Question

If the velocity of flow as well as the diameter of the flowing pipe are respectively doubled through pipe system in use since long, the head loss will thereafter be

• A. Halved
• B. Doubled
• C. Increased 4 times
• D. No change

Answer 1

The correct option is B Doubled

According to Darcy Weisback

$h_f=\frac{fL{V}^2}{d\times 2g}$

Now, d' = 2d, V' = 2V

$\therefore h_f^{\prime }=\frac{fL(2V{)}^2}{2d\times 2g}=2\times \frac{fL{V}^2}{d\times 2g}$

$\therefore h_f^{\prime }=2h_f$