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Follow-up to Service Request #7000721384, pertaining to air ingress velocity

In an attempt to be more clear on the subject service request, I would like to see if HAMMER can output time history results of mass flowrate of air ingress through a combination air & vacuum valve. If I can get mass flowrate of air ingress and the pressure and temperature of air are known, then I can figure out the air density and air velocity versus time, and get the maximum value of calculated air ingress velocity. I am NOT interested in knowing the sonic velocity. I am interested in knowing whether the computed air ingress velocity through an air valve might exceed the limit recommended by the air valve manufacturer. I have entered a non-zero "report period" within the data field for air valve properties. I do not see where air mass flowrate versus time is reported.

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  • Hello Tom,

    With a number entered in the "report period" field of the air valve, you will see a table of extended results in the Transient Analysis Output Log. This report can be found under View > Transient Reports > Analysis Detailed Report. You will need to scroll near the bottom (and may need to search on the air valve label if needed). It will look like this:

    ** Air valve at node Air Valve**

    Time Volume Head Mass Air-Flow
    (s) (m3) (m) (kg) (cms)
    ---- ----- ----- ----- -----
    0.0000 0.000 150.57 0.0000 0.000
    0.1000 0.000 150.57 0.0000 0.000
    0.2000 0.000 150.57 0.0000 0.000
    0.3000 0.000 150.57 0.0000 0.000
    0.4000 0.000 150.57 0.0000 0.000
    ...

    The table in this report includes air flow rate, but per the response in the Service Request, it is the flow rate of air inside the pipeline, not the air flow rate at the opening of the air valve (to the atmosphere). The difference in flow rates is due to air density. You should be able to use the "mass" result in the table to determine the "free air" flow rate and thus velocity.

    As a result of the Service Request in question, I had made some additions to the following article in our Wiki:

    Modeling Reference - Air Valves

    See the sections "air flow rate calculation' and "Air valve types and attributes" > "General" > "Report Period".

    With that said, I see that we could improve HAMMER to make it easier for you to find this information. Therefore, Enhancement # 802517 has been filed for Product Management to consider adding the ability to directly report free-air flow rate and velocity. I have linked this Enhancement to your Service Request.


    Regards,

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

Reply
  • Hello Tom,

    With a number entered in the "report period" field of the air valve, you will see a table of extended results in the Transient Analysis Output Log. This report can be found under View > Transient Reports > Analysis Detailed Report. You will need to scroll near the bottom (and may need to search on the air valve label if needed). It will look like this:

    ** Air valve at node Air Valve**

    Time Volume Head Mass Air-Flow
    (s) (m3) (m) (kg) (cms)
    ---- ----- ----- ----- -----
    0.0000 0.000 150.57 0.0000 0.000
    0.1000 0.000 150.57 0.0000 0.000
    0.2000 0.000 150.57 0.0000 0.000
    0.3000 0.000 150.57 0.0000 0.000
    0.4000 0.000 150.57 0.0000 0.000
    ...

    The table in this report includes air flow rate, but per the response in the Service Request, it is the flow rate of air inside the pipeline, not the air flow rate at the opening of the air valve (to the atmosphere). The difference in flow rates is due to air density. You should be able to use the "mass" result in the table to determine the "free air" flow rate and thus velocity.

    As a result of the Service Request in question, I had made some additions to the following article in our Wiki:

    Modeling Reference - Air Valves

    See the sections "air flow rate calculation' and "Air valve types and attributes" > "General" > "Report Period".

    With that said, I see that we could improve HAMMER to make it easier for you to find this information. Therefore, Enhancement # 802517 has been filed for Product Management to consider adding the ability to directly report free-air flow rate and velocity. I have linked this Enhancement to your Service Request.


    Regards,

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

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