A study on the rotating stall of centrifugal compressors. (1st report, Effect of vaneless diffuser width on rotating stall).

The rotating stall of centrifugal compressors which often causes low frequency shaft vibration in high pressure compressors is experimentally examined. Pressure fluctuations of low specific speed centrifugal compressors with a vaneless diffuser are measured by pressure transducers. Rotating stall is caused by a vaneless diffuser. The critical inlet flow angle for rotating stall depends not only on diffuser width ratio b/r2 but also contraction ratio b/b2. An empirical prediction formula of critical flow angle for stall based on the Senoo method is derived.