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Valve closure modeling in Hammer

Hi

I am trying to simulate a pumping main from a low elevation sump to a high elevation sump (HES). To simplify the system practically i am planning on using a altitude valve at the HES, so when the HES is filling to top level the altitude valve will start throttling the flow  and the pressure switch located at the pump will shut down the pump.

I used a TCV to simulate the altitude valve and gave it valve closure pattern to close in 60s. I used a pump shut down time 70s (assuming that the pressure sensor fails and the pump will shut down after the TCV fully closes). An animation of the resulting Pressure  Vs distance graph shows that max_surge developed  is a gradual build up of pressure from about 40 s to 70 s. And the maximum pressure goes above the pump shut off head.  Can the pump during the simulation go above its specified (3 point curve) shut off head?.

 

  • Yes - HAMMER uses a four-quadrant pump curve during the transient simulation, which can be different than the pump curve entered in the pump definition. So, the operating points during the transient simulation may not fall on the pump definition's curve unless you specified a custom specific speed that exactly matches your pump characteristics.

    The pump definition is used to establish the head and flow in the initial conditions, which HAMMER then uses to construct the four quadrant pump curve based on the dimensionless values in the quadrantcurvespredefined.txt file (in the HAMMER8 install folder). The dimensionless curve it uses depends on the Specific Speed you selected in the pump definition. If that specific speed doesn't exactly match your pump characteristics, you may not necessarily see equivalent results (though they are often a good enough approximation) unless you specify your own four quadrant curve.

    For more help on this, please contact technical support.


    Regards,

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