[Polo23]

Hi guys,

As many of you I'm doing my final degree project on VAWT. Mine is a 3-bladed 2.5 radius turbine, using the NACA 0012 airfoil.

I have been facing some mistakes for so long and I can't find a way to solve them, that's the reason why I've decided to ask for help. I know reading a post this long is tiring so I really thank you in advance.

I first run a steady simulation in order to use it as an initial solution for the transient case. I use 10 m/s for the inlet velocity.

Then I move to the transient case, using the mesh motion with 4 rad/s. I use a time step of 0.0043611 (1º). But I can't get to have positive values for the cm. At first I only got negative ones, then I restarted the geometry and the mesh and eventually got both positive and negative values, but very low ones. I think the problem should be in the setup, so I'm posting it here to see if anyone sees something wrong.

-For turbulence I use the sst model (4 eqn)
-For the reference values, I set area as the diameter and length as the radius (all the others as default, computed from inlet)
-In the transient case i use PISO as the pressure-velocity coupling (simple in steady), and presto for pressure (standard in steady), all the others I leave them as first order.

I also attach some pictures of the mesh just in case they were needed.

https://dl.dropboxusercontent.com/u/...2014.01.32.png

https://dl.dropboxusercontent.com/u/...2014.01.02.png



Thank you very much for your help.

Pol.