In-compressible Fluid Flow

[tironel]

Main Question or Discussion Point

A little help.

I want to calculate the volumetric flow rate (SCFM (standard cubic feet per minute) of a pipe knowing the pressure inside the pipe as well as the diameter of the pipe. I know

​

Q=vA

Where v is velocity and A cross sectional area.


However, I need help finding out my velocity from my known pressure. I also know that water is the media that is being used inside the pipe. Can I relate the velocity back to the pressure via density? Any help please.

 

[Smed]

What you need is the Bernoulli equation: http://hyperphysics.phy-astr.gsu.edu/hbase/pber.html

But it sounds like you don't have enough information to solve the problem. You'll need to know the pressure at two locations in the pipe in order to calculate the velocity.

 

[Chestermiller]

What you need is the Bernoulli equation: http://hyperphysics.phy-astr.gsu.edu/hbase/pber.html

But it sounds like you don't have enough information to solve the problem. You'll need to know the pressure at two locations in the pipe in order to calculate the velocity.

The pressure drop in the pipe is 4L/D times the shear stress at the wall τ

The shear stress at the wall τ is equal to the friction factor f times ρV²/2

For turbulent flow, the friction factor f is equal to 0.0791/Re^0.8, where Re is the Reynolds number

The Reynolds number is equal to the density ρ times the average velocity V times the diameter, divided by the viscosity