Self-Excited Vibration of Axial-Flow Compressor Blades

Blade vibration, with the possibility of a failure, is one of the major factors controlling the reliability of axial-flow compressors. Self-excited vibration occurring at part load, when some blade rows are stalled, often causes most trouble. In this paper an investigation which has been undertaken into this phenomenon is described. The main objective has been to determine the major factors governing the vibration, and to establish, if possible, some design rules which would reduce the chances of a failure to an acceptable minimum.The self-excited vibration of blades in cascade has been studied, and a simple theoretical correlation attempted. This has been supplemented by single-stage work and by multistage full-scale tests. Both flutter and stall cell excitation have been encountered, and are described. A semi-empirical design rule is suggested, and its interpretation in terms of the normal blade design parameters is included.