Hydraulic Vibration and Possible Exciting Sources Analysis in a Hydropower System

To understand the hydraulic vibration characteristics in a traditional hydropower system and identify possible exciting sources that may induce serious vibrations flow passage, experimental tests numerical calculations were conducted for different operating conditions. The results show pressure fluctuations are mainly related to vortex rope phenomena draft tube, dominant frequency of fluctuation is 0.2~0.4 times runner rotational (fn). all attenuating factors negative, which indicates itself stable on condition elements have steady performance. free analyses confirm range tube partly overlaps natural frequencies system. Apart from rope, another common approximately equal 10th mode. From mode shapes, it inferred small disturbance its close or specific could large oscillations tail tunnel. In light system’s response forcing frequencies, formed under off-design conditions verified be potential source system, 0.2 fn much more dangerous than other disturbances