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The Influence of cooling configuration and tip geometry on gas turbine blade tip leakage flow and heat transfer

Sakaoğlu, Sergen
In gas turbine engines, an increase in the thermal efficiency and power output can be ensured by increasing the turbine inlet temperature. This causes the high-pressure turbine (HPT) blades to be exposed to extremely high temperatures that requires the introduction of cooling flow in order to keep the temperatures within the allowable material limits and to reduce the high thermal loads on the blade. However, cooling flow introduced around the blade tip region affects the blade tip leakage flow and blade tip heat transfer. This work explores the effects of various combinations of location, size, and number of cooling holes used for blade tip cooling and different tip types with varying geometry on pressure loss and thermal performance. These combinations are analyzed either in the stationary or the rotating domain using computational fluid dynamics (CFD). The first-stage high-pressure turbine blade profile of the well-known General Electric Energy Efficient Engine (GE-E3) is used in the research. Findings suggest that squealer tips are superior to flat tips in terms of both aero and thermal performances and they give the best cooling performance when a larger number of cooling holes is located closer to the blade pressure side. v For squealer tips, rotation and addition of cooling at the tip are observed to alter the tip gap flow. Heat transfer coefficient on the squealer blade tip is found to increase with the addition of cooling, while higher film-cooling effectiveness is obtained with increasing the rim height