Comparison between steady and unsteady double-entry turbine performance using the quasi-steady assumption


Copeland, C., Martinez-Botas, R. and Seiler, M., 2009. Comparison between steady and unsteady double-entry turbine performance using the quasi-steady assumption. In: ASME Turbo Expo 2009, 2009-06-08 - 2009-06-12. ASME, pp. 1203-1212.

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The experimental performance evaluation of a circumferentially divided, double-entry turbocharger turbine is presented in this paper with the aim of understanding the influence of pulsating flow. By maintaining a constant speed but varying the frequency of the pulses, the influence of frequency was shown to play an important role in the performance of the turbine. A trend of decreasing cycle-averaged efficiency at lower frequencies was measured. One of the principal objectives was to assess the degree to which the unsteady performance differs from the quasi-steady assumption. In order to make the steady-unsteady comparison for a multiple entry turbine, a wide set of steady equal and unequal admission flow conditions were tested. The steady state data was then interpolated as a function of three, non-dimensional parameters in order to allow a point-by-point comparison with the instantaneous unsteady operation. As an average, the quasi-steady assumption generally under-predicted the mass flow and efficiency loss through the turbine, albeit the differences were reduced as the frequency increased. Out-of-phase pulsations produced unsteady operating orbits that corresponded to a significant steady state, partial admission loss, and this was reflected as a drop in the quasi-steady efficiency. However, these differences between quasi-steady in-phase and out-of-phase predictions were not replicated in the measured results, suggesting that the unequal admission loss is not as significant in pulsating flow as it is in steady flow.


Item Type Conference or Workshop Items (UNSPECIFIED)
CreatorsCopeland, C., Martinez-Botas, R. and Seiler, M.
Related URLs
DepartmentsFaculty of Engineering & Design > Mechanical Engineering
Research CentresPowertrain & Vehicle Research Centre
ID Code32238


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