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-   -   NEED HELP! Flow through nozzle vanes with clerance (http://www.cfd-online.com/Forums/numeca/50906-need-help-flow-through-nozzle-vanes-clerance.html)

C K Tang July 29, 2003 01:00

NEED HELP! Flow through nozzle vanes with clerance
 
Hi, is anyone out there having experience on modelling flow through nozzle vanes with hub clearance? I am using IGG 4.4 and Euranus 5.21 and I am trying to model flow with this configuration for a turbine stage. However, Euranus keeps crashing and it keeps giving me this error prompt: Unknown reason. Any advice will be very much appreciated.

Steve July 29, 2003 12:38

Re: NEED HELP! Flow through nozzle vanes with cler
 
Ah, the infamous crash for "unknown reasons" - I feel your pain!

I have done modelling of a turbine stage (nozzle + rotor) in which the nozzle had hub clearance. In general, this is no different than modelling with tip clearance. Same issues apply. What I found for crashes on these cases:

* First thing (I can't stress this one enough) is to check your grid quality on both sides of the interface. The solver is very, very, very, very, very sensitive to grid quality and clustering here. If there is a problem that you can't seem to improve, suggest sending it to your support team. I found they are extremely responsive and will not only give you guidelines for acceptable quality, but also on how to improve it.

* Check that your turbulence model is compatible with grid resolution that you have set. Again, I found solver very sensitive in this area.

* Check that your initial solution, inlet bc, and outlet bc are all compatible.

* Check that your geometry, inlet flow angle, and rotor rotation are all compatible.

* Check that your bc's ensure near design conditions with nominal incidence and loading. Off-design or overloaded blades will cause their own challenges for the solver.

Good luck!! Would be interested in knowing what you ultimately determine is causing the crash.

Allan D. Grosvenor July 29, 2003 13:07

Re: NEED HELP! Flow through nozzle vanes with cler
 
Dear C K Tang,

Could you verify which release you are running? The latest official release of FINE/Turbo was version 6.1-3. This included IGG ver. 4.7-3 and EURANUS ver. 4.8-4. In case it is actually FINE/Turbo ver. 5.2-21 or 5.2-22 (IGG was at ver. 4.5-1 at this point) that you are running, please note that this release is more than a year and a half old and that there have been several releases since then. In case you are running an old version, my first recommendation would be to install the latest version.

As always, we will be happy to help you diagnose the issue, if it persists with a supported version of FINE/Turbo. Please feel free to send details to your support contact.

Best regards, Allan


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