Predict Wing’s Flutter Using Aerodynamic Damping

[gstzortz]

Dear Ansys Team,

 

I am trying to predict wing's flutter with a less expensive computational method than 2WAY-FSI. I have seen a method about calculating aerodynamic damping (if AD>0 then system damped if AD<0 then flutter occured).

 

i Have some questions:

 

1)One kind of tutorial video is this: [ https://www.youtube.com/watch?v=cYjR...AC8Org7rDlYZ4 ] and i have this Question

 

At timestep: 10:17-11:05 I've seen an approach that involves performing a transient CFX analysis to derive the excitation frequencies of the structure (in that way i could know what natural frequency are close enough, in order to include them into simulations, and avoid unecessary simulations about modes,AoA and velocity). 

How can I replicate this in my own model? Do you know of any ANSYS tutorials that cover this method? Also, would I need to model the structure's geometry within the CFX analysis as well?

 

2. Regarding Normalization: I've discovered how to extract the kinetic and strain energy for each mode through in Mechanical from this video [https://www.youtube.com/watch?v=sFNGXjlnIFQ&list=LL&index=1&t=189s ]. However, when applying the mode shape as a periodic displacement in CFX, I need to adjust the amplitude to 1% of the wingtip chord (as suggested in various papers). This is primarily to ensure the aerodynamic damping value remains constant (as suggested in various papers) and to avoid generating negative volume elements from excessive displacement. With that in mind, do you happen to know how I can calculate the energy magnitude for each mode shape at a specific amplitude value?

 

I appreciate any further insights you can offer—thanks for your help!