Math question...

[TwoSeven]

How do you calculate how much liquid will flow thru a pipe ?

I have a pipe that is 5mm long and an i.d. of 2.5mm I need to work out how much liquid (assume water for now) will flow thru at normal air pressure and temp.

I need to know the formula, not the answer.

:)

[jrandom]

Google for 'fluid dynamics'.

Here's something from the list returned:

http://www.jgsee.kmutt.ac.th/exell/Thermo/AddPhysics.htm

Should give you what you need.

[Hitcher]

How do you calculate how much liquid will flow thru a pipe ?

I have a pipe that is 5mm long and an i.d. of 2.5mm I need to work out how much liquid (assume water for now) will flow thru at normal air pressure and temp.

I need to know the formula, not the answer.
That's not a pipe, it's a pigeon's leg ring!

At "normal air pressure" (presumably 1 atmosphere) no liquid will flow through. The pipe is sufficiently small for capilliary attraction to be significant in a low pressure application. This will become more significant as the viscosity of the liquid increases (more of a problem for oil than water). In practical terms this pipe is so short the formula you should be using would be to calculate fluid flow through an orifice.

I am busy rummaging for my agricultural engineering notes. I used to know all of this stuff and it should be lying around here somewhere...

[jrandom]

That's not a pipe, it's a pigeon's leg ring!

Yes, but the first chapter of this semester's textbook starts with "Consider a liquid pigeon's leg..."

[Hitcher]

Found it. You need to use the extended Bernoulli equation:

Rather than type if for you, follow this link. It looks the same as in my old notes.

http://www.engineersedge.com/fluid_flow/extended_bernoulli.htm
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But I still think that the pipe is too small (length and diameter) for any calculations based on this formula to be valid.
<!--[endif]-->

[Jantar]

Found it. You need to use the extended Bernoulli equation:

But I still think that the pipe is too small (length and diameter) for any calculations based on this formula to be valid.
<!--[endif]-->[/font]


You are quite right, the pipe IS too small. Liquid will only flow through due to capilliary action unless it is driven by a pressure or head differential.

Liquid will flow from an area of higher pressure to one of lower presure through a small pipe. In this case where you state normal air pressure and temp, I assume that means the liquid is discharging to air. It still needs a head to drive the liquid into the pipe.

The velocity at which liquid will travel into and through this pipe is given by the formula V = sqrt(2*G*H)
Where V is Velocity measured in m/s
G is Gravity at 9.81 m/s^2
H is the effective head (how far is the intake below the surface of the liquid) measured in m

Once you know the velocity, then the total flow is simply velocity * cross sectional area of the pipe. Roughness co-efficient and viscosity can be neglected as the total pipe length is less than 5 times its diameter.


I hope this helps.

[TwoSeven]

Cheers folks..

Pigeon leg ring ? orifice ?? liquid pigeons leg ?

You mean the person measuring the pigeons ass forgot it was still full of shit :)

[ching_ching]

You are quite right, the pipe IS too small. Liquid will only flow through due to capilliary action unless it is driven by a pressure or head differential.

Liquid will flow from an area of higher pressure to one of lower presure through a small pipe. In this case where you state normal air pressure and temp, I assume that means the liquid is discharging to air. It still needs a head to drive the liquid into the pipe.

The velocity at which liquid will travel into and through this pipe is given by the formula V = sqrt(2*G*H)
Where V is Velocity measured in m/s
G is Gravity at 9.81 m/s^2
H is the effective head (how far is the intake below the surface of the liquid) measured in m

Once you know the velocity, then the total flow is simply velocity * cross sectional area of the pipe. Roughness co-efficient and viscosity can be neglected as the total pipe length is less than 5 times its diameter.


I hope this helps.

Fucking Hell!!! :spudwhat:

[Hitcher]

Cheers folks..

Pigeon leg ring ? orifice ?? liquid pigeons leg ?

You mean the person measuring the pigeons ass forgot it was still full of shit :)
The pigeon's arse, thank you.

BDOTGNZA are we!

[vifferman]

The pigeon's arse, thank you.

BDOTGNZA are we!
Maybe the pigeon had an ass (or donkey, or mule) for a pet? :spudwhat:
Or for transport (it was a lazy pigeon).

[XTC]

The pigeon's arse, thank you.

BDOTGNZA are we!
Jeez hitcher you really like your arse's dont you?

[ManDownUnder]

I've heard of some people being as tight as a snapper's arse...

and other being arseholes!

... glad we don't have any of either around here !!!!!

[Hitcher]

Jeez hitcher you really like your arse's dont you?
Somebody has to make a stand against keeping naff Americanisms out of our language. And why not start with the arse!

[Sniper]

Well I stand with Hitcher. It is arse, and not ass. An ass is a donkey foul mouthed heathens