@inproceedings{GoettenFingerMarinoetal.2019, author = {G{\"o}tten, Falk and Finger, Felix and Marino, Matthew and Bil, Cees and Havermann, Marc and Braun, Carsten}, title = {A review of guidelines and best practices for subsonic aerodynamic simulations using RANS CFD}, series = {Asia-Pacific International Symposium on Aerospace Technology (APISAT), At Gold Coast, Australia, 04. - 06. Dezember 2019}, booktitle = {Asia-Pacific International Symposium on Aerospace Technology (APISAT), At Gold Coast, Australia, 04. - 06. Dezember 2019}, isbn = {978-1-925627-40-4}, pages = {19 Seiten}, year = {2019}, language = {de} } @inproceedings{FingerdeVriesVosetal.2020, author = {Finger, Felix and de Vries, Reynard and Vos, Roelof and Braun, Carsten and Bil, Cees}, title = {A comparison of hybrid-electric aircraft sizing methods}, series = {AIAA Scitech 2020 Forum}, booktitle = {AIAA Scitech 2020 Forum}, doi = {10.2514/6.2020-1006}, pages = {31 Seiten}, year = {2020}, abstract = {The number of case studies focusing on hybrid-electric aircraft is steadily increasing, since these configurations are thought to lead to lower operating costs and environmental impact than traditional aircraft. However, due to the lack of reference data of actual hybrid-electric aircraft, in most cases, the design tools and results are difficult to validate. In this paper, two independently developed approaches for hybrid-electric conceptual aircraft design are compared. An existing 19-seat commuter aircraft is selected as the conventional baseline, and both design tools are used to size that aircraft. The aircraft is then re-sized under consideration of hybrid-electric propulsion technology. This is performed for parallel, serial, and fully-electric powertrain architectures. Finally, sensitivity studies are conducted to assess the validity of the basic assumptions and approaches regarding the design of hybrid-electric aircraft. Both methods are found to predict the maximum take-off mass (MTOM) of the reference aircraft with less than 4\% error. The MTOM and payload-range energy efficiency of various (hybrid-) electric configurations are predicted with a maximum difference of approximately 2\% and 5\%, respectively. The results of this study confirm a correct formulation and implementation of the two design methods, and the data obtained can be used by researchers to benchmark and validate their design tools.}, language = {en} } @inproceedings{StrieganStruthDickhoffetal.2019, author = {Striegan, Constantin J. D. and Struth, Benjamin and Dickhoff, Jens and Kusterer, Karsten and Funke, Harald and Bohn, Dieter}, title = {Numerical Simulations of the Micromix DLN Hydrogen Combustion Technology with LES and Comparison to Results of RANS and Experimental Data}, series = {Proceedings of International Gas Turbine Congress 2019 Tokyo, November 17-22, 2019, Tokyo, Japan.}, booktitle = {Proceedings of International Gas Turbine Congress 2019 Tokyo, November 17-22, 2019, Tokyo, Japan.}, isbn = {978-4-89111-010-9}, pages = {1 -- 9}, year = {2019}, language = {en} } @inproceedings{FingerKhalsaKreyeretal.2019, author = {Finger, Felix and Khalsa, R. and Kreyer, J{\"o}rg and Mayntz, Joscha and Braun, Carsten and Dahmann, Peter and Esch, Thomas and Kemper, Hans and Schmitz, O. and Bragard, Michael}, title = {An approach to propulsion system modelling for the conceptual design of hybrid-electric general aviation aircraft}, series = {Deutscher Luft- und Raumfahrtkongress 2019, 30.9.-2.10.2019, Darmstadt}, booktitle = {Deutscher Luft- und Raumfahrtkongress 2019, 30.9.