@misc{MischkePohlHoeschleretal., author = {Mischke, Marcel and Pohl, Michael and H{\"o}schler, Klaus and Huppertz, Andr{\´e}}, title = {GAS PATH DESIGNER - zeiteffiziente Vorauslegung von Triebwerks-Ringr{\"a}umen und zus{\"a}tzlichen Strukturen}, series = {Conference Paper des Deutscher Luft- und Raumfahrtkongress 2020}, volume = {Deutscher Luft- und Raumfahrtkongress 2020}, journal = {Conference Paper des Deutscher Luft- und Raumfahrtkongress 2020}, publisher = {Deutsche Gesellschaft f{\"u}r Luft- und Raumfahrt - Lilienthal-Oberth e.V.}, address = {Bonn}, doi = {https://doi.org/10.25967/530098}, url = {http://nbn-resolving.de/urn:nbn:de:101:1-2020121112494640076557}, pages = {10}, abstract = {Der Beginn einer jeden Triebwerksentwicklung startet mit der Auslegung des Ringraumes des Prim{\"a}rgasstromes. Hier m{\"u}ssen einige vorl{\"a}ufige aber auch grundlegende Entscheidungen zu Entwurfsparametern wie Eintrittsquerschnitte, Subsysteml{\"a}ngen, axiale Stufenanzahl in Verdichter und Turbine, usw. definiert werden. F{\"u}r die Vorauslegung sollte die Palette an anf{\"a}nglichen Entwurfsparametern so gering wie m{\"o}glich gehalten werden, um die Menge an m{\"o}glichen Ringraumentw{\"u}rfen nicht fr{\"u}hzeitig einzuschr{\"a}nken. Dieses Paper pr{\"a}sentiert das Vorauslegungswerkzeug „Gas Path Designer" (GPD), welches in der Lage ist Ringraumentw{\"u}rfe f{\"u}r Turbotriebwerke {\"u}ber zeiteffiziente Berechnungsmethoden in k{\"u}rzester Zeit bereitzustellen. Das Interface bietet eine Auswahl an Einstellungen, um die genannten Variationsm{\"o}glichkeiten zu unterst{\"u}tzen. Der Aufbau ist {\"u}bersichtlich, um im Rahmen grundlegender konzeptorientierter Gespr{\"a}che mit dem Kunden eine schnelle und beidseitig nachvollziehbare Variation und Visualisierung des Konzeptentwurfes zu erm{\"o}glichen. Des Weiteren k{\"o}nnen die erhaltenen Ringraumstrukturen der Triebwerksentw{\"u}rfe als Leitstruktur f{\"u}r CAD-Programme sowie weiterf{\"u}hrende Optimierungsstrategien genutzt werden.}, language = {de} } @misc{XieStarickMosgowetal., author = {Xie, Tianxiao and Starick, Tommy and Mosgow, Anatol and Berg, Heinz Peter and H{\"o}schler, Klaus and Schmidt, Heiko}, title = {Thermofluiddynamic pre-design of a primary surface heat exchanger under the influence of heat radiation using 1D/3D coupled simulation method}, series = {NAFEMS World Congress 2021, online, 25-29. Oktober 2021}, journal = {NAFEMS World Congress 2021, online, 25-29. Oktober 2021}, pages = {25}, abstract = {Within the Framework of the "TurboFuelCell (TFC)" a highly integrated and compact energy conversion system based on Micro Gas Turbine Solid Oxide Fuel Cell (MGT-SOFC) hybrid process is being developed by the team at BTU-Cottbus Senftenberg. This work focuses on the extension of the pre-design process of a primary surface heat exchanger (PSHX), which is a key component for the coupling between MGT and SOFC, using an 1D/3D hybrid simulation method for the understanding of its behaviour under the influence of heat radiation. In a MGT-SOFC hybrid process the high temperature heat exchanger plays an important role in preheating the fresh air to a minimum operation temperature necessary for SOFC. Due to the special location of this PSHX in the TFC, it is constantly exposed to heat radiation from the SOFC module, which requires additional consideration of its influence for better model accuracy. A first design, which is later extended through an 1D Flow network model, based on 𝜖 - 𝑁𝑇𝑈 method is presented. A complete 3D-CFD simulation with consideration of heat radiation is initially employed for the whole flow process to examine the first design. However, this approach proves to be highly computationally expensive due to the large dimensional difference between the plenum for cathode exhaust air and the fine channels in the PSHX. To reduce the computational effort, the flow and heat transfer in the PSHX is modelled by 1D elements. The flow in the plenum is simulated by 3D-CFD, which better accounts for convection and thermal radiation. A comparison between 3D-CFD and 1D/3D hybrid model is performed. A significant reduction of simulation time and computing resources can be achieved for well calibrated hybrid model without compromising on accuracy. In the talk, the effect of insulation layer thickness variations on the heat transfer on the plenum side due to heat radiation and their influence on the heat exchanger efficiency are discussed. Consequently, design improvements are realized based on the previous findings. Finally, the 1D/3D hybrid simulation method is evaluated and prepared for the general applications in thermal management of machines based on coupled MGT-SOFC process.