軸危険速度以上で回転する遠心羽根車に生じる自助軸振動と強制軸振動

抄録

Higher speed and smaller size are the tendencies for high-performance turbopumps. Under these circumstances, it is important to secure the stability of the shaft system for whirling motion. In this study, vibrations of a centrifugal impeller operating at supercritical speed are studied experimentally under the condition that the effects of shrouds and seal forces are minimized. Forward or backward whirl is observed depending on the diffuser vane angle over a wide flow range including impeller design point. These are self-excited vibrations due to the interaction effect between the impeller and vaned diffuser. Forced vibrations due to the impeller or diffuser rotating stalls are also observed at smaller flow rates, discussion on the relations between those vibrations and the pressure distribution around the impeller is presented.