MECHANICAL TIPS AND STUDY MATERIAL
- Major losses in pipe
- Minor losses in pipe
- Surface of pipe and layer of fluid flowing over it.
- Subsequent layer of fluids creating resistance to neighboring layer.
Darcy - weisbach formula
Where,
hf = head loss
L = length of pipe
d = diameter of pipe
f = coefficient of friction
V = mean velocity of flow
Chezy's formula.
Where,
hf = loss of head due to friction
P = perimeter of pipe
A = area of cross section of pipe
L = length of pipe
V = mean velocity of flow
Minor losses in energy can arise from several factors. Some of them are as under.
- Any obstruction in pipe
- Bending in pipe
- Unanticipated contraction
- Unexpected expansion
- Fittings etc in pipe
Loss of head due to sudden enlargement and contraction
Consider a pipe of diameter D1 (smaller) with sudden enlargement having diameter D2 (larger). The liquid moving from smaller to larger diameter pipe experiences sudden change in boundry an is not able to follow the abrupt change in boundary resulting into formation of turbulence or eddies. This adds to the loss of head in the pipe.
When fluid is flowing in larger diameter pipe and suddenly experiences change in diameter (reduced diameter of flow), the flow goes on decreasing upto section C - C and then suddenly increases causing loss of head. Then section C - C is also known as vena-contracta.
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