Question

It is proposed to increase the discharge by 20% in circular pipe carrying oil in laminar regime. If all other factors remain unchanged, power consumption to maintain the modified flow relative to the original flow would increase by

• A. 10%
• B. 20%
• C. 44%
• D. 52%

Answer 1

The correct option is C 44%

$P=\dot{m}g{h}_L=\rho Qg{h}_L$

$Now{h}_L=\frac{fL{Q}^2}{12\times D^5}$

$\therefore P\propto Q^2$

$\Rightarrow P_2={\left(\frac{Q_2}{Q_1}\right)}^2\times P_1$

$P_2=\left(1.44P_1\right)$

$\therefore$ Power will increase by 44%