遠心圧縮機の逆流・逆回転時における軸振動発生メカニズム解明に向けた非定常CFD解析

抄録

In a centrifugal compressor, when a trip occurs during operation and the driving force is lost, a reverse flow occurs inside the compressor, and a large shaft vibration may occur. For example, in a two stage compressor, after tripping, large rotor vibration occurred along with reverse flow and rotation. Although rotor vibration is considered to be caused by fluid force, the mechanism has not been clarified. In this study, unsteady fluid simulation was carried out for the compressor in order to clarify the flow mechanism. As a result, the pressure fluctuation in the same frequency band as that of the actual machine could be reproduced, which was triggered by rotating stall at trailing edges of the 1st impeller. Rotor vibration of the actual machine is considered to be caused by non-uniform pressure distribution around impeller generated by rotating stall.