Characteristics of Unsteady Lift in Transitional Accelerated Flow

Abstract

Characteristics of unsteady lift in transitional accelerated flow are studied theoretically and experimentally. A theoretical method for an unsteady force acting on arbitrary-shaped airfoils in two-dimensional potential flow is presented. With this method, the force due to the apparent mass, initial lift and drag of inditial response are obtained analytically and the force due to the wake vortex is calculated by the discrete vortex method. A numerical study shows that unsteady lift in a transitional accelerated flow is mainly characterized by a Strouhal number as in an oscillating flow. An experimental study was also done to verify this.