Research Papers: Flows in Complex Systems

Flow Characteristics of Gerotor Pumps With Novel Variable Clearance Designs

[+] Author and Article Information
Chiu-Fan Hsieh

Department of Mechanical
and Computer-Aided Engineering,
National Formosa University,
64 Wunhua Road,
Huwei, Yunlin 63201, Taiwan
e-mail: cfhsieh@nfu.edu.tw

Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received March 16, 2014; final manuscript received November 24, 2014; published online January 20, 2015. Assoc. Editor: Frank C. Visser.

J. Fluids Eng 137(4), 041107 (Apr 01, 2015) (12 pages) Paper No: FE-14-1137; doi: 10.1115/1.4029274 History: Received March 16, 2014; Revised November 24, 2014; Online January 20, 2015

Although gerotor pumps are used in a wide range of industrial applications, higher work pressure causes shock or collision among pump components, which leads to large stress fluctuations and shortened pump life expectancy. This paper therefore proposes a novel variable clearance design that diminishes such component collisions. After a geometric mathematical model is constructed of variable clearance rotors, a fluid analysis model is developed based on a relief groove design. Applying the model to two fixed clearance and three variable clearance designs demonstrates the effects of various fixed clearance sizes on gerotor pump performance and identifies the differences between fixed and variable clearance designs. The results support the feasibility of the proposed design: the appropriate variable clearance designs maintain robust flow characteristics and effectively reduce shock and collision among pump components, thereby reducing stress level, increasing stability, and extending the life expectancy of the gerotor pumps.

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Fig. 3

Coordinate system for generating outer rotor

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Fig. 4

Illustration of clearance positions

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Fig. 6

The model of fluid analysis

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Fig. 7

Calculations of dynamic mesh and fluid flow. (a) Pressure calculation and (b) flow velocity calculation.

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Fig. 8

Analysis of the outlet flow rate. (a) Convergence conditions, (b) comparisons of average flow rate, (c) flow rate ripple in one revolution, and (d) comparisons of flow rate irregularity.

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Fig. 9

Analysis of Reynolds number at the outlet. (a) Reynolds number ripple in one revolution and (b) comparisons of average of Reynolds number.

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Fig. 10

Analysis of outlet pressure. (a) Outlet pressure ripple, (b) Euler number ripple in one revolution, and (c) comparisons of average of Euler number.

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Fig. 11

Analysis of hydrodynamic effect on the rotors. (a) Fluid moment ripple on the inner rotor for one revolution and (b) fluid moment ripple on the outer rotor for one revolution.

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Fig. 12

Prediction of cavitation risk

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Fig. 13

Survey positions inside the pump

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Fig. 14

Analysis of pressure ripple inside the pump. (a) R1 position, (b) R2 position, (c) R3 position, (d) R4 position, (e) L4 position, (f) L3 position, (g) L2 position, and (h) L1 position.



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