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TECHNICAL PAPERS

Pump Performance Improvement by Restraining Back Flow in Screw-Type Centrifugal Pump

[+] Author and Article Information
Yasushi Tatebayashi

Department of Mechanical Information, Science and Technology,  Kyushu Institute of Technology, 680-4 Kawazu, Iizuka-City, Fukuoka 820-8502, Japantate@mse.kyutech.ac.jp

Kazuhiro Tanaka

Department of Mechanical Information, Science and Technology,  Kyushu Institute of Technology, 680-4 Kawazu, Iizuka-City, Fukuoka 820-8502, Japankazuhiro@mse.kyutech.ac.jp

Toshio Kobayashi

 Japan Automobile Research Institute, 1-1-30 Shibadaimon Minato-ku, Tokyo 105-0012, Japankobaya@jari.or.jp

J. Turbomach 127(4), 755-762 (May 10, 2005) (8 pages) doi:10.1115/1.2019217 History: Received March 14, 2005; Revised May 10, 2005

The authors have been investigating the various characteristics of screw-type centrifugal pumps, such as pressure fluctuations in impellers, flow patterns in volute casings, and pump performance in air-water two-phase flow conditions. During these investigations, numerical results of our investigations made it clear that three back flow regions existed in this type of pump. Among these, the back flow from the volute casing toward the impeller outlet was the most influential on the pump performance. Thus the most important factor to achieve higher pump performance was to reduce the influence of this back flow. One simple method was proposed to obtain the restraint of back flow and so as to improve the pump performance. This method was to set up a ringlike wall at the suction cover casing between the impeller outlet and the volute casing. Its effects on the flow pattern and the pump performance have been discussed and clarified to compare the calculated results with experimental results done under two conditions, namely, one with and one without this ring-type wall. The influence of wall’s height on the pump head was investigated by numerical simulations. In addition, the difference due to the wall’s effect was clarified to compare its effects on two kinds of volute casing. From the results obtained it can be said that restraining the back flow of such pumps was very important to achieve higher pump performance. Furthermore, another method was suggested to restrain back flow effectively. This method was to attach a wall at the trailing edge of impeller. This method was very useful for avoiding the congestion of solids because this wall was smaller than that used in the first method. The influence of these factors on the pump performance was also discussed by comparing simulated calculations with actual experiments.

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Copyright © 2005 by American Society of Mechanical Engineers
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Figures

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Figure 1

Schematic configuration of a screw-type centrifugal pump

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Figure 2

Computational grid systems: (a) Impeller; (b) Disk; (c) Volute casing; (d) Suction pipe; (e) Discharge pipe

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Figure 3

Cross section of a screw-type centrifugal pump

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Figure 7

Velocity vectors and total pressure distributions at each cross section with a ring-type wall: (a) Cross-section I; (b) Cross-section II; (c) Cross-section III

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Figure 8

Pressure distributions in pumps with or without ring-type walls: (a) In impeller; (b) In volute casing

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Figure 9

Improvement of pump performance with a ring-type wall in Cal.

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Figure 10

Best height of ring-type wall

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Figure 11

Velocity vectors distributions at each cross-section with a TE-type wall: (a) Cross-section I; (b) Cross-section II; (c) Cross-section III

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Figure 6

Velocity vectors and total pressure distributions at each cross-section without a ring-type wall: (a) Cross-section I; (b) Cross-section II; (c) Cross-section III

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Figure 4

Configurations of volute casing and cross section: (a) R-type; (b) C-type

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Figure 5

Configurations of restraint walls: (a) ring-type; (b) Trailing edge type (TE-type)

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Figure 12

Improvement of pump performance using a TE-type wall

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Figure 13

Pump performance in Exp. with a ring-type wall

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Figure 14

Pump performance in Exp. with a TE-type wall

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