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-   -   Need help about boundary conditions for a francis runner flow simulation (http://www.cfd-online.com/Forums/main/245-need-help-about-boundary-conditions-francis-runner-flow-simulation.html)

 Rodrigo Escobar Moragas October 9, 1998 16:49

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.

 Arild Hartmann October 26, 1998 09:20

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

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