Effect of Blade Tip Geometry on Heat Transfer Coefficients on Gas Turbine Blade Tips and Near Tip Regions

Detailed heat transfer coefficient distributions on two types of gas turbine blade tip, plane tip and squealer tip, were measured using a hue-detection base transient liquid crystals technique. The heat transfer coefficients on the shroud and near tip regions of the pressure and suction sides of the blade were also measured. The heat transfer measurements were taken at the three different tip gap clearances of 1.0%, 1.5%, and 2.5% of blade span. Results show the overall heat transfer coefficients on the tip and shroud with squealer tip blade were lower than those with plane tip blade. By using squealer tip, however, the reductions of heat transfer coefficients near the tip regions of the pressure and suction sides were not remarkable.