Modelling of a spring with limited output and overflow
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Gianluca Pozza
Apr 7, 2020, 5:41:31 AM4/7/20
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Hello, I need some help to model a complex system made of multiple reservoirs, all with limited output but I dont know how to properly model those kind of systems for two reasons:
- Pipe diameter going out of the reservoirs is to big for the flow (my hypotesis is that the pipe is not pressurized) and I have negative pressure until I hit the a tank (and often thos pipe doesnt go into a tank, but into a main pipe);
- I cant choose between a fictional FCV to limit the flow or PSV just before the tank or junction to limit the pressure and then the flow trying to achieve a more reasonable flow value.
See attachments for the general scheme I'm using to simulate a limited reservoirs using an FCV filling a tnak with variable demand and an overflow valve (troppopieno.net). The other file is the general scheme (still simplified) of the system I was talking (network.net).
Santiago Arnalich
Apr 7, 2020, 5:55:52 AM4/7/20
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Hi Gianluca,
I just posted a video on that: https://www.youtube.com/watch?v=-KU43lo3ZAs
FCV work but they flood you with error messages. As you are seeing in your files.
FCV valve unable to deliver just means that the flow is less than the setting so the valve is not controlling it.
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Gianluca Pozza
Apr 7, 2020, 6:08:59 AM4/7/20
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As you said FCV are not the ideal way because I do like the flow to be less than the max output of the reservoir as it reflect reality way better. Ill check your video!
Gianluca Pozza
Apr 7, 2020, 6:14:56 AM4/7/20
to Epanet and Development
Thank you Santiago! I was thinking of something similar using the negative demand node but placed a single overflow in a tank that cause overpressure as you show in the video. I didn't think about using a reservoir directly near the negative demand node! Ill go check my model right away! Thank you again!
Il giorno martedì 7 aprile 2020 11:41:31 UTC+2, Gianluca Pozza ha scritto:
Gianluca Pozza
Apr 7, 2020, 7:41:55 AM4/7/20
to Epanet and Development
Now I'm having another problem I had while experimenting with negative demand nodes: the nodes seems to give not always the same amout but more. I'll attach the .net and the pattern for the consumption.
Il giorno martedì 7 aprile 2020 11:41:31 UTC+2, Gianluca Pozza ha scritto:
Gianluca Pozza
Apr 7, 2020, 9:01:38 AM4/7/20
to Epanet and Development
I've done some troubleshooting and looked like that EPANET assigned (even if not written everywhere) the consumption pattern to the negative demand nodes even if not specified in the node attributes as the field was blank.
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