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This work explores the design and optimization of electrified configurations in aviation, focusing on the application and adaptation of these technologies across various aircraft classes. It utilizes a range of methodologies, including the development of a novel engine design approach, multi-disciplinary frameworks and the integration of surrogate modeling techniques, to enhance the conceptual design process and facilitate efficient exploration of complex design spaces.

This work demonstrates that electrified systems can significantly improve fuel efficiency and reduce emissions, particularly in short-haul applications where the current limitations of battery technology are less restrictive. The work identifies critical design trade-offs, such as the impact of battery weight on overall aircraft performance and the benefits of distributed propulsion systems in reducing aerodynamic drag and enhancing energy efficiency.

An uncertainty analysis further reveals the critical role of technological advancements in electrical powertrain components and their implications for the operational viability of electrified aircraft. The findings indicate that while near-term benefits can be achieved with current hybrid configurations, fully electrified aircraft will depend on future improvements in battery energy density and powertrain technologies.

Through these diverse methodologies and analyses, this work contributes to a deeper understanding of the challenges and opportunities in electrified aircraft design, offering insights that are crucial for advancing sustainable aviation.

This work delves into the design and operation of a series/parallel partial hybrid-electric architecture for regional aircraft. Employing a comprehensive approach, this study leverages mission-level analysis to optimize a 19-passenger hybrid-electric aircraft. The conceptual design framework employed is based on the OpenConcept library, and a systematic computational scheme is developed to effectively investigate the concept’s performance, utilizing the supplied and shaft power ratios. Through the examination of three distinct mission ranges and consideration of two technological scenarios, this work offers valuable insights. For the longest mission, an aircraft design optimization problem is posed, and a 23% reduction in total energy consumption is achieved for the optimistic technological scenario. On the other hand, the focus shifts to optimize the power management for shorter missions, where a 26% and a 32% reduction in energy consumption are achieved for the typical and short missions. The results highlight the potential of hybrid-electric propulsion for regional aircraft.

This study addresses the uncertainties in hybrid-electric powertrain technology for a 19-passenger commuter aircraft, focusing on two future Entry-Into-Service timeframes: 2030 and 2040. The methodology is split into a preliminary optimization of aircraft design based on nominal technology scenarios followed by Monte Carlo simulations to investigate the impact of diverse technology projections and distribution types. Advanced surrogate modeling techniques, leveraging deep neural networks trained on a dataset from an aircraft design framework, are employed.

Key outcomes from this work reveal a marked increase in computational efficiency, with a speed-up factor of approximately 500 times when utilizing surrogate models. The results indicate that the 2040 EIS scenario could achieve larger reductions in fuel and total energy consumption—20.4% and 15.8% respectively—relative to the 2030 scenario, but with higher uncertainty. Across all scenarios examined, the hybrid-electric model showcased superior performance compared to its conventional counterpart. The battery specific energy density is proved to be a critical parameter of the aircraft's performance across both timeframes. The findings emphasize the importance of continuous innovation in battery and motor technologies to target towards greater system-level efficiency and reduced environmental impact.

This work presents a comprehensive analysis of hybrid electric propulsion systems in commuter aircraft, aimed at enhancing energy efficiency. The study utilizes an aircraft conceptual design library, OpenConcept, to perform evaluations of various aircraft components and their interrelationships. The methodology integrates aerodynamics, propulsion, and mission analysis within a common framework to optimize the aircraft design. The analysis focuses on a 19-passenger commuter aircraft, employing a series/parallel hybrid-electric architecture. The gradient-based Sequential Least Squares Programming optimizer is utilized to optimize design variables such as battery weight, engine power, and the selected power ratios, while adhering to operational constraints. Through a rigorous Design of Experiments study, the paper highlights that even when considering the current battery technology, hybrid-electric propulsion yields substantial energy savings for short-haul missions. The fuel and energy consumption reductions are evident, particularly for shorter ranges. However, for extended missions, the critical role of advanced battery energy density is emphasized to achieve significant energy efficiency improvements. 

