Hi all,
I'm new to Autopipe here so excuse me if it's a dumb question!
What's the best way to model thrust via a flowing fluid on Autopipe (Ie the impulse-momentum change equation if I was to do it manually)?
I see a lot of mention of pressure thrust only, but I'm struggling to find out how I'd model the thrust due to the fluid rapidly changing direction (ie at a 90 degree bend).
Greetings,
Thank you for choosing to use AutoPIPE!
As a new user, please take the time to review this WIKI here. There is a ton of excellent material available for both inexperienced and seasoned users. Therefore, it is advised to evaluate each hyperlink on these pages and, if it relates to a modeling method in AutoPIPE help, to actually do the help tasks rather than just reading about them.
To answer your question, I believe you are talking about modeling a Water Hammer load:
1. Select the WIKI link above
2. Read about all of the offerings available on this page, be sure to go back later and thoroughly explore this section, for your issue, select the hyperlink for "Available Tutorial - Training - Distance Learning - etc... options with Bentley AutoPIPE"
3. Again, read about all of the offerings available on this page and then under "AutoPIPE Help" section, select the hyperlink at the bottom, "Click here for more information"
4. This page exposes you to the vast amount of information on modeling approaches available in AutoPIPE. Since your issue is related to loading, see "Modeling approaches: Loading on pipe" and open this help area in AutoPIPE.
5. Take the time to read and actually perform the Water Hammer Time history example located under "Executing Water Hammer Example (apham1)".
After reading and performing this example a few times, you should be able to simulate your water hammer load in your model.
Regards, Mike Dattilio Design Analysis Engineering Group Senior Analyst Bentley Systems Inc=============================================================================
Hi Mike,
Thank you for taking the time to respond, much appreciated. Thanks for the advice, I have begun/just completed the tutorial document which i downloaded from the application somewhere (that one was more static conditions) I will take a look at the rest, however, at an initial glance I'd say water hammer isn't what I'm after. I'm not looking for an instantaneous load/pressure spike, it would be continuous as the pipe flows under normal operation. It's more the thrust force you would want to consider at the bends, tees etc if you had a low pressure but high velocity flow through a pipe (although technically it would be present in all cases, it may just become negligible at high pressure low flow). Engineering toolbox discusses the velocity component of thrust here
www-engineeringtoolbox-com.cdn.ampproject.org/.../forces-pipe-bends-d_968.html Or another example would be shown in the derivation from first principles on youtube here which considers thrust from both pressure and velocity in one formula https://youtu.be/1RKz3P7vBXY Hopefully this clarifies what I'm looking for? Kind regards, Ryan
Hi Ryan,
In this case (steady state) you have to manually add calculated forces along each segment/pipeline. You are right that these forces usually are neglectable, however in some cases, like hanging pipelines or large diameter pipelines it is worth considering.
Best regards,
Maciej Rydlewicz, PhD Eng.
maciej.rydlewicz@softdesk.pl
+48 512206994
Answer Verified By: Mike Dattilio
Thank you Maciej, I suspected that might be the case. Fingers crossed for an update in future then!
I have posted a new WIKI per this forum post. See WKI here, section 4