This paper presents an experimental investigation of a novel approach for controlling the rotor tip leakage and secondary flow by injecting cooling air from the stationary casing onto the rotor tip. It contains a detailed analysis of the unsteady flow interaction between the injected air and the flow in the rotor tip region and its impact on the rotor secondary flow structures. The experimental investigation has been conducted on a one-and-1/2-stage, unshrouded turbine, which has been especially designed and built for the current investigation. The turbine test case models a highly loaded, high pressure gas turbine stage. Measurements conducted with a two-sensor fast-response aerodynamic probe have provided data describing the time-resolved behavior of flow angles and pressures, as well as turbulence intensity in the exit plane of the rotor. Cooling air has been injected in the circumferential direction at a 30 deg angle from the casing tangent, opposing the rotor turning direction through a circumferential array of ten equidistant holes per rotor pitch. Different cooling air injection configurations have been tested. Injection parameters such as mass flow, axial position, and size of the holes have been varied to see the effect on the rotor tip secondary flows. The results of the current investigation show that with the injection, the size and the turbulence intensity of the rotor tip leakage vortex and the rotor tip passage vortex reduce. Both vortices move toward the tip suction side corner of the rotor passage. With an appropriate combination of injection mass flow rate and axial injection position, the isentropic efficiency of the stage was improved by 0.55 percentage points.
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July 2008
Research Papers
Control of Rotor Tip Leakage Through Cooling Injection From the Casing in a High-Work Turbine
Thomas Behr,
Thomas Behr
Turbomachinery Laboratory,
e-mail: behr@lsm.iet.mavt.ethz.ch
ETH Zurich
, CH-8092 Zurich, Switzerland
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Anestis I. Kalfas,
Anestis I. Kalfas
Department of Mechanical Engineering,
Aristotle University of Thessaloniki
, GR-54124 Thessaloniki, Greece
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Reza S. Abhari
Reza S. Abhari
Turbomachinery Laboratory,
ETH Zurich
, CH-8092 Zurich, Switzerland
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Thomas Behr
Turbomachinery Laboratory,
ETH Zurich
, CH-8092 Zurich, Switzerlande-mail: behr@lsm.iet.mavt.ethz.ch
Anestis I. Kalfas
Department of Mechanical Engineering,
Aristotle University of Thessaloniki
, GR-54124 Thessaloniki, Greece
Reza S. Abhari
Turbomachinery Laboratory,
ETH Zurich
, CH-8092 Zurich, SwitzerlandJ. Turbomach. Jul 2008, 130(3): 031014 (12 pages)
Published Online: May 5, 2008
Article history
Received:
January 26, 2007
Revised:
March 16, 2007
Published:
May 5, 2008
Citation
Behr, T., Kalfas, A. I., and Abhari, R. S. (May 5, 2008). "Control of Rotor Tip Leakage Through Cooling Injection From the Casing in a High-Work Turbine." ASME. J. Turbomach. July 2008; 130(3): 031014. https://doi.org/10.1115/1.2777185
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