Effect of stator blade orientation on the performance of an axial flow compressor

A mean streamline analysis of the effect of stator blade orientation on the performance of an axial flow compressor was performed by means of a computer program. Measurement were made on a 3-stage axial flow compressor at the Naval Postgraduate School at six stator stagger angles between 23.8 degrees and 44.3 degrees for a fixed orientation of the rotor blades. Maximum efficiency and pressure ratio were measured at a stator stagger angle of 31.8 degrees. Results at other blade settings showed that by varying stator stagger angle with flow rate optimum efficiencies and pressure rations can be achieved over a wide range of operating conditions. The result of this analysis were compared with the measured results. Suggestions are made for improving the manner of adapting cascade test data to performance predictions. By applying a non-dimensional deflection coefficient it could be shown that minimum work input corresponded to maximum efficiency. The test compressor has a tip diameter of 36 in. and a hub/tip ratio of 0.6. The blading tested is of the free-vortex type with a design degree of reaction of 0.5. Tip speed was about 185 ft/sec.