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Measured and Predicted Flow Characteristics of Mixed-Flow Turbocharger Turbines
Published November 03, 1998 by Institution of Mechanical Engineers in United Kingdom
The steady performance of high-pressure ratio mixed-flow turbines for automotive turbochargers has been investigated and the results indicate superior performance of a rotor having a constant inlet blade angle relative to that with a nominally constant incidence angle. These results have been complemented by a survey of the steady flow conditions upstream and downstream of the rotors: at the inlet the three components of velocity and the flow angle were measured by laser doppler velocimetry (LDV), and at the exit the axial and tangential velocity components which were also compared with computations using a fully 3-D Navier-Stokes solver. The turbine test conditions corresponded to the peak efficiency point of the 50% and 70% design speeds, equivalent to 29,400 and 41,300 rpm, respectively. The flow and performance tests have jointly indicated that a rotor design combining a nominally constant incidence angle with a longer blade length may offer advantages relative to the three mixed- flow rotors examined in the present study.