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RESEARCH PAPERS: Natural and Mixed Convection

Heat Transfer in a Radially Rotating Square-Sectioned Duct With Two Opposite Walls Roughened by $45Deg$ Staggered Ribs at High Rotation Numbers

[+] Author and Article Information
Shyy Woei Chang

Thermal Fluids Laboratory, National Kaohsiung Marine University, No. 142 Haijhuan Road, Nanzih District, Kaohsiung City 81143, Taiwan, Republic of Chinaswchang@mail.nkmu.edu.tw

Tong-Minn Liou, Jui-Hung Hung

Department of Power Mechanical Engineering, National Tsing Hua University, 300 Hsinchu, Taiwan, Republic of China

Wen-Hsien Yeh

Department of Marine Engineering, National Kaohsiung Marine University, No. 142 Haijhuan Road, Nanzih District, Kaohsiung City 81143, Taiwan, Republic of China

J. Heat Transfer 129(2), 188-199 (May 02, 2006) (12 pages) doi:10.1115/1.2409988 History: Received January 03, 2006; Revised May 02, 2006

Abstract

This paper describes an experimental study of heat transfer in a radially rotating square duct with two opposite walls roughened by $45deg$ staggered ribs. Air coolant flows radially outward in the test channel with experiments to be undertaken that match the actual engine conditions. Laboratory-scale heat transfer measurements along centerlines of two rib-roughened surfaces are performed with Reynolds number (Re), rotation number (Ro), and density ratio $(Δρ∕ρ)$ in the ranges of 7500–15,000, 0–1.8, and 0.076–0.294. The experimental rig permits the heat transfer study with the rotation number considerably higher than those studied in other researches to date. The rotational influences on cooling performance of the rib-roughened channel due to Coriolis forces and rotating buoyancy are studied. A selection of experimental data illustrates the individual and interactive impacts of Re, Ro, and buoyancy number on local heat transfer. A number of experimental-based observations reveal that the Coriolis force and rotating buoyancy interact to modify heat transfer even if the rib induced secondary flows persist in the rotating channel. Local heat transfer ratios between rotating and static channels along the centerlines of stable and unstable rib-roughened surfaces with Ro varying from 0.1 to 1.8 are in the ranges of 0.6–1.6 and 1–2.2, respectively. Empirical correlations for periodic flow regions are developed to permit the evaluation of interactive and individual effects of ribflows, convective inertial force, Coriolis force, and rotating buoyancy on heat transfer.

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Figures

Figure 2

Rotating test facility

Figure 3

Details of heat transfer test module

Figure 5

Axial variation of Nusselt number ratio along leading and trailing edges for Ro=0

Figure 8

Axial distributions of normalized rotational Nusselt number at various Re for Ro=(a) 0.1; (b) 0.3; (c) 0.5; and (d) 0.7

Figure 9

Variation of normalized rotational Nusselt number with rotation number at repeated: (a) rib top; and (b) midrib location

Figure 10

Variation of normalized rotational Nusselt number with buoyancy number for various Ro at repeated: (a) rib top(L); (b) rib top(T); (c) midrib location(L); and (d) midrib location (T)

Figure 4

Local Nusselt number distributions along leading and trailing edges at various Re for Ro=0

Figure 1

Δρ∕ρ versus Ro×Re

Figure 6

Typical variation of local rotational Nusselt number along trailing and leading edges with three density ratios

Figure 7

Axial distributions of rotational Nusselt number ratio along: (a) leading; and (b) trailing edges at various Ro; and (c) illustrative data set of rotational tests

Figure 11

Variations of evaluated zero-buoyancy heat transfer ϕ1 with rotation number at repeated: (a) rib top; and (b) midrib location

Figure 12

Variations of ϕ2 with rotation number for repeated rib flow region

Figure 13

Comparison of experimental data with correlation results at repeated: (a) rib top; and (b) midrib location

Errata

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