06 Fakultät Luft- und Raumfahrttechnik und Geodäsie

Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/7

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Institute: search.filters.UBSInstitut.Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)Institute: search.filters.UBSInstitut.Fakultätsübergreifend / Sonstige EinrichtungSubject: search.filters.subject.620

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    Icy ocean worlds - astrobiology research in Germany
    (2024) Klenner, Fabian; Baqué, Mickael; Beblo-Vranesevic, Kristina; Bönigk, Janine; Boxberg, Marc S.; Dachwald, Bernd; Digel, Ilya; Elsaesser, Andreas; Espe, Clemens; Funke, Oliver; Hauber, Ernst; Heinen, Dirk; Hofmann, Florence; Hortal Sánchez, Lucía; Khawaja, Nozair; Napoleoni, Maryse; Plesa, Ana-Catalina; Postberg, Frank; Purser, Autun; Rückriemen-Bez, Tina; Schröder, Susanne; Schulze-Makuch, Dirk; Ulamec, Stephan; de Vera, Jean-Pierre Paul
    Icy bodies with subsurface oceans are a prime target for astrobiology investigations, with an increasing number of scientists participating in the planning, development, and realization of space missions to these worlds. Within Germany, the Ocean Worlds and Icy Moons working group of the German Astrobiology Society provides an invaluable platform for scientists and engineers from universities and other organizations with a passion for icy ocean worlds to share knowledge and start collaborations. We here present an overview about astrobiology research activities related to icy ocean worlds conducted either in Germany or in strong collaboration with scientists in Germany. With recent developments, Germany offers itself as a partner to contribute to icy ocean world missions.
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    Dynamic-stall measurements using time-resolved pressure-sensitive paint on double-swept rotor blades
    (2021) Weiss, Armin; Geisler, Reinhard; Müller, Martin M.; Klein, Christian; Henne, Ulrich; Braukmann, Johannes N.; Letzgus, Johannes
    The study presents an optimized pressure-sensitive paint (PSP) measurement system that was applied to investigate unsteady surface pressures on recently developed double-swept rotor blades in the rotor test facility at the German Aerospace Center (DLR) in Göttingen. The measurement system featured an improved version of a double-shutter camera that was designed to reduce image blur in PSP measurements on fast rotating blades. It also comprised DLR’s PSP sensor, developed to capture transient flow phenomena (iPSP). Unsteady surface pressures were acquired across the outer 65% of the rotor blade with iPSP and at several radial blade sections by fast-response pressure transducers at blade-tip Mach and Reynolds numbers of Mtip=0.282-0.285 and Retip=5.84-5.95×105. The unique experimental setup allowed for scanning surface pressures across the entire pitch cycle at a phase resolution of 0.225deg azimuth for different collective and cyclic-pitch settings. Experimental results of both investigated cyclic-pitch settings are compared in detail to a delayed detached eddy simulation using the flow solver FLOWer and to flow visualizations from unsteady Reynolds-averaged Navier–Stokes (URANS) computations with DLR’s TAU code. The findings reveal a detailed and yet unseen insight into the pressure footprint of double-swept rotor blades undergoing dynamic stall and allow for deducing “stall maps”, where confined areas of stalled flow on the blade are identifiable as a function of the pitch phase.
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    Proton exchange membrane-like alkaline water electrolysis using flow-engineered three-dimensional electrodes
    (2024) Rocha, Fernando; Georgiadis, Christos; Van Droogenbroek, Kevin; Delmelle, Renaud; Pinon, Xavier; Pyka, Grzegorz; Kerckhofs, Greet; Egert, Franz; Razmjooei, Fatemeh; Ansar, Syed-Asif; Mitsushima, Shigenori; Proost, Joris
    For high rate water electrolysers, minimising Ohmic losses through efficient gas bubble evacuation away from the active electrode is as important as minimising activation losses by improving the electrode’s electrocatalytic properties. In this work, by a combined experimental and computational fluid dynamics (CFD) approach, we identify the topological parameters of flow-engineered 3-D electrodes that direct their performance towards enhanced bubble evacuation. In particular, we show that integrating Ni-based foam electrodes into a laterally-graded bi-layer zero-gap cell configuration allows for alkaline water electrolysis to become Proton Exchange Membrane (PEM)-like, even when keeping a state-of-the-art Zirfon diaphragm. Detailed CFD simulations, explicitly taking into account the entire 3-D electrode and cell topology, show that under a forced uniform upstream electrolyte flow, such a graded structure induces a high lateral velocity component in the direction normal to and away from the diaphragm. This work is therefore an invitation to start considering PEM-like cell designs for alkaline water electrolysis as well, in particular the use of square or rectangular electrodes in flow-through type electrochemical cells.