Rim-Rotor Rotary Ramjet Engine, Part 2: Quasi-One-Dimensional Aerothermodynamic Design

Abstract

The rim–rotor rotary ramjet engine is a new propulsion-system design with the potential to significantly improve power density and reduce complexity over conventional gas turbines, thus making it an interesting alternative for future transportation and stationary power systems. This paper presents a quasi-one-dimensional aerothermodynamic design model, taking into account the dominant physics of the rim–rotor rotary ramjet engine: 1) shock-wave compression, 2) high-g field combustion, 3) viscous losses, 4) heat transfer, 5) inlet and outlet periodic condition, and 6) windage losses. It is shown that high flame velocity due to buoyant forces leads to a very compact combustion chamber and possibly very low nitrogen oxides. A 500 kW rim–rotor rotary-ramjet-engine version is designed with the model and could produce 7:6 kW=kg at a tangential velocity of 1000 m=s, which is more than twicetheactualgas-turbinepowerdensity.Aproof-of-conceptprototypeistestedatlowspeed(Mach1),andshows good agreement with the model for both indicated power without combustion and windage losses. Combustion efficiency is measured to over 85% at 220;000g. These results confirm the design model capabilities, at least within the range of tested Mach numbers.