Business Aviation Turbofan Efficiency Improvement by Electrical Assistance During Transient Operations

The growth in popularity of business jets heightens environmental concerns and increases pressure on the industry to develop more sustainable propulsion systems. Fully electric or hydrogen propulsion remains unsuitable in the near term due to energy density limitations and infrastructure constraints. This study investigates a mild hybrid-electric concept in which electric power is supplied to the high-pressure spool during rapid acceleration phases to relax compressor stability constraints. A numerical model based on the Honeywell HTF7000 shows that providing 339 W h of electrical energy, with a peak power of 451 kW (605 hp), during a single acceleration enables a turbomachinery redesign. This redesign increases the high-pressure compressor pressure ratio, resulting in a potential 0.78% reduction in cruise thrust-specific fuel consumption. A full flight-envelope assessment demonstrates efficiency improvements across all operating conditions, with the smallest gains near the cruise operating point. To assess aircraft-level impacts on mission fuel burn, the redesigned engine is evaluated within the Bombardier Research Aircraft Configuration. Results show that the additional weight of a standalone electric powertrain can substantially reduce turbofan-level benefits, particularly for conventional battery architectures. Overall, the viability of the electrically assisted turbofan depends heavily on aircraft-level integration and electrical storage technology.