A fully elliptic computational method for the analysis of steady viscous flowin high speed subsonic centrifugal compressor impellers with tip leakage, ispresented. A generalised curvilinear, non-orthogonal grid is utilised and the timeaveragedNavier-Stokes equations are transformed and expressed in a fullyconservative form. The discretisation of the governing equations is performedthrough finite volume integration. The solution procedure employs a non-staggeredvariable arrangement and a SIMPLE based method for coupling the velocity andpressure fields. The turbulence effects are simulated with the use of the k-e model,modified to account for rotation and streamline curvature, and the near-wall viscousphenomena are modelled through the wall function method.The numerical model is implemented for the flow prediction in a series oftwo and three dimensional test cases. Incompressible flow predictions in twodimensionalcascades and three-dimensional ducting systems with differentgeometrical features and inlet conditions are initially performed and the numericalresults are compared against available experimental data. The final objective of thepresent study is achieved through the comparative study of the predictions obtainedagainst the results of Eckardt's experimental investigation of the viscouscompressible flow in a high speed radial impeller operating at design condition andin a backswept impeller at design and off-design conditions. In addition, the flow issimulated in the passages of the Rolls Royce GEM impeller which was tested atCranfield at design and off-design flow rates.A jet/wake pattern was discerned in all the simulated centrifugal compressorcases and a good overall agreement was achieved with the measured wake formationand development; and, encouraging results were obtained on the evolution of thesecondary flows. The tip leakage effects influenced the loss distribution, the size andthe location of the wake flow pattern at the rotor exit. The effects of the flow massrate on the detailed flow pattern and on the compressor performance have been wellrepresented. In certain cases, the quality of the present predictions is animprovement over that obtained by other "state-of-the-art" Navier-Stokes solvers.In conclusion, the developed finite volume flow model has captured a large numberof complex flow phenomena encountered in the tested impellers and is expected toprovide a useful aerodynamic analysis tool for stationary or rotating, axial or radialturbomachinery components.
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