Excessively large vibration zone of the hydro-turbine generator unit affects the safe operation of the hydropower plants. It will not only lead to unstable operation of the units

but also cause the fatigue of the welds of the unit parts and wetted components

the loosening or fracture of fastening components

thus intensifying the vibration of the unit

increasing pressure fluctuation of draft tube and cavitation erosion of wetted components

and accelerating the damage to the unit. More seriously

the resonance between the generator unit and hydro-structures may cause greater damage to both equipment and factory buildings. Therefore

how to solve the problem of excessively wide vibration zone in the hydro-turbine generator unit has become a top priority for all production and operation units. This paper proposes a method of installing tail water air supply device to improving tailrace flow pattern

the width of the vibration zone of the hydro-turbine generator uni has been greatly reduced.