RESEARCH PAPERS: Forced Convection

Internal Cooling in 4:1 AR Passages at High Rotation Numbers

[+] Author and Article Information
Fuguo Zhou, Jonathan Lagrone, Sumanta Acharya

Turbine Innovation and Energy Research (TIER) Center, College of Engineering, Louisiana State University, Baton Rouge, LA 70803

J. Heat Transfer 129(12), 1666-1675 (May 16, 2007) (10 pages) doi:10.1115/1.2767676 History: Received January 30, 2006; Revised May 16, 2007

Heat transfer and pressure drop measurements are reported for a rotating 4:1 aspect ratio (AR) smooth two-pass coolant passage for Reynolds number in the range of 10,000–150,000, rotation number in the range of 0–0.6, and density ratios in the range of 0.1–0.2. The measurements are performed for both 90deg and 45deg orientations of the coolant passage relative to the rotational axis. A large-scale rotating heat transfer rig is utilized, with the test section consisting of segmented foil-heated elements and thermocouples. Results for the 4:1 AR indicate that beyond specific Ro values (different values for the inlet and outlet passages), the expected trends of heat transfer enhancement on the destabilized surface and degradation on the stabilized surface are arrested or reversed. Unlike the 1:1 AR, the inlet-leading surface for the 4:1 AR shows enhancement with Ro at low Re (less than 20,000) and shows the expected degradation only at high Re. Increasing the density ratio enhances the heat transfer on all walls. Orientation of the coolant passage relative to the rotational axis has an important effect, with the 45deg orientation reducing the heat transfer on the destabilized surface and enhancing it on the stabilized surface.

Copyright © 2007 by American Society of Mechanical Engineers
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Figure 2

(a) Lower portion of the smooth model; (b) copper element with heater and spacer

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Figure 3

Rotation effects in the two-pass channel for DR=0.1 at (a) Re=10,000 and (b) Re=40,000. L-leading wall, T-trailing wall.

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Figure 4

Rotation effects on destabilized surfaces at DR=0.1. (a) and (b) inlet-trailing wall at X∕Dh=8.0; (c) and (d) outlet-leading wall at X∕Dh=26.7.

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Figure 5

Rotation effects on stabilized surfaces at DR=0.1. (a) and (b) inlet-leading wall at X∕Dh=8.0; (c) and (d) outlet-trailing wall at X∕Dh=26.7.

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Figure 6

Rotational effects on the heat transfer in the bend at DR=0.1.

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Figure 8

Average Nu∕Nu0 versus buoyancy parameter at Re=20,000. (a) Inlet and (b) outlet.

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Figure 9

Orientation effects with orientation angles 90deg and 45deg, DR=0.1, and (a) Re=20,000 and (b) Re=70,000

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Figure 10

Total average of (Nu45−Nu90)∕Nu0 on the four walls (inlet leading and trailing and outlet leading and trailing)

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Figure 11

Frictional factors in the inlet at DR=0.1

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Figure 7

Density ratio effects at Re=20,000. (a) Inlet, (b) bend, and (c) outlet.



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