UNSTEADY AERODYNAMIC CHARACTERISTICS OF A DUAL-ELEMENT AIRFOIL

Unsteady aerodynamic behavior and load characteristics of a VR-7 slat/ airfoil combination oscillating sinusoidally between 5-25 deg have bee n studied. The unsteady, compressible Navier-Stokes equations are solv ed on a multiblock grid using an approximate factorization finite diff erence scheme. In the case of a single airfoil, a massive flow separat ion and formation of a strong vortex is observed. The vortex-induced s uction and the shedding of the vortex into the wake is responsible for high aerodynamic loads and the subsequent stall of the airfoil. In th e case of a slat/airfoil combination, the suction peak at the leading edge of the airfoil is reduced significantly in comparison to the sing le airfoil. Flow separation is confined to the trailing edge of the ma in airfoil, and the formation of a strong vortical structure is not ob served. The slat/airfoil combination does not experience a massive flo w separation, and the aerodynamic lift does not undergo the characteri stic deep dynamic stall hysteresis loops.