The multistage centrifugal pump produces noise and vibration during operation, and is accompanied by flow rate, head and efficiency. The reduction, sometimes even does not work; When inspecting this pump, it can often be found that there are pitting or honeycomb damage near the front cover plate and near the population edge of the blade entrance, and the whole blade and front and back cover plate have this phenomenon in serious cases, and even the blade and cover plate are penetrated, which is the damage caused by cavitation.
Usually, the impeller of the multistage centrifugal pump is the place where the pressure is lowest. If the pressure of the liquid in this place is equal to or lower than the vaporization pressure of the liquid at this temperature, pv, there will be a large amount of steam and gas dissolved in the liquid escape from the liquid, forming many small bubbles of steam and gas mixed. If these bubbles are ruptured near the metal surface due to pressure differences and recondense, the liquid particles are like countless small warheads, continuously hitting the metal surface. The metal surface gradually breaks down from fatigue. In addition, there are also some active gases in the bubble to chemically corrode the metal. The phenomenon of metal damage caused by the joint action of chemical corrosion and mechanical denudation is called cavitation damage phenomenon.