| Gas turbine is a type of internal combustion engine. Cooling of turbine airfoils is one useful way to obtain higher thermal efficiency and lower fuel consumption. In this study, an experimental investigation is carried out to study the heat transfer performance in a mid-chord turbine airfoil cooling channel roughened with wrap-around ribs. Steady-state liquid crystal thermography technique is employed for the heat transfer tests. The experiments are focused on two channel geometries of aspect ratio 1 and 3 that are roughened with several rib geometries with and without wrap-arounds. The Reynolds number range is from 10000 to 80000. The effect of wrap-arounds, pitch to height ratio, rib angle and rib arrangement (staggered and criss-cross) are discussed. In addition to the measurement of heat transfer coefficient, for each geometry, the pressure drop along the test section is measured and the Darcy friction factor is reported.;Major conclusions of this study are: a) wrap-arounds generally produce higher heat transfer coefficients than the ribs without wrap-arounds, b) ribs with wrap-arounds produced higher friction factors, c) area-weighted average Nusselt numbers monotonically increase with the Reynolds number, d) enhancement factors decrease with the increase of Reynolds number, e) with almost the same friction factors, staggered ribs are more effective than the criss-crossed ribs. |
