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Not able to control down surge even with surge vessel

HI,

I'm not able to control the downsurge with any capacity of Surge vessel & the graph is attached herewith, D2A is used at the discharge end. when the pump shutdown at 6.5 seconds there is a continuous downsurge.

Kindly suggest the possibilities of setting the surge vessel that could mitigate the downsurge. The graph is captured with 10 m3 surge vessel

  

  • Hello Nagesh, 

    This appears to be a similar question to one you posed earlier.

    This may be related to the setup of the model If the downstream reservoir or point of discharge has a lower elevation than the elevation of the hydropneumatic tank, you may find that the tank drains over the course of the simulation. I would recommend reviewing the following link for more information: Negative pressures occur during a transient simulation no matter what protection is used. If the setup of the model is correct, you may need to look into the timing of when your pump turns back on. 

    Regards,

    Scott

  • To add to Scott's answer - is the pump shutdown on the far left side of the profile, or is it in the middle from where the downsurge appears to be emanating? If you are seeing a downsurge occurring where it should not be, see this article on initial surges. Otherwise, see Scott's advice on situations where no mitigation will help as long as the pump remains off.


    Regards,

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

    Answer Verified By: Nagesh Nagaraju 

  • Yes, it is at the left side of the profile It is controlling only when I increase the pump head. It is not possible without doing that, may I know what the reason would be & without increasing the pump head isn't it possible?

    I have checked with both using reservoir & D2A at the end and I'm getting the same result for both the cases.

    I've increased the pressure at the discharge point now its controlled with surge vessel

  • Can you elaborate on what you mean by "controlling"? I am not quite clear by your response if you are saying that the issue is an unexpected surge in the middle of the model or if you are just generally wanting to know how to prevent undesirable max/min pressures throughout your system. If needed, you can provide a copy of the model file for review, along with steps to reproduce:  Sharing Hydraulic Model Files on the OpenFlows | Hydraulics & Hydrology Forum  


    Regards,

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