[ghp]

hi, im currently doing analysis on elbow pipe when applying fluid flow into it. So, what kind of analysis system should i use? fluent or structural?

[Steffen595]

fluent and check the forces on the walls? Or do you look for deformations? Suppose the total pressure has a bigger influence. This can be done in structural. Influence of the working pressure is bigger than that of the pressure drop in the elbow.

[ghp]

i would like to analyses the formation of pipe.
when i apply fluid and the fluid hit on the elbow pipe, i would like to found out the effect of fluid on the elbow pipe..

[Steffen595]

what is the elbow made of? I think there is something in Ansys where the geometry of the fluid domain can change. But again, in most cases the static/system pressure has a bigger influence than the flow/pressure drop

[ghp]

carbon steel...do you mean apply hydrostatic force?

[Steffen595]

yes. I did some flow simulation on elbows recently, for 8kg gas per second only 5000 Pa pressure drop. But the hydrostatic pressure is 250 000 Pa. So the pressure drop does not really matter for the wall thickness.

[ghp]

can screenshot or email me?

[Steffen595]

[Steffen595]

normal elbow, welded on reducer, piece of pipe. 250kPa inlet, 18kg R134a mass flow

you should not put your email address in here, better send as private message

[ghp]

thanks for your remind..ur analysis system in static structural?and your elbow pipe in solid or hollow with cap?

[Steffen595]

its done in CFX. Its the volume of the gas. Then in the post processor you can display all sorts of things, velocity, pressure, density, force...
Maybe you can do 2 domains, one is the fluid, the other the elbow. Then calculate the fluid and see what the elbow does?
Depends really what you want to do. If its a really thin walled elbow the different forces make a difference, but for ours they don't, the pressure is enough. I did the calculations for different shapes to see which has the smallest pressure drop.

[ghp]

alright..i will try it again...thx for ur suggestion xD

[wobo]

Originally Posted by Steffen595

hi,
Can you please verify whether your elbow modelled using ansys as i have been struggling to model elbows on ansys workbench. thanks

[Steffen595]

no, its done in some other software and then exported as .igs
modeling in Ansys is not much fun

[wobo]

the reason i asked is because i tried to model 45 degree bends using solidworks and the profile of the bend doesnt sweep properly. also can you please confirm what boubdary conditions you applied on your model? thanks

[Steffen595]

-the profile should sweep properly. Make sure, the profile plane of the sketch plane is normal to the sweep sketch. And the radius of the sweep should be bigger than the radius of the profile.

-the boundary conditions
are Domain R134a real gas Redlich-Kwong, at 7 Celsius and 250kPa gage
-inlet 0 MPa
-outlet 7.9kg/s mass flow

Make sure, you put some straight run before and after the bend, so the flow can establish. Otherwise you may end up with fluid trying to leave the domain on the inlet and your results are messy.

[Amin50]

hi,
i need a reply ASAP. i have ran my fluent simulation for Ansys15. My project is to simulate the elbow pipe.During the setup, i need to insert the heat flux into the certain part at the elbow pipe.The problem is, my results did not match with the expectation values. The temperature are expected to get only below than 70 celcius, but i've got around 2300 celcius. Can u help me sir?

[Steffen595]

sorry, I did not calculate heat flux yet.
Did you give proper units? Proper flow rate? Check the heat capacity of the material.

[Amin50]

hi steffen,
tq for your reply ..the value of heat flux is 8500w/m2.The area of pipe received the heat flux is 0.078m2. i didnt change any flow rate. In the boundry condition,at the pipe outlet, i've change from outlet pressure into outflow.

[Amin50]

hgg.jpg
cedcedc.jpg



the images are for the velocity and temperature inside the pipe