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Problem in simulating turbine blade with periodic BC

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Old   January 18, 2011, 14:33
Default Problem in simulating turbine blade with periodic BC
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Hi there,

I am currently doing my final year project - simulate design turbine blade and validation. I am using steam as my working fluid. I manage to set the sides as periodic BC and exported successfully to Fluent. However, I encountered problem when doing iteration. The problem is 'Error: Floating point error: invalid number'. The setting in fluent is as below.

Solver: Density>explicit
Viscous: Standard K-e model with standard wall functions.
Material: water vapour
Operationg condition: 0 Pa
Boundaries conditions:
Inlet(pressure inlet)> gauge total pressure 6bar> supersonic/initial gauge pressure>5 bar>other remain in default
Outlet(pressure outlet> gauge pressure 101325Pa>other remain in default.
Other boundary conditions remain default.

I'm not sure where went wrongs or any step that I have missed out.
Have anyone encountered similar problem before? Please help.

Many thanks.

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Old   January 18, 2011, 19:23
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Try FMG-i (Full multigrid initialisation) in TUI. Useful for turbo cases
but looks like a setup issue.
Also I see no moving zone details (MRF or sliding)?
Are the periodics conformal or non conformal?
Ensure axis of rotation is correct in fluid zone panel (typical mistake - this is also needed for any relative stationary zone for MRF (eg if you have stators too))
Start simple and work up.
Start with air and segregated solver or PBCS.
Start with low rpm and ramp up gradually.
Start steady state but you can also run transient at 1-2 iterations per time step.
As you apply more complexity the source of the problem should become clear.
It may be material properties, bc setup etc
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