- Laminar flow
- Transition between laminar and turbulent flow
- Fully turbulent flow in smooth conduits
- Fully turbulent flow in rough conduits
- Free surface flow
Most of the industrial applications (like transportation of fluids) requires moderate velocity and volume of flow rate. As the pipe used are kept moderately small diameters due to economy and space considerations, the industrial flow of liquid will be often in the turbulent regime. Air flow through exhaust ducts system should have sufficient velocity to capture and carry dust particles and thus the condition is turbulent.
Reynolds Number and Turbulent Flow
The Reynolds number expresses the ratio of inertial (resistant to change or motion) forces to viscous (heavy and gluey) forces. It is well known from experiments now that turbulent flow occurs at Re > 4000.
* f is the Darcy friction factor
* Roughness height, e
* Hydraulic diameter,d
* Re is the Reynolds number.
* hf is the head loss due to friction;
* L is the length of the pipe;
* D is the hydraulic diameter of the pipe;
* V is the average velocity of the fluid flow, = Q/A = volumetric flow rate Q per unit cross-sectional wetted area A;
* g is the local acceleration due to gravity;
* f is a dimensionless coefficient called the Darcy friction factor. It can be found from a Moody diagram or Colebrook equation.
Head Loss and Pressure Loss
* the density of the fluid, r;
* g is the local acceleration due to gravity
- Pf , friction power loss in Watt
- Q , flow rate in Cubic Meter /s
- Dp, friction loss in Pa
- h is efficiency factor to account for the efficiency of the pump.