@inproceedings{FingerBraunBil2017, author = {Finger, Felix and Braun, Carsten and Bil, Cees}, title = {A Review of Configuration Design for Distributed Propulsion Transitioning VTOL Aircraft}, series = {Asia-Pacific International Symposium on Aerospace Technology 2017, APISAT 2017, Seoul, Korea}, booktitle = {Asia-Pacific International Symposium on Aerospace Technology 2017, APISAT 2017, Seoul, Korea}, pages = {15 Seiten}, year = {2017}, language = {en} } @inproceedings{FingerBraunBil2019, author = {Finger, Felix and Braun, Carsten and Bil, Cees}, title = {Impact of Engine Failure Constraints on the Initial Sizing of Hybrid-Electric GA Aircraft}, series = {AIAA Scitech 2019 Forum}, booktitle = {AIAA Scitech 2019 Forum}, doi = {10.2514/6.2019-1812}, year = {2019}, language = {en} } @article{FingerBraunBil2020, author = {Finger, Felix and Braun, Carsten and Bil, Cees}, title = {Comparative assessment of parallel-hybrid-electric propulsion systems for four different aircraft}, series = {Journal of Aircraft}, volume = {57}, journal = {Journal of Aircraft}, number = {5}, publisher = {AIAA}, address = {Reston, Va.}, issn = {1533-3868}, doi = {10.2514/1.C035897}, year = {2020}, abstract = {Until electric energy storage systems are ready to allow fully electric aircraft, the combination of combustion engine and electric motor as a hybrid-electric propulsion system seems to be a promising intermediate solution. Consequently, the design space for future aircraft is expanded considerably, as serial hybrid-electric, parallel hybrid-electric, fully electric, and conventional propulsion systems must all be considered. While the best propulsion system depends on a multitude of requirements and considerations, trends can be observed for certain types of aircraft and certain types of missions. This Paper provides insight into some factors that drive a new design toward either conventional or hybrid propulsion systems. General aviation aircraft, regional transport aircraft vertical takeoff and landing air taxis, and unmanned aerial vehicles are chosen as case studies. Typical missions for each class are considered, and the aircraft are analyzed regarding their takeoff mass and primary energy consumption. For these case studies, a high-level approach is chosen, using an initial sizing methodology. Only parallel-hybrid-electric powertrains are taken into account. Aeropropulsive interaction effects are neglected. Results indicate that hybrid-electric propulsion systems should be considered if the propulsion system is sized by short-duration power constraints. However, if the propulsion system is sized by a continuous power requirement, hybrid-electric systems offer hardly any benefit.}, language = {en} } @inproceedings{FingerBraunBil2020, author = {Finger, Felix and Braun, Carsten and Bil, Cees}, title = {Comparative assessment of parallel-hybrid-electric propulsion systems for four different aircraft}, series = {AIAA SciTech Forum 2020, 06.01.2020 - 10.01.2020, Orlando}, booktitle = {AIAA SciTech Forum 2020, 06.01.2020 - 10.01.2020, Orlando}, doi = {10.2514/6.2020-1502}, pages = {15 Seiten}, year = {2020}, language = {en} } @article{FingerBraunBil2020, author = {Finger, Felix and Braun, Carsten and Bil, Cees}, title = {Impact of Battery Performance on the Initial Sizing of Hybrid-Electric General Aviation Aircraft}, series = {Journal of Aerospace Engineering}, volume = {33}, journal = {Journal of Aerospace Engineering}, number = {3}, publisher = {ASCE}, address = {Reston, Va.}, issn = {1943-5525}, doi = {10.1061/(ASCE)AS.1943-5525.0001113}, year = {2020}, abstract = {Studies suggest that hybrid-electric aircraft have the potential to generate fewer emissions and be inherently quieter when compared to conventional aircraft. By operating combustion engines together with an electric propulsion system, synergistic benefits can be obtained. However, the performance of hybrid-electric aircraft is still constrained by a battery's energy density and discharge rate. In this paper, the influence of battery performance on the gross mass for a four-seat general aviation aircraft with a hybrid-electric propulsion system is analyzed. For this design study, a high-level approach is chosen, using an innovative initial sizing methodology to