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Jpret March 11, 2022 00:41

Using pressure for both inlet and outlet boundary conditions
Hi all,

I am running a simple CFX for a gas turbine blade, however i am struggling to decide on inlet and outlet boundary conditions as i only know the inlet pressure that the first stage turbine blade is subject too. This value is 1.5 MPa which i have divided evenly across the number of first stage blades, leading to an inlet pressure of 0.0237 MPa. As i am running a very simple analysis, i am going with the assumption that the pressure drops uniformly across each stage of turbine blades (4 stages). As such, the pressure drop across the inlet and outlet of the fluid domain of a single blade is 0.006 MPa. Also, i dont have any idea on the mass flow rate of the hot gas etc. Also i am only interested in the temperature and pressure distribution on the blades surface.

Based on these estimations, my model has an inlet Temperature and Static Pressure of 0.0237 MPa and 1500 degrees C respectively, with flow direction normal to the boundary, and an outlet Average Static Pressure of 0.0177 MPa which is averaged over the whole outlet.

The conditions are sub-sonic and in-compressible flow is assumed.

Would these boundary conditions produce a suitable simulation ? I have read that using pressure conditions for both inlet and outlet is not advisable.

Thanks !

ghorrocks March 14, 2022 00:51

I recommend you read the best practises guide in the CFX documentation. There are guides for numerical accuracy and turbomachinery so you really need to have read these before doing any analysis.

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