Studies of N+3 and N+4 Technology Level Propulsion Systems with Alternative Fuels using NPSS

This paper describes the study of the effect of various types of fuels on the performance of NASA N+3 and N+4 technology level engines using the software called Numerical Propulsion Simulation System (NPSS). Along with the incorporation of various fuel types (Jet A, LNG, LH2, NH3, and hydrogen carrier Ammonia – Borane (AB)) in NPSS, several studies are performed to understand the effect different fuels on bypass ratio, thermal and propulsive efficiency, and compressor surge margin. An emissions estimation method is also proposed based on an assumed combustion reaction which can be validated and improved with experimental data and CFD modeling. The same method is applied to calculate emissions for all the above mentioned fuel types. Finally, the paper discusses possible environmental implications of alternative fuel options, and recommendations are provided for potential commercial N+3 and N+4 engine technology level vehicles and propulsion systems.