OOPS - Oldenburger Online-Publikations-Server (Univ. Oldenburg)
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Numerical Simulation of Ice Accretion on Coated Wind Turbine Blades
Get PDFThis thesis aims to develop new OpenFOAM codes to simulate the ice accretion on wind turbine blades in cold climates and the effects of ice-phobic coatings on the overall anti-icing heat. To avoid high computational costs of resolving complex profiles of ice, rough wall functions are used to model the effects of roughness on the airflow without completely resolving the flow field. Water particles carried by air are then tracked using Lagrangian particle tracking to calculate the exact locations of impingement on the surface to determine whether the particles are pinned or bouncing on the surface. The water mass on the surface is determined and the thermodynamic model of icing is solved to determine the ice profile. A 3D rotating wind turbine blade is simulated using the quasi-3D technique and compared with other CFD codes for validation and the expected minimum anti-icing heat in case ordinary surfaces is compared to the ice-phobic case to study the feasibility of such coatings
Continental Pans in Southern Africa and their Potential as Paleoclimatic and Paleoecological Geoarchives
Get PDFReconstruction of Quaternary climate data in southern Africa plays an important role to estimate regional climate mechanisms and the vulnerability to global environmental influences. In this study environmental data was reconstructed via biomarkers of salt pan sediments from eastern Namibia. The focus was laid on the assemblage of leaf wax n alkanes and their composition of carbon and hydrogen isotopes. The data shows dynamic changes around 18000 And 12000 years before present and a tendency to dryer conditions during the Holocene. There were challenges with the reconstruction of hydrological conditions via hydrogen isotopes and new potentials in variations of relative concentrations of long chain n alkanes. The study shows that salt pans are an usable archive to close paleoclimatic gaps in central southern Africa
Analysis of the effect of intermittent wind on wind turbines by means of CFD
Get PDFThe goal of this thesis is to quantify the impact of in atmosphere measured higher order increment statistics on fatigue loads of wind turbines. As the main tool for the generation of wind fields with the corresponding statistics, an improved stochastic turbulent wind model based on Continous Time Random Walks (CTRWs) is developed and used as an input for Computational Fluid Dynamics simulations. After the comparison of different inflow methods with respect to the evolution of the turbulence along an open channel, it can be shown in rotor simulations that an increased kurtosis of the increment distribution of the wind field leads to higher fatigue loads for the airfoil as well as the whole rotor. Furthermore, a relation between correlations within the inflow plane and fatigue loads could be found
Augmented Reality zur Unterstützung des selbstgesteuerten Lernens in der praktischen Techniklehrkräfteausbildung: Vorstellung des Projekts SelTecAR und erste Befunde zu Unterstützungsbedarfen bei Studierenden
No full textDie Realität durch Augmented Reality (AR) zu erweitern, kann zur Unterstützung selbstgesteuerter Lernprozesse ein nützliches Werkzeug sein. Diese Möglichkeit wird im Projekt SelTecAR (Selbstgesteuertes Lernen im Technikstudium durch Augumented Reality) der AG Technische Bildung der Universität Oldenburg zur Verbesserung der handwerklich-praktischen Ausbildung von Techniklehramtsstudierenden genutzt. Innerhalb dieses Projekts wird eine AR-Umgebung in den Lehrwerkstätten etabliert und die Einführung des Systems wissenschaftlich begleitet. Zu dieser Begleitung zählt unter anderem die Erfassung der Unterstützungsbedarfe der Studierenden in den Werkstätten. Der Artikel beschreibt, welche Möglichkeiten die AR-Technologie im Bereich des selbstgesteuerten Lernens bietet und zeigt erste Ergebnisse einer Bedarfsanalyse, die aufzeigt, bei welchen praktischen Inhalten des Studiums Studierende besonders hohen Unterstützungsbedarf sehen
