Preliminary design study of a centrifugal jet engine with a supersonic propeller

Abstract

A theoretical analysis was made of an aircraft propulsion system incorporating a centrifuga1 jet engine and a supersonic propeller. The primary aim was to increase the economy of a jet configurated engine. The design for a supersonic propeller was included, since it was necessary to use a propeller, in order to create maximum thrust for the installation. The engine unit consists of a rotating disc with an internal combustion flow channel using essentially the ram-jet cycle, and the design configuration embodied only three basic moving parts for the entire propulsion plant. The performance of the engine was treated as an aerodynamic and thermodynamic problem. Computations were made on the internal flow system covering the effects of all the variables. Then, using these results, specific engines were analyzed introducing pertinent losses. In general, the numerical calculations showed theoretically that this type of engine would have slightly better economy than a reciprocating engine and was far superior to a turbojet at an aircraft speed range down to low subsonic values. The ana1yis for the supersonic propeller indicated that the author's design approach, which includes three dimensional effects, could theoretically produce completely supersonic blades with efficiencies above 80%. Computations were made on a 10' diameter propeller which would produce 7,500 pounds of thrust with an efficiency of 83.5% t an aircraft speed of Mach number 1. This power absorption could easily be doubled, while at cruising powers efficiencies ranged up to 86%.