Design of High Performance Pump Stage

TURBOdesign1 can be used in the design of high efficiency and compact pump stages. The flow field within a pump diffuser has been improved by controlling three-dimensional pressure fields in the blade passage using TURBOdesign1. The flow separation, often observed on the hub surface of a highly loaded diffuser, has been eliminated. See Figures 1 to 4.

Fig.1: CFD results of the conventional diffuser pump stage.

Fig.1: CFD results of the conventional diffuser pump stage. A large separation vortex exists at the hub-suction surface corner of the diffuser, which causes poor overall performance of the machine.

Fig.2: CFD results of a diffuser pump stage obtained by TURBOdesign1.

Fig.2: CFD results of a diffuser pump stage obtained by TURBOdesign1. The separation vortex, observed in the conventional diffuser, has been completely eliminated.

Fig.3: Multi-colour oil-film flow visualisation of the conventional diffuser.

Fig.3: Multi-colour oil-film flow visualisation of the conventional diffuser.

Fig.4: Multi-colour oil-film flow visualisation of the diffuser obtained by TURBOdesign1

Fig.4: Multi-colour oil-film flow visualisation of the diffuser obtained by TURBOdesign1 confirms successful elimination of the separation vortex observed in the conventional diffuser.   

 

TURBOdesign1 enables designers to control secondary flows in an impeller by directly specifying the blade loading distribution and optimizing the three-dimensional pressure fields to improve machine performance. The blade shapes of the impellers obtained by TURBOdesign1 are significantly different from those of the corresponding conventional impellers, see Figures 5 and 6. Such a unique blade shape is difficult to obtain by a conventional design approach even if a large number of CFD predictions are repeated.

Fig.5: Blade angle distribution of the impeller obtained by TURBOdesign1

Fig.5: Blade angle distribution of the impeller obtained by TURBOdesign1, which is too unique to be reached by the conventional approach.

Fig.6: Blade angle distribution of the conventional impeller.

Fig.6: Blade angle distribution of the conventional impeller. Smooth distribution does not guarantee favourable flow fields.

Fig.7: Comparison of head-flow characteristic curves.

Fig.7: Comparison of head-flow characteristic curves. Pump head was significantly increased due to the loss reduction in the pump stage obtained by TURBOdesign1.

Fig.8: Comparison of efficiency - flow characteristic curves.

Fig.8: Comparison of efficiency - flow characteristic curves. The peak efficiency was improved as much as 5.3 points by the application of TURBOdesign1.

 

The high performance pump stage was manufactured and tested in a pump loop test facility. Experimental validation confirms the improvements in stage efficiency by 5.3 points. The matching between the impeller and the diffuser can be achieved at the specified design flow rate without any empiricism.

Reference: Goto, A. and Zangeneh, M., 1998, “Hydrodynamic Design of Pump Diffuser using Inverse Design Method and CFD”, ASME Fluids 98, FEDSM98-4854

Design of Super Compact Pump Stages

Flow field optimization by TURBOdesign1 has enabled significant improvements in both stage efficiency and suction performance compared to the State of- the-Art conventional design for the similar machine size.

Super compact design is also possible by the careful control of the three-dimensional flow fields by TURBOdesign1. In fact by using TURBOdesign1 more than 50% reduction in volumetric machine size has been achieved with minimum penalty in stage efficiency and the suction performance.

TURBOdesign1 enables challenging and innovative design beyond our experience.

Fig.9: Pressure contours of CFD results for the super compact pump stage obtained by TURBOdesign1.

Fig.9: Pressure contours of CFD results for the super compact pump stage obtained by TURBOdesign1.

Fig.10: Pressure contours of CFD results for the high performance pump stage obtained by TURBOdesign1.

Fig.10: Pressure contours of CFD results for the high performance pump stage obtained by TURBOdesign1.

Fig.11: Comparison of suction performance curves.

Fig.11: Comparison of suction performance curves. The application of TURBOdesign1 enables extremely high peak suction specific speed without efficiency penalty.

Fig.12: Comparison of efficiency-flow characteristic curves.

Fig.12: Comparison of efficiency-flow characteristic curves. The peak efficiency was improved as much as 5.8 points by the application of TURBOdesign1.

Reference: Goto, A., Ashihara, K., Sakurai, T., and Saito, S., 1999, “Compact Design of Diffuser Pumps using Three-Dimensional Inverse Design Method”, ASME Fluids 99, FEDSM99-6847

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