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TECHNICAL PAPERS

# Unsteady Hydrodynamic Forces due to Rotor-Stator Interaction on a Diffuser Pump With Identical Number of Vanes on the Impeller and Diffuser

[+] Author and Article Information
M. Zhang

Department of Mechanical Engineering,  Kyushu Institute of Technology, 1-1 Sensui-cho, Tobata, Kitakyushu, 804-8550 Japan

H. Tsukamoto

Department of Biological Functions and Engineering, Graduate School of Life Science and Systems Engineering,  Kyushu Institute of Technology, 2-4, Hibikino, Wakamatsu, Kitakyushu, 808-0196 Japan

J. Fluids Eng 127(4), 743-751 (Apr 01, 2005) (9 pages) doi:10.1115/1.1949640 History: Received August 20, 2003; Revised March 26, 2005; Accepted April 01, 2005

## Abstract

Experimental and computational study was developed for unsteady hydrodynamic forces on a diffuser pump impeller excited by the interaction between the impeller and the vaned diffuser with the same number of vanes as impeller. Unsteady flow calculations are made using commercially available CFD software, CFX-TASCflow, as well as the two-dimensional vortex method. Calculated pressure and fluid forces on the impeller show good agreement with measured ones. It has been demonstrated that the fluid forces on the impeller with the same number of vanes as the vaned diffuser are smaller compared with other combinations of vane numbers. However, the pressure fluctuations are found to be greater than other cases.

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## Figures

Figure 5

Computational domain and grids: (a) Impeller and diffuser; (b) casing and pipe systems

Figure 6

Schematics of coordinate system and control volume for fluid force calculation

Figure 7

(a) Effect of time step on dynamic fluid forces for rated condition and (b) effect of grid density on dynamic fluid forces for rated condition

Figure 8

Steady characteristic curves of test pump; experimental uncertainty in ϕ=±2.1%, in Ψ=±2.3%, in KR¯=±2.5%

Figure 11

Velocity diagram calculated by TACS flow (at t=t1 in Fig. 1(b): (a) Zd=6 and (b) Zd=5

Figure 13

Pressure fluctuation at station (r1,c1),ϕ∕ϕ0=1.0, experimental uncertainty in f=±3.1%, in Sxx=±5.5%, (a) time histories of ΔCp and (b) power spectrum

Figure 14

Calculated pressure fluctuation in vaned diffuser passage ϕ∕ϕ0=1.0: (a) Station (r1,c1), (b) station (r2,c1), and (c) station (r3,c1)

Figure 15

Pressure fluctuations at pump inlet, ϕ∕ϕ0=1.0: (a) CFD predicted and (b) measured

Figure 16

Calculated pressure fluctuation at pump discharge

Figure 17

Power spectra of measured pressure fluctuation at pump suction and discharge pipe; experimental uncertainty in f=±2.3%, in Sxx=±4.1%

Figure 1

Schematic view of test rig and instrumentation system

Figure 2

Schematics of fluid force measurement system

Figure 3

Schematics of reference coordinate systems for test diffuser pump

Figure 4

Locations of pressure taps in vaned diffuser

Figure 9

Time histories of dynamic fluid forces; Zd=6; experimental uncertainty in Kx=±1.7%: (a) Effect of rotational speed, ϕ∕ϕ0=1.0; (b) effect of flow rate, N=1750min−1

Figure 10

Time histories of dynamic fluid forces for various diffuser vane numbers (N=1750min−1,ϕ∕ϕ0=1.0), experimental uncertainty in Kx=±1.7%: (a) Measured, (b) CFD predicted, and (c) calculated by vortex method

Figure 12

Vorticity distribution and velocity vectors calculated by vortex method (at t=t2 in Fig. 1(c)): (a) Zd=6 and (b) Zd=5

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