-2.10.2019, Darmstadt}, pages = {15 Seiten}, year = {2019}, abstract = {In this paper, an approach to propulsion system modelling for hybrid-electric general aviation aircraft is presented. Because the focus is on general aviation aircraft, only combinations of electric motors and reciprocating combustion engines are explored. Gas turbine hybrids will not be considered. The level of the component's models is appropriate for the conceptual design stage. They are simple and adaptable, so that a wide range of designs with morphologically different propulsive system architectures can be quickly compared. Modelling strategies for both mass and efficiency of each part of the propulsion system (engine, motor, battery and propeller) will be presented.}, language = {en} } @inproceedings{QuitterMarinoBauschat2019, author = {Quitter, Julius and Marino, Matthew and Bauschat, J.-Michael}, title = {Highly Non-Planar Aircraft Configurations: Estimation of Flight Mechanical Derivatives Using Low-Order Methods}, series = {Deutscher Luft- und Raumfahrtkongress 2019, DLRK 2019. Darmstadt, Germany}, booktitle = {Deutscher Luft- und Raumfahrtkongress 2019, DLRK 2019. Darmstadt, Germany}, pages = {10 Seiten}, year = {2019}, language = {en} } @article{KhayyamJamaliBabHadiasharetal.2020, author = {Khayyam, Hamid and Jamali, Ali and Bab-Hadiashar, Alireza and Esch, Thomas and Ramakrishna, Seeram and Jalil, Mahdi and Naebe, Minoo}, title = {A Novel Hybrid Machine Learning Algorithm for Limited and Big Data Modelling with Application in Industry 4.0}, series = {IEEE Access}, journal = {IEEE Access}, publisher = {IEEE}, address = {New York, NY}, isbn = {2169-3536}, doi = {10.1109/ACCESS.2020.2999898}, pages = {1 -- 12}, year = {2020}, abstract = {To meet the challenges of manufacturing smart products, the manufacturing plants have been radically changed to become smart factories underpinned by industry 4.0 technologies. The transformation is assisted by employment of machine learning techniques that can deal with modeling both big or limited data. This manuscript reviews these concepts and present a case study that demonstrates the use of a novel intelligent hybrid algorithms for Industry 4.0 applications with limited data. In particular, an intelligent algorithm is proposed for robust data modeling of nonlinear systems based on input-output data. In our approach, a novel hybrid data-driven combining the Group-Method of Data-Handling and Singular-Value Decomposition is adapted to find an offline deterministic model combined with Pareto multi-objective optimization to overcome the overfitting issue. An Unscented-Kalman-Filter is also incorporated to update the coefficient of the deterministic model and increase its robustness against data uncertainties. The effectiveness of the proposed method is examined on a set of real industrial measurements.}, language = {en} } @article{HailerWeberNevelingetal.2020, author = {Hailer, Benjamin and Weber, Tobias and Neveling, Sebastian and Dera, Samuel and Arent, Jan-Christoph and Middendorf, Peter}, title = {Development of a test device to determine the frictional behavior between honeycomb and prepreg layers under realistic manufacturing conditions}, series = {Journal of Sandwich Structures \& Materials}, journal = {Journal of Sandwich Structures \& Materials}, number = {Volume 23, Issue 7}, publisher = {Sage}, address = {London}, issn = {1530-7972}, doi = {10.1177/1099636220923986}, pages = {3017 -- 3043}, year = {2020}, abstract = {In the friction tests between honeycomb with film adhesive and prepreg, the relative displacement occurs between the film adhesive and the prepreg. The film adhesive does not shift relative to the honeycomb. This is consistent with the core crush behavior where the honeycomb moves together with the film adhesive, as can be seen in Figure 2(a). The pull-through forces of the friction measurements between honeycomb and prepreg at 1 mm deformation are plotted in Figure 17(a). While the friction at 100°C is similar to the friction at 120°C, it decreases significantly at 130°C and exhibits a minimum at 140°C. At 150°C, the friction rises again slightly and then sharply at 