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Recent analysis of scientific data from Cassini and earth-based observations gave evidence for a global ocean under a surrounding solid ice shell on Saturn's moon Enceladus. Images of Enceladus' South Pole showed several fissures in the ice shell with plumes constantly exhausting frozen water particles, building up the E-Ring, one of the outer rings of Saturn. In this southern region of Enceladus, the ice shell is considered to be as thin as 2 km, about an order of magnitude thinner than on the rest of the moon. Under the ice shell, there is a global ocean consisting of liquid water. Scientists are discussing different approaches the possibilities of taking samples of water, i.e. by melting through the ice using a melting probe. FH Aachen UAS developed a prototype of maneuverable melting probe which can navigate through the ice that has already been tested successfully in a terrestrial environment. This means no atmosphere and or ambient pressure, low ice temperatures of around 100 to 150K (near the South Pole) and a very low gravity of 0,114 m/s^2 or 1100 μg. Two of these influencing measures are about to be investigated at FH Aachen UAS in 2017, low ice temperature and low ambient pressure below the triple point of water. Low gravity cannot be easily simulated inside a large experiment chamber, though. Numerical simulations of the melting process at RWTH Aachen however are showing a gravity dependence of melting behavior. Considering this aspect, VIPER provides a link between large-scale experimental simulations at FH Aachen UAS and numerical simulations at RWTH Aachen. To analyze the melting process, about 90 seconds of experiment time in reduced gravity and low ambient pressure is provided by the REXUS rocket. In this time frame, the melting speed and contact force between ice and probes are measured, as well as heating power and a two-dimensional array of ice temperatures. Additionally, visual and infrared cameras are used to observe the melting process.
Die Batterie ist eine der absolut zentralen Komponenten des Elektrofahrzeugs. Die serielle Entwicklung und Produktion dieser Batterien und die Verbesserung der Leistungen wird entscheidend für den Erfolg der Elektromobilität sein. Die Batterie ist jedoch nicht das einzige elektrofahrzeugspezifische System, das neu entwickelt, umkonzipiert oder verbessert werden muss. So sind ebenso die Entwicklung der neuen Fahrzeugstruktur sowie des elektrifizierten Antriebsstranges Teil dieses Kapitels. Weiterhin wird ein Blick auf das bedeutende Thema des Thermomanagements geworfen.
Forschendes Lernen ist dazu geeignet, epistemische Neugier – definiert als Freude an neuen Erkenntnissen - anzuregen und zu befriedigen. Neben der Selbstwirksamkeit zeigt sich die Neugier als relevant für den Studienerfolg. Allerdings ist bisher nicht geklärt, in welcher Beziehung diese beiden Konstrukte zueinanderstehen.
Impact of electric propulsion technology and mission requirements on the performance of VTOL UAVs
(2018)
One of the engineering challenges in aviation is the design of transitioning vertical take-off and landing (VTOL) aircraft. Thrust-borne flight implies a higher mass fraction of the propulsion system, as well as much increased energy consumption in the take-off and landing phases. This mass increase is typically higher for aircraft with a separate lift propulsion system than for aircraft that use the cruise propulsion system to support a dedicated lift system. However, for a cost–benefit trade study, it is necessary to quantify the impact the VTOL requirement and propulsion configuration has on aircraft mass and size. For this reason, sizing studies are conducted. This paper explores the impact of considering a supplemental electric propulsion system for achieving hovering flight. Key variables in this study, apart from the lift system configuration, are the rotor disk loading and hover flight time, as well as the electrical systems technology level for both batteries and motors. Payload and endurance are typically used as the measures of merit for unmanned aircraft that carry electro-optical sensors, and therefore the analysis focuses on these particular parameters.
