15th European Conference on Turbomachinery Fluid dynamics & Thermodynamics

Paper ID:


Main Topic:

Heat Transfer & Cooling



Logan Tuite - Purdue Experimental Turbine Aerothermal Laboratory, United States of America
Douglas Straub - National Energy Technology Laboratory, United States of America
Guillermo Paniagua - Purdue Experimental Turbine Aerothermal Laboratory, United States of America


Tip flow leakage can account for nearly a third of the losses in an axial turbine stage, and considerable effort has been put forth to minimize these losses. Optimizations of coolant flow injection and squealer tip geometries have been able to show considerable decrease in the heat load to a blade tip, which results in higher efficiency and longer life. Such studies have shown the importance of combined aerothermal effects on the overall efficiency of tip design. In this work, a large scale symmetric canonical axial turbine geometry with a squealer tip is developed, which allows for the investigation of the interaction of incoming gas path flow with coolant flow injected into the squealer cavity. The model is developed to investigate high Reynolds numbers flows at the leading edge, on the order of 1 million. Flow is injected via a pressurized plenum, which minimizes effects of the injection air source flow on the development of coolant flow through the channels and into the squealer cavity. Coolant flow injected near the leading edge of an airfoil is of interest due to the efficient use of mass flow as it advects downstream through the cavity. In this work, four configurations are investigated: a single hole at the leading edge of the airfoil and three three-hole backward step configurations near the leading edge. Results from RANS, URANS, and DES models are compared to highlight the needed fidelity to accurately capture the flow features emanating from coolant injection flow, such as the bifurcation of the coolant stream and counter-rotating vortex pair interaction, which have a profound effect on the heat transfer within the squealer cavity. The key contributors to the change in thermal effectiveness between cooling schemes are identified.


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