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    Item type:Publication, Access status: without files ,
    Engine cycle adaptation method for aircraft on-board systems evaluation considering system-engine interaction
    (American Institute of Aeronautics and Astronautics (AIAA), 2024-01)
    Kriewall, Vivian
    ;
    Jünemann, Marc
    ;
    Thielecke, Frank
    In the assessment of different aircraft on-board systems (OBS) using mission-level metrics like fuel burn, typically the same engine performance model is employed. One example is the comparison of conventional versus bleedless architectures with respect to their impact on mission block fuel. However, especially with the application of ultra-high bypass ratio (UHBR) turbofans, the cycle performance of such engines increasingly varies depending on the power offtakes (POT) requirements of the considered OBS architecture. This paper proposes a method for adapting the thermodynamic engine cycle to accommodate OBS POT requirements based on a given reference cycle. The method iteratively adjusts relevant engine design parameters by employing physical and semi-empirical correlations. The gas turbine simulation software NPSS is embedded into this process, ultimately posing the adapted cycle design point based on the input design parameters. The presented method is applied in the scope of an OBS architecture trade study for a modern mid-range concept aircraft. The results show a -0.7% reduction in block fuel mass for a bleedless OBS architecture with an adapted bleedless engine compared to the same bleedless architecture in combination with a conventional reference engine designed for bleed offtakes. This highlights the importance of integrated OBS architecture studies, for which the engine’s cycle design point and the employed engine performance model is adapted to the POT requirements for more accurate evaluation results.
    Publicationtype: Conference Paper
      21
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    Overall Systems Design Method for Evaluation of Electro-Hydraulic Power Supply Concepts for Modern Mid-Range Aircraft
    (2022-06)
    Jünemann, Marc
    ;
    Bielsky, Thimo
    ;
    Kriewall, Vivian
    ;
    Thielecke, Frank
    It is an important task during conceptual design of aircraft on-board systems to identify tipping points, at which novel system technology concepts become superior to a state-of-the-art solution. Such a tipping point can occur, inter alia, at a specific size of an aircraft. For instance, zonal hydraulic power supply concepts, which generate the hydraulic power in the vicinity of the respective hydraulic actuation systems, reduce the amount of hydraulic pipe installations. While it has already been shown, that for a short-medium range aircraft the associated mass savings are outweighed by the additional electro-hydraulic power supply modules, the result might be different for a larger aircraft size. To answer such “what if” questions during the early design phases, system design methods are required, which balance fidelity and flexibility of analysis models on an overall systems level. In this paper, overall systems design (OSD) methods for an evaluation of electro-hydraulic (eH) power supply concepts are presented. They are exemplified by a system trade study comparing two eH power supply architectures for a modern mid-range aircraft – i.e. a centralized and a zonal arrangement. The results underline the importance of OSD methods, because the calculated mass savings on system-level which can be achieved with both eH supply concepts do not translate to savings in mission fuel mass and direct operating costs. Instead, a preliminary analysis of direct operating cost (DOC) indicates, that the system acquisition costs need to be lower for both eH power supply concepts compared to the conventional architecture to achieve the same total net present value (NPV) as a conventional systems architecture over an assumed product lifespan of 25 years.
    Publicationtype: Conference Paper
      48
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    Validation of an Aerodynamic Model for the Analysis of Subscale Test Aircraft with Distributed Electrical Propulsion
    (2021-09)
    Luderer, Oliver
    ;
    Jünemann, Marc
    ;
    Thielecke, Frank
    In this publication an aerodynamic model for the estimation of aerodynamic effects of propeller-wing-interaction for analysis, design and construction of subscale test aircraft (STA) is presented. The well-established programmes XFOIL, XROTOR and LIFTING_LINE are used as subroutines in an automated analysis process. The model for propeller-induced velocities is based on a combination of blade-element theory and a vortex theory. The effect of propeller slipstream contraction on the simplified velocity field is considered with a semi-empirical model. To estimate the spanwise lift distribution of the wing, a multi-lifting line method was chosen which accounts for the additional axial and transverse slipstream velocities. Comparison of simulation results with measurement data from wind tunnel tests shows satisfying accuracies regarding thrust, wing polars, and spanwise lift distribution. In addition, the toolchain is integrated into a modular software framework for design and construction of SubsCALe test AircRaft (SCALAR). Its application is exemplified with a resizing study of a subscale aicraft model with distributed electrical propulsion. The study shows that the overall impact on the layout of the subscale test aircraft is of minor importance. Nonetheless, it is outlined that the presented aero-dynamic toolchain serves well as a basis for mission-dependent wing load estimation in planned technology demonstration campaigns.