For fuel flexibility enhancement hydrogen represents a possible alternative gas turbine fuel within future low emission power generation, in case of hydrogen production by the use of renewable energy sources such as wind energy or biomass. Kawasaki Heavy Industries, Ltd. (KHI) has research and development projects for future hydrogen society; production of hydrogen gas, refinement and liquefaction for transportation and storage, and utilization with gas turbine / gas engine for the generation of electricity. In the development of hydrogen gas turbines, a key technology is the stable and low NOx hydrogen combustion, especially Dry Low Emission (DLE) or Dry Low NOx (DLN) hydrogen combustion. Due to the large difference in the physical properties of hydrogen compared to other fuels such as natural gas, well established gas turbine combustion systems cannot be directly applied for DLE hydrogen combustion. Thus, the development of DLE hydrogen combustion technologies is an essential and challenging task for the future of hydrogen fueled gas turbines. The DLE Micro-Mix combustion principle for hydrogen fuel has been in development for many years to significantly reduce NOx emissions. This combustion principle is based on cross-flow mixing of air and gaseous hydrogen which reacts in multiple miniaturized “diffusion-type” flames. The major advantages of this combustion principle are the inherent safety against flashback and the low NOx-emissions due to a very short residence time of the reactants in the flame region of the micro-flames.
On the flight performance impact of landing gear drag reduction methods for unmanned air vehicles
(2018)
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.
The Dry-Low-NOx (DLN) Micromix combustion technology has been developed as low emission combustion principle for industrial gas turbines fueled with hydrogen or syngas. The combustion process is based on the phenomenon of jet-in-crossflow-mixing (JICF). Fuel is injected perpendicular into the air-cross-flow and burned in a multitude of miniaturized, diffusion-like 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. In the Micromix research approach, computational fluid dynamics (CFD) analyses are validated toward experimental results. The combination of numerical and experimental methods allows an efficient design and optimization of DLN Micromix combustors concerning combustion stability and low NOx emissions. The paper presents a comparison of several numerical combustion models for hydrogen and hydrogen-rich syngas. They differ in the complexity of the underlying reaction mechanism and the associated computational effort. The performance of a hybrid eddy-break-up (EBU) model with a one-step global reaction is compared to a complex chemistry model and a flamelet generated manifolds (FGM) model, both using detailed reaction schemes for hydrogen or syngas combustion. Validation of numerical results is based on exhaust gas compositions available from experimental investigation on DLN Micromix combustors. The conducted evaluation confirms that the applied detailed combustion mechanisms are able to predict the general physics of the DLN-Micromix combustion process accurately. The FGM method proved to be generally suitable to reduce the computational effort while maintaining the accuracy of detailed chemistry.
Urbane Mobilitätskonzepte der Zukunft erfordern neue Unternehmensformen, idealerweise aus Old Economy und New Economy, sowie eine enge Anbindung an die gesellschaftsrelevante Zukunftsforschung. Für neue Fahrzeugkonzepte des Carsharing bedeutet dies, dass alle kostenverursachenden Faktoren erfasst und analysiert werden müssen. Die FH Aachen, share2drive und FEV geben einen Ausblick auf die zukünftige Fahrzeugklasse der Personal Public Vehicles als „Rolling Device“.
In modernen Fahrzeugkarosserien der Großserie kommen zunehmend Materialmischbauweisen zur Anwendung. In Zusammenarbeit der Daimler AG, der Tower Automotive Holding GmbH, der Imperia GmbH sowie der Partnerunternehmen KSM Castings GmbH und Schaufler Tooling GmbH & Co. KG wird das Leichtbaupotenzial von Aluminiumverbundguss-Stahlblech-Hybriden am Beispiel des vorderen Dachquerträgers des Mercedes-Benz Viano/Vito ausführlich untersucht.
In modernen Fahrzeugkarosserien der Großserie kommen zunehmend Materialmischbauweisen
zur Anwendung. In Zusammenarbeit der Daimler AG, der Tower Automotive Holding
GmbH, der Imperia GmbH sowie der Partnerunternehmen KSM Castings GmbH und Schaufler
Tooling GmbH & Co. KG wird das Leichtbaupotenzial von Stahlblech-AluminiumverbundgussHybriden
am Beispiel des vorderen Dachquerträgers des Mercedes-Benz Viano/Vito ausführlich
untersucht.
