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Article

Effects of Inlet Geometry on Turbine Performance

Authors: Fjällman, J.F., Mihaescu, M, Fuchs, L.F.
Document Type: Article
Pubstate: Published
Journal: In the Proc. of Int. Conf. on LES for Internal Combustion Engine Flows (LES4ICE)
Volume:   
Year: 2012

Abstract

The flow in the turbine of a turbocharger is unsteady, pulsating, and geometry dependent. In the automotive industry the matching the turbocharger with the engine has traditionally been done using 1D-simulation tools and turbine/compressor efficiency maps. Nowadays, 3D Reynolds averaged Navier-Stokes (RANS) models are intensively used. The problem with both RANS and 1D modelling tools is that they cannot account for many important and very complex existent flow phenomena (i.e. pulsating flow, turbine hysteresis, flow asymmetry due to non-symmetric geometry etc.). All of these effects will introduce flow losses which need to be captured in order to improve the design of both the turbocharger and of the turbocharger matching. Such requirements make from Large Eddy Simulations (LES) the method of choice, even for an industrial environment. With the full 4D (in space and time) compressible simulations the flow information retrieved is much more complete and more insights into the flow structures and geometry dependent flow characteristics can be studied. Thus, one of the roles with the LES results is to determine the range of validity of the simpler tools/models and to extend the “operational range” of these by providing proper calibration parameters for unsteady turbine operating conditions.