Flow in pipes( Laminar and Turbulent flow)

Flow in pipes( Laminar and Turbulent flow)
Types of flow in pipes;
Steady ( ?v/?t=0), or unsteady(?v/?t?0).
Uniform ( ?v/?x=0), or non-uniform(?v/?x?0).
Laminar, or turbulent.
Laminar flow: is the smooth and steady flow.
Turbulent: is the fluctuating and agitated flow.
The primary parameter to distinguish between them is the Reynolds number (Re).
Re=VD?/?=VD/v

The experiments showed the following:
At ( Re< 2100) the flow is laminar.
At ( Re>4000) the flow is turbulent.
Recrit= 2300
For turbulent flow in pipes the head losses of friction hf is:
Losses in Pipes
The losses in energy in pipes are of two types;
1. Major losses due to friction with pipe wall( depend on pipe material).
2. Minor losses due to fittings and bends in pipes.
it is a chart plotted by scientist Moody in 1944 for pipes
friction, and for open channel flow. It depended on the following formula:
1/f^(1/2) = -2.0log((?/d)/3.7+2.51/(?Re?_d f^(1/2) ))
Where:
f= friction factor of pipe.
d= diameter of pipe
?= roughness height.
Re= Renold number for pipe.
Specific gravity is the ratio of specific weight of the given fluid to the specific weight of standard fluid, water (for liquids), and air (for gases):. It is denoted by the letter ‘SG’. It has no unit.


Specific gravity may also be defined as the ratio between density of the given fluid to the density of standard fluid.

?SG?_gass= ?_gass/?_air =?_gass/(1.205 kg/m^3 )
?SG?_liquid= ?_liquid/?_water =?_liquid/(998 kg/m^3 )