Method for eliminating bow-shaped cyclotron self-excited vibration of main shaft of mixed-flow water turbine generator

The invention discloses a method for eliminating bow-shaped cyclotron self-excited vibration of a main shaft of a mixed-flow water turbine generator. The method comprises the following steps that whena unit structure is designed, a semi-umbrella mixed-flow water turbine generator with thrust bearings arranged below a generator rotor is preferred; and if a suspension type water turbine generator is selected, four or more air supplement pipes need to be uniformly arranged in the gap of a rotary wheel chamber, and compressed air can be supplemented into the labyrinth gap through the air supplement pipes in case of self-excited bow-shaped rotation so as to change the pressure condition of the gap and eliminate self-excited vibration. The design and operation maintenance method is clear in scheme, simple to operate, targeted, high in pertinence, comprehensive and effective. 本发明公开了一种消除混流式水轮发电机主轴弓状回旋自激振动的方法，包括：机组结构设计时优选推力轴承布置于发电机转子下方的半伞式混流式水轮发电机；如选用悬垂式水轮发电机，则需对准转轮室间隙均匀布置4个或以上补气管，如遇自激弓状回旋可通过补气管向迷宫间隙补入压缩空气，以改变间隙压力状况，消