Comparative assessment of transient characteristics of conventional and hybrid gas turbine engine

Reduction of CO₂ emission of future aircraft is the main objective of agreements like Flightpath 2050 from the European Commission and the Vision 2020 from the ACARE. For achieving these emission reduction goals, hybrid propulsion systems are considered as a meantime solution on the way to universally electric propulsion systems and are hence the subject of numerous investigations. These studies, however, almost exclusively focus on steady-state behaviour and energy analysis and leave out the benefit on transient performance that comes from hybridisation. To assess the benefit of the hybridisation on a gas turbine engine, multiple simulations of conventional engines and their hybrid versions are performed with a Matlab Simulink® model and the results are compared with time response diagrams and commonly used metrics. It could be shown that the acceleration time of a hybrid gas turbine engine can be reduced by half compared when the shaft power share of the electric motor is 25%. Furthermore, the study shows that the primary benefit of the hybridisation comes from the larger torque range of the electric motor compared to the turbine.