[tony00]

Hello,
I am modelling the 2D vertical axis wind turbine (VAWT). The turbulence model is k-epsilon with std wall function. I simulate 4 angular velocities: 5, 10, 15 and 20 rad/s. Wind velocity is 11 m/s. Model is using U-RANS with sliding mesh.
Problem is that I obtain excessively high torque calculated from the Cm (4 to 5 times larger than it should be). Cm is obtained from Fluent, torque calculated with the Cm definition(Cm=T/(0.5 x rho x v^2 x A x R).
Time step: tried both time steps corresponding to 1 degree and 1/8th degree. Results perfectly match so the 1deg step is fine enough.
I would be very grateful to the one who can spot if and/or where I am making a mistake and can contribute to making this simulation happen the best way.

Thanks
All the best
TonyMac

[bennn]

that might sound - and actually be - silly but check that you actually divided the torque by the appropriate value, to get a reduced coefficient instead of a Nm torque. That happened here not too long ago.

[tony00]

Hello Benoit,
all solved and getting pretty good results now. As you suggested it was indeed a problem with the constants entered in report-> reference values.
Thanks
Tony

[harishameed33]

Change fluent reference values

compute velocity form inlet
and change reference area to swept area
your cm will change
hope this work

[skshivas]

Originally Posted by tony00

Hello,
I am modelling the 2D vertical axis wind turbine (VAWT). The turbulence model is k-epsilon with std wall function. I simulate 4 angular velocities: 5, 10, 15 and 20 rad/s. Wind velocity is 11 m/s. Model is using U-RANS with sliding mesh.
Problem is that I obtain excessively high torque calculated from the Cm (4 to 5 times larger than it should be). Cm is obtained from Fluent, torque calculated with the Cm definition(Cm=T/(0.5 x rho x v^2 x A x R).
Time step: tried both time steps corresponding to 1 degree and 1/8th degree. Results perfectly match so the 1deg step is fine enough.
I would be very grateful to the one who can spot if and/or where I am making a mistake and can contribute to making this simulation happen the best way.

Thanks
All the best
TonyMac

Dear Tony,

I m also facing the same problem. still i m not able to reasolve the fluent case. please give some idea to predict the Torgue and Co efficient of the performance (Cp) of the wind Turbine.

With Regards

S.SIVAKUMAR

[esp-m1000]

Hi tony, maybe I'm affected by the same problem you solved.
I hope you will share with me your solution.

Thanks

[Poojitha]

In the Cm definition, what is A(area)?

[shahizare]

Originally Posted by harishameed33

Change fluent reference values

compute velocity form inlet
and change reference area to swept area
your cm will change
hope this work

what is the swept area in 2D model for vawt ?

[aalisha]

Originally Posted by skshivas

Dear Tony,

I m also facing the same problem. still i m not able to reasolve the fluent case. please give some idea to predict the Torgue and Co efficient of the performance (Cp) of the wind Turbine.

With Regards

S.SIVAKUMAR

Hey I am also facing the same problem. I am trying to change the values for the references. IF you can share how you have solved this problem? Thanks.

-Aalisha

[mshaheen]

For a 2D case should I take the area = 1, and in this case what should be the depth.

[nima2472]

hi
can anybody help me please
what is A and L in equation of CM blow:
cm=M/0.5*RHO*U^2*A*I
my case is a vertical axis wind turbine
archimedes spiral wind turbine blade

[danakalu]

Originally Posted by tony00

Hello Benoit,
all solved and getting pretty good results now. As you suggested it was indeed a problem with the constants entered in report-> reference values.
Thanks
Tony

can you please tell me the reference value that you have used.