Conceptual Design of a 19 Passenger Hybrid Electric Aircraft

Field: Engineering (Physical Sciences)

Electric aircraft designs aim at electrifying existing state of art (SoA) aircraft configurations and/or research into fundamentally different, synergistic & tightly coupled configurations that pave the way towards a sustainable & greener tomorrow. Additionally, it sets a platform for the implementation of the rapid progress that the renewable energy sector has shown the world. Several studies on aircraft electrification have been made to-date focused on configurations ranging from turbo-electric, partially turbo-electric, hybrid-electric to universally electric (Fully electric) systems. Conceptual design studies have used physics-based models in proving their feasibility on account of reduction in block fuel consumption, emissions and noise levels with realistic progress in electric propulsion systems. Development in electric system architectures aims at meeting the requirements of mega-watt class power demand, greener energy storage systems (example: better batteries), and weight-controlled power management and distribution systems. One of the challenging parts when it comes to electrification is the significantly low specific energy of the storage system causing weight cascading effects. In this scenario, lighter aircrafts are deemed more viable solutions for the near future and radically new technologies can be employed. Also, adhering to airworthiness standards, these aircrafts provide the opportunity of faster and easier certification. The current study approaches the aviation emission mitigation through a technological level approach, by the implementation of electrification alongside boundary layer ingestion (BLI). Series/Parallel Partial hybrid electric architecture is found best for the implementation of this technology combination. The partial hybrid-electric architectures have electricity generation from the turbofans as well as batteries, with batteries being the primary source. Under these scenarios, it was aimed by this study to set the design formulation: Electrification of a 19-passenger twin-engine turbofan (under-wing podded) aircraft to a tri-fan concept with aft tailcone electric fan working under boundary layer ingestion. The design follows a physics-based approach with flexibility applied in terms of size, performance and operating configuration. Three different aircraft configurations are examined, namely: a) the conventional, (b) fully electric and (c) hybrid-electric. These are investigated maintaining the same design specifications. The level of hybridization in terms of power is maintained within 40-50%. The results of this study have shown that the lower degree of hybridization (40%) in terms of power is observed to have a higher energy efficiency (12% lower energy consumption) and lower CO2 emissions (13%), compared to the higher degree of hybridization (50%). This is mainly due to the 14% increase in design takeoff gross weight from lower to higher level of hybridization. It was also found the range sensitivity and limitations of the hybrid-electric commuter aircraft for different technological scenarios under current airworthiness requirements