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Research Papers

Effects of Large Scale High Freestream Turbulence and Exit Reynolds Number on Turbine Vane Heat Transfer in a Transonic Cascade

[+] Author and Article Information
Shakeel Nasir, Jeffrey S. Carullo, Wing-Fai Ng, Karen A. Thole, Hong Wu

Department of Mechanical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061

Luzeng J. Zhang, Hee Koo Moon

Heat Transfer Department, Solar Turbines Inc., San Diego, CA 92186

J. Turbomach 131(2), 021021 (Feb 03, 2009) (11 pages) doi:10.1115/1.2952381 History: Received September 18, 2007; Revised October 21, 2007; Published February 03, 2009

Abstract

This paper experimentally and numerically investigates the effects of large scale high freestream turbulence intensity and exit Reynolds number on the surface heat transfer distribution of a turbine vane in a 2D linear cascade at realistic engine Mach numbers. A passive turbulence grid was used to generate a freestream turbulence level of 16% and integral length scale normalized by the vane pitch of 0.23 at the cascade inlet. The base line turbulence level and integral length scale normalized by the vane pitch at the cascade inlet were measured to be 2% and 0.05, respectively. Surface heat transfer measurements were made at the midspan of the vane using thin film gauges. Experiments were performed at exit Mach numbers of 0.55, 0.75, and 1.01, which represent flow conditions below, near, and above nominal conditions. The exit Mach numbers tested correspond to exit Reynolds numbers of $9×105$, $1.05×106$, and $1.5×106$ based on a vane chord. The experimental results showed that the large scale high freestream turbulence augmented the heat transfer on both the pressure and suction sides of the vane as compared to the low freestream turbulence case and promoted a slightly earlier boundary layer transition on the suction surface for exit Mach 0.55 and 0.75. At nominal conditions, exit Mach 0.75, average heat transfer augmentations of 52% and 25% were observed on the pressure and suction sides of the vane, respectively. An increased Reynolds number was found to induce an earlier boundary layer transition on the vane suction surface and to increase heat transfer levels on the suction and pressure surfaces. On the suction side, the boundary layer transition length was also found to be affected by increase changes in Reynolds number. The experimental results also compared well with analytical correlations and computational fluid dynamics predictions.

Figures

Figure 1

Virginia Tech transonic cascade wind tunnel

Figure 2

Cascade diagram showing the vanes and the axis orientation for measurements with the traverse

Figure 3

Cascade inlet temperature and Mach number history

Figure 4

Photograph of thin film gauges in wind tunnel

Figure 13

Flow periodicity through vane passages

Figure 14

Acceleration parameter distribution

Figure 18

Heat transfer augmentation at all exit Ma cases

Figure 19

Suction side data compared to the flat plate correlations at exit Ma 0.75

Figure 15

Heat transfer distribution at exit Ma 0.55

Figure 16

Heat transfer distribution at exit Ma 0.75

Figure 17

Heat transfer distribution at exit Ma 1.01

Figure 20

Pressure side data compared to the flat plate correlations at exit Ma 0.75

Figure 21

Heat transfer distribution at Tu=2%

Figure 22

Heat transfer distribution at Tu=16%

Figure 23

Stagnation region data compared to Dullenkopf and Mayle’s correlation

Figure 24

Computational domain for CFD predictions

Figure 25

Local Mach number distribution comparison

Figure 26

FLUENT prediction at exit Ma 0.55, 2% Tu

Figure 27

FLUENT prediction at exit Ma 0.75, 2% Tu

Figure 28

FLUENT prediction at exit Ma 1.01, 2% Tu

Figure 29

FLUENT prediction at exit Ma 0.75, 16% Tu

Figure 30

TEXSTAN prediction at exit Ma 0.55, 2% Tu

Figure 5

Typical vane surface and adiabatic wall temperatures history

Figure 6

Typical vane surface heat flux and heat transfer coefficient history

Figure 7

Square mesh turbulence grid

Figure 8

Square mesh turbulence grid location relative to the test section

Figure 9

Turbulence intensity along the inlet pitch

Figure 10

Integral length scale along the inlet pitch

Figure 11

Velocity ratio distribution along the inlet pitch

Figure 12

Local Mach number distribution

Figure 34

TEXSTAN prediction at exit Ma 0.75, 16% Tu

Figure 35

TEXSTAN prediction at exit Ma 1.01, 16% Tu

Figure 31

TEXSTAN prediction at exit Ma 0.75, 2% Tu

Figure 32

TEXSTAN prediction at exit Ma 1.01, 2% Tu

Figure 33

TEXSTAN prediction at exit Ma 0.55, 16% Tu

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