Benefits of Parallel Hybrid Electric Propulsion for Aircraft and Rotorcraft
Open Access
- Author:
- Decerio, Dalton
- Graduate Program:
- Aerospace Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- March 03, 2022
- Committee Members:
- Amy Pritchett, Program Head/Chair
David K Hall, Thesis Advisor/Co-Advisor
Karen Ann Thole, Committee Member
Edward Smith, Committee Member - Keywords:
- hybrid
electric
aircraft
rotorcraft
conceptual design
optimization
propulsion - Abstract:
- As interest in the reduction of the environmental impact of commercial aviation grows alongside the continued pursuit of improved efficiency, electrification of aircraft propulsion systems may have potential to reduce the energy consumption and emissions of aircraft. Incorporating electrical components adds a dimension to the propulsion system design space and introduces new tradeoffs between weight and efficiency. In this thesis, we apply numerical optimization to conceptual design of regional transport category turboprop airplanes and light rotorcraft using geometric programming. A design optimization framework was developed for modeling hybrid propulsion systems in the context of vehicle conceptual design and used to evaluate the benefit over conventional systems, optimal operation strategy, and design changes with changes in electrical technology improvements. The objectives of this research are to quantify the energy savings benefits of parallel hybrid electric propulsion, identify the mechanisms of the benefits, and characterize the scaling effects of design parameters such as range and electrical technology parameters such as battery specific energy. The results show incorporation of current state-of-the-art electrical components may provide energy savings up to 7.7% over conventional turboprop engines, while projected improvements in technology may allow savings of up to 14.1%, albeit at a reduced range relative to conventional gas turbine powered aircraft. The rotorcraft considered differ from transport aircraft in that they are capable of vertical takeoff and landing which require higher power relative to cruise; rotorcraft with short-duration hover missions may save up to 12.7% energy using parallel hybrid electric propulsion systems with state-of-the-art technology and up to 25.3% with projected technology improvements. By supplementing the gas turbine engine with electrical power in high-power conditions, the overall efficiency of the propulsion system can be improved throughout the mission. Improvements in battery specific energy and power electronics specific power have the largest impact on improvements in energy savings, and thus they are identified as enablers for efficient hybrid electric aircraft propulsion.