Shenyang Getai Hydropower Equipment Co., Ltd.

Causes Of Water Turbine Vibration

Dec. 24, 2019

Mechanical equipment will vibrate during operation, and hydraulic turbine units often generate vibration due to mechanical, hydraulic and electrical reasons. The vibration of the hydraulic unit is different from that of the general power machinery. In addition to the rotation of the rotating part and the vibration of the fixed part, the electromagnetic force and the fluid pressure acting on the water diversion system of the hydropower station and the over-flow parts of the hydraulic turbine must be considered. Effects of vibration. The hydraulic, mechanical, and electrical factors that cause unit vibration are interdependent. Therefore, the vibration of a hydraulic unit is a combination of hydraulic, mechanical, and electrical vibration. The following is the introduction of the Hydraulic Turbine Generator Supplier.

According to the cause of the vibration of the hydraulic unit, the unit vibration can be divided into the following three categories:

1. Mechanical vibration. It is caused by mechanical reasons such as static imbalance of the rotating part of the unit, zigzag axis, friction or collision between the rotating parts of the unit and fixed parts, excessive bearing clearance or loosening of the fastening bolts.

2. Hydraulic vibration.

(1) When the water flows through the turbine's volute and Casting Guide Vane, due to design or manufacturing defects or changes in working conditions (incoming conditions), the water flow becomes uneven and an asymmetrical flow is generated on the runner Acting on torque, which causes the runner to vibrate. For example, the number of guide vanes and the number of runner blades does not match, the openings of the guide vanes and runner blades are not uniform, the distance between the guide vanes and the runner is too small, the gap of the runner leakage ring is not uniform, or the comb tooth structure type is inappropriate, Caused by hydraulic factors such as eccentric vortex zone of draft tube, guide vane or tail of runner blade.

(2) Vibration caused by deflow of runner blades. When the unit is operating at low or high head, due to the deviation from the high efficiency zone, there will often be outflow near the inlet or outlet edge of the runner blades. Outflow will generate irregular pulsating pressure and noise. Under certain operating conditions, outflow Flow may also cause periodic alternating forces to form regular vibrations and noise.

(3) Turbine blade and guide blade vibration caused by vortex rows.

Pelton Turbine Generator

3. Electrical vibration. The generator rotor is not round, the field windings are short-circuited, the stator and rotor magnetic field axes are not coincident, the stator core is not tightly pressed, the core gap at the split seam is large, the stator and rotor gap is uneven, and the rotor It is caused by electrical reasons such as unbalanced magnetic pull force during rotation.

There are various causes of unit vibration, and the phenomenon of vibration varies widely, but there are always basic laws in it. In order to find out the main cause of vibration of a unit and eliminate it, the following aspects can usually be analyzed:

1.Measure and analyze the frequency of vibration

The frequency of vibration should be measured with a vibrometer, but it must be measured in different parts and in different directions in order to fully grasp the vibration of the unit. Experienced people can be distinguished to a certain degree by feeling, but they cannot be very accurate.

2. Grasp the relationship between amplitude and unit operating parameters

The vibration amplitude of the unit, especially the amplitude of the severe vibration part, often changes with certain operating parameters.

3. Find and eliminate the main cause of vibration during the test.

It is not difficult to see from the above that the work of finding the cause of vibration should be carried out in conjunction with experiments. It is necessary to continuously change the operating status or operating parameters of the unit, deliberately eliminate some reasons, and highlight others. Repeat the test and comparison in this way until you find the main cause of the unit vibration, and then take corresponding measures to reduce the unit vibration.

The above is the reason why the Pelton Turbine Generator supplier introduces the vibration of the turbine unit.

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