Windmilling with FINE/Turbo
 

Salut,

I am student who is working on Windmilling, where the rotor blade of a compressor is in a freewheeling mode. I am working with NUMECA (FINE/Turbo V8.6). For the calculation I use Radial Equilibrium condition at the outlet. I have data from the experiment: the rotation speed, the mass flow and the delta static pressure between the outlet and the inlet (the pressure at the outlet is smaller than the pressure at the inlet). My problem is, when I compare my results of FINE/Turbo, especially the mass flow (with a rotation speed and a delta static like the data of the experiment) I receive a much higher value with FINE/Turbo than from the essay. I have considered several options, like Y+, k, omega, grid… I know that the efficiency of the compressor is very low and there is high turbulence but I thought with FINE/Turbo and the SST(shear stress transport) turbulence model it would work.
The reason is a negative pressure gradient which leads easy to stall. To predict stall with numerical simulation is difficult. I have the feeling that all turbulence models don’t work in a freewheeling mode.

Has somebody an idea how to simulate Windmilling properly with Numeca? Thanks!

Gerhard :)

Hi Gerhard, i have read your thread and i am very interested in your topic, because i will do the same. Currently i try to generate the mesh in AutoGrid 5. But the problem is, that i get negative cells in the far field. Maybe you have an idea what i can do to solve this problem.

Import in AG:
The 3D blade is defined by one face defining the pressure and suction side.
Thereby the airfoil contour is not self contained.
There is a little gap at the trailing edge.
The leading and trailing edges are simple curves.

Matthias :-)

Hi Matthias,
i am sorry to tell you that i can't help you with your problem of negative cells in the far field. I already had a good working mesh and changed only some parameters in Fine/Turbo. However I am interested in your project too.

Are you using a axial or radial compressor? Are you doing your "Diplomarbeit" or "Studienarbeit" at the Uni of Stuttgart?

I was using a axial compressor. I have to tell you that my results were not satisfying.

See u, Gerhard