Aeroelastic Characteristics of a Cascade of Blades.

Abstract : A general aerodynamic theory and a numerical lifting surface technique based on velocity potential formulation for predicting aerodynamic derivatives of a cascade of blades in subsonic flow is described. The unsteady airload prediction method is applied for predicting the flutter boundaries of a single degree-of-freedom in torsion of a cascade of blades. Also, a general flutter program is developed for a two degree-of-freedom staggered cascade in subsonic flow. By utilizing an iterative procedure which permits frequency variation. The flutter frequency and the flutter speed of the reference airfoil are obtained as a function of cascade parameters. The computer program uses very efficient techniques in computing unsteady loads, the flutter frequency, and the flutter speeds. (Author)