TY - GEN A1 - Neubauer, Moritz A1 - Pohl, Michael A1 - Kucher, Michael A1 - Böhm, Robert A1 - Höschler, Klaus A1 - Modler, Niels T1 - DMA of TPU Films and the Modelling of Their Viscoelastic Properties for Noise Reduction in Jet Engines T2 - Polymers N2 - Due to current developments in jet engine design, the acoustic performance of conventional acoustic liners needs to be improved with respect to lower frequency spectrums and broadband absorption. In this context, the present study aimed to determine the viscoelastic material properties of a thermoplastic polyurethane (TPU) film for targeted application in novel acoustic liners with integrated film material for enhanced noise reduction. Therefore, a dynamic mechanical analysis (DMA) was performed to determine these viscoelastic material properties. Based on the acquired data, the time-temperature shift (TTS) was applied to obtain the material’s temperature- and frequency-dependent mechanical properties. In this regard, the William-Landel-Ferry (WLF) method and an alternative polynomial approach determining the shift factors were investigated and compared. Furthermore, a generalized Maxwell model—so-called Prony-series—with and without pre-smoothing utilizing of a fractional rheological model was applied to approximate the measured storage and loss modulus and to provide a material model that can be used in finite element analyses. Finally, the results were discussed concerning the application of the films in acoustic liners under the conditions of a standard flight cycle and the applied loads. The present investigations thus provide a method for characterizing polymer materials, approximating their mechanical behavior for vibration applications at different ambient temperatures and enabling the identification of their operational limits during the application in acoustic liners. Y1 - 2022 U6 - https://doi.org/10.3390/polym14235285 SN - 2073-4360 VL - 14 IS - 23 ER - TY - GEN A1 - König, Paul A1 - Mischke, Marcel A1 - Pohl, Michael A1 - Kazula, Stefan A1 - Höschler, Klaus T1 - Concept Development and Evaluation for a Broadband Noise Absorbing Acoustic Liner Concept for Aviation T2 - 24th International Society For Air Breathing Engines (ISABE-2019-24261), 22.-27. September 2019 N2 - This paper presents design adaptations during the further development of innovative broadband acoustic liner concepts (Foil Helmholtz Resonator Liner; FHR-Liners) which utilise flexible foils within a honeycomb structure to attenuate engine and aircraft noise. The requirements for acoustic liners in aviation are described and utilised to derive evaluation criteria. Modifications of the FHR-Liner concept are introduced. A suitable concept evaluation method based on VDI 2225 is applied to evaluate the modified liner concepts concerning the main evaluation criteria. Y1 - 2019 UR - https://2019.isabe.org/content/uploads/ISABE2019_Technical_Program.pdf ER - TY - GEN A1 - Mischke, Marcel A1 - Pohl, Michael A1 - Höschler, Klaus A1 - Huppertz, André T1 - A Holistic Approach for the Generic Preliminary Design of Axial Compressor and Turbine Annulus Contours T2 - Conference Paper of the DLRK 2020 N2 - An essential aspect in the whole engine modelling of modern aircraft engines is the preliminary design of the meridional gas path definition. Especially the annulus dimensioning and topological characterisation of engine core subsystems are usually time-consuming. This paper presents a holistic and parametric approach to predesign the geometric 2D annulus contours of compressor and turbine subsystems without complex thermodynamic calculations. It is based on distribution functions of the axial and radial dimensions, as well as the variations of compressor and turbine stages and realises a time-efficient re-dimensioning and topological variation of the complex annulus geometry. Parametric methods for an optimised arrangement of the blade stages in a turbomachinery subsystem configuration are shown and integrated into a mathematical model. KW - Gas Path; Annulus Contour; Generic Preliminary Design; Turbine; Compressor Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:101:1-2020121112463561159960 UR - https://publikationen.dglr.de/?tx_dglrpublications_pi1%5bdocument_id%5d=530097 VL - Deutscher Luft- und Raumfahrtkongress 2020 PB - Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V. CY - Bonn ER - TY - GEN A1 - Mischke, Marcel A1 - Pohl, Michael A1 - Höschler, Klaus A1 - Huppertz, André T1 - GAS PATH DESIGNER – zeiteffiziente Vorauslegung von Triebwerks-Ringräumen und zusätzlichen Strukturen T1 - GAS PATH DESIGNER – Time Efficient Pre-Design of Aero Engine Annulus Contours and Additional Structures T2 - Conference Paper des Deutscher Luft- und