SIMULTANEOUS EVALUATION OF THE AERODYNAMIC CHARACTERISTICS AND SOUND FIELD OF A DUCTED PROPELLER

The mathematical model of a ducted propeller in a subsonic flow is ana lyzed in the linear approximation. A system of two integral equations for simultaneous evaluation of aerodynamic loads on the blades and duc t surface is derived. In a system of coordinates tied with the propell er, expressions for harmonics of the sound field of such a source are obtained. As an example, the thrust and the first harmonic of the soun d held for a ducted eight-blade propeller are simultaneously calculate d. The feasibility of the useful acoustic interference of the sound fi elds produced by the blade and duct sources is demonstrated. The effec t of axial excursions of the propeller in the duct on the sound field is considered.