Combined Effect of Grid Turbulence and Unsteady Wake on Film Effectiveness and Heat Transfer Coefficient of a Gas Turbine Blade With Air and CO2 Film Injection

[+] Author and Article Information
S. V. Ekkad, A. B. Mehendale, J. C. Han

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

C. P. Lee

General Electric—Aircraft Engines, Cincinnati, OH 45215

J. Turbomach 119(3), 594-600 (Jul 01, 1997) (7 pages) doi:10.1115/1.2841163 History: Received February 01, 1994; Revised November 01, 1995; Online January 29, 2008


Experiments were performed to study the combined effect of grid turbulence and unsteady wake on film effectiveness and heat transfer coefficient of a turbine blade model. Tests were done on a five-blade linear cascade at the chord Reynolds number of 3.0 × 105 at cascade inlet. Several combinations of turbulence grids, their locations, and unsteady wake strengths were used to generate various upstream turbulence conditions. The test blade had three rows of film holes in the leading edge region and two rows each on the pressure and suction surfaces. Air and CO2 were used as injectants. Results show that Nusselt numbers for a blade with film injection are much higher than that without film holes. An increase in mainstream turbulence level causes an increase in Nusselt numbers and a decrease in film effectiveness over most of the blade surface, for both density injectants, and at all blowing ratios. A free-stream turbulence superimposed on an unsteady wake significantly affects Nusselt numbers and film effectiveness compared with only an unsteady wake condition.

Copyright © 1997 by The American Society of Mechanical Engineers
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