[Michalina]

Hello!
I'm writting a master thesis about analysis of the Darrieus turbine.
I have done a steady state simulation with six wind velocities on the inlet (range 6-16 m/s) and one rotational speed. The solution has converged to a max residual of 1e-4 but I get an excessive torque value with velocity of 6 m/s and ridiculously low value for velocity of 16 m/s. I'm having my doubts on the physics setup, especially the boundary conditions.
The streamlines look reasonable and the rotor rotates in the correct direction. But efficiency for 6 m/s equals 160% (!!!), for 8 m/s - 60% and for 16 m/s - 4%. For nominal speed the efficiency seems correct (34% for this type of turbine).
I would be very grateful for any help.

[ghorrocks]

FAQ: http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F

[urosgrivc]

1- I suspect that torque is a function of (angle of rotation) in this case, if it is, you will need to average out at least 120° of rotation (3blades).
-> transient or menymeny steady states with angle parameter come to mind.
so yes I think physics setup is wrong.
2- Mesh is nowhere to be seen.

This could be done in 2D, that way you would be able to reduce the mesh size and run transient as it is probably computationaly wery demanding, I hope you hawe some hardware to back up a problem like this in 3D.

[Ajinkya Patil]

I am working on a project that on hybrid sovonius Darius vawt please give me some guidelines.

[urosgrivc]

More information is neded, geometry? do blades move or not? ...
It is not posible to give an ansver to no question.

Look at the pdf file in (post1), the geometry shoved here is ok but the phenomena is transient so it is not possible to get results from one static flow analysis (post3).

It is even posible to simulate this as an imersed solid so rotation is actualy induced by moment caused by the wind.
for this you need to know inertia of the rotor and some loses due to friction in bearings and other

[Ajinkya Patil]

I am designing for 1kw power and analysis it. So for that what are basic procedure to design it ?
It will be very helpful if you give guidelines for me.
Thank you.

[urosgrivc]

Parametric design comes to mind, but it is not that straight forward as you must have some specific parameters I am not aware of.
Or maybe if the geometry is constant with length (power/length) can be obtained so you can than detemine how "tall" it must be to suply that 1kw and at what flow speeds.
So I am sory but this would take to much of my time and I can not help you with the design. Maybe someone else that already has a similar design can help
But maybe when you have a basic design we can discus about a CFD simulation in cfx here in this thread.

[Ajinkya Patil]

Where I gate the basic design

[urosgrivc]

Google is probably a good way to start as a lot of designs were alredy done and tested, there is a lot of papers on this topic.