This paper describes an investigation into the use of CFD for highly loaded pump diffuser flows. A reliable commercial Navier-Stokes code with the standard k-ε turbulence model was used for this work. Calculations of a simple planar two-dimensional diffuser demonstrate the ability of the k-ε model to predict the measured effects of blockage and area ratio on the diffuser static pressure recovery at low loading levels. At high loading levels with flow separation the k-ε model underestimates the blockage caused by the recirculation in the flow separation region and overestimates the pressure recovery in the diffuser. Three steady-state calculations of a highly loaded vaned diffuser of a medium specific speed pump have been carried out using different inlet boundary conditions to represent the pump outlet flow. These are compared to LDA measurement data of the flow field and demonstrate that although the Navier-Stokes code with the standard k-ε turbulence model is able to predict the presence of separation in the flow, it is not yet able to accurately predict the static pressure rise of this highly loaded pump diffuser beyond the flow separation point.

ASC, 1994, TASCflow Documentation Version 2.3, Advanced Scientific Computing Ltd., Waterloo, Ontario, Canada.
Casey, M. V., 1994, “The Industrial Use of CFD in the Design of Turbomachinery,” AGARD Lecture Series Turbomachinery design using CFD, AGARD LS-195.
Dalbert, P., and Wiss, D., 1995, “Numerical Transonic Flow Field Predictions for NASA Compressor Rotor 37,” ASME Gas Turbine Conference, Houston.
Dawes, W. D., 1994, “A Simulation of the Unsteady Interaction of a Centrifugal Impeller with its Vaned Diffuser: Flow Analysis,” ASME Paper 94-GT-105.
Drtina, P., Go¨de, E., and Schachenmann, A., 1992, “Three-Dimensional Turbulent Flow Simulation for Two Different Hydraulic Turbine Draft Tubes,” First European CFD conference, Brussels, Sept. 7–11.
Eisele, K., Muggli, F., et al., 1993, “Pump Development with Laser and Computer,” Technical Review Sulzer, 93/2, pp. 37–39.
Eisele, K., Casey, M. V., Zhang, Z., Giu¨lich, J., and Schachenmann, A., 1997, “Flow Analysis in a pump Diffuser, Part 1: LDA and PTV Measurements of the Unsteady Flow,” ASME JOURNAL OF FLUIDS ENGINEERING, published in this issue.
Eisele, K., Zhang, Z., and Muggli, F., 1994, “Investigation of the Unsteady Diffuser Flow in a Radial Pump,” 7th International Symposium on Applications of Laser Techniques to Fluid Dynamics, Lisbon, Portugal, July.
Gu¨lich, J., Favre, J.-N., and Denus, K., 1997, “An Assessment of Pump Impeller Performance Predictions by 3D-Navier-Stokes Calculations,” Proc. of the 1997 ASME Fluids Engineering Division Summer Meeting, June 22–26.
Keck, H., Drtina, P., and Sick, M., 1996, “Numerical Hill Chart Prediction by Means of CFD Stage Simulation for a Complete Francis Turbine,” Proc. of the XVIII IAHR Symposium, Valencia, Spain.
Muggli, F., Wiss, D., Eisele, K., Zhang, Z., Casey, M. V., Galpin, P., 1996, “Unsteady Flow in the Vaned Diffuser of a Medium Specific Speed Pump,” Proc. of the 1996 Int. Gas Turbine and Aeroengine Congress & Exhibition, 10–13 June, ASME-Paper 96-GT-157, New York.
Renau, L. R., Johnston, J. P., and Kline, S. J., 1967, “Performance and Design of Straight, Two-Dimensional Diffusers,” ASME Journal of Basic Engineering, pp. 141–150.
Runstadler, P. W., Dolan, F. X., and Dean, R. C., 1975, Diffuser Data Book, Creare Inc., TN-186, Hanover, NH.
Schachenmann, A., Muggli, F., and Gu¨lich, J., 1993, “Comparison of three Navier-Stokes Codes with LDA-Measurements on an Industrial Radial Pump Impeller,” ASME Fluids Engineering Conference, Washington D.C.
D. C.
, “
Comparison of Two-Equation Turbulence Models for Boundary Layers with Pressure Gradient
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