garage19
|
| posted on 30/5/08 at 04:14 PM |
|
|
Anyone with CFD experience? I have a Q.
I have got a copy of solidworks 07 which comes with COSMOS express. This is a limited version of their full CFD package.
Now i ran a test on an inlet manifold and the rsults it shows me are in m/s. It will only show me air velocity not flow.
My question is how closely are veocity and actual flow related. The full package will show me velocity, flow and pressure through the vessel.
|
|
|
|
|
ed_crouch
|
| posted on 30/5/08 at 04:29 PM |
|
|
Tricky.
I guess it gives you a velocity profile from the wall to the middle of the section?
you can mathematically slice the section up into concentric onion rings, calculate the cross sectional (i.e. perdendicular to flow) area of each. Then
you can use the velocity info to work out what volumetric flow rate is. Then, if you have pressure data, you can calculate the density of the air at
that point and calculate mass flow rate. Do all this for each onion ring, then add the flow rates up to give total flow.
This all assumes laminar flow conditions, i.e. no turbulence, Reynolds number of less than 500,000 IIRC. I dont know if the cut down CFD package would
give you that info.
HTH.
Ed.
[Edited on 30/5/08 by ed_crouch]
I-iii-iii-iii-ts ME!
Hurrah.
www.wings-and-wheels.net
|
|
|
D Beddows
|
| posted on 30/5/08 at 10:26 PM |
|
|
Yes, my degree dissertation was all about CFD... This is like FEA though in that it's a serious case of knowing enough to know what what the
question is you're asking and how to ask it before you ask it or you're just wasting your time - and you need to know the theory behind
it before you know what question you need to ask....... sound negative? yup, guilty but comos express is a toy that'll give you pretty pictures
but not much else.
Why do people think engineering is soooo easy - I did 4 years averaging 25 hours a week of lectures to get my degree and I knew nothing really at the
end of it apart from how little I knew 
|
|
|
ettore bugatti
|
| posted on 3/6/08 at 08:17 PM |
|
|
I heard that it is important to have equal lenght flow lines to every runner.
There are some interesting literature on the web
|
|
|
Alan B
|
| posted on 4/6/08 at 10:58 PM |
|
|
quote:
Originally posted by D Beddows
......Why do people think engineering is soooo easy......
I hear you.
I think it's because to some extent you can see it and touch it......in my experience electrical and software guys are the worse...seem to think
that mech. engineering is a doddle and will implement mechanical changes that are very ill advised.
Usual the mechanical guys will end up getting them out of trouble.
Oh well.....
|
|
|
martyn_16v
|
| posted on 5/6/08 at 08:35 AM |
|
|
quote:
Originally posted by Alan B
in my experience electrical and software guys are the worse...seem to think that mech. engineering is a doddle
Well it is isn't it? What's so difficult about big chunks of metal? You should try electron herding, fiddly little buggers let me tell
you. Don't get me started on civil engineers/concrete jockeys 'make it like it looks strong enough then add 4 more tons of hardcore'
|
|
|
