Cavitation of engine

[Virgo]

[Feilong Jiangli Edition]At a certain temperature, the liquid reduces the pressure to the gasification pressure at that temperature, and the liquid produces bubbles. The phenomenon of producing bubbles is called cavitation erosion. When cavitation bubbles flow to high pressure, their volume decreases and bursts. This phenomenon is called cavitation collapse. Cavitation limit: when the pump speed is constant, the flow rate is reduced by 3%, which is considered to be cavitation erosion. Cavitation allowance: the difference between the inlet pressure and the cavitation limit pressure of the engine.
When the absolute pressure of the pumping liquid drops to the gasification pressure of the liquid at the current temperature, the liquid begins to gasify there, producing a large amount of vapor, forming bubbles, and when the liquid containing a large number of bubbles passes forward through the impeller. In the high pressure area, the high pressure liquid around the bubble causes the bubble to shrink rapidly and even burst. At the same time of bubble condensation and fracture, the liquid particle fills the cavity with high velocity, and produces very strong water hammer action at this instant, and strikes the metal surface with high impact frequency. The impact stress can reach hundreds to thousands of atmospheric pressure, and the impact frequency can reach tens of thousands of times per second. In serious cases, the pump shell and impeller will be broken down.
After cavitation, besides destroying the flow passage parts, the pump will also produce noise and vibration, which will lead to the performance degradation of the pump. In serious cases, the liquid in the pump will be interrupted and can not work properly.