Question

A Venturi tube may be used as a fluid flow meter. If the fluid flow rate in m3/s is 2.2 * 10-3 and the radius R1 = 2.4 *10-2 m of the inlet tube is 2.1 times the radius R2 of the outlet tube, and the fluid is water (ρ = 1000 kg/m3).

Find the pressure difference P1 - P2 in units of kPa.

Answer 1

Assuming that the fluid will be eventually in atmospheric pressure at both inlet as well as outlet, hence atmospheric pressure is not considered.

From Bernoulli's equation we can say that the pressure difference will be equal to the difference in kinetic energies of the fluid at both the points. First we have to calculate the velocities from the given fluid flow rates. We can write the velocity of the strem v as,

Substituing values we get,

For the inlet tube we get, (The fluid flow rate will be same)

Now, from Bernoulli's equation we can write,