Hydraulics

If a pool is organized, I'll take the one-minute square. Just instinct.

That'd be the volume divided by the flow rate.

If the vessel is not open where does the oil go? Also a environmental question.

there is one hole at bottom no?

with dia of 0.375 inch

Is there?

One hole and the oil goes where?

yes

Explain with words how you would intend to solve the problem.

If you do it one of readers will give you the help to understand your errors (if you made any, may be you think the right way) and you will have the pleasure to have solved by yourself.

On CR4 NOBODY will solve the problem for you.

Here's a novel idea. Get a stopwatch.

Fill the vessel( which is made up of mild steel of 2 m height with inner dia of vessel is 100mm), with castrol 68(viscosity =68). Add the 40kg of mass to the top of the fluid.

Remove the plug from the 0.375 inch orifice and measure the time it takes to drain the tank.

Unless, of course, you have no tank and this is just a homework problem.

Remind the instructor it is not a good idea to mix metric and Imperial units.

Do your own homework!!!!

How much effort have you made so far? If you've made some we don't mind commenting, but we're not going to do it all for you.

Is the viscosity 68 centistokes? A bit thin for engine oil.

When you say "vessel is not open to atmosphere instead a 40kg of mass is fixed there", do you mean something like a 40kg piston in the vessel? If so, the pressure due to that is about 0.5 bar. I leave you to work out the pressure due to head of oil.

The orifice Reynolds number affects the discharge coefficient, hence the flow, but the Reynolds number depends on viscosity and the velocity, so an iterative calculation needed, but it's not difficult. There's a graph in Perry (I have an old edition) which covers it.

See how you get on from there and if you want I'll comment further.

This whole exercise is a joke.

If this is real, which I doubt, the test temperature could have a profound effect on the viscosity and flow of the imaginary fluid.

Then, there's that troublesome 40kg "mass". Unless there is a very good seal between that mass and the cylinder walls, the mass will simply sink in the oil and end up at the bottom of the cylinder, blocking the .375 inch hole.

Then, if we assume that there is an effective seal between the cylinder wall and the mass, that's a completely different kettle of fish.

Friction will rear its ugly head and throw another unknown variable into the pot.

Waiting patiently to hear from our student, I'll go about my artistic project for the day.

Cheers.

Agreed it's all a bit hypothetical, but I don't mind helping him if he shows some signs of helping himself.

It caught my interest as I've never dealt with orifice flow of viscous fluid, but checking in Perry, for these sorts of viscosity it doesn't make much difference. I estimate Reynolds No. ~ 300, and Perry gives discharge coeff ~ 0.65, similar to water flow. The CD only starts to drop off for Re < 40, going as √Re, which means (after a bit of algebra) flow varies as 1/μ, as expected for laminar flow.

Cheers to you too!

i am providing good seal and at the same time i would prefer some honing process inside dia of vessel

Give up! You are doomed to fail.

thank you for the reply sir

what is this perry chart?

It's the Chemical Engineers Handbook (if you have a big hand!) commonly called Perry. I have 5th edition, © 1973. There are several later editions but I doubt if fundamentals like that have changed much. The graph is Figure 5-18.

I gave enough information in #7 and #9 to work it out, if you know basic fluid mechanics. You also need the oil density.

Assuming the 40kg is acting on a frictionless piston (OK for a homework question, though maybe not in practice, as several posters have said) I would add the pressure from the average head of fluid i.e. 1 m deep. As flow varies as √P, this will give a time erring on the low side. If you want something more accurate you could do an integration.

I looked for Perry on the internet and Edition 7 (1999) is available free, link below. That's pretty good, considering there are 2582 pages! I believe the latest is 8th edition, Dec 2007.

The graph in question is unchanged but it's now Fig 10-20.

http://www.google.co.uk/url?url=http://rushim.ru/books/spravochniki/Perrys-Chemical-Engineers-handbook-1999.pdf&rct=j&frm=1&q=&esrc=s&sa=U&ei=fMdZVZChCKre7AbMoILIDw&ved=0CBoQFjAB&usg=AFQjCNGlVQ-gEnKqN4lhw3vLoQMEjypT2g

Volume of cylinder....

http://www.mathwarehouse.com/solid-geometry/cylinder/formula-volume-of-cylinder.php

Flow rate through orifice....

http://www.tlv.com/global/TI/calculator/water-flow-rate-through-orifice.html

Density and mass of oil...

http://www.viscopedia.com/viscosity-tables/substances/engine-oil/

http://physics.info/density/

http://www.thecalculatorsite.com/conversions/substances/oil.php

Nice venting!

Absolute vacuum is pulled at about 10m so i think it would empty but i am sure it would slow down the emptying. But i cannot say by how much as it would be progressive. Either way, probably not much effect.

Jim

So you've never seen the trick with a pint glass full of water that has a piece of paper over it and is then turned upside down?

Del

A pint glass full of WATER? Are you really an Englishman? "I know the trick and to you i will show it". Charlie Drake, My Boomerang Won't Come Back.
Try the same thing with a 2L soft drink bottle as it is closer in scale.
The glass works because of a large surface area vs mass. The bottle doesn't work due to a small surface area and large mass. The 'bottle' in the quiz has a very small surface area and a large mass. If the OP is still here i may be giving away a bit too much, but hey! all good fun.Jim

You think I'd risk beer?

Del

Trust me I know - it's ten minutes. Just put that answer in and tell the instructor you saw it on the internet so it must be true!

He gets extra credit for his search skills in ferreting out no other than CR4 Anonymous Poster #1 to get a wrong answer. Win some, lose some.

It's not fair, I was going to say something snide and demeaning as AP#1, but that other person beat me to the #1 title.

Now there is some green thinking!

And why would the time matter? Better save than sorry!