Comments, Questions, and Answers related to AutoPIPE's "Fluid Transient" Dialog screen
Pressing OK button closes the dialog and the following report is displayed about the transient. This file is saved in the same folder as the model (example: W1.THL):
In addition, the fluid transient utility automatically creates the relevant force-time histories (*.TIH) and can handle either a positive or negative shock wave at each point listed in the *.THL file, see example below (W1C01N.TIH):
Note:
1. TIH files are always in English units regardless of the Model units file specified on the General Options dialog screen. To see the unit conversion factor used, open the respective Units file (ex. SI.UNT) in any text editor (i.e. Notepad), and locate "Force" in the right column, read to the left for the factor conversion value to English units. See the following WIKI here for more details.
2. The transient path can traverse different segments as long as it is continuous (end point of previous range of the 1st segment should be the beginning point of the next range of the 2nd segment). The program will block ranges when the defined beginning point is not on the same segment of the end of the previous range.
3. Although the fluid transient utility is limited to a single transient path (with no branches), the user can specify branches as separate transients with different start times. This is not necessarily an accurate representation, since attenuation and reflections are ignored. The user can specify a new transient that starts when the first one ends.
4. Cannot evaluate the fluid cavitation due to the negative pressure rise.
5. Cannot evaluate attenuation effects of the reflective shock wave
6. Limited to any type of non-compressible fluid and steam
7. Limited to one shock wave transient although can simulate multiple shock waves converging
8. 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.
See the following WIKI page that address questions about this particular example.
Item #1: How do I accommodate 240 secs for time for Fluid Transient to reach full load in AutoPIPE?
Item #2: How does AutoPIPE account for the surge pressure pressure based on slow valve closure time in a Fluid Transient?
Item #3: Is it possible to perform a time history analysis on imposed support displacement movements in AutoPIPE?
Item #4: Could you possibly explain what output we are seeing when we look at the results from a force time history analyses in AutoPIPE?
Item #5: Does rotating the model after performing a Fluid transient analysis affect AutoPIPE's results?
Item #6: Why should the flow rate be positive or negative in AutoPIPE Fluid transient?
Item #7: What are the Fluid Transient load case assumptions in AutoPIPE?
Item #8: Should the fluid transient use Linear or Sine rise in AutoPIPE analysis?
Item #9: What are the criterion for generating a forcing function (i.e. new TIH file) at a point along the fluid transient path?
Item #10: How to define a Reflected Transient in AutoPIPE?
Item #11: Why are Fluid transient loads different from other programs?
Item #12: Can all 3 transient profiles be started at the same time in Fluid transient module?