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Determining the occurrence time for max and min transient pressure at all nodes

I have carried out transient simulation for an irrigation network. Based on client requirement, I want the occurrence time of the maximum and minimum transient pressures at all junctions. How can we extract this information that at what instant/time we encounter the maximum transient pressure and the minimum transient pressure at every node/junction. Please help.

  • Hello,

    The time that the maximum or minimum pressure occurs usually isn't as important as the extent of the maximum or minimum value, so this is not something HAMMER currently reports. You could certainly find this looking at a time history graph, but typically it is less the timing of the pressure surge or negative pressure, but that it happens at all.

    You can pretty quickly view the maximum and minimum pressures and hydraulic grades either in element flextables, where you can include results for the minimum and maximum transient results, or in the Transient Calculation Summary. The Transient Calculation Summary is generated after computing and available by going to Home > Calculation > Transient Summary. There is a tab for the Extreme Pressure and Head.

    Is there a reason that the timing of the maximum and minimum pressure is important? Something occurring 10 seconds into a simulation versus 15 seconds into a simulation seems to be relatively minor compared to the extent of the pressure results.

    Regards,

    Scott

  • Hello Akash,

    Can you elaborate on the importance of "time" for the maximum and minimum pressures? Typically when conducting a transient analysis, the maximum and minimum pressure values are enough to get a fair idea of the range of pressures your system is subjected to in a transient event. For a hydraulic modeler the next step would be to use effective surge protection equipment to counter these extreme pressures.

    Is this timing related to some valve operation or opening or closing of pipes to control transients?

    Ideally you would try different combinations of surge protection equipment and test the system for the effectiveness in controlling transients. You can view results for multiple scenarios in such cases to get a better understanding.


    Regards,

    Yashodhan Joshi

  • Hello Scott and Yashodhan,

    The transient analysis is done for pump shut down case and we have also provided surge protection devices to limit the transient pressures to the allowable pressures. However, the additional requirement to know the occurence time for the maximum and minimum pressures is being asked by the client for information purpose.

    In one of the previous commenced project, there were few issues observed at site during surge events and client was not very confident of the surge analysis and the protection devices we had proposed then. Therefore, client has asked us to provide the time of occurence for additional verification and further review at site. Hence, in view of the above, would request you to help us with a methodology to record the occurence time for maximum and minimum pressures at all junctions.

  • Hello,

    The time of minimum or maximum pressure is not reported at this time. However, profile animations and time history graphs can document when these peaks can occur. You can include time history graphs in custom reports, which will make it relatively easy for the client to see when the peak would occur in graphical form. 

    Otherwise, you could pull that data from the time history graphs to be included in a document. If there are a lot of nodes, this may be cumbersome, however you could also just include key areas in the model.

    Regards,

    Scott Kampa

    Bentley Technical Support