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TECHNICAL PAPERS

Experimental and Numerical Investigation of the Flow Field in the Tip Region of an Axial Ventilation Fan

[+] Author and Article Information
Xiaocheng Zhu

School of Mechanical Engineering,  Shanghai Jiaotong University, Shanghai, 200030, Chinazhxc@sjtu.edu.cn

Wanlai Lin

School of Mechanical Engineering,  Shanghai Jiaotong University, Shanghai, 200030, Chinawllin@sjtu.edu.cn

Zhaohui Du

School of Mechanical Engineering,  Shanghai Jiaotong University, Shanghai, 200030, Chinazhdu@sjtu.edu.cn

J. Fluids Eng 127(2), 299-307 (Dec 28, 2004) (9 pages) doi:10.1115/1.1881654 History: Received July 08, 2003; Revised December 28, 2004

The tip leakage flow in an axial ventilation fan with various tip clearances is investigated by experimental measurement and numerical simulation. For a low-rotating-speed ventilation fan with a large tip clearance, both experimental measurement and numerical simulation indicate that the leakage flow originating from the tip clearance along the chord rolls up into a three-dimensional spiral structure to form a leakage flow vortex. The mixing interaction between the tip leakage flow and the main flow produces a low axial velocity region in the tip region, which leads to blockage of the main flow. As the tip clearance increases, the tip leakage flow and the reverse flow become stronger and fully developed. In addition, the position of the first appearance of the tip leakage vortex moves further downstream in a direction parallel to the mid chord line.

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Copyright © 2005 by American Society of Mechanical Engineers
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Figures

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Figure 1

General schematic of the fan performance test

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Figure 2

General geometry shape of the blade

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Figure 3

Velocity-component definitions

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Figure 4

Computation grid for the fan

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Figure 5

(a) Static efficiency at different grid number and (b) static pressure rise at different grid number

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Figure 6

Model of tip leakage vortex

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Figure 7

(a) Static efficiency at different flow rate and (b) Static pressure rise at different flow rate

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Figure 8

Relative velocity vector and radial velocity contour in the blade-to-blade surface at R=101% blade span for the normalized tip clearance of 1.98%

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Figure 9

Secondary flow, contour of axial velocity, and total velocity on the surface 100% axial chord location after the leading edge for the normalized tip clearance of 1.98%

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Figure 10

Secondary flow field at 70% axial chord location

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Figure 11

Secondary flow at 100% axial chord location

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Figure 12

Distribution of the pressure coefficient at the 99% of the blade span (numerical simulation)

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Figure 13

Radial variation of mass averaged axial velocity (X=1.20Cx)

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Figure 14

Radial variation of mass-averaged flow angle (X=1.20Cx)

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