Cavitation Number

An introduction to and a definition of the Cavitation Number

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

The Cavitation Number is useful when analyzing fluid flow dynamics problems where cavitation may occur.

The Cavitation Number can be expressed as

σ = (pr - pv) / (1/2 ρ v2)                              (1)


σ = Cavitation number

pr = reference pressure (Pa)

pv = vapor pressure of the fluid (Pa)

ρ = density of the fluid (kg/m3)

v = velocity of fluid (m/s)

To prevent cavitation

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

Related Topics

  • Fluid Mechanics - The study of fluids - liquids and gases. Involves velocity, pressure, density and temperature as functions of space and time

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