Effects of the Shape Modification of the Leading Edge Impingement Cooling for Turbine Blade

In impingement cooling, it is important to consider eliminating the influence of crossflow to improve the heat transfer coefficient. Therefore, in this work, the effects of shape modification on the leading edge impingement cooling for the turbine blade with crossflow conditions have been investigated numerically and experimentally. The heat transfer coefficient on the cooling side of the leading edge was calculated using CFD (RANS) in a static system. The CFD model was created using a shape that resembles a partial cut of the midspan position of the turbine blade leading edge, incorporating impingement cooling and film cooling. This was based on the effective heat transfer coefficient considering the area of impingement target surface. Shapes with installed pin-fins and varied impingement pitches were expected to have high cooling performance and be less affected by crossflow. Therefore, these shapes were selected as Opt-A and Opt-B configurations for rig testing. In the experiment, the shape of the specimen was the same as the CFD model. The mainstream temperature and pressure were adjusted to achieve a Reynolds number equivalent to the actual operating conditions. And the cooling air for impingement and crossflow can be supplied separately. The impingement Reynolds number was varied from 9.0 × 103 to 3.0 × 104. Furthermore, to investigate the effect of crossflow, the flow rate was also varied at half, double, and zero flow rates compared to the base value. Surface temperature was measured using calibrated Infrared thermal cameras and converted into cooling effectiveness.