CUED Publications database

High efficiency cavity winglets for high pressure turbines

Coull, JD and Atkins, NR and Hodson, HP (2014) High efficiency cavity winglets for high pressure turbines. In: UNSPECIFIED.

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Abstract

Copyright © 2014 by ASME. The flow leaking over the tip of a high pressure turbine blade generates significant aerodynamic losses as it mixes with the freestream flow. This paper examines the potential for reducing these losses using winglets with recessed cavities on the tip. These features combine the loss-reduction mechanisms of cavity tips, which reduce the discharge coefficient, and winglet overhangs, which reduce the mixing Mach number, leakage flow angle mismatch, and the driving pressure ratio. RANS calculations are performed for an un-cooled HP rotor blade to explore the cavity-winglet design space and examine the impact on the aerothermal performance of the blade. Relative to a plain-tip design, a cavity tip can reduce the sensitivity to clearance by around 30%. Similar performance can be achieved using a flat-tip winglet with an overhang around the whole blade perimeter. However, by adding a cavity to this winglet it is possible to out-perform the cavity tip at all clearances, and reduce the sensitivity to clearance by 46% relative to the plain tip. This sensitivity is equivalent to a two-fin attached shroud, but the winglet blade will exhibit lower stress and require less coolant flow. Furthermore this cavity-winglet may offer some cooling advantages over the cavity tip.

Item Type: Conference or Workshop Item (UNSPECIFIED)
Subjects: UNSPECIFIED
Divisions: Div A > Turbomachinery
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 19:45
Last Modified: 03 Aug 2017 03:15
DOI: