Fluid flow velocity and Pressure calculation

Using your pipe diameter and velocity I came up with a flow rate of 56.55m³/hr not 200m³/hr. Granted I could have made a mistake in the math so I welcome a double check.

V=A (√2gh) velocity equals area times the squareroot of two times gravity times head.

v= velocity

A= area

g=gravity

h=head

Solve for h and this should get you close to the answer you seek. You will still need to do a little converstion work depending on the units of measure you want for pressure.

See http://en.wikipedia.org/wiki/Bernoulli%27s_equation for more information.

The pressure of the pipe is a function of many things (but not velocity)

Outlet pressure, static above point , friction above point.

Closed valve pressure must also be considered with the choice of pipe class.

Example if the zero flow pressure of a pump is X the pressure at a specific point will be x - delta static.

Water hammer must also be considered.

Actually, pressure is related to velocity if you refer to good old Bernoulli:

(p₁/γ) + [(V₁)²/2g] + Z₁ + h_a - h_r - h_l = (p₂/γ) + [(V₂)²/2g] + Z₂

where P=pressure, γ=gamma or specific weight of fluid, g=gravity, Z=elevation, h=head lost or head added or head removed.

As you can see, the second "chunk" represents the velocity head which is usually minumal and almost negligable in a lot of cases, but it is still there.

Perhaps you are speaking only in regards to static situations, but the original question was referring to flow.

Yes it is true but minimal.

There is another effect that need consideration.

The pressure reduces relative to velocity.

It is possible to control the flow in a system by using this principle.

Made a venturi flow controller about 30 years ago. My memory is not what it used to be but i will consult my notes if i can remember where it is stored.

Yes it is true but minimal.

There is another effect that need consideration.

The pressure reduces relative to velocity.

I'm not sure what you mean, if first you say it is minimal, then immediately you state that velocity is factor when dealing with pressure

no

There are not enough data to give you an answer. In fact the pressure at a point when there is a flow depends of the resistance offered by the hydraulic pipes and other components of the net between the considered point and the outlet. It depends as well of the static pressure at the outlet. To make it clear if you pump into a reservoir where the pressure is P2 (units) the pressure at considerd point will be P1= P2+ Σ ς*v^2 where v is the velocity at each resistance level between locations 1 and 2.

ς- can be either a local loss coefficient or a loss coefficient depending on type of flow (Reynolds number) and length of the portion considered. So that as you see with what you mention it is not possible to give you an answer. For details look in a book about flow dynamics or consult wikipedia.

Please give more information. The pressure can be calculated if for example another point in the system is known. If the system is connected to a reservior which is exposed to the atmosphere, the pressure can be found. Likewise, is the system is dumping into an atmospheric pressure reservior, pressure can be found. Is there a pump in the system prior to the point you are measuring? If so, include the head produced by the pump.

You should have information about the pipe being used as well to accurately calculate the friction factor and reynolds number. You should be using the "moody diagram" to find your friction factor if the relative roughness of the pipe (d/ε) which is a look-up value is known.

Once you have this friction factor from the "moody diagram" (there are equations for it as well that I don't feel like looking up right now), then you can proceed to calculate your head losses over the system.

Either way, you need some information regarding some other point in the system and what exists between the two points you are analyzing.

Remember the equation in my previous post. Also, remember this equation: Q=A*V, where Q=volumetric flow rate, A=cross-section area of pipe, and V=Velocity of fluid.

Another equation you should know: h_l=f*(L/D)*(V²/2g), where h_l=head loss, L=length of pipe, D=Diameter, V=velocity, and g=gravity

Read more about this in a free book at http://www.drbratland.com/. A long chapter about pipe friction.

HI

you can calculate pressure after knowing the length of the pipe , the density of fluid after that using bernoles eqn

please you need more inf to calculate the pressure

1- the sourse of pressure as, pump , cravity etc ,,,,,

2- the length and type of pipe

3- deside the point which you need to calculate pressure

Yes it does make one think. considering the ques. may b its fairly correct to take in account the Bernoulli's eqn. but giving it 2nd thots using that ber. eqn may not get u a proper ans. therefore to cal. pr. u will need to get to numerical analysis and find out pr. by iterative techniques using an initial guess. taylors series can b of help.

I think you'd need to know the properties of the fluid such as the mass or density. The heavier the fluid, the greater the pressure assuming equivalent conditions.