Dear Bentley Team,
I would like to ask about Water Hammer analysis, as I have design a Water Supply system on Gravity and there is no change of velocity. But I have to perform hammer analysis. Should I perform Hammer analysis considering rapid valve closure. I have performed valve closure analysis but not sure about results
Thanks & Regards,
Syed Ahmed.
Please note that a subsequent reply to this thread has been split to a new thread here: Values for pressure wave and time step interval
Regards,
Sushma Choure
Bentley Technical Suppport
Thanks Scott for helping me out. I was stuck and confused in this simulation but now got my results.
Thanks and Regards,
Syed
Hello Syed,
Using the TCV should work fine. The issue is the length of time you are computing the model. You are currently using "Time Steps" as the Run Duration Type, with a setting of 240 time steps. At the Time Step Interval you are using, this is only about 14 seconds. Since the model takes 90 seconds to fully close (and longer to reopen), this short run time is not sufficient to see the impact of the valve closure
Set the Run Duration Type to "Time" and set the value to a sufficient value. I tested this at 100 seconds, and saw the flow and velocity drop to zero in that time. Running it for longer (like 240 seconds) should pick up on the valve reopening as well. You will want to run the model long enough to see the impact of the transient event and for the system to reach a new equilibrium. This link has more information: What should the run duration of a HAMMER model be set to?
Scott
Answer Verified By: Sushma Choure
Thanks Sushma,
I am using TCV, Please suggest me valve type. I have uploaded my model for your review. I have performed same Modelling Reference - Valve Closure.
Which type valve is it for which you are modeling valve closure, is it TCV or other, please specify.
If it is a gravity system still you can model valve closure transient simulation by setting the operating rule for the valve in transient properties. Here is detailed information on that for your reference. You can model both scenarios with rapid valve closure and slow valve closure.
There is a sample model on valve closure which you can refer, C:\Program Files (x86)\Bentley\HAMMER\Samples - Valve_Closure_Example.
Modeling Reference - Valve Closure
To understand the valve closure results and its effects on the model elements, you can create a profile of that route and see the transient results viewer to see if there is any vapor formation which you need to tackle.
Using Transient Results Viewer animations for visualizing a transient simulation
If required you may upload model files for our review.