Nozzles and mouthpieces
An analysis of the head lost in a nozzle and the resulting velocity of the jet.
IntroductionIt is assumed that the Head H is the head behind the nozzle, and that all pipeline and valve losses have been accounted for elsewhere. There are, of course, losses in the nozzle itself, and the actual velocity of discharge will be less than the theoretical value by one to five percent. This is catered for by the use of The Coefficient of Velocity , The Coefficient of Contraction , and the Coefficient of Discharge , given by:
The Power Of A JetLet the weight of fluid discharged be . Then if the effective cross sectional area of the jet is and the velocity of discharge is , then :
Example - Discharge through nozzle
A Nozzle discharges 175 galls per min. under a head of 200 ft. The diameter of the nozzle is 1 in. and the diameter of the jet is 0.9 in. Find the:
- a) The coefficient of velocity for the jet.
- b) The head lost in the nozzle.
- c) The horse power available in the jet.
(a) The Coefficient of Contraction, is given by:
a) The coefficient of velocity for the jet = 0.932 b) The head lost in the nozzle = 26.28 ft c) The horse power available in the jet = 9.21 h.p
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