Dear Bentley Team,
We have done one surge calculation with Pump trip case (Shut down after time delay), in this case, Max transient pressures showing in Hydro-pneumatic flex table (showing 1.06 bars) is very less value compared to the value showing on the flex pipe table (5.83 bars). Please refer attached screenshots taken from Hammer.
Could you please tell me why this difference is showing, Max transient pressures should be same in both the tables.
Thank you
Hello Jayakanthan,
The results you are seeing are for different elements. The pipe flex table shows you results for pipe elements whereas the hydropneumatic tank table shows the results for hydropneumatic tanks. In pipe flex table the values for maximum and minimum transient pressures are that for the pipeline from Surge Vessel-1 to J-12 and not the transient pressures at the hydropneumatic tank "Surge Vessel-1".
See the "Transient Results Viewer" to see transient results for a better understanding of your results. This is done by "animating the profile" to observe fluctuations in pressures and air volume. You can also see extended results such as pump speed for pumps and gas volume for hydropneumatic tanks. See the article below for details;
Using Transient Results Viewer animations for visualizing a transient simulation
Let me know if this helps.
Regards,
Yashodhan Joshi
Thank you for your reply,
but still, pipe line max transient pressure (Surge Vessel-1 to J-12) is 5.83 bars where as this line is only connected surge vessel & max transient pressure of the surge vessel is showing 1.06 bars only. if there is a small difference then we can understand, but here difference between line & surge vessel is 4.77 bars.
Request you to check & provide the resolution.
Thank you.
I am using Hammer-10.03.01.08
Yes, it changed to zero & verified, still only min transient pressure is matching with pipe table value, where as max trasient pressure is not matching with pipe table value.
transient pressure related to pipe lines only, why this is included in surge vessel table as well, Normally Gas volume & gas pressure are the two parameters define the performance of the surge vessel. In this case why max transient pressure & Min transient pressure in the vessel is important
And one more thing why gas volume & gas pressure graphs are straight lines, there should be a fluctuations, but these graphs are showing straight line, why it is so
Thanks for the screenshot - you may be encountering a known issue that can happen if you do not enter a value for the Report Period field in the properties of the tank. See: Hydropneumatic tank Extended Node Data graph shows linear continuous increase
Jesse DringoliTechnical Support Manager, OpenFlowsBentley Communities Site AdministratorBentley Systems, Inc.
Thank you for your reply, second point related to vessel gas pressure & volume is clear, but still software updation required for this.
and please provide the resolution for my first point :
"Yes, it changed to zero & verified, still only min transient pressure is matching with pipe table value, where as max trasient pressure is not matching with pipe table value.
transient pressure related to pipe lines only, why this is included in surge vessel table as well, Normally Gas volume & gas pressure are the two parameters define the performance of the surge vessel. In this case why max transient pressure & Min transient pressure in the vessel is important "
I shared software file as per option-2. File name is :Simulation files.rar
As far as your gas volume & gas pressure graphs coming as straight lines; this is because you have not set the Report Period in the hydropneumatic tank properties. I set the Report Period to 10 and was able to the graph curved and not a straight line.
Please go through the article that Jesse shared in the earlier response on rectifying this.
As for your query on why the hydropneumatic tank maximum transient pressure is not matching up with the maximum transient pressure for the connected pipe; it is not always true that these values should be the same. See the image below for reference;
In the above image, I have used the Transient Thematic Viewer to map maximum transient pressures in the system. You can see that the maximum transient pressure in the pipe P-472 is at the downstream side at the node J-12 which is due to the connecting pipeline from your pumps. The maximum transient pressure in the pipe is the "maximum transient pressure at any point in the pipeline". The pressure in the pipe P-472 is within the range of pressures at the hydropneumatic tank.
Ok, 1st point is clear, but it is better to update this point in next version of in the software, we may forget to enter report period as we are not entering this report time for any of other equipment in Hammer because default it is showing zero.
Second point is also clear and i hope there is no error in calculation.
All points are closed, thank you & your all team members for sparing your valuable time & providing quick response.