Ensuring an adequate life of high pressure turbines requires efficient cooling methods such as rim seal flow ejection from the stator-rotor wheel space cavity interface, which prevents hot gas ingress into the rotor disk. The present paper addresses the potential to improve the efficiency in transonic turbines at certain rim seal ejection rates. To understand this process, a numerical study was carried out, combining computational fluid dynamic (CFD) simulations and experiments on a single stage axial test turbine. The three dimensional steady CFD analysis was performed, modeling the purge cavity flow ejected downstream of the stator blade row at three flow regimes: subsonic , transonic , and supersonic . Experimental static pressure measurements were used to calibrate the computational model. The main flow field-purge flow interaction is found to be governed by the vane shock structures at the stator hub. The interaction between the vane shocks at the hub and the purge flow has been studied and quantitatively characterized as a function of the purge ejection rate. The ejection of 1% of the core flow from the rim seal cavity leads to an increase in the hub static pressure of approximately 7% at the vane trailing edge. This local reduction of the stator exit Mach number decreases the trailing edge losses in the transonic regime. Finally, a numerically predicted loss breakdown is presented, focusing on the relative importance of the trailing edge losses, boundary layer losses, shock losses, and mixing losses, as a function of the purge rate ejected. Contrary to the experience in subsonic turbines, results in a transonic model demonstrate that ejecting purge flow improves the vane efficiency due to the shock structure modification downstream of the stator.
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November 2010
Research Papers
Investigation of the Flow Field on a Transonic Turbine Nozzle Guide Vane With Rim Seal Cavity Flow Ejection
M. Pau,
M. Pau
Department of Turbomachinery and Propulsion,
e-mail: marcopau@mail.com
von Karman Institute for Fluid Dynamics
, B-1640 Rhode-Saint-Genèse, Belgium
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G. Paniagua
G. Paniagua
Department of Turbomachinery and Propulsion,
von Karman Institute for Fluid Dynamics
, B-1640 Rhode-Saint-Genèse, Belgium
Search for other works by this author on:
M. Pau
Department of Turbomachinery and Propulsion,
von Karman Institute for Fluid Dynamics
, B-1640 Rhode-Saint-Genèse, Belgiume-mail: marcopau@mail.com
G. Paniagua
Department of Turbomachinery and Propulsion,
von Karman Institute for Fluid Dynamics
, B-1640 Rhode-Saint-Genèse, BelgiumJ. Fluids Eng. Nov 2010, 132(11): 111101 (9 pages)
Published Online: November 18, 2010
Article history
Received:
March 25, 2009
Revised:
August 26, 2010
Online:
November 18, 2010
Published:
November 18, 2010
Citation
Pau, M., and Paniagua, G. (November 18, 2010). "Investigation of the Flow Field on a Transonic Turbine Nozzle Guide Vane With Rim Seal Cavity Flow Ejection." ASME. J. Fluids Eng. November 2010; 132(11): 111101. https://doi.org/10.1115/1.4002887
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