determine the minimum required aircraft mass for a specific set of requirements and constraints. Only the peak-load shaving operational strategy is analyzed. Both parallel- and serial-hybrid propulsion configurations are considered for two different missions. The specific energy of the battery pack is varied from 200 to 1,000 W⋅h/kg, while the discharge time, and thus the normalized discharge rating (C-rating), is varied between 30 min (2C discharge rate) and 2 min (30C discharge rate). With the peak-load shaving operating strategy, it is desirable for hybrid-electric aircraft to use a light, low capacity battery system to boost performance. For this case, the battery's specific power rating proved to be of much higher importance than for full electric designs, which have high capacity batteries. Discharge ratings of 20C allow a significant take-off mass reduction aircraft. The design point moves to higher wing loadings and higher levels of hybridization if batteries with advanced technology are used.}, language = {en} } @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}, language = {en} } @article{FingerGoetten2019, author = {Finger, Felix and G{\"o}tten, Falk}, title = {Neue Ans{\"a}tze f{\"u}r die Entwicklung von unbemannten Flugger{\"a}ten}, series = {Ingenieurspiegel}, volume = {2019}, journal = {Ingenieurspiegel}, number = {1}, isbn = {1868-5919}, pages = {67 -- 68}, year = {2019}, abstract = {Wie sieht das unbemannte Flugzeug von {\"U}bermorgen aus? Dieser Frage stellen sich Forscher an der Fachhochschule Aachen. Die weltweit rasant fortschreitende Entwicklung des Marktes f{\"u}r unbemannte Flugger{\"a}te (UAVs - „Unmanned Aerial Vehicles") bietet großes Potenzial f{\"u}r Wachstum und Wertsch{\"o}pfung. Unbemannte fliegende Systeme k{\"o}nnen - f{\"u}r bestimmte Anwendungsgebiete - wesentlich g{\"u}nstiger, kleiner und effizienter ausgelegt werden als bemannte L{\"o}sungen. Dabei sind sich viele Unternehmen {\"u}ber das m{\"o}gliche Potential dieser Technologie noch gar nicht bewusst.}, language = {de} } @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{FingerGoettenBraunetal.2019, author = {Finger, Felix and G{\"o}tten, Falk and Braun, Carsten and Bil, C.}, title = {On Aircraft Design Under the Consideration of Hybrid-Electric Propulsion Systems}, series = {APISAT 2018: The Proceedings of the 2018 Asia-Pacific International Symposium on Aerospace Technology (APISAT 2018)}, booktitle = {APISAT 2018: The Proceedings of the 2018 Asia-Pacific International Symposium on Aerospace Technology (APISAT 2018)}, publisher = {Springer}, address = {Singapore}, isbn = {978-981-13-3305-7}, doi = {10.1007/978-981-13-3305-7_99}, pages = {1261 -- 1272}, year = {2019}, abstract = {A hybrid-electric propulsion system combines the advantages of fuel-based systems and battery powered systems and offers new design freedom. To take full advantage of this technology, aircraft designers must be aware of its key differences, compared to conventional, carbon-fuel based, propulsion systems. This paper gives an overview of the challenges and potential benefits associated with the design of aircraft that use hybrid-electric propulsion systems. It offers an introduction of the most popular hybrid-electric propulsion architectures and critically assess them against the conventional and fully electric propulsion configurations. The effects on operational aspects and design aspects are covered. Special consideration is given to the application of hybrid-electric propulsion technology to both unmanned and vertical take-off and landing aircraft. The authors conclude that electric propulsion technology has the potential to revolutionize aircraft design. However, new and innovative methods must be researched, to realize the full benefit of the technology.