THEORETICAL STUDY OF DUCTED PROPELLER BLADE LOADING, DUCT STALL AND INTERFERENCE

A theoretical analysis was made to predict the performance of an isolated ducted propeller, with emphasis on real propeller and frictional effects. The various tasks performed are the following. An analysis was developed to predict, for a specified propeller and duct configuration, the performance in axial flow. The quantities predicted include propeller and duct thrust, propeller inflow velocity, and radial distribution of propeller loading and angle of attack. As a special case of this analysis, a method was developed to design a propeller for uniform loading in axial flow for a given duct. Two FORTRAN IV computer programs were developed for these methods and are available from the sponsor. A relatively simple and rapid method for estimating the flow conditions for onset of duct stall was developed. The effects of radial and circumferential variations of blade loading on ducted propeller performance were estimated. Finally, the effects of mutual interference between pairs of ducted propellers were investigated. (Author)