Filters

Settings

Now showing1 - 3 of 3
  • Some of the metrics are blocked by your 
    consent settings
    Item type:Publication, Access status: without files ,
    Interactions and synergies between aircraft on-board systems and hydrogen turbofans
    (American Institute of Aeronautics and Astronautics (AIAA), 2025-01)
    Kriewall, Vivian
    ;
    Herrmann, Jannik
    ;
    Thielecke, Frank
    The intensive research currently being conducted on hydrogen-powered aircraft concepts poses several integrational challenges. Given that the hydrogen is stored in a liquid state on board the aircraft, a comprehensive analysis is necessary to determine the source of energy required to heat the hydrogen for direct combustion in turbofans. Since the engine itself poses a high-power heat source, it seems feasible that its waste heat may be used for hydrogen conditioning. This paper proposes three different hydrogen engine fuel heat management concepts. These comprise a finned flat tube heat exchanger at different positions within the core engine’s gas stream. A fourth option is presented, which postulates the use of hydrogen instead of fan air to cool customer bleed air. The concepts are evaluated at engine and at mission level, employing an enhanced engine resizing and heat exchanger conceptual design methodology. The results propose that in terms of thrust-specific energy consumption and mission block fuel mass, the intercooler concept is the favorable option. This is mainly attributed to a lower aircraft mass and lower air-side pressure losses compared to the other concepts subject to the study. In addition, the engine cycle efficiency benefits from intercooling the core airflow.
    Publicationtype: Conference Paper
      32
  • Some of the metrics are blocked by your 
    consent settings
    Item type:Publication, Access status: without files ,
    Identification of critical test scenario groups for aircraft functions based on operational design domains
    (American Institute of Aeronautics and Astronautics (AIAA), 2025-01)
    Krause, S.
    ;
    Reglitz, S.
    ;
    Hillig, Dennis
    ;
    Thielecke, Frank
    ;
    Franke, Marco
    The development of aircraft systems requires robust verification and validation processes to ensure safety, reliability, and functionality. The rapid advancements in system automation have introduced a level of complexity where traditional testing methods reach their limits. Such methods often encounter challenges in identifying critical test scenarios early in the development cycle, which can cause delays. This delay can lead to significant cost implications due to late error detection and subsequent redevelopments. The primary objective of this research is to develop a method that enhances the early identification of critical test scenarios, thereby improving the efficiency and effectiveness of the testing process by using the concept of operational design domains (ODD) as a framework. By employing a hierarchical ODD approach, this study creates smaller, priority test groups that can be continuously used and shared among stakeholders throughout the testing process. As a further step, a stochastic test exploration method is used to generate a variety of scenario-based test cases, including critical test cases. These test cases, written in TA-SCXML, are analyzed using ODD-based observers within a virtual integration environment. To identify test cases to be shared between stakeholders, a grouping concept is proposed. The groups contain critical test cases that verify the behavior as described by the ODD, as well as test cases that explore behavior outside of the ODD. The method is applied on a flight control use case involving a virtually integrated software prototype for investigating new flight automation concepts for an UAV. The proposed method successfully identifies critical scenario-based test cases, which are then grouped and provided to suppliers and other stakeholders.
    Publicationtype: Conference Paper
      22
  • Some of the metrics are blocked by your 
    consent settings
    Item type:Publication, Access status: without files ,
    Buckling tests of cylindrical composite shells in multiaxial loading
    (American Institute of Aeronautics and Astronautics (AIAA), 2025-01)
    Panek, Stefan
    ;
    Reuter, Niklas
    ;
    Hartwich, Tobias S.
    ;
    Kriegesmann, Benedikt
    ;
    Krause, Dieter
    Thin-walled cylindrical composite shells are prone to buckling failure in a variety of load cases. The number of influencing factors and comparably small amount of test data on combined load cases, which regularly occur in application, pose a major design challenge. Two experimental campaigns on the buckling of thin-walled cylindrical composite shells in multiaxial loading are carried out with two nominally identical specimens with a radius-to-thickness-ratio of 375. The results of buckling tests with combined axial compression and torsion, compression and bending, as well as all three buckling critical load types are presented. The influence of the loading direction of bending and torsion is shown, and the effects of repeated mounting of the specimens in the test rig as well as the scatter of buckling loads are discussed. Comparison of test results with the established NASA SP-8007 guideline and perfect buckling loads shows major qualitative and quantitative differences in the load interaction curves.
    Publicationtype: Conference Paper
      45