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Research Papers: Forced Convection

# Heat Transfer in Trailing Edge, Wedge-Shaped Cooling Channels Under High Rotation Numbers

[+] Author and Article Information
Lesley M. Wright

Department of Aerospace and Mechanical Engineering, The University of Arizona, Tucson, AZ 85721-0119

Yao-Hsien Liu

Turbine Heat Transfer Laboratory, Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843-3123

Je-Chin Han

Turbine Heat Transfer Laboratory, Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843-3123jc-han@tamu.edu

Sanjay Chopra

Siemens Power Company, 4400 Alafaya Trail, Orlando, FL 32826

J. Heat Transfer 130(7), 071701 (May 16, 2008) (11 pages) doi:10.1115/1.2907437 History: Received February 23, 2007; Revised October 31, 2007; Published May 16, 2008

## Abstract

Heat transfer coefficients are experimentally measured in a rotating cooling channel used to model an internal cooling passage near the trailing edge of a gas turbine blade. The regionally averaged heat transfer coefficients are measured in a wedge-shaped cooling channel ($Dh=2.22cm$, $Ac=7.62cm2$). The Reynolds number of the coolant varies from 10,000 to 40,000. By varying the rotational speed of the channel, the rotation number and buoyancy parameter range from 0 to 1.0 and 0 to 3.5, respectively. Significant variation of the heat transfer coefficients in both the spanwise and streamwise directions is apparent. Spanwise variation is the result of the wedge-shaped design, and streamwise variation is the result of the sharp entrance into the channel and the $180deg$ turn at the outlet of the channel. With the channel rotating at 135° with respect to the direction of rotation, the heat transfer coefficients are enhanced on every surface of the channel. Both the nondimensional rotation number and buoyancy parameter have proven to be excellent parameters to quantify the effect of rotation over the extended ranges achieved in this study.

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## Figures

Figure 1

Rotating test facility for internal turbine blade heat transfer studies

Figure 2

Details of the wedge-shaped trailing edge test section

Figure 3

Cross-sectional view of the trailing edge test section with experimental details

Figure 4

Test case combinations with the resulting rotation numbers

Figure 5

Surface identification with a conceptual view of the rotation induced secondary flow

Figure 6

Spanwise variation of the Nusselt number ratios in stationary channels

Figure 7

Streamwise averaged Nusselt number ratios in stationary channels

Figure 8

Spanwise variation of the Nusselt number ratios in rotating channels (500rpm)

Figure 9

Effect of rotational speed on the Nusselt number ratios in the entrance, fully developed, and exit regions of the channel

Figure 10

Effect of rotation number on the Nusselt number ratios in the entrance, fully developed, and exit regions of the channel

Figure 11

Effect of buoyancy parameter on the Nusselt number ratios in the entrance, fully developed, and exit regions of the channel

Figure 12

Effect of rotation number on the streamwise averaged Nusselt number ratios

Figure 13

Effect of buoyancy parameter on the streamwise averaged Nusselt number ratios

Figure 14

Effect of rotation number on the streamwise and spanwise averaged Nusselt number ratios

Figure 15

Effect of buoyancy parameter on the streamwise and spanwise averaged Nusselt number ratios

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