160°C. Since the viscosity of the M18/1 prepreg resin drops significantly before it cures [23], the minimum friction at 140°C could result from a minimum viscosity of the mixture of prepreg resin and film adhesive before the bond subsequently cures. Figure 17(b) shows the mean value curve of the friction measurements at 140°C. The error bars, which represent the standard deviation, reveal the good repeatability of the tests. The force curve is approximately horizontal between 1 mm and 2 mm. The friction then slightly rises. As with interlaminar friction measurements, this could be due to the fact that resin is removed by friction and the proportion of boundary lubrication increases. Figure 18 shows the surfaces after the friction measurement. The honeycomb cell walls are clearly visible in the film adhesive. There are areas where the film adhesive is completely removed and the carrier material of the film adhesive becomes visible. In addition, the viscosity of the resin changes as the curing progresses during the friction test. This can also affect the force-displacement curve.}, language = {en} } @inproceedings{EnglhardWeberArent2021, author = {Englhard, Markus and Weber, Tobias and Arent, Jan-Christoph}, title = {Efficiency enhancement for CFRP-Prepregautoclave manufacturing by means of simulation-assisted loading optimization}, series = {Proceedings of SAMPE Europe Conference 2021}, booktitle = {Proceedings of SAMPE Europe Conference 2021}, pages = {8 Seiten}, year = {2021}, abstract = {A new method for improved autoclave loading within the restrictive framework of helicopter manufacturing is proposed. It is derived from experimental and numerical studies of the curing process and aims at optimizing tooling positions in the autoclave for fast and homogeneous heat-up. The mold positioning is based on two sets of information. The thermal properties of the molds, which can be determined via semi-empirical thermal simulation. The second information is a previously determined distribution of heat transfer coefficients inside the autoclave. Finally, an experimental proof of concept is performed to show a cycle time reduction of up to 31\% using the proposed methodology.}, language = {en} } @article{PeloniCeriottiDachwald2016, author = {Peloni, Alessandro and Ceriotti, Matteo and Dachwald, Bernd}, title = {Solar-sail trajectory design for a multiple near-earth-asteroid rendezvous mission}, series = {Journal of Guidance, Control, and Dynamics}, volume = {39}, journal = {Journal of Guidance, Control, and Dynamics}, number = {12}, publisher = {AIAA}, address = {Reston, Va.}, issn = {0731-5090}, doi = {10.2514/1.G000470}, pages = {2712 -- 2724}, year = {2016}, abstract = {The scientific interest for near-Earth asteroids as well as the interest in potentially hazardous asteroids from the perspective of planetary defense led the space community to focus on near-Earth asteroid mission studies. A multiple near-Earth asteroid rendezvous mission with close-up observations of several objects can help to improve the characterization of these asteroids. This work explores the design of a solar-sail spacecraft for such a mission, focusing on the search of possible sequences of encounters and the trajectory optimization. This is done in two sequential steps: a sequence search by means of a simplified trajectory model and a set of heuristic rules based on astrodynamics, and a subsequent optimization phase. A shape-based approach for solar sailing has been developed and is used for the first phase. The effectiveness of the proposed approach is demonstrated through a fully optimized multiple near-Earth asteroid rendezvous mission. The results show that it is possible to visit five near-Earth asteroids within 10 years with near-term solar-sail technology.