We have already seen the derivation of

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*continuity equation**,**Bernoulli’s equation**,**momentum equation**,**velocity of sound in an isothermal process*,*velocity of sound in an adiabatic process*and also the basic fundamentals of*stagnation properties i.e. stagnation pressure,stagnation temperature and stagnation density*for compressible fluid flow in our previous posts.
Now we will start here the basics and derivation of
expression of force exerted by jet on stationary vertical plate with the help
of this post. Let us first brief here the basic concept of impact of jets
and after that we will derive the expression of force exerted by jet on
stationary vertical plate.

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**Impact
of jets **

Let us consider that we have one pipe through which
liquid is flowing under pressure. Let us assume that a nozzle is fitted at
outlet of pipe. Liquid which will come through the outlet of nozzle will be in
the form of jet.

If a plate, which may be moving or fixed, is placed
in the path of jet, there will be one force which will be exerted by the jet
over the surface of plate. The force which will be exerted by the jet over the
surface of plate, which might be moving or fixed, will be termed as impact of
jet.

In order to determine the expression of force exerted
by the jet over the surface of plate i.e. impact of jet, we will use the basic
concept of Newton’s second law of motion and impulse-momentum equation.

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**Force
exerted by jet on stationary vertical plate **

Let us consider a jet of water, which is coming from
the outlet of nozzle fitted at the pipe, strikes a flat vertical flat plate as
displayed here in following figure.

V = Velocity of the jet

d = Diameter of the jet

a = Area of cross-section of the jet = (Ï€/4) x d

^{2 }
Liquid jet will move along the vertical plate after
striking the plate. As we can see from the figure, vertical plate is located at
right angle to the direction of liquid jet and hence liquid jet will be deflected at right angle i.e. 90

^{0}after striking the vertical plate.
The component of velocity of liquid jet, in the
direction of jet, after striking will be zero.

Force exerted by liquid jet on the plate in the
direction of jet will be determined by using the concept of impulse momentum
equation.

Above equation, derived here, provides the force
exerted by the liquid jet on the plate in the direction of jet.

Now we will discuss the force exerted by the liquid jet on the stationary inclined flat plate in our next post.

Do you have any suggestions? Please write in comment
box.

### Reference:

Fluid mechanics, By R. K. Bansal

Image courtesy: Google

Where will we use this formula in real life

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