Hello good morning;
I am modeling a surge tank to protect a pipe for transient event.
When I dont consider headloss coefficient ( Headloss coefficient = 0) tthe system works normally but when I consider a headloss coefficient different to 0 (always positive), HAMMMER dont compute.
Additional Surge Tank input data:
Where do you think is the error? Maybe the little diameter of the onlet and surge tank (4"=0.1m = 100mm)
Thank you very much for your support
Kind regards.
Hello Gustavo, what version of HAMMER are you using? (you can check under File > Help > About, or Help > About for older versions). There was a similar issue in version 10.01.01.04 but I am not certain if it an exact match to the issue you're describing. If you're on version 10.01.01.04 or earlier, are you able to upgrade? can you provide a copy of the model for us to test in the older and newer versions?
Regards,
Jesse DringoliTechnical Support Manager, OpenFlowsBentley Communities Site AdministratorBentley Systems, Inc.
Hello Jesse and thank you for you help.
The version of hammer I am using is HAMMER Connect Edition Update 2 - 22/04/2019 10.02.01.06 64-bit
In order to solve the problem, I have been trying differents diameters of the Surge Tank and Inlet Orifice and when I put something more normal (1 m. instead of 0.1m (surge tank) and 250mm instead of 100mm. (inlet orifice)) it works with a headloss coefficient diferent to 0 (positive). the problem is that i am checking a design and they projected a 0.1m Surge tank with 100 mm inlet orifice.
Anyway, if you show me the better way to send you the model, I ll send you.
Thank you.
Kind Regards.
Hello Gustavo,
As suggested by Jesse in his reply, the problem here is with small surge tank diameter, in your case diameter is 0.1 m i.e. 100 mm, is that correct diameter ? If you change the diameter of surge tanks to say 0.5 m or 1 m, model runs fine.
How is your system ending in real, is it discharge into a water body i.e. open to atmosphere, there is a junction in your model at end. You could model it as discharge to atmosphere element i.e. D2A element.
Here is information about it, for your reference.
Modeling Reference - Discharge To Atmosphere
Sushma Choure
Bentley Technical Suppport
Hello Sushma and thank you four your answer.
First I thought the pipe of my sistem was a pipe section that continues like a pipe but i dont have more data about it. Only to know about the program... How could I model this situation?
Now I am realizing that it drains into a secundary distribution storage tank that it is open to atmosphere preasure. I am going to change this in the model. but how could I model a demand at the end of the pipe if it ends with a orifice to atmosphere?
Thank you very much.
Kind Regards
You would want to make sure your system is modeled as accurately as possible (and that the model is calibrated). The reason for this is that you want to make sure that the initial conditions at the start of the transient simulation is as accurate as possible.
Regarding the demand at the end of the pipe, the link that Sushma provided as steps for setting up the typical flow and typical pressure drop for the discharge to atmosphere element. These values will define the demand at the open end of the pipe. The link further describes how to derive these and which equations are used to do that. See the section called "Common applications of the D2A acting as an Orifice" in the link provided for more information on that.
Scott
Gustavo Montero said:Now I am realizing that it drains into a secundary distribution storage tank that it is open to atmosphere preasure.
Are you saying that the 4" discharges water to the atmosphere, which then spills into a tank? If so, the D2A approach may work well if there is always water discharge. If upon downsurge, the pipe drains down, then the surge tank approach may still be best. (otherwise with the D2A, air will enter when the pressure drops to zero, but air tracking has limitations.
If you are saying that the 4" pipe connects to the bottom of a tank, and that the tank is open to the atmosphere, then this would be modeled with the surge tank element as well (4" pipe connected to surge tank element).
If you need further help, a clear diagram of what you are trying to model may help.
Hello Jesse;
No, according to the Sushma entry, I mean that the end of the system (450mm pipe) drains to a secundary distribution tank not to other pipe (juction) like I modeled,
I model the system according this (with a D2A at the end) and it works much better,
The 4" stand pipes (model like surge tank) are open to the atmosphere as well, but not to a tank.( please see the following figure)
thank you very much.