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The aviation industry is facing major challenges due to increased environmental requirements that are driven by economic constraints. For this reason, guidelines like "Flightpath 2050", the official guide of European aviation, call for significant reductions in pollutant emissions. The concept of the More Electric Aircraft offers promising perspectives to meet these demands. A key-enabler for this concept is the integration of new technologies on board of the next generation of civil transportation aircraft. Examples are electro-mechanical actuators for primary and secondary flight controls or the fuel cell technology as innovative electrical energy supply system. Due to the high complexity and interdisciplinarity, the development of such systems is an equally challenging and time-consuming process.

This paper focuses on the virtual integration and test approach used for the evaluation of an automation system developed for the multifunctional operation of fuel cells in commercial aircraft. In order to accomplish the virtual integration a model of the overall automation system is linked with a dynamic model of the complete fuel cell system. For this purpose a modeling approach for complex physical systems is described in this paper. During virtual testing various simulation runs are executed based on automatically generated test cases, which cover a complete flight mission. For this reason a flight mission is modeled as a Statechart that includes next to time- based flight phases also potential events and malfunctions (e.g. engine flame-out, cargo fire). An algorithm is described, which can find all possible state combinations including parallel event sequences.

Fuel cell technology will play a decisive role in the process of achieving the ambitious ecological goals of the aviation industry. However, apart from its obvious environmental advantages, the integration of fuel cell technology into commercial aircraft represents a challenging task in terms of operational and economical aspects. Since fuel cell systems are currently exposed to an intense competition with well-established power sources onboard an aircraft, engineers are in pursuit of highly efficient and particularly lightweight fuel cell systems. Supported by model-based design in conjunction with elaborate optimization techniques this pursuit has led to highly specialized systems. These systems tend to use their components to full capacity, which typically implies marginal system robustness. In consequence, preliminary design studies propose fuel cell systems that are sensitive to partial faults, or even to the slightest deviation, or degradation of their components' behavior.

The integration of fuel cell systems as an independent energy source (Auxiliary Power Unit, APU) requires enhanced aircraft cooling architectures. New environmental control systems and systems with an increased cooling demand are investigated in various research projects. Cooling system architectures can be designed which benefit from similar requirements, e.g. by using the same cooling loops. Additionally, an increased cooling demand makes the investigation of alternative heat sinks necessary. For detailed system investigations simulation studies are used. A model library has been created in Dymola/Modelica containing the necessary component models to simulate cooling systems. The used modeling approaches and main model information are presented in this article. In order to understand the basic system behavior a Design of Experiment (DOE) is useful. If only two or three parameters are considered, simulation studies can be performed for each possible parameter combination.

The All-Electric-Engine with only electrical power offtake is a main goal in aircraft system development. The use of electric-motor pumps instead of engine-driven pumps for powering the central hydraulic systems could be a part of this objective. Additionally, the concept would meet the incremental development strategy performed by the aerospace industry today and saves costs by using state-of-the-art hydraulic actuation technology. This paper describes a process for optimizing such systems regarding their architecture and design parameters. For this task a methodology for the hydraulic consumer allocation called OPAL is used and extended by an automatic power system sizing. Feasible allocations, called permutations, are determined on the basis of preliminary system safety assessments regarding multiple top failure events. In the next step an automated sizing of the permutations is performed based on simplified hydraulic load analyses.