Session: 15-04 Turbulated Cooling

Paper Number: 129107

129107 - Heat Transfer Coefficients in a Three-Passage Ribbed Channel Using a Transient Liquid Crystal Technique 

One-dimensional (1D) transient heat conduction in a semi-infinite solid material with a convection boundary condition has been widely used for determining the surface convection heat transfer coefficient distribution. Particularly in complex turbine blade cooling passages, which the test model is very difficult to be instrumented by using the standard steady-state tests. In this work, the full heat transfer coefficient maps of a turbine blade with realistic three-passage ribbed channel are examined using the 1D transient heat conduction model with narrow-band liquid crystal. The tests were conducted at two different engine representative flow conditions. The time map for the blade’s internal surfaces to reach a target temperature was obtained from the liquid crystal using the maximum green intensity approach. The conventional hue value approach was also applied to obtain the surface time map for data comparison. Since the test channel is of high blockage, delayed flow history was observed and a time correction is needed to address the asynchronous behavior between the flow and heat transfer. In addition, the difficulty for accurately capturing the bulk mean flow temperature within the three-passage channel leads to additional uncertainty for heat transfer coefficient calculations. The effects of delayed flow, time correction, and using different reference fluid temperatures on the heat transfer coefficient calculations are demonstrated and analyzed. Using the current blade as an example, this study compares two different temperature interpretation approaches (maximum green intensity and hue value). In addition, other factors that affect the measurement of detailed heat transfer coefficient distributions using 1D transient conduction model are presented and discussed.

Keywords: Turbine Blade Internal Cooling, Transient Liquid Crystal.

Presenting Author: Lesley Wright Texas A&M University

Presenting Author Biography: Dr. Lesley Wright is an Associate Professor of Mechanical Engineering. Prior to joining Texas A&M, she was a member of the Mechanical Engineering faculty at Baylor University for ten years. She returns to Texas A&M where she earned her Ph.D. in Mechanical Engineering in 2006. Currently she is investigating enhanced convective cooling technology, including heat transfer enhancement for gas turbine cooling applications. This experimental research has led to the development of innovative cooling technology for both turbine blade film cooling and internal heat transfer enhancement. In addition, Dr. Wright continues to investigate the effect of rotation on the thermal performance of rotor blade cooling passages. Her research interests have also led to the development of novel experimental methods for the acquisition of detailed surface and flow measurements in highly turbulent flows.

Authors:

Lesley M. Wright Texas A&M University
Chao-Cheng Shiau Texas A&M University
Je-Chin Han Texas A&M University
Robert Krewinkel MAN Energy Solutions SE