Development of a Multi-Disciplinary Analysis and Optimization framework and applications for innovative efficient regional aircraft

An in-depth market analysis of the regional aircraft segment has revealed that world passenger traffic is expected to maintain 4.4% annual growth over the next two decades. In a context of economical growth, oil price is expected to double in the next 20 years, regardless of temporary fluctuations. Thus, fuel price will again be a key decision factor for airlines. Furthermore, in terms of regional market, fuel price is higher in regional airports than in main airports due to higher fuel transportation costs, which translates to a worldwide average extra cost of +34%. At the same time world air transport demand will increase 2.5 times by 2037, reaching 17 trillion Revenue Passenger Kilometers (RPKs) for all commercial aircraft segments. As middle-class and consumer spending increase in many regions, the propensity to travel will develop with new emerging regional markets taking the lead. By 2037, the Middle East and Asia Pacific will be the fastest growing markets, with an annual growth rate of 5.7%, followed by Latin America with 5.2%, Africa with 4.8%. In this scenario, turboprops, as typical first movers, offer higher rewards for exploring new routes and developing regional networks. However, being the aircraft one of the most polluting means of transport, future aircraft must also comply with the environmental issue. The climate change and the increasing lack of resources claim for a clear reduction of the aviation impact on citizens and the environment. The integration of innovative and affordable technologies in future aircraft platforms plays a key role to increase the appeal and the benefits for both customers and airlines. The combination of all these factors results in a very challenging design process for engineers to come up with innovative aircraft configurations and technologies. Regional aircraft are playing an increasingly role in the evolution of the airline operations. For many years, this growth has been faced by a wide adoption of regional jets. Their success can be largely attributed to their popularity with passengers, who prefer them because they are more comfortable and faster than turboprops. The regional jet market has grown to be a strong sector based on a combination of higher loads and greater profitability. Embraer foresees world demand for 8230 new jets up to 150-seat segment over the next 20 years. However, despite the regional jets success, turboprop engines are 10-30% more efficient than jet engines in cruise conditions leading to a potential consistent reduction of the amount of fuel used per mission as well as pollutant emissions. According to ATR forecasts, assuming all short haul flights operated by regional jets today are replaced by modern turboprops, 11% of overall regional aviation CO2 emissions could be saved. State this, regional jets provides for faster connections with a higher payload in spite of higher fuel consumptions and pollutant emissions; while turboprop aircraft allows to reduce air transport environmental impact but with lower passengers capacity and lower speed. Thus, the research question at the base of this thesis is: “What could be the impact, in terms of performance, that innovative high-capacity turboprop aircraft configurations can have on the current regional aircraft scenario?” To answer this question this work will define a set of Top-Level Aircraft Requirements (TLARs) suitable for modern regional transport applications which will be used to design several innovative turboprop aircraft platforms. Each of them will undergo a complete Multi-Disciplinary Analysis and Optimization (MDAO) process to define the set of optima configurations. Finally, a comparison with the current state of the art regional jet platform, represented by the Airbus A220, will be performed. The MDAO process will be carried out using the Java toolchain of Programs for Aircraft Design (JPAD) framework developed at the University of Naples Federico II by the Design of Aircraft and Flight technologies (DAF) group. The author has personally developed most of the JPAD modules that will be presented with particular focus on the performance and the MDAO modules. The first one has been completely designed using a simulation-based approach to easily perform accurate and fast flight and ground performance analyses; while the second one uses all the advantages provided by Object-Oriented Programming (OOP) to perform a full factorial Design Of Experiments (DOE) followed by a multi-objective optimizations process involving computational intelligences like Genetic Algorithms (GA) or Particle Swarm Optimization (PSO) algorithms. The JPAD framework, especially in term of performance evaluation, has been widely used during the first two loops of the Clean Sky 2 European project named IRON from which all innovative turboprop configurations under examination have been derived. JPAD is the result of the efforts of the DAF research group which involved several PhD students in a virtuous collaboration process, including the author of this thesis work. Because of the multidisciplinary nature of research, an added value of this thesis can be found in the combination of two complementary branches of engineering: Aerospace, in terms of Aircraft Design, and Computer Science, in terms of Software Engineering