@inproceedings{RoedderFrankKirschneretal.2017, author = {R{\"o}dder, Maximilian and Frank, Lena and Kirschner, Daniel and Neef, Matthias and Adam, Mario}, title = {EnergiBUS4home - Sustainable energy resourcing in low-energy buildings}, series = {12th Conference on Sustainable Development of Energy, Water and Environment Systems, 04.-08.10.2017, Dubrovnik}, booktitle = {12th Conference on Sustainable Development of Energy, Water and Environment Systems, 04.-08.10.2017, Dubrovnik}, editor = {The International Centre for Sustainable Development of Energy, Water and Environment Systems,}, year = {2017}, language = {en} } @inproceedings{NeefHummel2000, author = {Neef, Matthias and Hummel, Dietrich}, title = {Euler solutions for a finite-span flapping wing}, series = {"Fixed, flapping and rotary wing vehicles at very low Reynolds numbers, Notre Dame, Indiana, USA}, booktitle = {"Fixed, flapping and rotary wing vehicles at very low Reynolds numbers, Notre Dame, Indiana, USA}, year = {2000}, language = {en} } @phdthesis{Neef2002, author = {Neef, Matthias}, title = {Analyse des Schlagfluges durch numerische Str{\"o}mungsberechnung}, volume = {ZLR-Forschungsbericht, 2}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:084-14501}, pages = {245}, year = {2002}, abstract = {Mit Hilfe eines Finite-Volumen-Verfahrens wird die dreidimensionale reibungsbehaftete Stroemung um einen schlagenden Fluegel berechnet. Die Bewegungsparamter sind dabei vergleichbar mit den Bedingungen im Reiseflug grosser Voegel. Das numerische Verfahren wird fuer den gezeigten Anwendungsfall, indem eine Methode zur Realisierung von beliebigen periodischen Bewegungen implemetiert wird. Eine Verifizierung erfolgt durch den Vergleich mit analytischen, numerischen und experimentellen Ergebnissen aus der Literatur. Mit dem verifizierten Verfahren werden die instationaeren Groessen wie Druck und Geschwindigkeiten in der Umgebung des bewegten Fluegels berechnet. Daraus ergeben sich ferner die zeitlich gemittelten Groessen wie Schub und Wirkungsgrad des Schlagfluges. Ausserdem wird die Interaktion von Laengs- und Querwirbeln im Nachlauf des schlagenden Fluegels untersucht. Es zeigt sich ein dominanter Einfluss der pulsierenden Randwirbel aufgrund der endlichen Spannweite, waehrend die Anfahr- und Stoppwirbel, verursacht durch die Fluegelbewegung, im Reiseflug grosser Voegel nahezu vernachlaessigbar erscheinen.}, language = {de} } @inproceedings{NeefSuldaSuerkenetal.2006, author = {Neef, Matthias and Sulda, Erik and S{\"u}rken, Norbert and Walkenhorst, Jan}, title = {Design Features and Performance Details of Brush Seals for Turbine Applications}, series = {Proceedings of the ASME Turbo Expo 2006 : presented at the 2006 ASME Turbo Expo, May 6 - 11, 2006, Barcelona, Spain}, volume = {3}, booktitle = {Proceedings of the ASME Turbo Expo 2006 : presented at the 2006 ASME Turbo Expo, May 6 - 11, 2006, Barcelona, Spain}, publisher = {ASME}, address = {New York}, organization = {American Society of Mechanical Engineers Corporation; International Gas Turbine Institute Corporation}, isbn = {0-7918-4238-X}, doi = {10.1115/GT2006-90404}, pages = {1385 -- 1392}, year = {2006}, abstract = {Adaptive and contacting seals such as brush seals have been successfully applied to turbomachinery for several years. In large steam turbine applications, however, various challenges still persist. Special focus is directed at the long-term performance and longevity of brushes on conventional spring-backed seal segments in steam turbines. This issue is particularly related to wear during startup conditions. This paper discusses the results of wear tests, derived from simulated transient turbine behavior, where the resultant seal leakage under steady state conditions is monitored. It is shown that the brush seal is significantly capable of adapting to varying operating conditions, but exhibits a degree of performance degradation during the initial startups. Together with previously reported mid-term wear data and an experience based long-term phenomenological approach a general model for brush seal performance degradation is developed. This model can be used for performance prediction and exerts influence on brush seal design.}, language = {en} } @incollection{JonesCastroMahmoudetal.2002, author = {Jones, Kevin and Castro, Breno and Mahmoud, Osama and Pollard, S. and Platzer, Max and Neef, Matthias and Gonet, K. and Hummel, D.}, title = {A collaborative numerical and experimental investigation of flapping-wing propulsion}, series = {40th AIAA Aerospace Sciences Meeting \& Exhibit}, booktitle = {40th AIAA Aerospace Sciences Meeting \& Exhibit}, publisher = {American Institute of Aeronautics and Astronautics}, address = {Reston, Virigina}, doi = {10.2514/6.2002-706}, pages = {36}, year = {2002}, abstract = {An international, collaborative investigation is undertaken to evaluate the relative merits and limitations of various numerical methods and experimental measurement techniques, specifically for the analysis of flapping-wing propulsion. A finite aspect-ratio configuration is extensively investigated, both quantitatively and qualitatively, in a low-speed wind tunnel. Direct force measurements are made, as well as time-accurate and time-averaged laser Doppler velocimetry and unsteady flow visualization. The reduced frequency, mean angle of attack, aspect ratio and Reynolds number are varied in the experiments. The experiment is numerically simulated using flatplate theory, two and three-dimensional panel codes, and two and three-dimensional Euler and Navier- Stokes solvers. The ability of each of the methods to capture important aspects of the flow physics are evaluated through comparisons with each other and the experimental data. Additionally, the comparisons indicate areas where further research is needed. The collaborative effort provides a survey of available capabilities and provides a fixed set of flappingwing data for others to compare against.}, language = {en} }