Experimental Investigation of Discrete to Continuous Vortex Gust Encounters

This study considers a flat plate encountering a discrete vortex gust and a continuous form of the same discrete gust at different encounter frequencies. The experiments are performed in a free-surface water channel at Re=10 000 and a flat plate of AR=4 is used as a test model. 2D2C Digital Particle Image Velocimetry (DPIV) is used to visualize the flow structures, in conjunction with simultaneous force measurements with an F/T sensor attached to the leading edge of the wing model. The results show that one period of gust generation as downtime between consecutive gusts is enough to have the same loading effect. On the other hand, the lift transient is affected when no downtime is given. For continuous gust encounter cases (t=0), nearly periodic loading is observed when the lift transient is high. The amplitude of the lift transient observed in the discrete gust diminish for continuous gust encounter cases (t=0).