Session: 32-13 High Pressure Turbines 2

Paper Number: 121742

121742 - High Effectiveness Tip Cooling Using Inclined Slots 

The tip of the High Pressure Turbine (HPT) blade is critical for gas turbine performance and operation. Hot gas leaking through the tip gap tends to oxidize and erode the blade, while generating significant aerodynamic loss. Squealer tips are often used to maximize efficiency, but the thin rims are thermally vulnerable and difficult to cool. The resultant degradation often limits engine life, as well as firing temperatures and thermal efficiency. This work considers means to improve the tip cooling of such squealer designs.

This paper develops a new tip cooling concept that can achieve a step-change in cooling effectiveness compared to conventional, cylindrical-hole cooling. The concept utilizes a near-tip slot, which ejects coolant in an approximately streamwise direction along the pressure side rim. By carefully controlling the coolant trajectory, this arrangement allows the cooling flow to cover a larger area than is possible with cylindrical holes, with higher effectiveness.

An initial slot concept is developed to improve the manufacturability while maintaining high performance. Experiments in a representative linear cascade show that even with these constraints, the inclined slot design can more than double the cooling effectiveness on the pressure side rim. Furthermore, this advantage remains when coolant density is matched to engine conditions.

Presenting Author: Macdonald Mutekwa University of Oxford

Presenting Author Biography: Macdonald Mutekwa is a PhD student under Dr. Coull and Dr. Bacic at the University of Oxford. His research focuses on novel approaches to turbine blade tip design towards achieving step-change improvements in thermal and aerodynamic performance.

Authors:

Macdonald Mutekwa University of Oxford
Joao Vieira Rolls-Royce plc
Maximilian Farfaras University of Oxford
John Coull University of Oxford
Marko Bacic Rolls-Royce plc
Peter Ireland University of Oxford