Water flows through a circular pipe with a 180° horizontal elbow and exits to the atmosphere through a nozzle as shown in Fig. Q3. The diameter of the pipe is 300 mm and the diameter of the nozzle exit is 160 mm. The density of water is 999 kg/m3 . The mass flow rate of water is 140 kg/s. Incompressible, inviscid flow may be assumed. Determine:
(i) the velocity of the water at sections 1 and 2 respectively,
(ii) the gauge pressure at section 1, and
(iii) the magnitude and direction of the force Rx exerted by the water on the elbow
The Attempt at a Solution
I have determined that Vin=1.98m/s and Vout=6.97m/s and i know how to determine Rx, but i have no idea how to get the gauge pressure
Do you use bernoulli's equation and let P2 equal atmospheric pressure? But does that mean you let the exit velocity equal zero?