Characterization of Novel Large Amplitude Gust Generator

Understanding the unsteady load response of a wing to a gust is of critical importance in aerodynamics. Many different designs of gust generator have therefore been built and tested in both wind and water tunnels, each design coming with distinct advantages and drawbacks. This study presents a cascade of 58 oscillating airfoils as a novel large amplitude gust generator. The gust produced was tested at different Reynolds numbers and reduced frequencies. It was found to be two-dimensional, uniform, and repeatable, and therefore representative of a Sears-type gust. In contrast to vortical gust generators such as plunging wing wakes, the new gust generator produces highly correlated gusts, even at low reduced frequencies. Large-amplitude, coherent, transverse velocity is superimposed by small-scale vorticity fluctuations in the wakes of the oscillating multi-vane cascade. Two airfoil sections, NACA 0012 and NACA 63-421, were then tested. The normalized lift amplitude was found to follow the theoretical Sears prediction.