Wind Turbine Tower Side-Side Spectrum

If side-to-side bending moment is a problem, consider front-to-back bending moment instead; if that also is too hard, top-to-bottom bending moment might be easier.

Sometimes FEA = GIGO.

There are clearly several forces at play here. I am not getting a crystal clear picture of your issue from the description but I THINK I get what you are saying. But first lets list the forces. 1 the force of the rotor. 2 As any one of the blades arrive at the top where the wind in most cases is higher speed thus changes the forces on the tower and can also at certain speeds possibly cause a resonant frequency. If that is the case there are several ways to deal with getting rid of ANY and all resonant freqancys as they will tear the thing apart in time much like The Tacoma Narrows Bridge ( Do a search on that when you have time ). OK Other forces to keep in mind that are not as obvious. No need to list the obvious as you will have covered them I.E. The high pressure when a blade goes past the tower as the blade comes to the bottom much like ground effect on a low wing aircraft. That will also as you know cause forces that would act like the blades are out of balance. Finally and here is where I think you will find the reason your graf does not line up. In fact it does IF you keep gyroscopic presesion on mind. Also killed Igor Sicorscky when he was inventing and test flying HELIOCOPTERS. He learned about it very fast. In Short check that graf and see if it is 90 Degrees out of phase of what you THINK it should be. If so there is you answer. Jim Davison

How are your edges around the side by side turbine shaped? I would need to see a pic to help answer your question.

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Check the rules!

I did not know about posting emails it wont happen again, I apologize.

An interesting topic, of which, you obviously know orders of magnitude more than I do. It seems not too far off, considering you are looking at real data compared to a theory that may not include all variables that are introducing air flow perturbations to the blades. Hard to apply symmetry rules to an asymmetric problem.