}, language = {en} } @inproceedings{FingerGoettenBraunetal.2019, author = {Finger, Felix and G{\"o}tten, Falk and Braun, Carsten and Bil, Cees}, title = {Mass, Primary Energy, and Cost - The Impact of Optimization Objectives on the Initial Sizing of Hybrid-Electric General Aviation Aircraft}, series = {Deutscher Luft- und Raumfahrtkongress 2019, DLRK 2019. Darmstadt, Germany}, booktitle = {Deutscher Luft- und Raumfahrtkongress 2019, DLRK 2019. Darmstadt, Germany}, doi = {10.25967/490012}, pages = {1 -- 17}, year = {2019}, language = {en} } @inproceedings{FingerGoettenBraunetal.2019, author = {Finger, Felix and G{\"o}tten, Falk and Braun, Carsten and Bil, Cees}, title = {Cost Estimation Methods for Hybrid-Electric General Aviation Aircraft}, series = {Asia Pacific International Symposium on Aerospace Technology. APISAT 2019}, booktitle = {Asia Pacific International Symposium on Aerospace Technology. APISAT 2019}, pages = {1 -- 13}, 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} } @article{FischerKowalskiPudasaini2012, author = {Fischer, Jan-Thomas and Kowalski, Julia and Pudasaini, Shiva P.}, title = {Topographic curvature effects in applied avalanche modelling}, series = {Cold Regions Science and Technology}, volume = {74-75}, journal = {Cold Regions Science and Technology}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1872-7441}, doi = {10.1016/j.coldregions.2012.01.005}, pages = {21 -- 30}, year = {2012}, abstract = {This paper describes the implementation of topographic curvature effects within the RApid Mass MovementS (RAMMS) snow avalanche simulation toolbox. RAMMS is based on a model similar to shallow water equations with a Coulomb friction relation and the velocity dependent Voellmy drag. It is used for snow avalanche risk assessment in Switzerland. The snow avalanche simulation relies on back calculation of observed avalanches. The calibration of the friction parameters depends on characteristics of the avalanche track. The topographic curvature terms are not yet included in the above mentioned classical model. Here, we fundamentally improve this model by mathematically and physically including the topographic curvature effects. By decomposing the velocity dependent friction into a topography dependent term that accounts for a curvature enhancement in the Coulomb friction, and a topography independent contribution similar to the classical Voellmy drag, we construct a general curvature dependent frictional resistance, and thus propose new extended model equations. With three site-specific examples, we compare the apparent frictional resistance of the new approach, which includes topographic curvature effects, to the classical one. Our simulation results demonstrate substantial effects of the curvature on the flow dynamics e.g., the dynamic pressure distribution along the slope. The comparison of resistance coefficients between the two models demonstrates that the physically based extension presents an improvement to the classical approach. Furthermore a practical example highlights its influence on the pressure outline in the run out zone of the avalanche. Snow avalanche dynamics modeling natural terrain curvature centrifugal force friction coefficients.}, language = {en} } @article{FischerKowalskiPudasainietal.2009, author = {Fischer, Jan-Thomas and Kowalski, Julia and Pudasaini, Shiva P. and Miller, S. A.}, title = {Dynamic Avalanche Modeling in Natural Terrain}, series = {International Snow Science Workshop, Davos 2009, Proceedings ; Proc. ISSW 2009}, journal = {International Snow Science Workshop, Davos 2009, Proceedings ; Proc. ISSW 2009}, pages = {448 -- 452}, year = {2009}, abstract = {The powerful avalanche simulation toolbox RAMMS (Rapid Mass Movements) is based on a depth-averaged hydrodynamic system of equations with a Voellmy-Salm friction relation. The two empirical friction parameters μ and � correspond to a dry Coulomb friction and a viscous resistance, respectively. Although μ and � lack a proper physical explanation, 60 years of acquired avalanche data in the Swiss Alps made a systematic calibration possible. RAMMS can therefore successfully model avalanche flow depth, velocities, impact pressure and run out distances. Pudasaini and Hutter (2003) have proposed extended, rigorously derived model equations that account for local curvature and twist. A coordinate transformation into a reference system, applied to the actual mountain topography of the natural avalanche path, is performed. The local curvature and the twist of the avalanche path induce an additional term in the overburden pressure. This leads to a modification of the Coulomb friction, the free-surface pressure gradient, the pressure induced by the channel, and the gravity components