The mechanism of cavitation in water turbine

Water turbines play an important role in industrial production, and their operating efficiency directly affects the benefits of industrial production. Because the operating medium of the water turbine is mainly water, and cavitation will occur at a certain temperature of water, which is a gasification phenomenon that all liquids have.

During the operation of the impact turbine, cavitation is very likely to occur due to changes in boundary conditions. In the flow channel, the local flow velocity is too high, which will cause the pressure to drop. Under the action of the runner blades, it will affect the dynamic moment of the water flow, thereby creating a negative pressure on the back of the blade. Because water generally contains 5% of air or steam nuclei, when the pressure in the water is lower than a certain limit, and the cavitation pressure is exceeded, cavitation will occur, leading to the generation of air bubbles. When cracking occurs, it is the process of cavitation.

During the operation of the water turbine, water flows in the water turbine's flow channel. After cavitation, the bubbles enter the high-pressure area of the flow channel with the flow of water. Under the action of high pressure, the pressure outside the bubble and the The pressure is not balanced, and under this pressure, the bubbles will burst. In the process of bubble burst, a large impact force is generated due to the difference in pressure, and a high jet is formed. This instant jet impact is very large. Under the high-frequency jet water, the surface of the flow needs to bear a large impact load. In the long run, the toughness of the metal material will be affected and it will change into a brittle state. In this process, the yield point gradually decreases. After the yield point reaches a certain threshold, under the impact of the jet, particles on the metal surface will fall off, which will directly cause plastic deformation and cause great damage to the water turbine.