}, language = {en} } @misc{NeubauerGensslerRadmannetal., author = {Neubauer, Moritz and Genßler, Julia and Radmann, Vincent and Kohlenberg, Fleming and Pohl, Michael and B{\"o}hme, Kurt and Knobloch, Karsten and Sarradj, Ennes and H{\"o}schler, Klaus and Modler, Niels and Enghardt, Lars}, title = {Experimental and Numerical Investigation of Novel Acoustic Liners and Their Design for Aero-Engine Applications}, series = {Aerospace}, volume = {10}, journal = {Aerospace}, number = {1}, issn = {2226-4310}, doi = {10.3390/aerospace10010005}, abstract = {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.}, language = {en} } @misc{NeubauerPohlKucheretal., author = {Neubauer, Moritz and Pohl, Michael and Kucher, Michael and B{\"o}hm, Robert and H{\"o}schler, Klaus and Modler, Niels}, title = {DMA of TPU Films and the Modelling of Their Viscoelastic Properties for Noise Reduction in Jet Engines}, series = {Polymers}, volume = {14}, journal = {Polymers}, number = {23}, issn = {2073-4360}, doi = {10.3390/polym14235285}, abstract = {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.}, language = {en} } @misc{KazulaRichHoeschleretal., author = {Kazula, Stefan and Rich, Beatrice Monique and H{\"o}schler, Klaus and Woll, Ralf}, title = {Interest High School Students in STEM Studies, while Preparing STEM Students for Leading Positions}, series = {2021 IEEE Global Engineering Education Conference}, volume = {2021}, journal = {2021 IEEE Global Engineering Education Conference}, isbn = {978-1-7281-8478-4}, doi = {10.1109/EDUCON46332.2021.9454011}, pages = {910 -- 914}, language = {en} } @misc{KazulaHoeschler, author = {Kazula, Stefan and H{\"o}schler, Klaus}, title = {Sustainable Supersonic Transport: a Case Study on Variable Pitot Inlets}, series = {9th European Conference for Aeronautics and Space Sciences (Eucass)}, journal = {9th European Conference for Aeronautics and Space Sciences (Eucass)}, doi = {10.13009/EUCASS2022-4600}, pages = {14}, language = {en} } @misc{KoenigMuellerHoeschler, author = {K{\"o}nig, Paul and M{\"u}ller, Phillip and H{\"o}schler, Klaus}, title = {Assessment of (hybrid)-electric drive-train architectures for future aircraft applications}, series = {Journal of Physics: Conference Series}, volume = {2526}, journal = {Journal of Physics: Conference Series}, issn = {1742-6596}, doi = {10.1088/1742-6596/2526/1/012023}, abstract = {Future regional aircraft and propulsion systems will have to address both a growing market and stricter environmental constraints. Besides the increase of component efficiencies, the technological transformation from conventional to (hybrid)-electric propulsion systems represents a paradigm shift with great potential for the aviation industry. In this context, economic, market-relevant as well as technological boundary conditions for the electrical and mechanical components are developed in this paper for a reference regional aircraft and are based on current research results from different institutions. The propulsion performance analysis of a conventional turboprop is compared and evaluated with a serial-hybrid and a fully-electric configuration (both battery-electric), status today as well as status ~2035, as an example, whereby the presented process can also be applied to other hybrid configurations too. An energy-optimised propulsion and operating concept is derived with regard to minimum resulting system weight. The results of this analysis help to define necessary boundary conditions for future subsystem investigations and identify key research items, especially in the field of the battery.}, language = {en} } @misc{KazulaHoeschler, author = {Kazula, Stefan and H{\"o}schler, Klaus}, title = {Review of variable leading-edge patents for aircraft wings and engine inlets and their relevance for variable pitot inlets in future supersonic transport}, series = {CEAS Aeronautical Journal}, volume = {12}, journal = {CEAS Aeronautical Journal}, number = {3}, issn = {1869-5582}, doi = {10.1007/s13272-021-00520-y}, pages = {685 -- 700}, abstract = {The motivation for designing variable pitot inlets for future supersonic transport (SST) is explained. A comprehensive overview of existing technological solutions for variable leading edges of aircraft wings and engine inlets is given. The advantages and limitations of over 80 solutions, as well as their relevance for application on variable pitot inlets for SST are described. The challenges of existing solution options concerning design methodologies, level of detail, and experience with a technology are identified.