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-   -   Wind turbine simulation problem (http://www.cfd-online.com/Forums/star-ccm/97060-wind-turbine-simulation-problem.html)

sanchovg2 February 8, 2012 04:19

Wind turbine simulation problem
 
5 Attachment(s)
in the velocity vector plot i dont see the vortices that are supposed to be generetad by the fluid flow after a body.the stream lines are a representation with lines of this vortices.isnt it? or im wrong :s ?
I design myself a wind turbine in pro e with some data and studies i found on the internet.the wind velocity is 10 m/s and the rpm are 22.5
So what i did was to put the velocity with a normal velocity inlet and the rotation i did it over the reference frames and the gave rpm.
I extracted the turbine from a small circular volumen and then this one from a bigger fluid area. i connected the circular volumen and the fluid volumen with 2 interfaces.
the first one the circular front/back is an In place-FAN interface and the second one is the other area and i did it with an In plane-Baffle Interface. Then i said that the turbine region should have an tagential velocity specification method: none and reference frame absolut. im not sure if it works this way for the rotion and the flow from wind.
the physics models that im using: 3D,Steady,Ideal Gas,Segregated flow,turbulent,K-epsilon T. and im runing another simulation with Stadard Spalart-Allmaras (eddie). but im not to familiarized with this turbulenz modell.
can somebody help me to interpreted this plots i got.i think i have some trouble with the MRF or with the interfaces :s
as it where complete separeted from the flow area. no effect from the wind turbine. the wind velocity doesn't changes the value after going through the turbine.is it possible to make that happen?
the last pic is how it shoul look like
i also wanted to ask something like this is possible with star ccm+
http://www.youtube.com/watch?v=nj_iL8PXOD8

sanchovg2 February 8, 2012 07:41

1 Attachment(s)
so i was still working on the turbine and came with the idea to make a velocity plot from the blades.and i do have a problem with the MRF or the Interfaces. because i se the rotion velocity values after the blades but not before. the fluid velocity is 0.
how can i fix this?

abdul099 February 18, 2012 07:58

Not sure what you did at all, but for me it seems like the basic setup is wrong.

For simulating a wind turbine, you neither need a baffle interface nor a fan interface. (The baffle at the perimeter face is not that critical, but the fan interface is just WRONG, it needs to be an in-place internal interface).

When you want to see any effects due to rotation of the turbine, you need to apply the moving reference frame to the region instead of the absolute reference frame.

What diameter does your turbine has? So which velocity do you expect at the blade tips? Do you really need a ideal gas model?

Regarding the streamlines: Sorry I didn't understand your explanation what you think what streamlines are.
Streamlines are just lines following some vector (e.g. the velocity field) field through the domain. A lot of people mix it up with particle tracks, but this is NOT the same.

Regarding the video in the provided link: Yes, it's possible to do that with Star-CCM+, but I recommend first to fix your current problems before doing the next step. It's not that hard to enhance your model when you've got a working setup.

sanchovg2 February 20, 2012 03:58

thank you very much abdul.
as i wrote that i was starting to use star ccm+ and i was working with some tutorials so i dint knew more. now im so far already did a RFM that runned pretty well i changed the interfaces for inplace. and now im trying to make it work with MRF. but im having some trouble choosing the right time step i think, because the turbine rotated just 25 deg by 180 iterations or should i just leave it run longer? i choosed a time step 0.05s and a maximum inner it. 5 and maximum physical time 2s. im just trying some values but i dont know exactly how i should choose this values.i was also wondering if i can do a velocity and pressure plot where i can see the usally velocity fall and the pressure rising in X?
For now im just simulating a small prototype just to see how star ccm+ works and the later apply it for other real dimensions.
about the video it would be cool if you can help me with this,would be really nice to show it to my proffesor.

husker February 20, 2012 13:03

Can anyone please tell me how XFLOW works without meshing?

husker February 20, 2012 13:10

I asked this question because of the XFLOW video which sanchovg2 posted.

sanchovg2 February 21, 2012 03:19

sorry husker but i dont know the program

sanchovg2 March 2, 2012 04:58

hey abdul, so im so far the simulation is rotating i have choosen a good time step and results are also ok. but regarding to the video i was hopping that you could help me through this.
thank you

abdul099 March 4, 2012 14:54

Just define a scene and save a picture for every time step. Put it together to a video file with an external program.

mulkanindonesia May 21, 2012 13:29

water current turbin simulation problem
 
1 Attachment(s)
i have a problem with my simulation, the contour of velocity is high,, whereas the velocity inlet only 1 m/s. and from experiment data i get the RPM 72 . please tell me where is my fault.
i design the turbine in gambit , the blade inside the volumen (tube) that i subtract. and then the subtracted tube by blade i put into the brick volume. and then i split that volume ( brick into a tube).. and the face that become interface between volume of turbe inside brick , i initialized as wall ( in fluent i changed it as interrior)

in fluent i used MRF rotational with include the RPM value (72) in cell zone fluid in tube. and stationary in fluid brick. boundary condition i set moving wall in wall blade ..
here is itthe result:eek::cool:

saleh alsubari August 7, 2012 01:48

hi.
i'm new to star ccm+ and i have a task to simulate turbine using star-ccm+ and find its RPM and the associated torque ,so i did use MRF but i need to find RPM first ,really lost ..any one can help .thnx

saleh alsubari August 7, 2012 01:50

if any one has a video ,about how to simulate the turbine or even fan, will be delighted


thanx

wangguobin14 March 5, 2013 04:18

them just xflow with meshless,that does not mean without mesh,we could say that xflow is a solver process take no care about the process of griding.yaya


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