Pipeng Toolbox : Relative Roughness Calculators Blank User
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Dimensionless Relative Roughness Number

Calculate the dimensionless relative roughness or roughness number for pipes and rectangular ducts.

`rr = (ir) / (ID) `

where :

rr = relative roughness or roughness number
ir = surface roughness
ID = pipe inside diameter

For rectangular ducts the hydraulic diameter is used

`ID = 2 w h / (w + h) `

where :

ID = hydraulic diameter
w = duct width
h = duct height

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CALCULATOR : Dimensionless Relative Roughness Number Rr From Roughness And Internal Diameter For Pipeline [FREE]   ±

Calculate dimensionless pipeline relative roughness number from the internal roughness r and the pipeline internal diameter.

The pipe relative roughness ratio is the ratio of the pipe wall internal surface roughness to pipe internal diameter.

Tool Input

  • schdtype : Pipe Schedule Type
  • diamtype : Pipe Diameter Type
    • ODu : User Defined Outside Diameter
    • IDu : User Defined Inside Diameter
  • wtntype : Wall Thickness Type
    • tnu : User Defined Wall Thickness
  • irtype : Internal Roughness Type
    • iru : User Defined Surface Roughness

Tool Output

  • ID : Inside Diameter
  • ir : Surface Roughness
  • rr : Relative Roughness
CALCULATOR : Dimensionless Relative Roughness Number Rr From Roughness And Hydraulic Diameter For Rectangular Duct [FREE]   ±

Calculate dimensionless rectangular duct relative roughness from the internal roughness and the hydraulic diameter.

The duct relative roughness ratio is the ratio of the duct wall internal surface roughness to duct hydraulic diameter. The hydraulic diameter is equal to four times the cross section area divided by the perimeter.

Tool Input

  • irtype : Internal Roughness Type
    • ru : User Defined Surface Roughness
  • W : Duct Inside Width
  • H : Duct Inside Height

Tool Output

  • D : Hydraulic Diameter
  • ir : Surface Roughness
  • rr : Relative Roughness
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