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Brendan September 2, 2013 03:58

Problem with gravity and rotating domain i.e. Rotor-Stator CFX
5 Attachment(s)
Hi all, this is my first post here and i am quite new to the CFD side of things. I am entering my 3rd year in college in Mechanical Engineering and Renewable Energy. I am starting my thesis now and i have run into siome problems in the post-cfx results, What i am trying to do is model a cross-flow turbine and determine the power avalible at the rotor due to a "rotational speed under the influence of the mass flow rate".

Here is my first problem, i have complete the mesh no problem, in the setup stage i defined two domains Stator and Rotor, i set the rotor to "water" fluid and the rotating domain was checked, but i cant understand how to allow the domain to rotate under the influence of the mass flow rate, therefore for the sake of getting some sort of results i entered a rotation of 300 rpm in the "Z" axis.

I set the stator as stationary and water fluid aswell. The inlet was set to a Total pressure of 132000 Pa, and the outlet as "opening and gage pressure of 0 Pa. My biggest problem is setting the gravity in the negative Y direction. I know i can turn on the bouyancy and enter the -9.81 m/s-2, but this then gives me the error i need to change my analysis from Steady state to transient which i think is due to the motion frame of refernce Rotor.
I ran the solution and plotted a velocity vector to show you the error!
All screenshots are attached below:
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All i want is a simple analysis but the little things are catching me out.

By the way i have absolutly no help in the ansys program from any lecture etc. as they do not know how to use it, i love the program although i have alot to learn, everything i know so far i what i taught myself!
So anybody willing to help me it will mean alot.

Kind regards B.

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