Characterization of unsteady on-engine turbocharger turbine performance
Abstract
The gas exchange process between a heavy duty diesel engine and its turbocharger turbine is characterized through measurements of the unsteady boundary conditions imposed by the engine environment on the turbine. Particle Image Velocimetry is implemented at the inlet of the twin-entry turbine to characterize the unsteady velocity field over a typical engine exhaust valve event. These data indicate that although the flow is highly unsteady, crank-ensemble-averaged discrete point measurements at the turbine inlet accurately represent the periodic unsteady boundary conditions. High frequency response instrumentation is employed to obtain measurements of the temperature, pressure, and velocity fluctuations at the inlet and exit of the twin-entry turbine over one engine cycle. The resulting boundary conditions indicate highly unsteady flow through the turbine with periods of significant mass and energy accumulation in the turbine. This large amount of energy storage during the engine cycle represents a significant departure from steady flow turbine performance descriptions, as the energy content of the inlet flow to the turbine is utilized over some finite period of time following the entrance of that flow into the turbine. This significantly reduces the likelihood that simply applied quasi-steady assumptions will ever demonstrate success in predicting unsteady turbine performance.
Degree
Ph.D.
Advisors
Fleeter, Purdue University.
Subject Area
Mechanical engineering|Automotive materials
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