}, language = {en} } @inproceedings{HauggKreyerKemperetal.2020, author = {Haugg, Albert Thomas and Kreyer, J{\"o}rg and Kemper, Hans and Hatesuer, Katerina and Esch, Thomas}, title = {Heat exchanger for ORC. adaptability and optimisation potentials}, series = {IIR International Rankine 2020 Conference}, booktitle = {IIR International Rankine 2020 Conference}, doi = {10.18462/iir.rankine.2020.1224}, pages = {10 Seiten}, year = {2020}, abstract = {The recovery of waste heat requires heat exchangers to extract it from a liquid or gaseous medium into another working medium, a refrigerant. In Organic Rankine Cycles (ORC) on Combustion Engines there are two major heat sources, the exhaust gas and the water/glycol fluid from the engine's cooling circuit. A heat exchanger design must be adapted to the different requirements and conditions resulting from the heat sources, fluids, system configurations, geometric restrictions, and etcetera. The Stacked Shell Cooler (SSC) is a new and very specific design of a plate heat exchanger, created by AKG, which allows with a maximum degree of freedom the optimization of heat exchange rate and the reduction of the related pressure drop. This optimization in heat exchanger design for ORC systems is even more important, because it reduces the energy consumption of the system and therefore maximizes the increase in overall efficiency of the engine.}, language = {en} } @article{Maurischat2022, author = {Maurischat, Andreas}, title = {Algebraic independence of the Carlitz period and its hyperderivatives}, series = {Journal of Number Theory}, volume = {240}, journal = {Journal of Number Theory}, publisher = {Elsevier}, address = {Orlando, Fla.}, issn = {0022-314X}, doi = {10.1016/j.jnt.2022.01.006}, pages = {145 -- 162}, year = {2022}, language = {en} } @incollection{HebelHerrmannRitzetal.2022, author = {Hebel, Christoph and Herrmann, Ulf and Ritz, Thomas and R{\"o}th, Thilo and Anthrakidis, Anette and B{\"o}ker, J{\"o}rg and Franzke, Till and Grodzki, Thomas and Merkens, Torsten and Sch{\"o}ttler, Mirjam}, title = {FlexSHARE - Methodisches Framework zur innovativen Gestaltung der urbanen Mobilit{\"a}t durch Sharing- Angebote}, series = {Transforming Mobility - What Next?}, booktitle = {Transforming Mobility - What Next?}, publisher = {Springer Gabler}, address = {Wiesbaden}, isbn = {978-3-658-36429-8}, doi = {10.1007/978-3-658-36430-4_10}, pages = {153 -- 169}, year = {2022}, abstract = {Das Ziel des INTERREG-Projektes „SHAREuregio" (FKZ: 34.EFRE-0300134) ist es, grenz{\"u}berschreitende Mobilit{\"a}t in der Euregio Rhein-Maas-Nord zu erm{\"o}glichen und zu f{\"o}rdern. Dazu soll ein elektromobiles Car- und Bikesharing- System entwickelt und in der Stadt M{\"o}nchengladbach, im Kreis Viersen sowie in den Gemeinden Roermond und Venlo (beide NL) zusammen mit den Partnern Wirtschaftsf{\"o}rderung M{\"o}nchengladbach, Wirtschaftsf{\"o}rderung f{\"u}r den Kreis Viersen, NEW AG, Goodmoovs (NL), Greenflux (NL) und der FH Aachen implementiert werden. Zun{\"a}chst richtet sich das Angebot, bestehend aus 40 Elektroautos und 40 Elektrofahrr{\"a}dern, an Unternehmen und wird nach einer Erprobungsphase, mit einer gr{\"o}ßeren Anzahl an Fahrzeugen, auch f{\"u}r Privatpersonen verf{\"u}gbar gemacht werden. Die Fahrzeuge stehen bei den jeweiligen Anwendungspartnern in Deutschland und den Niederlanden. Im Rahmen dieses Projektes hat die FH Aachen „FlexSHARE" entwickelt - ein methodisches Framework zur innovativen Gestaltung urbaner Sharing- Angebote. Das Framework erm{\"o}glicht es, anhand von messbaren Kenngr{\"o}ßen, bedarfsgerechte und auf die Region abgestimmte Sharing-Systeme zu entwickeln.}, language = {de} } @incollection{BauschatBennerKlingeetal.2022, author = {Bauschat, J.-Michael and Benner, Miriam and Klinge, Henner and Ziegler, Simon}, title = {Urbane Mobilit{\"a}t entdeckt die 3. Dimension}, series = {Transforming Mobility - What Next?}, booktitle = {Transforming Mobility - What Next?