Calculations of Inlet Distortion Induced Compressor Flowfield Instability,
MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF AERONAUTICS AND ASTRONAUTICS
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Calculations are presented predicting the onset of flow instability for a multistage low speed axial compressor operating in circumferentially distorted inlet flow. The most important feature of the model used is that it attempts to properly account for the fluid dynamic interaction between the spoiled and unspoiled sectors of the compressor. Calculations show that there is an approximate stability criterion, the annulus averaged slope of the compressor pressure rise characteristic equal to zero, that is valid whenever the dynamics of the compressor distorted flowfield can be considered independent of the compressor environment. This approximate criterion is used to investigate the relationship between the present model and the parallel compressor model. Further calculations are preformed to investigate cases of interest when the dynamics of the compressor flowfield are coupled to the environment. Resonant cases and cases when the distortion is unsteady are studied. It is shown that rotating distortion which propagate in the rotor direction can have a greater effect on stability margin than stationary or counter-rotational ones. It is also shown that the general predictions of the model are insensitive to the details of the unsteady bladerow dynamics.
- Fluid Mechanics
- Jet and Gas Turbine Engines