Thermal Performance of Cooled Tips in a High-Pressure Turbine Cascade

Reference:

Zhou, C., Hodson, H. and Lock, G., 2012. Thermal Performance of Cooled Tips in a High-Pressure Turbine Cascade. Journal of Propulsion and Power, 28 (5), pp. 900-911.

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Official URL:

http://dx.doi.org/10.2514/1.B34299

Abstract

The thermal performance of the three turbine tips was investigated. The results are presented in terms of heattransfer coefficient (h), cooling effectiveness (η), net heat-flux reduction (NHFR), and heat load. The calculations were performed using a cooled flat tip, a cooled cavity tip, and a cooled suction-side squealer tip in a cascade at a tip gap of 1.6%C. The results were validated using experimental data where possible. For an uncooled flat tip, the fluid dynamics are dominated by flow separation at the pressure-side edge. A significant benefit of ejecting coolant inside this separation bubble is shown. At the coolant mass-flow ratio M c = 0:52%, both the cooled flat tip and the cooled cavity tip are well-protected by the coolant. For the cooled suction-side squealer tip, the coolant lifts off from the tip floor and leads to not only low cooling effectiveness, but also to high heat-transfer coefficients. The effects of the coolant mass-flow ratio on the thermal performance of the tip were presented. The effects of end-wall motion on the thermal performance of the blade tip are found to be small in the current study.

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