Definition:
When the pressure at a certain point in the liquid flow is lower than the air separation pressure at the temperature of the liquid, the gas originally dissolved in the liquid will separate to generate bubbles, which is called cavitation, when the pressure is further reduced and lower than the liquid. When the vapor pressure is saturated, the liquid rapidly vaporizes to form a large amount of vapor bubbles, which makes the cavitation more serious, so that the liquid flow is discontinuous.
Causes of cavitation:
(1) Air split pressure.
(2) Saturated vapor pressure.
The nature of cavitation:
When cavitation occurs in the hydraulic system, a large number of bubble waves break the continuity of the flow. When a large amount of bubbles flow with the liquid to a higher pressure part, the bubbles rapidly rupture under high pressure, and then condense into a liquid, causing the volume to suddenly decrease to form a vacuum, and the surrounding high-pressure oil flows quickly to replenish. Due to the extremely short time of this process, the liquid particles collide at high speed, resulting in local high temperature, temperature up to 1149℃, impact pressure up to several hundred megapascals, and strong vibration and noise. Under such high temperature and high pressure, the hydraulic oil is partially oxidized and blackened, causing chemical corrosion to the metal pipe wall, causing the surface of the hydraulic component to be eroded and peeled off, forming a pitting point and a sponge-like small cave for a long time.
