Proposed Design and Feasibility Study of a Hybrid-Electric Propulsion System for a Ten Passenger Aircraft

Sammanfattning: This study aims to propose a hybridized version of a propulsion system for a 10-passenger aircraft and compare it to a conventional (reference) aircraft which uses a fossil fuelled turbofan for propulsion. The hybridized powertrain includes a fossil fuelled gas turbine, which is only used for producing electricity, coupled in a series configuration with a battery storage, that provide power to two electrically ducted fans. The comparison mainly aims towards total energy consumption and carbon dioxide emissions; hence, these are aimed to be reduced in the hybridized solution. The aircrafts are compared when flying the same pre-defined route that is a 900 km long distance, cruising at an altitude of 7500 m at 150 m/s. Rate of climb, climb speed and descent angle are optimized, with regards to energy demand. The hybridized propulsion system is evaluated in three different scenarios, that is: 2020, Near Future- and Advanced Future scenario, which contain different component properties that address different future predictions. An experiment is conducted with a small scale electrical ducted fan, operating in a wind tunnel, to measure different quantities such as power and thrust. These results are then scaled up and used as design parameters for a proposed fan design that is of sufficient size to propel the hybridized aircraft. The results show that the hybridized concept, at design conditions, proves feasible in all scenarios. The mass of the aircraft increases as the hybridized system is introduced, but nevertheless the fuel consumption decreases where the reduction depends highly on energy density of the batteries.