Unsteady Internal Flow and Loss Mechanism of a Turbocharger Turbine Under Pulsating Flow Condition

Abstract

Recently to improve thermal efficiency of an automobile engine, downsizing of turbochargers attracts more and more attention. An actual turbocharger operates under pulsating flow because of repeating operation of the engine valves. The turbine performance may decrease in such conditions. In this study, experimental and Computational Fluid Dynamics (CFD) investigation were carried out under a pulsating flow to clarify the loss mechanisms of the turbocharger turbine. Performance tests and Particle Image Velocimetry (PIV) were performed as an experimental approach to confirm the unsteady loss. CFD results have good agreement with the experimented results. The losses in the wheel and the exhaust diffuser under pulsating flow were larger than under steady flow.