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-   -   two stage steam turbine (http://www.cfd-online.com/Forums/fluent/41215-two-stage-steam-turbine.html)

sebastian June 1, 2006 07:25

two stage steam turbine
 
hi

I calculate two stage of steam turbine (high pressure stage), i have problem with mass flow - it is much lower than for 0D calculations (20%). I used both coupled and segregate solver. can you help me?

sam June 1, 2006 08:18

Re: two stage steam turbine
 
did u make grid indpendence study?

sebastian June 1, 2006 08:26

Re: two stage steam turbine
 
yes I made, and for all cases mass flow is similar I also checked different turbulence models and the problem still exist for different cases

sam June 2, 2006 15:34

Re: two stage steam turbine
 
can u send ur goemtry and boundary conditions file

sebastian June 5, 2006 01:46

Re: two stage steam turbine
 
no i cannot

Razvan June 6, 2006 15:27

Re: two stage steam turbine
 
Does your 0-dimensional model take into account effects like area shrinkage due to boundary layers, pressure losses at tip gaps, boundary layer separation, radial flow, etc.? 20% is not that much to me!

Razvan

sebastian June 7, 2006 02:15

Re: two stage steam turbine
 
this 0-dimensional model seems to be ok, it takes into account all the mentioned efects, maybe the problem are the magnitude of pressure losses (for 0-D model). the factor for calculation of them is not proper. i calculate partial admission stage (i have four valves) with the second stage. maybe the problem is with the area between these two stages (it is quite big) i am not sure. if i calculate the case where 2 valves are opened the mass flow is ok, for case with 4 opened valves the mass flow differences are big. when i calculate only admission stage the mass flow rate from my calculation is equal to the one from 0-D. so i am not sure what to do yet.



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