Experimental investigation of flow structure over pitching airfoil in the wake of circular cylinder

Abstract

The unsteady aerodynamics play an important role in fluid-structure interaction due to its engineering applications. These types of research can be utilized to improve the fundamental analysis of bluff body-airfoil wake interaction and to achieve better design and more efficiency in engineering applications. This paper aims to conduct experimental tests over parameter space to investigate flow around a NACA0012 pitching airfoil in the wake of a circular cylinder. The one-dimensional hot-wire anemometer probe was used in an open-type wind tunnel to examine the effect of the cylinder-airfoil gap, the amplitude of pitching oscillation, and reduced frequency on the time-averaged flow characteristics in Reynolds number Rec=105. The results show that the increase of the reduced frequency at the α0=5 has a negligible effect on the flow characteristics, while its increase at the α0=10 is consequential. Pitching oscillation creates a region with a higher fluctuation in the wake center of the upstream cylinder, whose width grows with the increase in the amplitude of pitching oscillation. In addition, the distributions of the turbulent flow characteristics for GD=6and10 cases in xc=2.4 are approximately similar but different from the GD=2 case. The analytical results presented in this paper provide basic information about cylinder-pitching airfoil wake interaction.