}, publisher = {Springer Gabler}, address = {Wiesbaden}, isbn = {978-3-658-36429-8}, doi = {10.1007/978-3-658-36430-4_53}, pages = {895 -- 916}, year = {2022}, abstract = {Der Themenkomplex urbane Mobilit{\"a}t ist getrieben durch den Verkehrsinfarkt in Ballungszentren, durch Luftverschmutzung und L{\"a}rm, sowie den Trend zum Leben in der Stadt in den st{\"a}dteplanerischen Fokus ger{\"u}ckt. Emissionsneutrale Antriebskonzepte in der Luftfahrt f{\"u}hren zu Ans{\"a}tzen Flugger{\"a}te einzusetzen, die batteriegetrieben vertikal aufsteigen und landen k{\"o}nnen. Flugphysikalisch und energetisch ist diese Technik nur dann sinnvoll, wenn es zwingende Gr{\"u}nde gibt (z.B. Rettungseins{\"a}tze), daher wird der flugphysikalische Hintergrund prinzipiell erl{\"a}utert. Es werden einige aktuelle Lufttransportkonzepte f{\"u}r eine urbane Personenbef{\"o}rderung vorgestellt. Sollte es verst{\"a}rkt zu Lufttransport {\"u}ber St{\"a}dten kommen, m{\"u}ssen betroffene Luftr{\"a}ume geordnet und {\"u}berwacht werden. Wie kompatibel Lufttransportsysteme mit den heute bereits relevanten urbanen Bef{\"o}rderungsmitteln sein m{\"u}ssen, wird kritisch diskutiert. Abschließend werden die Aspekte Akzeptanz durch die Kunden und Wirtschaftlichkeit ebenso angerissen, wie die hochproblematische Rohstoffgewinnung, die Entsorgung und das Recycling von Batterien.}, language = {de} } @inproceedings{FunkeBeckmannKeinzetal.2017, author = {Funke, Harald and Beckmann, Nils and Keinz, Jan and Abanteriba, Sylvester}, title = {Numerical and Experimental Evaluation of a Dual-Fuel Dry-Low-NOx Micromix Combustor for Industrial Gas Turbine Applications}, series = {Proceedings of the ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. Volume 4B: Combustion, Fuels and Emissions. Charlotte, North Carolina, USA. June 26-30, 2017}, booktitle = {Proceedings of the ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. Volume 4B: Combustion, Fuels and Emissions. Charlotte, North Carolina, USA. June 26-30, 2017}, publisher = {ASME}, address = {New York}, isbn = {978-0-7918-5085-5}, doi = {10.1115/GT2017-64795}, year = {2017}, abstract = {The Dry-Low-NOx (DLN) Micromix combustion technology has been developed originally as a low emission alternative for industrial gas turbine combustors fueled with hydrogen. Currently the ongoing research process targets flexible fuel operation with hydrogen and syngas fuel. The non-premixed combustion process features jet-in-crossflow-mixing of fuel and oxidizer and combustion through multiple miniaturized flames. The miniaturization of the flames leads to a significant reduction of NOx emissions due to the very short residence time of reactants in the flame. The paper presents the results of a numerical and experimental combustor test campaign. It is conducted as part of an integration study for a dual-fuel (H2 and H2/CO 90/10 Vol.\%) Micromix combustion chamber prototype for application under full scale, pressurized gas turbine conditions in the auxiliary power unit Honeywell Garrett GTCP 36-300. In the presented experimental studies, the integration-optimized dual-fuel Micromix combustor geometry is tested at atmospheric pressure over a range of gas turbine operating conditions with hydrogen and syngas fuel. The experimental investigations are supported by numerical combustion and flow simulations. For validation, the results of experimental exhaust gas analyses are applied. Despite the significantly differing fuel characteristics between pure hydrogen and hydrogen-rich syngas the evaluated dual-fuel Micromix prototype shows a significant low NOx performance and high combustion efficiency. The combustor features an increased energy density that benefits manufacturing complexity and costs.}, language = {en} } @inproceedings{StrieganHajAyedFunkeetal.2017, author = {Striegan, C. and Haj Ayed, A. and Funke, Harald and Loechle, S. and Kazari, M. and Horikawa, A. and Okada, K. and Koga, K.