Question

What is the formula for discharge when venturi meter is used?

(a) \(Q = C_d (a_2/\sqrt{(a_1^2 – a_2^2)})\sqrt{2h}\)

(b) \(Q = C_d (a_1 * a_2/\sqrt{(a_1^2  – a_2^2)})\sqrt{2gh}\)

(c) \(Q = (a_1 * a_2/\sqrt{(a_1^2  – a_2^2)})\sqrt{2g}\)

(d) \(Q = C_d (a_1/\sqrt{(a_1^2  – a_2^2)})\sqrt{2gh}\)

The question was asked in an interview.

I need to ask this question from Regulation Modules in chapter Regulation Modules and Canal Structure of Irrigation Engineering

Answer 1

Correct choice is (b) \(Q = C_d (a_1 * a_2/\sqrt{(a_1^2  – a_2^2)})\sqrt{2gh}\)

Easiest explanation: When the difference between the two stilling wells is h, then the discharge is given by the formula \(Q = C_d(a_1 * a_2 / \sqrt{(a_1^2  – a_2^2)})\sqrt{2gh}\) where, Cd = 0.95 to 1, a1 = area at entrance, and a2 = area at the throat.