Hybridization potential of a propulsion system with compressor electric drive

Assuming on-board batteries to supply the electric energy, the studies in HybVer focus on regional turboprop and mid-size helicopter applications. A feasible system layout having been selected, the propulsion system was sized for the design mission, optimizing key cycle parameters toward a hybridization degree (H_P,des) of 20 % for the helicopter and H_P,des= 11 % for the regional application.

As most aircraft are operated far below their actual design range, higher degrees of hybridization and improved fuel burn can be achieved on shorter missions when fully utilizing the installed electrical storage capacity. The recent performance investigation provides new insights into the maximum hybridization levels allowable under consideration of the operational limits of the turbo components involved. The results show that for the helicopter application, a maximum hybridization degree of 40 % during cruise conditions could be achieved. For the regional turboprop application, a maximum hybridization degree of 31 % is possible. Compared to the design mission, this means significant CO₂ and NO_x emission reductions on shorter stage lengths, enabling an optimized propulsion system sizing for the entire operating spectrum of the aircraft.