[bahieu]

Hi everyone,

I am a Master student. Now I have some problem with my VAWT verification for this paper "2D CFD Modeling of H-Darrieus Wind Turbines Using a Transition Turbulence Model"
http://www.sciencedirect.com/science...76610214000162

I using sliding mesh method, SST k-omega turbulence model.
Total number of grid is 180,000. Y+<1
However, the results show a big difference with the reference.

Here is some Figure of my mesh and the results.
If anyone have any experience of suggestion, please help me
Thank you!

[fluid23]

I suspect that your sliding mesh is not allowing for a realistic flow condition to exist. I encountered something like this many years ago using what was at the time called CFDesign. It turned out that having this huge disk of rotating mesh was essentially dragging the air around with the turbine in a way that didn't actually represent any real flow condition. Granted that software was fairly limited compared to Star-CCM.

Looking at the paper you posted, I wonder if you aren't seeing the same kind of issue. I see that their rotating mesh region is a donut shape and not a full disk. Try a setup similar to this and see if you don't get better results.

[bahieu]

Thanks, Mr. Matt

I have tried the mesh as your suggestion. But, the results is similar.

[arashfluid]

Hi friends,
I have simulated the 2D Darrieus wind turbine by pimpleDyMFoam.
To calculate the forces and moments coefficients for every blade I have added similar code in controlDict file, but I'm not sure about lRef and Aref in VAWT;
I've seen them with different definitions in different references.How could I calculate their correct values?

forceCoeffs1
{
type forceCoeffs;
enabled true;
functionObjectLibs ("libforces.so");
patches ("airfoil1");
pName p;
UName U;
rhoName rhoInf;
rhoInf 1.225;
CofR (0 0 0);
liftDir (0 1 0);
dragDir (1 0 0);
pitchAxis (0 0 1);
magUInf 5.0; //wind speed
lRef 1.0; //rotor length or chord?
Aref 2.0; //rotor length* rotor diameter or chord*rotor length?
outputControl timeStep;
outputInterval 10;
}

I want to extract moment instead of momnet coefficients as much as possible, because I can directly calculate the cp. But data do not store in a regular basis.
I want a suggestion for saving moments data regularly and extraction torque curve over time.


Thanks a lot,
Best regards,
Arash.

[Lprince]

I'm working on the same paper facing the same problem as TSR increases the power coefficient increases .. although I followed this paper step by step ..

[Ahmed attar]

Any luck to solve this problem
I am working on 2d vawt simulation and having the same problem as the tsr increases the cp increases

[usr0830]

Hello,
I am performing 2D VAWT simulations on Openfoam with a setup similar to the one mentioned in 2D CFD Modeling of H-Darrieus Wind Turbines using a Transition Turbulence Model. I face the same issue with the Cp values continuously increasing with increasing TSR. If anybody has solved the same issue, could you please give me some suggestions.

Thank you.