OPTIMIZATION OF A BATTERY ELECTRIC HYBRID PROPULSION SYSTEM FOR A SHORT RANGE AIRCRAFT

In this paper, a serial electric hybrid propulsion system with a technology level of an entry into service in 2035 is designed and evaluated in a multidisciplinary way. The propulsion system is targeted for a 70-passenger regional aircraft with an typical mission of 400nm. The boundary conditions are set in the LuFo VI project TELEM. In a novel approach the complete propulsion system consisting of propulsors, electric motors, electrical system, generator, batteries, gas turbine and nacelles is modelled. With this approach the propulsion system can be optimized regarding a given figure of merit and tailored to the specific boundary conditions in a multi-design point approach for all relevant operating points. Design rules for an electro-hybrid propulsion system were developed, which can consider any degree of hybridization in any operating point. In addition to the thermodynamic and aerodynamic design, weights, nacelle geometry, drag, thermal management, emissions and operating costs can be assessed, resulting in an integrated propulsion system design. Individual dependencies between the disciplines, such as the dependence of the nacelle drag on the performance of the thermal management are taken into consideration during the multi-design point sizing of the components. This allows the evaluation of the multidisciplinary figure of merit “block energy”.