    Publicationtype: Conference Paper
      231
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      82
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    Methodology for design and evaluation of more electric aircraft systems architectures within the AVACON project
    (Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V. (DGLR), 2019-01-11)
    Jünemann, Marc
    ;
    Thielecke, Frank
    ;
    Peter, F.
    ;
    Hornung, Mirko
    ;
    Schueltke, F.
    Within the research project AdVanced Aircraft CONfiguration (AVACON) a collaborative conceptual design of a mid-range aircraft with ultra high bypass ratio (UHBR) engines and an envisioned entry-into-service in the year 2028 is conducted. In this paper, the approach for overall architecting, sizing, and evaluation of aircraft on-board systems in AVACON is presented. To this end, important contributions to conceptual system design methods proposed in the literature are reviewed to identify directions for methodological improvements. The role allocation of contributing partners and their methodologies for system design activities is described. Having different contributors guarantees, that tasks from overall aircraft to detailed subsystem design with a successive increase in the fidelity of system models is covered. In addition, a state-of-the-art baseline architecture is defined, which will serve as a starting point to conduct trade-off studies for investigation of the potential of system architecture concepts and innovative technologies. Substantial system design requirements and novel boundary conditions, implied by the advanced aircraft configuration, are derived to give an outlook for planned technology studies.
    Publicationtype: Journal Article
      49
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    Aerodynamische Analyse verteilter Antriebe an einem Flügelsegment eines hochgestreckten Flügels
    (Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V. (DGLR), 2019)
    Lemke, Lars-Hendrik
    ;
    Luderer, Oliver
    ;
    Jünemann, Marc
    ;
    Montel, Mike
    ;
    Zumegen, Clemens
    In dieser Veröffentlichung wird der Einfluss von verteilten Antrieben an einem Flügelsegment auf die Tragflächenaerodynamik experimentell und numerisch untersucht. Für die numerische Modellierung werden die Bereiche Propellerebene, Propellernachlauf und Tragfläche betrachtet. Dabei wird für die Modellierung der Strömung innerhalb der Propellerebene eine Blattelement-Impuls-Theorie (BEMT), für den Propellernachlauf ein auf der Rankine?schen Strahltheorie basierendes Propellerstrahl- Kontraktionsmodell und zur Modellierung der Tragflächenaerodynamik ein Mehrfachtraglinienverfahren verwendet. Zusätzlich werden Experimente durchgeführt, um Versuchsdaten zu gewinnen und die theoretischen Modelle für eine spätere Verwendung in der Flugzeugvorentwurfsumgebung MICADO validieren zu können. Die implementierten Modelle werden mit Ergebnissen aus Windkanalversuchen für ein rechteckiges Flügelsegment mit drei verteilten Antrieben verglichen. Dazu wird ein modulares Flügelkonzept (TETRIS) zur Messung von dynamischen Drücken und aerodynamischen Lasten entwickelt. Die modulare Bauweise erlaubt für die betrachtete Reynoldszahl von ungefähr 5 105 eine flexible Anordnung der Komponenten und damit die Untersuchung unterschiedlicher Propeller-Flügel- Konfigurationen mit nur einem Windkanalmodell. Im Vergleich mit den Messdaten konnte gezeigt werden, dass die numerischen Ergebnisse mit dem entwickelten Propellermodell insbesondere im linearen Auftriebspolarenbereich eine geringe Abweichung zu den experimentellen Ergebnissen aufweisen. Die lokalen Auftriebsverläufe können zudem mit einem hohen Detailgrad abgebildet werden, wenngleich signifikante Abweichungen zu den experimentellen Daten auftreten. Diese können primär auf eine Unterschätzung der tangentialen Komponente der durch den Propeller induzierten Geschwindigkeit zurückgeführt werden.
    Publicationtype: Conference Paper
      29