}, language = {en} } @misc{KoenigHoeschlerHaridasu, author = {K{\"o}nig, Paul and H{\"o}schler, Klaus and Haridasu, Venkata Brahma Teja}, title = {Surface Heat Exchanger Assessment for Battery Powered Aircrafts}, series = {AIAA AVIATION Forum, San Diego, 2023}, journal = {AIAA AVIATION Forum, San Diego, 2023}, publisher = {American Institute of Aeronautics and Astronautics}, doi = {10.2514/6.2023-4534}, pages = {1 -- 13}, abstract = {The thermal management system represents a major challenge for a sustainable transformation of aviation industry from conventional to (hybrid)-electric propulsion. Although component efficiencies of motors, generators, power electronics and batteries are much higher compared to conventional gas turbines, heat dissipation is a challenge if flight characteristics are not to be compromised by massive drag growth. One solution is provided by structural surface heat exchangers, which use the aircraft's wetted surface to reject heat to the environment. Using the temperature-sensitive battery, the potential for fuselage-integrated surface heat exchangers will be evaluated. For this purpose, different flight conditions: take-off, climb, cruise and descent; operational concepts: battery-assisted take-off, battery-assisted climb and recuperative descent, and normal and hot day flight cycles will be investigated using a battery-hybridized reference flight of a Saab 340. A method for calculating reversible and irreversible heat fluxes in the battery is presented and used as a quantitative measure. The theoretical suitability of surface heat exchangers for battery heat rejection can be demonstrated for various flight conditions. Critical design points are not only the take-off but also the battery-assisted climb as well as a too power demanding recuperation during descent. The findings obtained are suitable for use in optimizing operating concepts, identifying suitable charging currents, and for transferability to different aircraft sizes as a function of their take-off weight.}, language = {en} } @misc{KimAsliHoeschler, author = {Kim, Dogsuk and Asli, Majid and H{\"o}schler, Klaus}, title = {On the Potentials of the Integration of Pressure Gain Combustion with a Hybrid Electric Propulsion System}, series = {Aerospace}, volume = {10}, journal = {Aerospace}, number = {8}, issn = {2226-4310}, doi = {10.3390/aerospace10080710}, pages = {1 -- 17}, abstract = {As the issue of pollutant emissions from aviation propulsion escalates, research into alternative powertrains is gaining momentum. Two promising technologies are the Hybrid Electric Propulsion System (HEPS) and Pressure Gain Combustion (PGC). HEPS is expected to reduce pollutant emissions by decreasing fuel consumption, whereas PGC uses detonation in the combustor to increase the thermal efficiency of engines by elevating the total pressure during combustion. This study extensively explores the integration of these two emerging technologies, thoroughly assessing the advantages that arise from their combination. First, the renowned turboprop engine PW127 is benchmarked and modeled using Gasturb software. The model is integrated into Simulink using the T-MATS tool, with HEPS and pressure gain components added to analyze the thermodynamics of various configurations under different pressure gain values and HEPS parameters. The analysis, conducted up to the cruise phase of the baseline aircraft, reveals that applying pressure gain combustion through Rotating Detonation Combustion (RDC) results in a more significant increase in efficiency and decrease in fuel consumption compared to HEPS with conventional gas turbines. However, HEPS helps maintain a more uniform combustor inlet condition and reduces the Turbine Inlet Temperature (TIT) at the takeoff phase, where the highest TIT otherwise occurs. The results suggest that integrating HEPS with PGC can be beneficial in maintaining optimal combustor conditions and mitigating turbine efficiency degradation.}, language = {en} }