Pipeng Toolbox : Cavitation Number Calculators Blank User
Short Cuts
GO
Main ±
Beams ±
References ±
Fluid Flow ±
Fluid Properties ±
Maths ±
Materials ±
Pipelines ±
Soils ±
Subsea ±
Demo

Dimensionless Cavitation Number

Calculate the dimensionless cavitation number for pipes and general flow.

Cavitation occurs when the static pressure in the fluid is less than or equal to the fluid vapour pressure. Bubbles of vapour form in the low pressure fluid, which then collapse when the fluid pressure increases causing noise and damage to equipment. The cavitation number is used to determine the likelihood of cavitation occurring.

`Ca = (Ps - Pv) / (Pd) `
`Pd = 0.5 ρ V^2 `

where :

Ca = Cavitation number
Ps = static pressure
Pv = vapour pressure
Pd = dynamic pressure
ρ = fluid density
V = fluid velocity

For flow with moving parts (eg an impellor), the maximum velocity of the moving part can be used rather than the fluid flowing velocity. The cavitation number is of similar form to the Euler number and the pressure loss factor or minor loss factor K (refer to Euler number and K factor).

For pumps the suction specific speed Nss and nett positive suction head NPSH are commonly used to determine the onset of cavitation.

Change Module :

Related Modules :

[FREE] tools are free in basic mode with no login (no plots, tables, goal seek etc). Login or Open a free account to use the tools in plus mode (with plots, tables, goal seek etc).
[PLUS] tools are free in basic CHECK mode with Login or Open a free account (CHECK values no plots, tables, goal seek etc). Buy a Subscription to use the tools in plus mode (with plots, tables, goal seek etc).
Try plus mode using the Plus Mode Demo tools with no login.   Help Using The Pipeng Toolbox (opens in the popup workbook)

Links : ±
CALCULATOR : Dimensionless Cavitation Number Ca General Case [FREE]   ±

Calculate dimensionless cavitation number Ca from fluid velocity (general case).

Cavitation occurs when the static pressure in the fluid is less than or equal to the fluid vapour pressure. Bubbles of vapour form in the low pressure fluid, which then collapse when the fluid pressure increases causing noise and damage to equipment. The cavitation number is used to determine the likelihood of cavitation occurring. The minimum allowable cavitation number is a function of the equipment design and is usually specified by the manufacturer (for pumps the net positive suction pressure NPSP is used). For flow with moving parts the velocity of the moving part can be used instead of the fluid velocity.

Tool Input

  • ρ : Fluid Density
  • Ps : Static Pressure
  • Pv : Vapour Pressure
  • V : Fluid Velocity

Tool Output

  • Ca : Cavitation Number
  • PΔ : Delta Pressure
  • Pd : Dynamic Pressure

CALCULATOR : Dimensionless Number Liquid Density [FREE]   ±

Calculate dimensionless number liquid density from specific gravity, degrees Baume, degrees Twaddell, or degrees API.

For liquids lighter than or equal to water the density can be defined as degrees API, or degrees Baume (Be-). For liquids heavier than water the density can be defined by degrees Baume (Be+), or degrees Twaddell.

Tool Input

  • sgtype : Density Type
    • SGu : User Defined Specific Gravity
    • Be+u : User Defined Degrees Baume SG > 1
    • Be-u : User Defined Degrees Baume SG <= 1
    • Twu : User Defined Degrees Twaddell SG > 1
    • APIu : User Defined Degrees API SG <= 1
    • ρu : User Defined Liquid Density

Tool Output

  • ρ : Fluid Density
  • API : Degrees API SG ≤ 1
  • Be+ : Degrees Baume SG > 1
  • Be- : Degrees Baume SG ≤ 1
  • SG : Specific Gravity
  • Tw : Degrees Twaddell SG > 1

CALCULATOR : Dimensionless Number Fresh Water Density From Temperature [FREE]   ±

Calculate dimensionless number fresh water density from temperature at atmospheric pressure (IAPWS R7-97 steam table).

The calculation is valid from the freezing point (0 C) to the boiling point (100 C). Use the Result Plot option to plot density versus temperature.

Tool Input

  • T : Temperature

Tool Output

  • ρ : Density

CALCULATOR : Dimensionless Number Salt Water Density From Temperature And Salinity [FREE]   ±

Calculate dimensionless number salt water density at atmospheric pressure from temperature and salinity (TEOS-10).

Practical salinity = parts per thousand of dissolved solids (mainly salt). The absolute salinity is taken as 35.16504 / 35 times the practical salinity. The absolute salinity anomaly δSA is ignored. Use the Result Plot option to plot density versus temperature.

Tool Input

  • T : Seawater Temperature

Tool Output

  • ρ : Seawater Density

CALCULATOR : Dimensionless Number Fresh Water Vapour Pressure From Temperature [FREE]   ±

Calculate dimensionless number fresh water vapour pressure from temperature (IAPWS R7-97 steam table).

Use the Result Plot option to plot vapour pressure versus temperature.

Tool Input

  • T : Temperature

Tool Output

  • P : Vapour Pressure

CALCULATOR : Dimensionless Number Salt Water Vapour Pressure From Temperature And Salinity [FREE]   ±

Calculate dimensionless number salt water vapour pressure from temperature and salinity (TEOS-10 and IAPWS R7-97 steam table).

Seawater vapour pressure is calculated from fresh water vapour pressure using the equation from Sharqawy (2010). The fresh water vapour pressure is calculated from temperature using the IAPWS R7-97 steam equations. Practical salinity = parts per thousand of dissolved solids (mainly salt). The absolute salinity is taken as 35.16504 / 35 times the practical salinity. The absolute salinity anomaly δSA is ignored.

Tool Input

  • T : Seawater Temperature

Tool Output

  • P : Seawater Pressure