Cavitationnumberet

Cavitation number is a dimensionless parameter used in fluid dynamics to characterize the susceptibility of a liquid to cavitation. It is defined as the ratio of the pressure difference between the free stream pressure and the vapor pressure of the liquid, to the dynamic pressure of the liquid. Mathematically, it is expressed as sigma = (P - Pv) / (0.5 * rho * v^2), where P is the absolute static pressure of the liquid, Pv is the vapor pressure of the liquid, rho is the density of the liquid, and v is the velocity of the liquid.

A low cavitation number indicates that the local pressure in the fluid is close to or below the vapor pressure, making cavitation more likely. Conversely, a high cavitation number suggests that the pressure is significantly above the vapor pressure, and cavitation is less probable. The cavitation number is a crucial parameter in the design and analysis of pumps, turbines, propellers, and other fluid machinery where the flow can experience significant pressure variations. It helps engineers predict where cavitation might occur and to what extent, allowing for design modifications to prevent or mitigate its detrimental effects, such as erosion and noise. The critical cavitation number, below which cavitation begins, is a property of the specific fluid and flow conditions.