Learning Forum

[Jpret99]

Hi all,

I am running a CFX of a first stage gas turbine blade. My set up can be seen in the attached image. I currently only know the inlet gas conditions which are a pressure of 1.5 MPa and a temperature of 750 degrees C. How would i go about defining the outlet gas boundary condition given that i only have inlet conditions ? I've seen tutorial videos where the outlet relative pressure is defined as 0, however this doesn't seem correct in the context of mutli-stage turbines.

I dont have a large amount of knowledge when it comes to the behaviour of gas pressure as it flows through the turbine stages, so any help, advice or guidance would be greatly appreciated, thanks !

[Rob]

For a model you typically need to know a pressure drop (solver calculates the mass flow) or a flow rate and outlet pressure (solver finds the pressure loss).

[Jpret99]

Hi Rob, correct me if im wrong but if i apply an inlet pressure of 1.5 MPa and an outlet pressure of say 1 MPa due to an estimated pressure drop, would this be acceptable in terms of running an accurate simulation ? I only know the inlet pressure condition, and have roughly estimated the outlet pressure condition based on the pressure dropping across each stage of blades at an even increment.

[Rob]

The result will be accurate from a computational point of view, however, whether the flow is representative of the turbine is a different question which I can't answer. It's a good starting point to learn how the solver works though.