Raumfahrtkongress 2020 N2 - Der Beginn einer jeden Triebwerksentwicklung startet mit der Auslegung des Ringraumes des Primärgasstromes. Hier müssen einige vorläufige aber auch grundlegende Entscheidungen zu Entwurfsparametern wie Eintrittsquerschnitte, Subsystemlängen, axiale Stufenanzahl in Verdichter und Turbine, usw. definiert werden. Für die Vorauslegung sollte die Palette an anfänglichen Entwurfsparametern so gering wie möglich gehalten werden, um die Menge an möglichen Ringraumentwürfen nicht frühzeitig einzuschränken. Dieses Paper präsentiert das Vorauslegungswerkzeug „Gas Path Designer“ (GPD), welches in der Lage ist Ringraumentwürfe für Turbotriebwerke über zeiteffiziente Berechnungsmethoden in kürzester Zeit bereitzustellen. Das Interface bietet eine Auswahl an Einstellungen, um die genannten Variationsmöglichkeiten zu unterstützen. Der Aufbau ist übersichtlich, um im Rahmen grundlegender konzeptorientierter Gespräche mit dem Kunden eine schnelle und beidseitig nachvollziehbare Variation und Visualisierung des Konzeptentwurfes zu ermöglichen. Des Weiteren können die erhaltenen Ringraumstrukturen der Triebwerksentwürfe als Leitstruktur für CAD-Programme sowie weiterführende Optimierungsstrategien genutzt werden. N2 - The beginning of each aircraft engine development starts with the design of the annulus contour of the primary gas path. In this case, preliminary but also fundamental decisions on design parameters such as inlet cross sections, subsystem lengths, number of stages in compressor and turbine and many more details have to be defined. For the preliminary design, the amount of initial design parameters should be kept as small as possible. Hence, the amount of possible annulus contours and future aero engine designs will not be limited at an early design stage. This paper presents the design tool "Gas Path Designer" (GPD) which is able to provide annulus designs for aero engines via time efficient calculation methods. The user interface offers a suitable range of settings to support the afore mentioned design variation possibilities. Hence, in the context of basic concept-oriented discussions with customers, the GPD allows a quick and mutually comprehensible variation and visualisation of conceptual designs. Furthermore, the resulting annulus contour of the aircraft engine designs can be used as a reference curves for CAD programs and advanced optimization strategies. KW - Gas Path Designer; Annulus Contour; Generic Preliminary Design; Aircraft Engine Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:101:1-2020121112494640076557 UR - https://publikationen.dglr.de/?tx_dglrpublications_pi1%5bdocument_id%5d=530098 VL - Deutscher Luft- und Raumfahrtkongress 2020 PB - Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V. CY - Bonn ER - TY - GEN A1 - Neubauer, Moritz A1 - Genßler, Julia A1 - Radmann, Vincent A1 - Kohlenberg, Fleming A1 - Pohl, Michael A1 - Böhme, Kurt A1 - Knobloch, Karsten A1 - Sarradj, Ennes A1 - Höschler, Klaus A1 - Modler, Niels A1 - Enghardt, Lars T1 - Experimental and Numerical Investigation of Novel Acoustic Liners and Their Design for Aero-Engine Applications T2 - Aerospace N2 - This paper presents a combined experimental and numerical investigation on a novel liner concept for enhanced low-frequency and broadband acoustic attenuation. In particular, two different realizations, derived from conventional Helmholtz resonators (HR) and plate resonators (PR) are investigated, which both deploy flexible materials with material inherent damping. In this context, a comprehensive experimental investigation was carried out focusing the identification and evaluation of various geometric parameters and material properties on the acoustics dissipation and related properties of various materials in a simplified setup of a single Helmholtz resonator with flexible walls (FHR concept). Furthermore, a parameter study based on analytical models was performed for both liner concepts, taking into account material as well as geometric parameters and their effects on transmission loss. In addition, design concepts that enable cylindrical or otherwise curved liner structures and the corresponding manufacturing technologies are presented, while considering essential structural features such as drainage. With respect to the potential application in jet engines, a structural–mechanical analysis considering the relevant load cases to compare and discuss the mechanical performance of a classical HR and the FHR concept liner is presented. Finally, both concepts are evaluated and possible challenges and potentials for further implementation are described. Y1 - 2023 U6 - https://doi.org/10.3390/aerospace10010005 SN - 2226-4310 VL - 10 IS - 1 ER -