along and normal to the curved and twisted reference surface. This eventually guides the flow dynamics and deposits of avalanches. In the present study, we investigate the influence of curvature on avalanche flow in real mountain terrain. Simulations of real avalanche paths are performed and compared for the different models approaches. An algorithm to calculate curvature in real terrain is introduced in RAMMS. This leads to a curvature dependent friction relation in an extended version of the Voellmy-Salm model equations. Our analysis provides yet another step in interpreting the physical meaning and significance of the friction parameters used in the RAMMS computational environment.}, language = {en} } @article{FornaciariGuidettiHavermannetal.2010, author = {Fornaciari, Andrea and Guidetti, Marco and Havermann, Marc and Lettini, Antonio}, title = {Maccine mobili pi{\`u} efficienti}, series = {Fluidotecnica}, journal = {Fluidotecnica}, number = {345}, publisher = {Quine Business Publisher}, address = {Milano}, pages = {11 -- 14}, year = {2010}, abstract = {Secondo le attuali normative tutte le macchine mobili, entro il 2012, dovranno essere soggette a un incremento di efficienza energetica. Un'evoluzione del sistema idraulico potr{\`a} contribuire in maniera significativa al miglioramento richiesto. Elettronica e idraulica sempre pi{\`u} protagoniste.}, language = {it} } @article{FrankeBosisNapoli2001, author = {Franke, Thomas and Bosis, R. and Napoli, M.-D.}, title = {{\"U}ber das Internet steuerbarer Gebl{\"a}sepr{\"u}fstand mit einstellbaren Eintrittsleitschaufeln}, series = {Virtuelle Instrumente in der Praxis : Begleitband zum Kongreß VIP 2001 / Rahman Jamal ; Hans Jaschinski}, journal = {Virtuelle Instrumente in der Praxis : Begleitband zum Kongreß VIP 2001 / Rahman Jamal ; Hans Jaschinski}, publisher = {H{\"u}thig Verlag}, address = {Heidelberg [u.a.]}, isbn = {3-7785-2829-7}, pages = {219 -- 225}, year = {2001}, language = {de} } @phdthesis{Frotscher2016, author = {Frotscher, Ralf}, title = {Electromechanical modeling and simulation of thin cardiac tissue constructs - smoothed FEM applied to a biomechanical plate problem}, year = {2016}, language = {en} } @book{Funke2001, author = {Funke, Harald}, title = {Analyse der Temperatur- und Str{\"o}mungsungleichf{\"o}rmigkeiten in mehrstufigen Turbinen / Harald Funke}, publisher = {Mainz}, address = {Aachen}, isbn = {3-89653-400-9}, pages = {VI, 135 S. : Ill., graph. Darst.}, year = {2001}, language = {de} } @book{Funke2008, author = {Funke, Harald}, title = {Optimierung und Miniaturisierung der Mikro-Misch-Diffusionsverbrennung von Wasserstoff zur potentiellen Anwendung in einer Ultra-Gasturbine. Schlussbericht.}, publisher = {Fachhochschule Aachen}, address = {Aachen}, pages = {85 S.}, year = {2008}, language = {de} } @article{FunkeBeckmann2022, author = {Funke, Harald and Beckmann, Nils}, title = {Flexible fuel operation of a Dry-Low-NOx Micromix Combustor with Variable Hydrogen Methane Mixture}, series = {International Journal of Gas Turbine, Propulsion and Power Systems}, volume = {13}, journal = {International Journal of Gas Turbine, Propulsion and Power Systems}, number = {2}, issn = {1882-5079}, pages = {1 -- 7}, year = {2022}, abstract = {The role of hydrogen (H2) as a carbon-free energy carrier is discussed since decades for reducing greenhouse gas emissions. As bridge technology towards a hydrogen-based energy supply, fuel mixtures of natural gas or methane (CH4) and hydrogen are possible. The paper presents the first test results of a low-emission Micromix combustor designed for flexible-fuel operation with variable H2/CH4 mixtures. The numerical and experimental approach for considering variable fuel mixtures instead of recently investigated pure hydrogen is described. In the experimental studies, a first generation FuelFlex Micromix combustor geometry is tested at atmospheric pressure at gas turbine operating conditions corresponding to part- and full-load. The H2/CH4 fuel mixture composition is varied between 57 and 100 vol.\% hydrogen content. Despite the challenges flexible-fuel operation poses onto the design of a combustion system, the evaluated FuelFlex Micromix prototype shows a significant low NOx performance}, language = {en} }