Influence of future airframe and propulsion technologies on energy-efficient aircraft

The competitive nature of the aviation sector and new environmental challenges have put difficult requirements for the next generation of aircraft. To significantly improve the energy efficiency of future aircraft, the maximization of current technologies may not be sufficient. Therefore, more radical solutions with respect to airframe and propulsion technologies are required to satisfy the given recommendation for future aircraft. The introduction of future technologies also requires the design of novel aircraft that could fully utilize the benefits of those technologies and maximize the overall energy efficiency. The present thesis investigates the influence of several promising future airframe and propulsion technologies on the design of future sustainable and energy-efficient aircraft. Laminar flow control, load alleviation, advanced materials and manufacturing processes, boundary layer ingestion, ultra-high bypass ratio turbofan engines, and various sustainable energy sources are considered for the present work. The goal of the study is to investigate potential configurations that could maximize the benefits of future technologies, determine the influence of technologies at the overall aircraft level, and assess their implementation from both performance and cost perspectives. Aviation sectors from short-range regional to long-range transatlantic and the business jet market are considered for potential implementations of selected technologies. To answer the given design questions, a multi-fidelity design environment is developed, which includes a wide range of conceptual design methods and energy system models to design various aircraft. Moreover, the initial sizing methodology is developed that obtained a robust sizing of both conventional and unconventional configurations and performed their multi-stage analysis and refinements using optimization algorithms. For each aviation sector, multiple configurations are studied to determine the best possible candidates to satisfy given mission requirements. Overall, advanced airframe technologies are capable of not only significantly improving the performance of aircraft but also introducing configurations that are not currently feasible due to technological limitations. Moreover, for commercial aircraft, results demonstrate strong relationships between emission reduction and operating costs that remain conflicting aspects and require a trade study to establish a balance between them. If a proper combination of energy sources, technologies, and aircraft configuration is used, both emission reduction and a market success opportunity can be achieved with future technologies. Moreover, the performance of future technologies may also affect the choice of future energy sources to satisfy both emissions and costs. However, future technologies shall be carefully considered with respect to their costs and complexities to ensure their commercially successful implementation. Moreover, apart from airframe and propulsion technologies improvements, operating aspects of future aircraft shall also be reconsidered depending on future goals to maximize the efficiency of next-generation aircraft.