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raj
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Join Date: Apr 2007
Posts: 91

Compartmented Tank-Water Flow

03/09/2011 8:39 AM

Hi,

Could you tell me the approach to the problem.

A water tank which is divided into some compartments and connected by a hole at the bottom of all separator plate.water supplied, is falling to one compartment and flow distributed to the other compartments through a holes at the bottom.I'm having one high level sensor at the 1st compartment (which gets water first).when water reaches this level water supply will be cutoff.because of insuffcient no. of holes at the bottom of separator plates, i'm getting spurious high level signal.But after stabilizing (after some seconds) the actual water level in the tank is lower than the high level.ie. there is a sudden rise in water level in the 1st compartment and becoz of high head available for the flow to the next compartment through bottom holes, flow takes place and it repeats...Assume the water supply is of constant known rate.

How to analyse this flow distribution analtically.any iteration methods?i need to find the required amount of flow area (no. of holes) for a particular water supply rate,in all the separator plate.

Is it possible to analyze (simulate) this in CFD softwares(Fluent...)
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rakesh_semwal
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#1

Re: Compartmented Tank-Water Flow

03/09/2011 9:57 AM

If you are talking of theoretical analysis of flow through holes at bottom I dont have any clue without having a look on some flow mechanics book, But if you talk of solution Then I think you should think of reducing flow as water level incraeses and stop flow when level reaches to sensor, It will slow down process but this the way to get precision,

Just look How PID Controllers work for trmprature control.
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raj
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Posts: 91
#11
In reply to #1

Re: Compartmented Tank-Water Flow

03/19/2011 1:00 AM

But sir, my requirement is i can't reduce the flow rate of water as the tank gets filling.
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TonyS
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#2

Re: Compartmented Tank-Water Flow

03/09/2011 10:26 PM

This sounds like a homework question!

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stargan
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Join Date: Aug 2010
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Good Answers: 1
#3
In reply to #2

Re: Compartmented Tank-Water Flow

03/10/2011 1:27 AM

Try analyse acc. to Bernuli equation, it will give you the velocity (and capacity) acc. to water level at any moment...
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raj
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Posts: 91
#6
In reply to #3

Re: Compartmented Tank-Water Flow

03/10/2011 7:59 AM

Could you tell,in this case which instant could be critical?
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stargan
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#7
In reply to #6

Re: Compartmented Tank-Water Flow

03/10/2011 8:07 AM

Yes, of course. You, or take someone to calculate it for you, have to invest some (short) time in developing the adequate equation/s for your process. Some mathematics knowledge is required.
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raj
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#12
In reply to #3

Re: Compartmented Tank-Water Flow

03/19/2011 1:04 AM

Yes,Bernoulli's equ. will give flow rate but the thing is under steady condition(a moment) but if i want to see the cumulative process over a time,i think it won't.
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stargan
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#4

Re: Compartmented Tank-Water Flow

03/10/2011 1:30 AM

Try analyse by Bernuli's equation - it will give you the water velocity (hence capacity) through the hole acc to watel level at any moment.
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stargan
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#5
In reply to #4

Re: Compartmented Tank-Water Flow

03/10/2011 1:33 AM

Sorry for sending twice - mistake...
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Fredski
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#8

Re: Compartmented Tank-Water Flow

03/10/2011 8:49 AM

Are all the compartments vented? Or are you compressing air as you flow from one compartment to another?
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raj
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#13
In reply to #8

Re: Compartmented Tank-Water Flow

03/19/2011 1:06 AM

Sir,

all compartments are vented (open) to atmosphere
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kevinm
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#9

Re: Compartmented Tank-Water Flow

03/10/2011 9:59 AM

You obviously have a tank that can be filled faster than you can distribute the water. I am not sure why the storage tank is compartmentalized and why you don't just simply remove the walled compartments altogether. I unfortunately cannot provide any magic math formula that will give you details of flow except to say to look at Bernulli formulae for some semblance of an answer. More detail is needed.

One way you can improve the distribution would be to re-pump from the first chamber to successive chambers to stop the back-up. I cannot tell you if this is possible with a single pump or if you may need multiple pumps. If the other chambers are closed or not vented properly water will not flow from chamber to chamber easily. You may have to add vents and that may in the end be the simplest of solutions to the problem. Again you need to provide better detail to the configuration of the tanks, the volume, the amount of water to pass through each chamber, and the size of the exit holes. I suspect a venting problem but you should know better as you are on site.

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Tornado
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Technical Fields - Technical Writing - New Member Engineering Fields - Piping Design Engineering - New Member

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Location: Richland, WA, USA
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#10

Re: Compartmented Tank-Water Flow

03/10/2011 10:24 PM

It would be nice to have tank and baffle dimensions, size of lower and upper limber holes, and gpm of entering water. If there are several baffles in series, the limber holes nearer the entry compartment may need to be larger than the ones further away.

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Users who posted comments:

Fredski (1); kevinm (1); raj (4); rakesh_semwal (1); stargan (4); TonyS (1); Tornado (1)

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