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-   -   BCs for a turbine blade passage (http://www.cfd-online.com/Forums/fluent/43107-bcs-turbine-blade-passage.html)

Babu December 12, 2006 12:25

BCs for a turbine blade passage
 
I'm simulating a sector of a 3D turbine blade passage. It also got a narrow clearance (gap) present between the blade tip and the outer casing. Flow is mostly incompressible except in the tip region.

I have given inlet velocity and outflow boundary conditions. I have used best used turbulence model (k-epsilon RNG & also tried with LES, second order) to simulate the flow around the arifoil and within the tip gap. When I give this boundary conditions, the total pressure, static pressure computed at the inlet exactly matched the TEST data but the exit static pressure it has calculated shows very much off (underpredicting by 30%).

I tried extending the domain, perfroming mesh refinement, testing turbulwence models, wall refinement, etc. But still I could not match my TEST close by atleast 5-10%.

Can anyone suggest me a solution.

I tried changing boundary condtions at inlet and exit to 1) both pressure kind and 2) velocity inlet and exit static pressure, etc. But in these cases the mass flow gets too much off from actual test inforamtion (25% under predicted).

At all these conditions the inputs I used are supplied through profiles not the constant value.

Please help me out with some solution.

Thanks in advance BABU


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