Abstract
Abstract Closed-loop controlled interactions between an airfoil and impinging vortices were experimentally investigated. This work aims to minimize the fluctuating flow pressure ( p) at the leading edge of the airfoil, which is a major source of the blade-vortex interaction noises commonly seen in rotorcrafts. Piezo-ceramic actuators were used to create a local surface perturbation near the leading edge of the airfoil in order to alter the airfoil-vortex interaction. Two closed-loop control schemes were investigated, which deployed p and the streamwise fluctuating flow velocity ( u) as the feedback signal, respectively. While the control effect on p was measured using a fast response pressure transducer, the oncoming vortical flow was monitored using a particle image velocimetry and a hot wire. It was found that the control scheme based on the feedback signal u led to a pronounced impairment in the strength of oncoming vortices and meanwhile a maximum reduction in p by 39%, outperforming the control scheme based on the feedback signal p. Physics behind the observations is discussed.
Published Version
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