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-   -   ERROR when i am using IAPWS table (https://www.cfd-online.com/Forums/cfx/64336-error-when-i-am-using-iapws-table.html)

kpsudhakar May 7, 2009 10:12

ERROR when i am using IAPWS table
 
Hi everyone,
I am working in single stage steam turbine with wet steam model.Initially I have tried with IAPWS table but i couldnt succede,so i start my sollution with RGP table(SteamLP) and converged the sollution.
Then finally I interpolate the RGP table results with IAPWS table defenition file,then i start the sollution with lower time scale(1e-6) I am getting the following error
" Fatal bounds error detected
---------------------------
Variable: Steam1v.Specific Heat Capacity at Constant Volume
Locale : Rotor1"

Please help me to sort it out this issue.

Adam Beevers May 13, 2009 09:37

Hi Sudhakar

The problem is that during the initial stages that not all of the flow has thermodynamic properties in the correct region of the steam table of which you hope to end up. So sometimes the steam tables go outside of their valid range and the properties such as Temperature and Pressure etc become unphysical.

Often, when dealing with wet steam, expecially with wetness at the inlet, you need to start with an initially dry simulation to set the pressure field, as the steam models require this pressure field to determine where nucleation takes place.

Regards

Adam

Timon May 13, 2009 11:04

Have a look at the expert parameter "prop interp option", which handles the interpolation and saturation clipping (which is performed by default) of the thermodynamic properties... Setting "prop interp option=1" disables the saturation clipping, which might improve things for you.

pacmaan May 20, 2009 13:09

I have another solution. You must create new material and choose IAPWS IF97 in Material Group (Basic Settings tab). Afterwards fill Table Generation in Material Properties tab.

Regards
Marcin


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