A review of compressor design for future aircraft propulsion architectures

A variety of aircraft propulsion architectures are available for a sustainable transformation, ranging from all electric to hybrid-electric, based on batteries, fuel cells and electric motors. These hybrid-electric architectures are an extension of the electric architecture with a gas turbine burning sustainable fuels. Most of these architectures require a compressor, either as part of the gas turbine or to supply gas to the fuel cell. The different system integration depending on the architecture specify new demands on the compressor compared to the compressor in a conventional turbofan engine. When fuel cell systems are used, further requirements for the compressor arise due to the necessary matching between the fuel cell stack and the air supply system. These new requirements must be developed during the system design. The compressor design is based on the requirements from the modeling of the propulsion architecture. Subsequently, the main dimensions can be determined followed by the meridional shape and the blade modeling before the design is simulated by computational fluid dynamics. Finally, the design is adjusted until the required boundary conditions are achieved. In this study the requirements for compressors in the cathode gas supply of a fuel cell are summarized. Afterwards a compressor for the cathode gas supply system is designed for a regional reference aircraft that uses fuel cells as part of the propulsion system. First, the boundary conditions for the design are determined, then the compressor performance map is calculated and the general challenges for the compressor design as part of the air supply system are discussed. Due to the different compressor operating points required for efficient fuel cell operation, detailed component matching between the fuel cell and the air management system as well as careful selection of an operating strategy is required prior to design.