}, title = {Numerical combustion and heat transfer simulations and validation for a hydrogen fueled "micromix" test combustor in industrial gas turbine applications}, series = {Proceedings of the ASME Turbo Expo}, booktitle = {Proceedings of the ASME Turbo Expo}, number = {Volume Part F130041-4B, 2017}, isbn = {978-079185085-5}, doi = {10.1115/GT2017-64719}, year = {2017}, language = {en} } @book{JanserHavermannHoeveleretal.2016, author = {Janser, Frank and Havermann, Marc and Hoeveler, Bastian and Hertz, Cyril}, title = {Inkompressible Profil- und Tragfl{\"u}gelaerodynamik}, series = {Str{\"o}mungslehre und Aerodynamik ; Band 2}, journal = {Str{\"o}mungslehre und Aerodynamik ; Band 2}, edition = {1. Auflage}, publisher = {Verlagshaus Mainz GmbH}, address = {Aachen}, isbn = {978-3-8107-0261-6}, pages = {XIII, 208 Seiten}, year = {2016}, language = {de} } @inproceedings{LudowicyRingsFingeretal.2018, author = {Ludowicy, Jonas and Rings, Ren{\´e} and Finger, Felix and Braun, Carsten}, title = {Sizing Studies of Light Aircraft with Serial Hybrid Propulsion Systems}, series = {Luft- und Raumfahrt - Digitalisierung und Vernetzung : Deutscher Luft- und Raumfahrtkongress 2018. 4. - 6. September 2018 - Friedrichshafen}, booktitle = {Luft- und Raumfahrt - Digitalisierung und Vernetzung : Deutscher Luft- und Raumfahrtkongress 2018. 4. - 6. September 2018 - Friedrichshafen}, pages = {11 S.}, year = {2018}, language = {en} } @inproceedings{FingerGoettenBraun2018, author = {Finger, Felix and G{\"o}tten, Falk and Braun, Carsten}, title = {Initial Sizing for a Family of Hybrid-Electric VTOL General Aviation Aircraft}, series = {67. Deutscher Luft- und Raumfahrtkongress 2018}, booktitle = {67. Deutscher Luft- und Raumfahrtkongress 2018}, pages = {14 S.}, year = {2018}, language = {en} } @inproceedings{LudowicyRingsFingeretal.2018, author = {Ludowicy, Jonas and Rings, Ren{\´e} and Finger, Felix and Braun, Carsten}, title = {Sizing Studies of Light Aircraft with Parallel Hybrid Propulsion Systems}, series = {Deutscher Luft- und Raumfahrtkongress 2018}, booktitle = {Deutscher Luft- und Raumfahrtkongress 2018}, doi = {10.25967/480227}, pages = {15 S.}, year = {2018}, language = {en} } @article{GoettenFingerHavermannetal.2018, author = {G{\"o}tten, Falk and Finger, Felix and Havermann, Marc and Braun, Carsten and Gomez, Francisco and Bill, C.}, title = {On the flight performance impact of landing gear drag reduction methods for unmanned air vehicles}, series = {Deutscher Luft- und Raumfahrtkongress 2018}, journal = {Deutscher Luft- und Raumfahrtkongress 2018}, publisher = {DGLR}, address = {Bonn}, doi = {10.25967/480058}, pages = {11 S.}, year = {2018}, abstract = {The flight performance impact of three different landing gear configurations on a small, fixed-wing UAV is analyzed with a combination of RANS CFD calculations and an incremental flight performance algorithm. A standard fixed landing gear configuration is taken as a baseline, while the influence of retracting the landing gear or applying streamlined fairings is investigated. A retraction leads to a significant parasite drag reduction, while also fairings promise large savings. The increase in lift-to-drag ratio is reduced at high lift coefficients due to the influence of induced drag. All configurations are tested on three different design missions with an incremental flight performance algorithm. A trade-off study is performed using the retracted or faired landing gear's weight increase as a variable. The analysis reveals only small mission performance gains as the aerodynamic improvements are negated by weight penalties. A new workflow for decision-making is presented that allows to estimate if a change in landing gear configuration is beneficial for a small UAV.}, language = {en} }