Date of Award

12-1991

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Aeronautics and Astronautics

First Advisor

William C. Elrod, PhD

Abstract

The effects of blade trailing edge crenulations on wake losses in a compressor cascade were investigated at the Air Force Institute of Technology. The cascade used NACA 64-A905 blades with a turning angle of about 30 to model last row stators of an axial flow compressor. Three blade configurations were used: unmodified blades, blades with large crenulations, and blades with small crenulations. Wake losses and mixing were evaluated in four flow conditions, generated by combinations of increased freestream turbulence and sidewall boundary layer removal. Injection of air perpendicular to the inlet flow increased freestream turbulence from about 0.15% to about 4%. The sidewall boundary layers could be removed by suction through sidewall slots immediately ahead of the cascade. A total pressure rake measured the difference between upstream and downstream total pressure, yielding pressure loss and velocity data, and hot wire anemometry was used downstream from the cascade to measure flow angle, relative turbulence, and velocity. For each test condition, the crenulated blades decreased total pressure loss, the wake velocity deficit, and wake velocity variance by about 10% to 20%, while slightly decreasing turning angle and increasing the turbulence level. The size of the crenulations had a small effect on these parameters.

AFIT Designator

AFIT-GAE-ENY-91D-1

DTIC Accession Number

ADA243902

Comments

The author's Vita page is omitted.

Download

Share

COinS