Learning Forum

[Akshay1993]

Hello friends,

i have a doubt regarding power generation in wind turbine. i have calculated the moment in y axis as my rotor also rotors along y axis.but the moment is way too small. i am getting correct thrust force but i am not able to understand why my moment value is in correct. My wind turbine blade is 64.5m and i am calculating at 10m/sec inlet velocity and and at -11.357 rpm. i am comparing between spalart and k-e realizable models. Please help me guys because i need to submit my work.   

[Keyur Kanade]

please check following. 

https://www.youtube.com/watch?v=b9obQ6FUj5E

if this helps you, please mark this post as 'is solution' to help others on forum. 

[Akshay1993]

 thanks a lot, but i have seen this video, i am applying right procedure for finding moment but i am getting huge difference between the values i get through ansys and theoretical values . usually for horizontal wind turbine the power coefficient should be between 0.35-0.45. but  i am getting 0.22. please help me out.   

[raul.raghav]

A quick calculation shows that your tip speed ratio (TSR) is ~7.7 and the power coefficient should definitely be greater than what you're getting.
Could you post a few pictures of your mesh, setup and some of the important results

[Akshay1993]

Yes you are right Raul. The below diagram is my domain. The name selections are as follows.The inlet is from left and outlet is at right. Outer wall is enclosure. for rotor i have given interface-in, interface -enclosure, interface-out and blades. My orthogonal quality is 0.046 and skewness is shown in below diagram. i have created inflation layer with first cell height 0.01m. Done face sizing of  0.3m and edge sizing of 0.13m.

My doubt in this post is, i need to calculate moment of the blade. When i am calculating only with respect to blade my cp value is 0.22. But when i am calculating with walls i am getting cp value around 0.48. And other important point, i have noticed these walls are not shown in display. can you guys tell me which procedure is correct. These walls are appearing when i am giving the name-selection for the rotor.

 

[raul.raghav]

Can you show the wall-17,18,19 & 20 regions in the schematic? 

[Akshay1993]

Those regions are invisible, i am not able to detect those regions.

[Akshay1993]

[raul.raghav]

Can you expand the geometry and also show us the mesh?

[Akshay1993]

[Akshay1993]

In beginning the element size was 71 and i changed to 56m.

 

[raul.raghav]

You need to have a conformal mesh in order to avoid the walls being automatically generated.

If you used Design Modeler: you need to select the two bodies and RMB to Form a New Part.

If you used Spaceclaim: you need to Share Topology to ensure you obtain a conformal mesh.

Let us know if you have questions regarding that.

[Akshay1993]

i have used sliding mesh technique, and i have followed many videos from youtube and videos posted from cornell univeristy.  Is there any other method to resolve this issue because i have almost completed my work using spalart and kepsilon models. And i have performed the simulation using 2 million cells. it will be difficult for me to start the work again.

[raul.raghav]

Akshay, it was just a suggestion to avoid the empty walls being generated.

Would you be able to attach your workbench archive file (.wbpz) so I could take a quick look at it? Please follow these directions to upload a .wbpz file.

Can you provide a screenshot of your Mesh Interfaces panel? Did you manually define the mesh interfaces?

[Akshay1993]

 my file

 

[Akshay1993]

yes i defined the mesh interfaces manually

 

[Akshay1993]

Raul did you get my file??

 

[raul.raghav]

Akshay, I did and I'm looking into it now. I'll get back to you soon.

[Akshay1993]

tq Raghav

 

[raul.raghav]

Akshay, I looked into your files and I don't see any problems in the setup. The results don't match up with the expected values even on refining the mesh. What airfoil is the turbine composed of?

[Akshay1993]

It is DOWEC 6 MW wind turbine. it has  5 DU and 1 NACA Airfoil. you can find all the values from the book https://www.researchgate.net/publication/265038104_Aeroelastic_Modelling_of_the_LMH64-5_Blade

 

[Akshay1993]

Raghav when you performed the mesh operation with refinement, what was the quality you achieved. and what was your meshing procedure. can you share the pics. Have you got any answers regarding my problem ???

 

[Akshay1993]

Raghav ?? 

[Akshay1993]

i think raghav is not answering can any one of you help me i solving this problem