Rigid and flexible wings subject to large intensity turbulence: a two-dimensional particle image velocimetry study*

A rigid and flexible wing were subjected to turbulent conditions generated by a Makita style active grid at Re=200,000. Both the suction and pressure side of the wing were illuminated in the chordwise plane, and two cameras were mounted such that full coverage of the surrounding flow field was obtained. Concurrently, a 6-axis load cell was used to determine the resulting forces and moments generated by the wings. Preliminary analysis suggests that there is an interaction between the freestream turbulence and the response of the wing. The study found that what can be perceived as random flow perturbations in the form of free stream turbulence can still cause excitations in the structural modes of a wing dependant on the length scale of those random perturbations. The study found a torsional mode was excited when the integral length scale was half of that of the airfoils chord, and a bending mode was excited when the integral length scale was equal to the airfoils chord.