[8gcynamonu]

Good Morning

I am doing a simulation of the flow in the first stage of a gas turbine. Geometry is a result of 1-D hand calculations, for a blade profile I used profile S9038A from Russian steam turbines atlas.
I made a geometry in CATIA then exported the points to TurboGrid through BladeGen module in DM. Stator crown has 151 blades and a rotor - 235.
I run a frozen-stator simulation with defined pitch angles for a stator and rotor row.
On inlet I have defined a total pressure 16 bars and at the outlet mass flow - both of these values I took from my hand calculations.

From the results though I can see that mass flows at the interface is zero and at the outlet - negative. Could anyone help me to judge what is causing that? I have attached picture of my mesh as well as the simulation report.

Thank you in advance for any support,
Natalia

[8gcynamonu]

Update: When I calculate mass flows in a table (density*velocity normal to outlet) I've got the expected value. Why do the automatic values look so weird?

Beside of that, The pressure drop over the stage is too little. From my hand calculations I expect total pressure 1.27e6 Pa. I don't know what to do with that, change the blade profile? Recalculate the whole stage? I will be very grateful for any reply.

[turbo]

In turbine stage, you specified massflow at rotor exit. How can you be sure of the flow value before simulation? Try a static pressure there.

[8gcynamonu]

Thank you Sir, I did what you suggested and I got desired pressure drop but to achieve that, the mass flow has to be bigger than the one I have assumed at the beginning. Good conclusion.

Could you please take a look at the pressure distribution over the rotor blade at span 0,5 graph? The pressure at the high blade is too low close to the leading and trailing edges. What is causing that and how it can be changed?

Best wishes,
Natalia

[turbo]

First of all, bear in mind that CFD is not a design tool, nothing but an analysis tool. CFD is never a great thing at all. It tells you that due to the wrong design you cannot get the massflow that you expected for the pressure drop. The overturned pressure near the leading-edge shows you have a bad incidence.

[8gcynamonu]

Thank you very much fr the reply. I use a CFD ans an indicator - the different mass flow brings me back to the design stage where I can recalculate the stage in order to achieve the boundary conditions I have. There is a long way in front of me. I really appreciate you reply!