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RESEARCH PAPERS: Forced Convection

# Heat Transfer Enhancement of a Circular Cylinder

[+] Author and Article Information
Takayuki Tsutsui

Department of Mechanical Engineering, The National Defense Academy, 1-10-20 Hashirimizu, Yokosuka, Kanagawa 239-8686, Japantsutsui@nda.ac.jp

Tamotsu Igarashi

Department of Mechanical Engineering, The National Defense Academy, 1-10-20 Hashirimizu, Yokosuka, Kanagawa 239-8686, Japan

J. Heat Transfer 128(3), 226-233 (Sep 15, 2005) (8 pages) doi:10.1115/1.2150832 History: Received November 17, 2004; Revised September 15, 2005

## Abstract

A rod was positioned upstream of a circular cylinder to enhance its heat transfer in an air stream. The diameter of the cylinder was $40mm$ and the diameter of the rod ranged from $1to12mm$. The distance between the axes of the cylinder and the rod was varied between 40 and $120mm$ and the Reynolds number ranged from $1.5×104$ to $6.2×104$. In the optimum configuration, the heat transfer on the front face of the cylinder increases remarkably relative to a single circular cylinder, and results in a 40% overall increase in heat transfer.

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## Figures

Figure 1

Coordinate system and symbols

Figure 2

Experimental models: (a) constant heat flux model and (b) constant temperature model

Figure 3

Local and overall Nusselt number of a circular cylinder: (a) local Nusselt number and (b) overall Nusselt number

Figure 4

Effect of distance x on a circular cylinder: (a) pressure distribution and (b) local Nusselt number

Figure 5

Flow visualizations around the cylinder (Re=2.1×104): (a) without rod; (b) pattern A (L∕D=1.75, d∕D=0.05); and (c) pattern B (L∕D=1.75, d∕D=0.25)

Figure 6

Classification of the flow patterns: (a) Re=1.5×104 and (b) Re=6.2×104

Figure 7

Pressure coefficient distributions around the cylinder (Re=4.1×104): (a) pattern A (L∕D=1.75, d∕D=0.05) and (b) pattern B (L∕D=1.75, d∕D=0.25)

Figure 8

Surface oil flow patterns (d∕D=0.25, L∕D=1.75, pattern B): (a) Re=1.5×104; (b) Re=3.1×104; (c) Re=4.1×104; and (d) Re=6.2×104

Figure 9

Flow characteristics: (a) separation point; (b) Strouhal number; and (c) drag coefficient

Figure 10

Local Nusselt number distributions around the cylinder: (a) pattern A (L∕D=1.75, d∕D=0.05); (b) pattern B (L∕D=1.25, d∕D=0.25); and (c) pattern B (L∕D=1.75, d∕D=0.25)

Figure 11

Local Nusselt number distributions around the cylinder Re=6.2×104: (a) L∕D=1.0, d∕D=0.25, pattern B; (b) L∕D=1.25, d∕D=0.3, pattern B; (c) L∕D=1.75, d∕D=0.15, pattern A; and (d) L∕D=2.5, d∕D=0.25, pattern A

Figure 12

Average Nusselt number: (a) front face and (b) rear face

Figure 13

Overall Nusselt number: (a) variation with L∕D and d∕D and (b) comparison of the present study with square prisms

Figure 14

Contour map of the rate of heat transfer enhancement of the cylinder: (a) Re=2.1×104; (b) Re=4.1×104; and (c) Re=6.2×104

## Errata

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