Transverse Gust Velocity Gradients at Low Reynolds Number Flows

This paper experimentally studies the details of the effect of transverse gust velocity gradients on a flat plate at 0 angle of attack by comparing sine-squared and trapezoidal gusts. A novel gust design system is introduced and characterized in a water-filled towing tank to have a trapezoidal gust profile which is then compared to a sine-squared transverse gust using the same experimental setup. Forces and flowfield measurements were acquired for both cases, and the circulation shed from the leading-edge was calculated. The results showed that the gust ratio parameter can be used to scale the lift responses and leading-edge vortex strengths of various gust amplitude encounters for both gusts within the investigation range. Moreover, Küssner’s theory was found to accurately predict the lift responses of both. The trapezoidal gust encounters were found to cause a larger circulation shed accompanied by a more prominent lift peak due to the sharper velocity gradients that the trapezoidal gust contains. The discrepancies between the lift responses of sine-squared and trapezoidal gust encounters were attenuated using a momentum flux-based normalization method.