Question

A venturi tube of throat diameter 60mm is placed in a water pipe of diameter 100 mm to measure a volumetric flow. The volumetric flow rate through the tube is $80\times {10}^{-3}\left(m^3/sec\right)$. Water has density of ${10}^3\left(kg/m^3\right)$ & a viscosity of ${10}^{-3}\left(Ns/m^2\right)$.
The Reynold's number is

• A. 1296000
• B. 1096000
• C. 1696000
• D. 1596000

Answer 1

The correct option is C 1696000

$R_e=\frac{\rho dV}{\mu }=\frac{\rho dQ}{\mu A}$

$\rho ={10}^3\left(kg/m^3\right)$

$d=60mm$

$Q=80\times {10}^{-3}\left(\frac{m^3}{sec}\right)$

$\mu ={10}^{-3}\left(Ns/m^2\right)$

$A=\frac{\pi d^2}{4}=\frac{\pi }{4}\times (60\times {10}^{-3}{)}^2{m}^2$

$R_{eq}=\frac{{10}^3\times 60\times {10}^{-3}\times 80\times {10}^{-3}}{{10}^{-3}\times 2.83\times {10}^{-3}}$

$R_e=1696\times {10}^3$