boundary conditions

vishal_kumar · February 9, 2011, 01:02

hi ,
i am doing analysis for steam turbine...so my inputs are
inlet pressure-125ata(12258310 pascals)
inlet temp -783K
inlet flow is 140 tonn/hr

now can any one tell me tht which type of boundary condition i have to choose...
coz i have pressure,temp and flow rate....so if i choose mass_inlet as my boundary type then where i have to give the inlet pressure...shall i give my inlet pressure in operating conditions...can any one suggest me reg this....

vishal_kumar · February 10, 2011, 02:06

hi,
can anyone take some effort to reply my query....thanks in advance....

Amir · February 10, 2011, 07:30

Hi Sudhir,
your problem is closed in incompressible region but in steam turbines compressibility effect is considerable! So you need to know the pressure where outflow exposed to.
e.g. consider a converge-diverge nozzle where mass flow rate and inlet pressure are known, by changing outlet pressure you will get different flow fields. therefore I think in compressible region your problem is not closed.

vishal_kumar · February 13, 2011, 11:35

Thanks amir...will try and let u know the result..

February 9, 2011, 01:02	boundary conditions	#1
vishal_kumar New Member sudhir Join Date: Feb 2011 Posts: 4 Rep Power: 15	hi , i am doing analysis for steam turbine...so my inputs are inlet pressure-125ata(12258310 pascals) inlet temp -783K inlet flow is 140 tonn/hr now can any one tell me tht which type of boundary condition i have to choose... coz i have pressure,temp and flow rate....so if i choose mass_inlet as my boundary type then where i have to give the inlet pressure...shall i give my inlet pressure in operating conditions...can any one suggest me reg this....

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February 10, 2011, 02:06		#2
vishal_kumar New Member sudhir Join Date: Feb 2011 Posts: 4 Rep Power: 15	hi, can anyone take some effort to reply my query....thanks in advance....

February 10, 2011, 07:30		#3
Amir Senior Member Amir Join Date: May 2009 Location: Montreal, QC Posts: 735 Blog Entries: 1 Rep Power: 22	Hi Sudhir, your problem is closed in incompressible region but in steam turbines compressibility effect is considerable! So you need to know the pressure where outflow exposed to. e.g. consider a converge-diverge nozzle where mass flow rate and inlet pressure are known, by changing outlet pressure you will get different flow fields. therefore I think in compressible region your problem is not closed.

February 13, 2011, 11:35		#4
vishal_kumar New Member sudhir Join Date: Feb 2011 Posts: 4 Rep Power: 15	Thanks amir...will try and let u know the result..