How to calculate the head required

[rtilford]

I have a tank with water flowing into it through a diffuser. The water is flowing out at a similar rate as it is flowing in. I am trying to find the head between the level of the water in the tank and the level of the diffuser to keep the water flowing into the tank.
Please see attched file for a diagram of the problem.
Thank you for any help

 

[maddocks]

Refer to Crane 410 technical paper - it covers this. But, this sounds just like a school question....

 

[dcasto]

IF you have the systems set up, go measure it.

This is a very complicated calculation. You will need to model the each and every hole in the diffuser and see how much it will flow at different rates and different heads.

The answer will be the head is dependant on flow into the diffuser.

A quick model would be to use the rule of equal areas of holes to a single hole and then look at pressure drop on the diffuser line and its single outlet hole. I'd bet that the line size of the diffuser controls 90% of the head loss.

 

[rtilford]

Thank you for your replies.
The system is set up, but there is no way for me to measure it.
I am not really sure what you mean dcasto. Are you using the Bernoulii's equation to get the pressure drop?
Using the continuity equation, I can get the velocities coming in and out of the difusser, but then what do I do?
Thanks

 

[MJCronin]

Pressure gauges are cheap.......

Good one ~$100...cheap one....~$35

http://www.grainger.com/Grainger/pr...instruments/ecatalog/N-bdk/Ntt-Pressure+Gauge