CPP, one of the pioneer aerodynamic laboratories in the study of solar tracker galloping, says that not all the wind tunnels are the same... and it is true.
Well, not all Stability Diagrams for the aeroelastic design of structures are the same either... or are they? Well, if you copy it, then it will match point for point... we usually call it plagiarism (we all should fight this stronger, seriously, I´ve noticed some cases - other disciplines - last month!).
Let me explain crystal clear, by telling a tale.
This is the original image, obtained two years ago by Dep. of Energy - Uniovi and given to a (hypothetical) company we used to work with. It was named "Diagrama de Estabilidad del Tracker" by the Authors (and it was depicted and properly published after months of huge work and dedication):
And guess what? That figure never reached its intended destination, a third-party (hypothetical, again) company. Now, this is the image that the (hypothetical) company presented in a live webinar (hypothetically speaking) some time ago, pretending it was their own...
And this is the "magic". The less detailed is the image you (well, they, hypothetically) pretend to present, the easier is to "fake" it. A simple geometrical retouching and cutting... and "voilà!", trick comes to the surface.
But beyond some unfortunate anecdotes on the sidelines, the science of civil aerodynamics unites many great engineers all over the globe since decades, each of them trying to do their bit to explain and master the terrible phenomenon of the one degree of freedom flutter. Blessed are the people of good will (the majority, btw)!!!
We publish this poster as a tribute to all those who precede and accompany us in this exciting endeavor.
By the way, we welcome all the "fake free" contributions that you want to share and include in!
Our Group (GIFD, Department of Energy, University of Oviedo) is developing a new method to calculate the structure of the Photovoltaic Solar Trackers against the effect of wind. Due to the lack of knowledge (there is only a little scientific knowledge because this is a very new and recent issue) we found in the national and international standard and codes, a few of laboratories and wind tunnels all over the world are trying to find out what is the aeroelastic mechanism which causes such a disaster called torsional galloping or 1DOF flutter.
We leave herein below one of our 2D CFD approaches, showing a real case of a single axis solar tracker placed at 30º of initial tilt angle panel and oscillating at 1,2 Hz and moderate amplitudes, under wind speed of 20 m/s.