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Water Hammer Pump Data

How does Hammer determine the pump speed during a power failure event?  It's unclear without the input of the a power curve or torque curve how that data is derived.  Are these values interpreted some way from the specific speed?

Also, what is the source for the specific speed parameters that are included as options in the pump transient parameters?  Does each of the available specific speed values have its own four quadrant curve?  And are they available to view?

  • Hello,

    Yes - you should be able to find some information on this in the Help documentation, but basically the pump inertia is coupled with a 4-quadrant characteristic curve to determine the speed, flow, head and torque for a "shut after time delay" pump. When the pump shuts down, the applied electrical torque drops to zero and the turbine impeller spins down based on momentum.

    When you select a Specific Speed in the pump definition, HAMMER will use a corresponding four quadrant curve, using the data seen in the QuadrantCurvesPredefined.txt file in the HAMMER installation folder. These curves are based on published data from a few different sources. In the help documentation, there is a chapter that goes into detail on the format of this data and how to enter your own curve if you so desire. The help also has an equation for estimating the specific speed. You can then do a sensitivity analysis using the two closest specific speeds.


    Regards,

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