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TECHNICAL PAPERS

# Effects of Bleed Flow on Heat/Mass Transfer in a Rotating Rib-Roughened Channel

[+] Author and Article Information
Yun Heung Jeon, Suk Hwan Park, Kyung Min Kim, Dong Hyun Lee

School of Mechanical Engineering, Yonsei University, Seoul 120-749, Korea

Hyung Hee Cho

School of Mechanical Engineering, Yonsei University, Seoul 120-749, Koreahhcho@yonsei.ac.kr

J. Turbomach 129(3), 636-642 (Jul 25, 2006) (7 pages) doi:10.1115/1.2720495 History: Received July 18, 2006; Revised July 25, 2006

## Abstract

The present study investigates the effects of bleed flow on heat/mass transfer and pressure drop in a rotating channel with transverse rib turbulators. The hydraulic diameter $(Dh)$ of the square channel is $40.0mm$. 20 bleed holes are midway between the rib turburators on the leading surface and the hole diameter $(d)$ is $4.5mm$. The square rib turbulators are installed on both leading and trailing surfaces. The rib-to-rib pitch $(p)$ is 10.0 times of the rib height $(e)$ and the rib height-to-hydraulic diameter ratio $(e∕Dh)$ is 0.055. The tests were conducted at various rotation numbers (0, 0.2, 0.4), while the Reynolds number and the rate of bleed flow to main flow were fixed at 10,000 and 10%, respectively. A naphthalene sublimation method was employed to determine the detailed local heat transfer coefficients using the heat/mass transfer analogy. The results suggest that for a rotating ribbed passage with the bleed flow of $BR=0.1$, the heat/mass transfer on the leading surface is dominantly affected by rib turbulators and the secondary flow induced by rotation rather than bleed flow. The heat/mass transfer on the trailing surface decreases due to the diminution of main flow. The results also show that the friction factor decreases with bleed flow.

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## Figures

Figure 1

Experimental apparatus

Figure 2

Geometry of the test channel

Figure 3

Coordinate system of the test section: (a) leading surface; (b) trailing surface

Figure 4

Sh ratio distributions in the ribbed channel at BR=0.0: (a) Ro=0.0; (b) Ro=0.2; (c) Ro=0.4

Figure 5

Line averaged Sh ratio distributions in the ribbed channel at BR=0.0

Figure 6

Sh ratio distributions on the leading surface in the smooth channel at BR=0.1: (a) Ro=0.0; (b) Ro=0.2; (c) Ro=0.4

Figure 7

Sh ratio distributions on the leading surface in the smooth channel at BR=0.1: (a) Sh ratio distributions on the center line; (b) Line averaged Sh ratio distributions

Figure 8

Sh ratio distributions in the ribbed channel at BR=0.1: (a) Ro=0.0; (b) Ro=0.2; (c) Ro=0.4

Figure 9

Line averaged Sh ratio distributions in the Ribbed channel at BR=0.1: (a) leading surface; (b) trailing surface

Figure 10

Regional averaged Sherwood number ratios (10.5⩽x∕Dh⩽13.25)

Figure 11

Sh ratio distributions on the leading surface in the ribbed channel: (a) Ro=0.0; (b) Ro=0.2; (c) Ro=0.4

Figure 12

Friction factor ratios at various rotation numbers

Figure 13

Mean Sherwood number ratios and thermal performance (10.5⩽x∕Dh⩽13.25)

## Errata

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