Question

P7 If separate piezo tubes and pitot tubes were placed in the upper surface of a channel of pressurized flow of water, the static and stagnation pressures respectively would be indicated by the difference in heights of the fluid rising up in the two tubes. If the difference in heights is 3 inches (1/4 foot), what is the velocity of water flow?

Answer 1

If P* represent the pressure measured by piezo tube and Po represent stagnation pressure then

Po/(pg) = P*/(pg) + V^2/ (2g) ........( Applying Bernoulli's theorem)

Where V is velocity of flow and g represent acceleration due to gravity and ( pg) represent product of density and acceleration due to gravity.

(Po - P*)/(pg) = V^2/(2g)

(Po - P*)/(pg) = h

V^2 = 2gh

Where h is differential head = 3 inch. (given)

V^2 = 2×385.826 × 3 .....( Value of g is written in units of inch/s^2)

V = √(2314.956)

= 48.113 inch/s

= 4.009 ft/ s

Hence velocity of water flow is 4.009 ft/s