Question
Download Solution PDFWhich of the following is NOT a reason for minor head loss in pipe flow?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFExplanation:
Minor Losses:
These occur due to various fittings, valves, bends, elbows, tees, inlets, exits, contractions, and expansions.
Usually expresses in terms of the loss coefficient KL or resistance coefficient, \({h_L} = {K_L}\frac{{{V^2}}}{{2g}}\)
| Reason for loss | Formula |
| Due to sudden expansion | \({h_L} = \frac{{{{\left( {{V_1} - {V_2}} \right)}^2}}}{{2g}}\) |
| Due to sudden contraction | \({h_L} = {\left( {\frac{1}{{{C_c}}} - 1} \right)^2}\frac{{V_2^2}}{{2g}}\) |
| Due to exit from a pipe | \({h_L} = \frac{{{V^2}}}{{2g}}\) |
| Due to the entrance of the pipe | \({h_L} = 0.5\frac{{{V^2}}}{{2g}}\) |
| Due to gradual contraction | \({h_L} = {K_L}\frac{{{V_1}^2}}{{2g}}\) |
| Due to gradual enlargement | |
| Due to bends or pipe fittings | \({h_L} = {K_L}\frac{{{V}^2}}{{2g}}\) |
| Due to nozzle | \({h_L} = \left( {\frac{1}{{C_v^2}} - 1} \right)\frac{{{V^2}}}{{2g}}\) |
Head loss due to friction in pipe is a major loss.
Additional Information
Major Losses
Due to friction
- When fluid flows from one section to another, there is a reduction in total energy due to friction between the pipe wall and the flowing fluid.
- It is given by Darcy Weisbach Equation:
\({h_f} = \frac{{4f'L{V^2}}}{{2gD}} = \frac{{fL{V^2}}}{{2gD}}\)
where, L = length of pipeline, f’ = friction coefficient, D = diameter of pipe, V = average velocity, f = friction factor
f’ is a dimensionless quantity whose value depends upon the roughness coefficient of pipe surface and Reynold's number of the flow.
|
Laminar flow |
Turbulent flow |
| Re < 2000 | Re > 4000 |
| \(f' = \frac{{64}}{{{R_e}}}\) | \(f' = \frac{{0.316}}{{{R_e}^{1/4}}}\) |
Last updated on May 28, 2025
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