted.Strong separation flows and passage vortices would appear in the rotor because of the swirling inflow,leading to inferior rotor performance.展开更多
基金the foundation of Science and Technology on Diesel Engine Turbocharging Laboratory(No.6142212190101)Young Elite Scientists Sponsorship Program by CAST(2021QNRC001)for the supports。
文摘The present study focuses on the influence of the swirling flows on flow behaviors and performance of a radial-flow turbocharger turbine under pulsating inflow condition.To characterize the effects of swirling flow,three sets of simulations of the turbine were carried out,which are an unsteady simulation under pulsating swirling inflow,an unsteady simulation under equivalent pulsating uniform inflow,and quasi-steady simulations under uniform inflow.Results proved that swirling flow has a considerable negative influence on turbine instantaneous performance and lead to 2.5%cycle-averaged efficiency reduction under pulsating flow condition.Swirling inflow would lead to significant losses in both the volute and the rotor,while the pulsating inflow leads to higher losses in the rotor and shows little influence on the losses in the volute.The instantaneous efficiency reduction of the turbine could be correlated with the time-varying inlet swirl strength.Under the influence of unsteady inlet swirls,the volute flow field is highly distorted and the free vortex relation is no longer valid.The swirling flow has strong interactions with the wake flow of the volute tongue,leading to additional losses.Relative flow angle at rotor inlet is remarkably reduced and its distribution is significantly distorted.Strong separation flows and passage vortices would appear in the rotor because of the swirling inflow,leading to inferior rotor performance.
