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TECHNICAL PAPERS

Measurements of Rotordynamic Forces on an Artificial Heart Pump Impeller

[+] Author and Article Information
Takayuki Suzuki1

Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japantaka8170@me.es.osaka-u.ac.jp

Romain Prunières, Hironori Horiguchi, Yoshinobu Tsujimoto

Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan

Tomonori Tsukiya, Yoshiyuki Taenaka

Department of Artificial Organs, National Cardiovascular Center of Japan, 5-7-1 Fujishiro-dai, Suita, Osaka 565-8565, Japan

1

Corresponding author.

J. Fluids Eng 129(11), 1422-1427 (Jun 13, 2007) (6 pages) doi:10.1115/1.2786477 History: Received November 15, 2006; Revised June 13, 2007

In centrifugal pumps for artificial hearts, a magnetic drive with lightly loaded journal bearing system is often used. In such a system, the rigidity of the bearing is small and the impeller usually rotates over the critical speed. In such cases, the rotordynamic fluid forces play an important role for shaft vibration. In the present study, the characteristics of the rotordynamic fluid forces on the impeller were examined. The rotordynamic fluid forces were measured in the cases with/without the whirling motion. It was found that the rotordynamic forces become destabilizing in a wide range of positive whirl. The effect of leakage flow was also examined.

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Copyright © 2007 by American Society of Mechanical Engineers
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Figures

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Figure 1

Experimental facility

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Figure 2

Cross section of the sleeve

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Figure 3

Impeller and casing geometry: (a) impeller and (b) casing

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Figure 4

Leakage flow system

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Figure 5

Coordinate system. Fn and Ft are the normal and tangential components to the whirl orbit. (ε, eccentricity, Ω, shaft rotational speed, ω, whirling speed, (x,y), rotating frame of the shaft, and (n,t), normal and tangential to the whirl orbit.)

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Figure 6

Pressure performance of the test impeller (ε=0, ω∕Ω=0) and pressure coefficient ψ versus flow coefficient ϕ

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Figure 7

Dimensionless normal and tangential fluid forces fn,ft, the dimensional fluid forces Fn, Ft, and steady eccentricity value on the impeller versus whirl speed ratio ω∕Ω at various flow coefficients ϕ(ε=1.08mm): (a) ϕ=0.01, (b) ϕ=0.02, (c) ϕ=0.03, and (d) ϕ=0.04

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Figure 8

Radial forces Fx′ and Fy′ on the impeller at various flow coefficients ϕ (ε=1.08mm, ω∕Ω=0)

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Figure 9

Location of pressure measuring points on the casing

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Figure 10

Blade shape and corresponding pressure points on the blade

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Figure 11

Comparison of the dimensionless normal direct fn, pressure fn′,fn″ and tangential direct ft, pressure ft′,ft″ fluid forces with estimated forces from unsteady pressure at flow coefficient ϕ=0.02(ε=1.08mm): (a) dimensionless normal fluid forces fn, fn′, fn″ and (b) dimensionless tangential fluid forces ft, ft′, ft″

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Figure 12

Leakage flow in the NCVC-2

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Figure 13

Effect of the leakage flow at flow coefficient ϕ=0.02(ε=1.08mm): (a) dimensionless normal fluid forces fn and (b) dimensionless tangential fluid forces ft

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