Hi,
Thanks for the question.
I believe you are looking for something utilizing The Darcy equation/law.
"Darcy's Law is a phenomologically derived constituative equation that
describes the flow of a fluid through a porous medium (typically water
through an aquifer). The law was formulated by Henry Darcy based on
the results of 1855 and 1856 experiments on the flow of water through
beds of sand. It, along with the conservation of mass, comprises the
groundwater flow equation, which is one the basic building
relationships of hydrogeology."
http://www.answers.com/topic/darcy-s-law
This equation may help you:
hL = f(L/D)v2/2g
hL - pressure
f - friction factor
L/D - the ratio of pipe length to internal diameter
v - velocity of flow
g - the acceleration of gravity
Fittings and valves & bends also affect the pressure drop. The above
equation requires a modification:
hL =K v2/2g
K is the resistance coefficient, which is defined as the number of
velocity heads (or pressure) lost due to the valve or fitting. If
desired, one can relate this resistance coefficient to equivalent pipe
length by using the Darcy equation:
K = f(L/D)
f is the friction factor and L and D are the length and diameter of
the pipe, in feet.
Fitting K coefficient
======================================
90 degree Mitre(elbow) 60f
90 degree Sweep 30f
45 degree sweep 10f
More details can be found here:
http://www.procooling.com/articles/html/maximizing_flow_rates_with_h2o.php
Crane Technical Paper No. 410 (TP-410) is the ultimate guide to
understanding the flow of fluid through valves, pipe and fittings,
assisting you to select the correct equipment for your piping system:
http://www.cranevalve.com/tech.htm
A very nice document that details other factors that affect flow rates
through pipes (velocity, friction, viscosity and density:
http://www.rosemount.com/document/pds/flowfund.pdf |