Thesis

Resilient power and propulsion system design for eVTOL aircraft

Creator
Rights statement
Awarding institution
  • University of Strathclyde
Date of award
  • 2024
Thesis identifier
  • T16866
Person Identifier (Local)
  • 201971462
Qualification Level
Qualification Name
Department, School or Faculty
Abstract
  • The continuous increase in population in megacities has led to a more pronounced issue of road congestion. Electrical vertical take-off and landing (eVTOL) aircraft have been proposed as a solution to alleviate road congestion by enabling greener and quieter aviation, providing a more time-efficient commuting option compared to helicopters. However, the realization of innovative eVTOL aircraft heavily relies on advancements in high-power and energy-dense power system technologies for lightweight electrical power systems (EPS). The limited maturity of lightweight EPS technologies and their safe integration into the aircraft pose challenges in terms of payload capacity and achievable range for eVTOL aircraft. This significantly impacts the performance of fully electric eVTOL aircraft for Urban Air Mobility (UAM) missions. Therefore, it is crucial to explore innovative approaches and new technologies for optimized EPS architecture and aerodynamic design at an early stage of the design process to achieve economical flight for UAM. These unique attributes of eVTOL aircraft differ significantly from conventional aircraft technologies and systems, emphasizing the need for a comprehensive understanding of aerodynamic-electrical failure interdependencies and EPS protection methodology to ensure a reliable EPS Therefore, the main research contributions of this thesis include the development of a novel design methodology to capture a certification-compliant EPS architecture for an eVTOL at the preliminary design phase. This methodology integrates mission requirements, aircraft aerodynamics, projected future availability of EPS technologies, and safety requirements. The development of the EPS architecture is carried out in parallel to the design of non-electrical systems to ensure future compliance with certification requirements. The methodology enables the identification of key design trades that minimise EPS system weight while ensuring that baseline safety criteria are met and future compliance with certification requirements. The results show that incorporating safety measures at a later stage will have a snowball effect on the aircraft design to meet certification requirements or stay within design constraints, such as weight. Furthermore, a novel abstract design methodology was developed to enable critical assessment of different aircraft aerodynamic configurations and explore new design spaces and novel architecture options. This methodology summarizes the relationship between aircraft aerodynamics and EPS requirements in a readily usable format. By combining the preliminary design methodology for a certification-compliant EPS architecture with the abstract design methodology, the complete assessment of various aircraft configurations and reliable EPS architecture designs and their weight for economic UAM missions can be achieved. Other main contributions of this thesis include the development of a preliminary certification compliance assessment for the use of non-resettable protection devices, specifically the Pyrofuse protection device, in eVTOL concept designs. The non-resettable nature of the device poses a challenge in the certification process for its integration into eVTOL electrical system protection. The assessment results demonstrate that the Pyrofuse protection device can achieve airworthiness in various roles as the primary protection for eVTOL EPS. However, the airworthiness is heavily influenced by the physical design of the aircraft, the proposed location of non-resettable protection devices, and their ability to withstand common mode and common cause failures to maintain minor failures. Model-based analysis plays a critical role in supporting this evaluation. Consequently, a comprehensive design methodology has been developed to transiently model Pyrofuse operation, which is publicly available. The results indicate that the Pyrofuse offers a significant level of resilience against transient events, minimising nuisance-tripping, while swiftly clearing short circuit faults. This model enables further assessment of Pyrofuse performance and susceptibility to different failure modes, including common mode failures.
Advisor / supervisor
  • Fong, Kenny (Chung Man)
  • Norman, Patrick J.
Resource Type
DOI

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