Hybrid electric propulsion system-based aircraft designs are paving the path toward a future greener aviation sector and thus, have been the major focus of the aeronautical community. The fuel efficiency improvement associated to such propulsion system configurations are realized at the aircraft level. In order to assess such benefits, a radical shift in the subsystem modeling requirements and of a conceptual-level aircraft design environment are necessary. This work highlights performance model development work pertaining to different hybrid electric propulsion system components and the development of a design platform that facilitates tighter integration of different novel propulsion system disciplines at the aircraft level. Furthermore, a serial/parallel partially distributed hybrid electric propulsion system is chosen as the candidate configuration to assess the potential benefits and associated tradeoffs by conducting multidisciplinary design space exploration studies. It is established that the distributed hybrid electric configurations pose the potential for aircraft structural weight reduction benefits. The study further illustrates the impacts of onboard charging during the low thrust requirement segments, quantitatively. The provision of onboard charging lowers the potential for block fuel savings, and improvement in battery specific energy can make it more promising, which is also dependent on the hybridization power level. It is established that distributed propulsion system configurations particularly benefit from a high aspect ratio wing structure, which manifests in high hybridization power levels. A high voltage level transmission system with more efficient electrical components enhances opportunities for achieving block fuel saving benefits.

Higher education has been crucially impacted by the pandemic during the past years. Despite the associated challenges, a wide portfolio of digital literacies has been developed for the delegates. This work evaluates the introduction of digital tools into in-person education. The “Process Optimization” course at Mälardalen University is reformed to operate in a digitally enhanced classroom mode. The course covers a variety of optimization methods applied on thermal and fluid machinery such as systems of compressors, pumps and heat exchangers, heat and power plants, aircraft trajectories and propulsion systems. The constructive alignment is presented to illustrate links between learning objectives, learning activities, and assessment tasks. A series of digital tools is introduced to elevate learning experience prior, during, and after class time. Those comprise digital quizzes, a video channel, polls, a digital whiteboard, and a digital forum. The course is systematically instrumented, yielding a vast set of statistics for evaluating the effectiveness of digital tools as well as engagement levels for learners. The contribution of digitalization into standardizing the formative and summative assessment is discussed. It is observed that digital tools complement the participation into pre- and post-classroom activities. An interactive and digitalized course evaluation activity is also designed. This allowed learners and educators to productively exchange feedback in an inclusive manner. The accrued data provides insight into the impact of digitalization on the delivery of an applied engineering course. Lessons learnt comprise quantitative and qualitative outcomes arising from the perspectives of both learners and teachers. Guidelines and recommended practices are provided for the penetration of digital tools into synchronous and asynchronous learning activities. This paper identifies opportunities as well as space for improvement arising from the penetration of digital tools into the new era for education.

The increasing environmental concern during the last years is driving the research community towards reducing aviation’s environmental impact. Several strict goals set by various aviation organizations shifted the research focus towards more efficient and environmentally friendly aircraft concepts. Boundary Layer Ingestion (BLI) is currently investigated as a potential technology to achieve different design goals such as energy efficiency improvement and noise emission reductions in the next generation of commercial aircraft. The technology principle is to place the propulsive unit within the boundary layer generated by the airframe body. Although several studies showed its theoretical benefits, a multidisciplinary nature is introduced in the design phase. This imposes new challenges on the current design tools. An increasing number of publications are focusing on assessing this technology while taking into account interlinks between different disciplines. The goal of this work is to review the current state-of-the-art of BLI evaluation studies. Particular focus is given to the underlying assumptions of each work, the methodology employed, and the level of fidelity of the tools used. By organizing the available work in a comprehensive manner, the up-to-date results are interpreted. The current trends and trade-offs emerging from studies are presented. Through reviewing the ongoing published work, the next steps for further development of the methods that will assess this technology are derived. 

