Surface Heat Transfer Measurements of a Scaled Rib-Roughened Serpentine Cooling Passage by Use of a Transient Liquid Crystal Technique

This study is aimed at providing heat transfer characteristics of the three-pass turbulated serpentine cooling channel inside a 10:1 scaled model of an actual turbine blade. A transient method using Thermochromic Liquid Crystal (TLC) is employed to measure the surface heat transfer distribution inside the model. Great attention is paid to the streamwise decrease in the mainstream temperature due to the heat absorption into the test model. To overcome this problem, the present study employed the linear interpolating method used by Ekkad and Han (1997) to estimate the local air bulk temperature. The soundness of the measuring method is verified through the heat transfer measurements of straight-duct models with and without turbulence promoting ribs. It follows from the heat transfer measurement of the serpentine model, in conjunction with the flow visualization, that the geometries of the cross-section of the cooling passage influence the flow pattern, resulting in substantial change in heat transfer distribution in the serpentine model in comparison with that of the straight-duct model.Copyright © 1998 by ASME