Gas turbine film cooling and heat transfer measurements using a transient liquid crystal techniqu

Modern gas turbines have high inlet temperatures due to which the various components undergo severe thermal stress and fatigue. Detailed measurements of heat transfer to gas turbine components from the damaging mainstream gases are required for better design. This study presents details of various image processing techniques for analysis of liquid crystal color changes occurring due to convection. There are many techniques to process the liquid crystal color change. These techniques differ in the way the color changes due to temperature are interpreted. A transient liquid crystal technique involving a single color capturing method was employed in this study. The detailed local heat transfer behaviors on gas turbine surfaces can be estimated using this technique. Film cooling measurements can also be obtained with liquid crystal color processing. Liquid crystal techniques are versatile and can be applied to complex geometries. Results are presented for a two-pass duct with a 180$spcirc$ turn, a flat plate with various film cooling hole orientations, flat plate spallation, and a turbine blade leading edge model.