Hybrid electric propulsion system based aircraft designs are paving the path towards a future greener aviation sector and thus, have been the major focus of the aeronautical community. The fuel efficiency improvements of such propulsion system configurations are realized at the aircraft level. In order to assess such benefits, a radical shift in the sub-system modeling requirements and an integrated conceptual aircraft design environment is necessary. This work highlights performance model development work pertaining to different hybrid electric propulsion system components and development of a design platform which facilitates tighter integration of different novel propulsion system disciplines at aircraft level. Furthermore, a serial/parallel partially distributed hybrid electric propulsion system is chosen as the candidate configuration to assess the potential benefits and associated trade-offs by conducting multidisciplinary design space exploration studies. It is established that the distributed hybrid electric configurations pose the potential for aircraft structural weight reduction benefits. The study further illustrates the impacts from onboard charging during the low thrust requirement segments, quantitatively. It is highlighted that the amount of off-take power extraction for onboard charging of the battery is limited due to engine operability and higher specific fuel consumption issues. Though provisioning of onboard charging lowers the potential for block fuel savings, improvement in battery specific energy can make it more promising, which is also dependent on the hybridization power level. It is established that distributed propulsion system configurations particularly benefit from a high aspect ratio wing structure, which manifests for high hybridization power levels. A high voltage level transmission system with more efficient electrical components, enhances opportunities for achieving block fuel saving benefits.

During the last years, the aviation industry has shifted its focus towards increasing the aircraft efficiency. The constant drive to search for more efficient systems has led to the introduction of novel concepts. These concepts expand the design space but, at the same time, bring several challenges to the design process. One of the challenges is to develop a conceptual engine design model that can work effectively and provide consistently accurate solutions, even when there are dramatic changes in design constraints. In this work, a multipoint synthesis approach is developed which considers multiple points during the design phase. By incorporating multiple operating points into the design analysis phase, it is ensured that all performance requirements and design constraints are satisfied. A comparison between the traditional engine design approach and the proposed approach is presented to showcase the advantages of the proposed method. A parametric analysis of a geared turbofan configuration is conducted for both design approaches. Then, the multi-point synthesis approach is employed for the design space exploration of a conventional geared turbofan engine and a parallel-hybrid (or boosted) turbofan engine. To enable these studies, surrogate models are developed which utilize machine learning methods in a database of converged engine designs and can ensure the effective and fast operation of the engine model. It is concluded that this surrogate adapted algorithm improves computational efficiency and can be used to evaluate alternative designs.

The parallel hybrid (or boosted) turbofan engine alleviates the system complexity of radical electrified powertrain architectures, while also demonstrates substantial benefits in reducing specific fuel consumption. This conservative, yet promising, electrified configuration incorporates an electrical drive coupled with the engine low-pressure or gearbox fan spool. Sophisticated models for the gas turbine and the electrical drive system are developed. The former deploys a multi-point design matching scheme coupled with an installed engine performance approach, as well as an engine sizing and weight estimation tool. The latter incorporates an analytical electrical machine sizing and performance methodology. The objective of this paper is to shed light on the optimal parallel hybrid engine design, considering installed cycle performance and tight coupling of engine and electrical drive systems. The impact of installation drag components on the integrated powertrain system performance is analyzed and design trade-offs are explored. Electrical machine efficiency, propulsion system weight and installed specificfuelconsumptiondemonstrateopposingtrendswithvaryingspecificthrustfordifferent electrical drive installation positions and mechanical connections. It is shown that fan spinner-mounted electrical machine which is mechanically coupled to the low-pressure spool presents the greatest potential in terms of electrical machine efficiency and propulsion system installed performance. A 11.23% and 15.11% increase in installed specific fuel consumption at Top of Climb and Cruise, respectively, is observed for the Cruise-based optimal specific thrust variant, rendering installation effects and electrical drive considerations critical for future low-specific thrust hybrid-electric aero-engine concepts.