Development and Testing of a Low NOX Micromix Combustion Chamber for an Industrial Gas Turbine
(2017)
The Micromix combustion principle, based on cross-flow mixing of air and hydrogen, promises low emission applications in future gas turbines. The Micromix combustion takes place in several hundreds of miniaturized diffusion-type micro-flames. The major advantage is the inherent safety against flash-back and low NOx-emissions due to a very short residence time of reactants in the flame region. The paper gives insight into the Micromix design and scaling procedure for different energy densities and the interaction of scaling laws and key design drivers in gas turbine integration. Numerical studies, experimental testing, gas turbine integration and interface considerations are evaluated. The aerodynamic stabilization of the miniaturized flamelets and the resulting flow field, flame structure and NOx formation are analysed experimentally and numerically. The results show and confirm the successful adaption of the low NOx Micromix characteristics for a range of different nozzle sizes, energy densities and thermal power output.
Der Beitrag fokussiert die Frage nach dem Stand des durch die Bologna-Reform angestoßenen Kulturwandels im Hinblick auf Kompetenzorientierung am Beispiel der Technischen Universität Hamburg (TUHH). An der TUHH wird bereits seit einigen Jahren daran gearbeitet, die Lehre grundlegend neu auszurichten. Hierfür setzt das hochschuldidaktische "Zentrum für Lehre und Lernen" (ZLL) verschiedene Maßnahmen ein, wie z.B. eine finanzielle und didaktische Unterstützung von Lehrenden bei der Umstellung ihrer Veranstaltungen, Weiterqualifizierungsangebote und Informationsmaterial. Die Maßnahmen ebenso wie die innovierten Veranstaltungen werden von Lehrenden und Studierenden gut evaluiert. Nach dem Ansatz des Constructive Alignments lässt sich jedoch davon ausgehen, dass der Bereich der Prüfungen für eine Einschätzung des Status Quo der Kompetenzorientierung besonders relevant ist. Dieser wird deshalb anhand der beiden Kriterien Prüfungsformate und Schwierigkeitsstufen von Prüfungsaufgaben näher beleuchtet, die eng mit der Kompetenzorientierung zusammen hängen. Ergebnisse hierzu aus einer universitätsweiten Datenbank zur Studienorganisation sowie aus einer Online-Umfrage unter Studierenden weisen darauf hin, dass das Prüfungsformat "Klausur" nach wie vor am stärksten verbreitet ist; zugleich sind die Studierenden nach einer Selbsteinschätzung in Prüfungen vorrangig mit Aufgaben auf den Taxonomieniveaus "Wiedergeben" und "Anwenden" konfrontiert. Dies lässt sich als Hinweis darauf interpretieren, dass es im Hinblick auf eine Kompetenzorientierung in den Prüfungen noch weiteren Veränderungsbedarf gibt.
Digitalisierung bezeichnet die Nutzung großer Datenmengen, die zu einer umfassenden Vernetzung aller Bereiche der Wirtschaft und Gesellschaft führen wird (BMWi, 2015 und ähnlich Köhler/Wollschläger, 2014: 79). Sie umfasst die Erhebung von analogen Informationen („Big Data“ in einem engen Sinne; z.B. O´Leary, 2013), ihre Speicherung in einem digitaltechnischen System (lokale Speicherung oder „Cloud Computing“ durch die Weiterentwickelung des Internets; z.B. Hashem et al., 2015: 101), die Analyse und Interpretation sowie den Transfer in andere Systeme („Internet der Dinge“ bzw. „Internet of Things“; z.B. Ashton, 2009).
The potential of SMART climbing robot combined with a weatherproof cabin for rotor blade maintenance
(2016)
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.
This work presents a methodology for automated
damage-sensitive feature extraction and anomaly
detection under multivariate operational variability
for in-flight assessment of wings. The
method uses a passive excitation approach, i. e.
without the need for artificial actuation. The
modal system properties (natural frequencies and
damping ratios) are used as damage-sensitive
features. Special emphasis is placed on the use
of Fiber Bragg Grating (FBG) sensing technology
and the consideration of Operational and
Environmental Variability (OEV). Measurements
from a wind tunnel investigation with a composite
cantilever equipped with FBG and piezoelectric
sensors are used to successfully detect an impact
damage. In addition, the feasibility of damage
localisation and severity estimation is evaluated
based on the coupling found between damageand
OEV-induced feature changes.