Aerodynamic Characteristics of Flat Plates with Various Angles of Attack in Oscillatory Flow

Abstract

Studies of the forces acting upon and the flow patterns around bluff bodies submerged in oscillatory flow are fundamental to fluid engineering structures. In this work, measurements were made of both in-line and transverse forces of flat plates at various angles of attack in a wide range of the Keulegan-Carpenter number(KC). The force signals were spectrally analyzed to determine dominant frequencies, and the flow visualization technique was also employed to understand the correspondence between flow patterns and force coefficients. In this paper we discussed how the angle of attack influences the flow and aerodynamic characteristic of a flat plate. It was found that, for the present bluff bodies, several classes of flow patterns appear which depend strongly on KC numbers. Furthermore, the correlations between KC numbers and flow patterns were revealed. From the predominant frequency components of the fluctuation transverse forces, it was found that Strouhal numbers, which are reduced at maximum velocity, agree well with the results in the case of steady flow.