A Venturi is to be used to measure the flow rate of water in a pipe of diameter D = 0.20 m. The maximum flow rate of water is 1.5 × 103 m3 h−1, density is 103 kg m−3, and viscosity is 10−3 Pa s. Venturis with throat diameters of 0.10 m, 0.14 m and 0.18 m are available from the manufacturer.

(a) Choose the most suitable Venturi for the application, assuming a differential pressure at maximum flow of approximately 3 × 105 Pa.

(b) Calculate an accurate value for the differential pressure developed across the chosen Venturi, at maximum flow rate. (Use the following formula for the coefficient of discharge:


d = Venturi throat diameter, and ReD = Reynolds number referred to pipe diameter.)