Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: N/A Area: Subarea: Original Author: Bentley Technical Support Group Comments, Questions, and Answers related to AutoPIPE's "Fluid Transient" Dialog screen Note: There is a complete Fluid transient (Water Hammer) tutorial and model example with complete details on the calculations performed by the program, etc.., please see the following AutoPIPE help section for details: Help Contents Contents Tab Modeling Approaches Water Hammer (Time History) Example Item #1: How do I accommodate 240 secs into the assessment. When the dialogue box in AutoPIPE for fluid transient loads is opened, the rise time is described as typically, the valve open/closure time. So can you confirm that me entering 240 seconds in this field is correct? Answer: As mentioned in the online help: This is the time it takes the pressure wave of the transient to reach the peak value. This value is typically the valve or pump closure/opening time. Therefore, if your system takes 240 sec for the valve to close and the the pressure to reach peak pressure, then yes, Rise time = 240 Sec. Item #2: What I notice in running a fluid transient analysis, as described in the Example tutorial mentioned above, that extending the rise time, these loads / displacements are reduced, however, the surge pressure remains constant. I assume that for pressure rise alone, AutoPIPE does not account for the slow valve closure. BUT, for pipe displacements / loads at anchors bends etc. AutoPIPE does account for this slow closure time?? This is fundamental in my analysis so need to be sure I am on the right track . I see extending the time on this rise input massively reduces forces, but the pressure is the same, please confirm. Answer: After assign the value on the "Fluid Transient" dialog, pressing the OK button displays a report about the transient. This report clearly shows an inverse proportion between Rise time and Force due to the transient; i.e. as the rise time for peak pressure increase the force due to the fluid transient decreases. However, remember the same peak pressures are reached, It still takes the Fluid transient a finite amount of time to cover a fixed length of piping from start to end of the transient path specified, etc.. Recommend to review the "Water Hammer (Time History) Example" mentioned at the top of the page, calculation section to understand how the rise time affects only the force of the transient and nothing else. See Also Bentley AutoPIPE External Links Bentley Technical Support KnowledgeBase Bentley LEARN Server Comments or Corrections? Bentley's Technical Support Group requests that you please submit any comments you have on this Wiki article to the "Comments" area below. THANK YOU!
↧