Acceleration data correlated with PIV images for self-induced vibrations of an airfoil

Self-induced vibrations of a NACA 0012 airfoil have been investigated via particle image velocimetry (PIV) in conjunction with simultaneous acceleration measurements. Although the CCD camera's speed is low with respect to the frequency of vibrations and does not allow resolving the evolution of vortical structures in a period of vibration, the acceleration data simultaneously acquired along with the laser pulse signal allows detailed analysis of vortex shedding for periodic vibrations of the airfoil. The acceleration data is integrated twice to yield the speed and the position of the airfoil; hence, the patterns of the near-wake vorticity are correlated with the motion of the airfoil. PIV images also constitute a reference and validation data for the instantaneous position of the airfoil. The equation of motion is then set based on measured structural properties of the system. The resulting unsteady moments are studied with respect to the angular motion of the airfoil.