Gas Turbine Tip Region Leakage Flow and Heat Transfer
Abstract
New, detailed flow field measurements and high resolution Nusselt number (Nu) distributions are presented for a very large low-speed cascade representative of a high-pressure turbine rotor blade with turning of 110 degrees and blade chord of 1.0 m. Data was obtained for tip leakage and passage secondary flow at a Reynolds number of 4.0 x 1 %%, based on exit velocity and blade axial chord. Tip clearance levels ranged from 0% to 1.68% of blade span (0% to 3% of blade chord). The relative motion between the casing and the blade tip was simulated using a motor-driven moving belt system. Particle Image Velocimetry (PIV) was used to obtain flow field maps of several planes parallel and normal to the tip surface within the tip gap, and adjacent passage flow. Secondary flow was measured at planes normal to the blade exit angle at locations upstream and downstream of the trailing edge. An infrared camera made detailed temperature measurements on a constant heat flux tip surface. The interaction between the tip leakage vortex and passage vortex is clearly defined, revealing the dominant effect of the tip leakage flow on the tip endwall secondary flow. A reduction in the magnitude of the under-tip flow near the endwall due to the moving wall is observed and the effect on the tip leakage vortex examined. The moving belt endwall significantly shifts the region of high Nu distribution and reduces the overall averaged Nu on the tip surface by up to 13.3%. The addition of a suction side squealer tip significantly reduced local tip heat transfer and resulted in a 32% reduction in averaged Nu.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 07, 2005
- Accession Number
- ADA443507
Entities
People
- John E. Lagraff
- Martin Oldfield
- Pepe Palafox
Organizations
- Syracuse University