Date of Award


Document Type


Degree Name

Master of Science


Department of Aeronautics and Astronautics

First Advisor

Paul I. King, PhD


The effects of changing the blade tip clearances on the velocity and pressure flowfields within a compressor cascade were investigated in this experimental thesis. All moving endwall measurements were taken at a constant flow coefficient of 0.5 and tip clearances of 0.5, 1.0 and 2.0 percent chord. Hot-wire/film probes were used to determine the three-dimensional velocity vector components in various transverse planes - one upstream of the leading edges of the blades, three within the blade cascade and one downstream of the trailing edges of the blades. The transverse velocity vector plots showed a scraping of the tip leakage vortex from the suction surface of one blade across the blade pitch to the pressure surface of the adjacent blade. A total pressure rake placed downstream of the trailing edges of the blades measured the pressure flowfield at the exit of the cascade. The mass-averaged values of total pressure loss coefficient decreased for reduced gaps. Finally, the tests performed on a crenulate blade geometry at a tip clearance of 0.01 chord showed a 15.5% reduction in the total pressure losses as compared to the straight blade geometry.

AFIT Designator


DTIC Accession Number