Conpressibility Effects on Dynamic Stall of Oscillating Airfoils

Abstract

A research proposal to investigate the "Compressibility Effects on Dynamic Stall of Oscillating Airfoils" was submitted to ARO and the project was funded in April 1986. The aim was to obtain a basic understanding of the effect of compressibility on the phenomenon of dynamic stall under typical flight conditions encountered by a helicopter in forward flight., so that eventually a means for its control can be devised and thus, its flight envelope can be expanded. The initial phase of the study was devoted to building a drive system to produce the necessary unsteady airfoil motion. A novel design was arrived at after reviewing the various possibilities and was built. It uses a four-bar chain mechanism of which the airfoil is one of the links.