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-   -   Outlet Boundary Condition for the cone of a turbine (http://www.cfd-online.com/Forums/fluent/118327-outlet-boundary-condition-cone-turbine.html)

 Barzanoni May 25, 2013 06:22

Outlet Boundary Condition for the cone of a turbine

hi dear friends

i'm modeling a cone (only) for the inlet of the turbine power, with ANSYS FLUENT 12. (the order of part: compressor+combustion chamber+cone+turbine)
i have the inlet mass flow rate, static pressure and static temperature, but have no data for the outlet of the cone.
if i choose the pressure outlet boundary condition, it ask me the pressure and back flow temperature, but i have no data about them.
T=640 C, P=95psi and mass flow rate is 80lb/s, Mach number is about 0.4.

thank you.

 Liufeng_ustb May 26, 2013 00:33

Quote:
 Originally Posted by Barzanoni (Post 429951) hi dear friends i'm modeling a cone (only) for the inlet of the turbine power, with ANSYS FLUENT 12. (the order of part: compressor+combustion chamber+cone+turbine) i have the inlet mass flow rate, static pressure and static temperature, but have no data for the outlet of the cone. if i choose the pressure outlet boundary condition, it ask me the pressure and back flow temperature, but i have no data about them. T=640 C, P=95psi and mass flow rate is 80lb/s, Mach number is about 0.4. please help me. thank you.
Hi, Barzanoni. I have the same question as you.

I am doing my undergraduate thesis now. My modeling is simulating Fixed-Bed heterogeneous reaction. I need to set outlet boundary conditions, because I choose Eulerian Multiphase Model, I must select pressure-outlet for mixture and the gas phase and solid phase.

In tutorial of FLUENT, there is such an example which is about Eulerian Granular Flow and Heat Transfer. It suggest us choose the same temperature as inlet for both phases. But my problem involves reaction, until now, I have no idea about the species setting.

Hope to continue discuss with you.

All the best

 Barzanoni May 26, 2013 02:34

Hi Liufeng

i think if the flow stream is supersonic, it is no matter that u set real value for pressure and temperature, and it is suficient to determine real order value. the below text is from Fluent tutorial:

Note: The momentum settings and temperature you input at the pressure outlet will be used only if flow enters the domain through this boundary. It is important to set reasonable values for these downstream scalar values, in case flow reversal occurs at some point during the calculation. (p 12-12, Fluent Tutorial Guide)

but, i'm not sure that this view are true for sub- and trasonic or for incomperesible flow????????????

 Barzanoni June 11, 2013 06:01

 diamondx June 11, 2013 10:46

Quote:
 if i choose the pressure outlet boundary condition, it ask me the pressure and back flow temperature, but i have no data about them.
Leave it 0

 Barzanoni June 12, 2013 01:32

Hi Ali.

i try to set some value for these parameters, but, each value has lead to different result!!!!!

Thank you Ali for your attantion

 JimKnopf June 12, 2013 02:45

As far as I understand you have a definite outlet e.g. a Boundary where no backflow occures. Hence you can set a Value that makes some sense, like 640°C in your case.

This should be ok since you don't assume to have a mass flow over the outlet into your domain in the final state.

Greetz
Jim

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