SEMI-EMPIRICAL MODEL FOR THE DYNAMIC STALL OF AIRFOILS IN VIEW OF THE APPLICATION TO THE CALCULATION OF RESPONSES OF A HELICOPTER BLADE IN FORWARD FLIGHT.

Abstract

A system of differential equations relating the aerodynamics forces and the variables defining the velocity of the airfoil section is employed to simulate the time delay effects of the flow. The model involves a number of identifications of test results of a 2-D airfoil in static and in small-amplitude harmonic oscillation or random vibration configurations. Tests at high-amplitude motions then permit a verification of the validity of the model.