Need help about boundary conditions for a francis runner flow simulation
 

Hello all of you CFD guys!!

As i`m an undergraduate Mechanical Engineering student here at Chile, one of my research projects consists on the stress analysis for a francis turbine runner. As i want to do a dynamical analysis, i have to model the flow trough the runner airfoils, expecting with this to obtain the pressure distributions over the entire airfoil. I work with Nekton and fluent in a Sillicon Graphics Origin 200, but i`m not sure at all about what kind of boundary conditions i have to use. I suppose that one good approach will be to consider a periodic section of the runner, i mean, one or two airfoils at all. This will allow to save lots of cpu time.

However, any useful information you can give to me will be greatefully thanks.

Rodrigo.

Re: Need help about boundary conditions for a francis runner flow simulation
 

Hello

If you would like to do a transient analysis, you will need to make a moving mesh of all runner channels and a stationary mesh of the all the guidevane channels and glue them together with a unmatching boundary. If you would like to do a stationary analysis, it is enough with one runner channel. Extend the channel a little at both ends. Put periodic boundaries in front of and after the blade suction/pressure sides. Specify the velocities at the inlet of the runner and the pressure at the outlet.

Good luck with your project!

Arild