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Valve Closure Modeling - HAMMER

Hello Forum,

I'm working on a model where the transient scenario is developed by a PRV closure. I entered the Operating Rule (A linear closure for now in 0.6 s) and established a User Defined valve because I have the Characteristic Curve.

The problem is that when I run the model, the decrease in the flow is steep, it is not shown the change in flow during the 0.6s as I expected and as I needed because I have to compute the amount of water that passes in this time.

I don't know if I'm making a mistake with the modeling, I hope you can help me.

Thanks in advance.

  • Hello Jessica,

    You should make sure that you have defined the headloss through the valve when it is fully open. HAMMER uses this value along with the valve characteristics curve you entered to compute the headloss through the valve at any point in time. If you do not specify a value (the default is zero), then there will be no headloss through the valve as it closes and you will only see a change when the valve becomes fully closed. In effect it will be like the valve slammed shut.

    To do this for a PRV you should set the "Minor Loss Coefficient" to a sensible value. This should represent losses through the valve when it is fully open.

    If you'd prefer to enter a discharge coefficient, simply change the 'Valve Coefficient Type' field to 'Discharge Coefficient' then enter a value in the 'Discharge Coefficient (fully open)' field.

    Regards,

    Mal

          

  • Jessica,

    You can also find some information on this subject in the below Support Solution article:

    communities.bentley.com/.../12683.gradual-closure-not-occurring-when-using-valve-operating-rule-solution-500000058523.aspx

    To help find answers to future questions or problems, I would recommend using the Search bar. You can click "Change search scope" to focus the search on Hydraulics & Hydrology products only. This will search through years of other forum discussions, plus a wealth of information we have built up in our Support Solutions article repository.


    Regards,

    Jesse Dringoli
    Technical Support Manager, OpenFlows
    Bentley Communities Site Administrator
    Bentley Systems, Inc.