Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Mechanical Engineering

First Advisor

Theodore H. Okiishi


The useful operating range of the multistage, axial-flow compressor component of a gas turbine engine limits the extent of operation of that engine. Generally, the compressor stalls or surges at low flow rates and chokes at high flow rates. Thus, any improvement in the range between these compressor aerodynamic limits is normally of benefit to the engine also. An idea for delaying the onset of rotating stall in a multistage, axial-flow compressor which involved circumferentially varying the blade setting angles of stationary blades upstream of the compressor rotors was investigated. Tests involving two low-speed, multistage, axial-flow compressors and an intermediate-speed, three-stage, axial-flow compressor were completed. Comparisons between baseline compressor (circumferentially uniform setting angles) and modified compressor (circumferentially varying setting angles) performance data were made. A variety of blade setting angle circumferential variation patterns were tested. Test results suggest that rotating stall onset in the low-speed compressors could be delayed slightly but consistently with circumferentially varying setting angles. The low-speed compressor results indicated that a small improvement in stall recovery was also possible. The intermediate-speed compressor data indicated that there was a slight stall margin improvement at low compressor rotational speeds only. At higher rotational speeds no improvement was noticed.



Digital Repository @ Iowa State University,

Copyright Owner

John Paul Rukavina



Proquest ID


File Format


File Size

193 pages