An introduction and definition of the cavitation number.

The Number Cavitation Number or Cavitation Parameter is a “special edition” of the dimensionless Euler Number.

• Euler's number – an introduction and definition of Euler's number

The cavitation number is useful when analyzing fluid flow dynamics problems where cavitation can occur.

The cavitation number can be expressed as

σ = (p _r – p _v ) / (1/2 p v ² ) (1)

Where

σ = cavitation number

p _r = reference pressure (Pa)

p _v = vapor pressure of the fluid (Pa)

ρ = fluid density (kg/m ³ )

v = fluid speed (m/s)

To avoid cavitation

• avoid low pressure – pressurize supply tanks if necessary
• reduce fluid temperature
• use larger suction tube diameters – reduce small losses
• use cavitation-resistant materials or coatings
• Small amounts of air supplied to the suction system can reduce the amount of cavitation damage
• maintain available NPSH well above required NPSH.

Source: https://www.engineeringtoolbox.com/cavitation-number-d_584.html