Question

A 30 cm diameter pipe conveys water in turbulent flow regime. The friction factor has been estimated as 0.02 for this flow. If the centre line velocity is measured as 3.57 m/s, what is the discharge in the pipe ?

• A. $0.212m^3/s$
• B. $2.12m^3/s$
• C. $0.212c{m}^3/s$
• D. None of these

Answer 1

The correct option is A $0.212m^3/s$

$\frac{u_m-V}{u^{\ast }}=3.75$

$f=0.02$

$u^{\ast }=V\times \sqrt{\frac{f}{8}}=V\times \sqrt{\frac{0.02}{8}}=0.05V$

$u_m-V=3.75\times 0.05V$

$u_m-V=0.1875V$

$u_m=1.1875V$

$3.57=1.1875V$

$V=3m/s$

$\text{Discharge},Q=A\times V=\frac{\pi }{4}\times (0.3{)}^2\times 3=0.212m^3/s$