TY - GEN A1 - Frank, Lena A1 - Rödder, Maximilian A1 - Neef, Matthias A1 - Adam, Mario T1 - Heizung, Lüftung, Weiße Ware – Ein integriertes Systemkonzept für das Haus der Zukunft T2 - KKA – Kälte Klima Aktuell KW - energiBUS4home Y1 - 2018 SN - 0722-4605 VL - 37 IS - 4 SP - 42 EP - 47 PB - Bauverl. BV ER - TY - GEN A1 - Frank, Lena A1 - Rödder, Maximilian A1 - Neef, Matthias A1 - Adam, Mario T1 - energiBUS4home – Integration von Haushaltsgeräten in ein multifunktionales Wärmepumpensystem T2 - KI Kälte Luft Klimatechnik KW - energiBUS4home Y1 - 2020 SN - 1865-5432 VL - 56 IS - 8/9 SP - 41 EP - 45 PB - Hüthig ER - TY - CHAP A1 - Rödder, Maximilian A1 - Frank, Lena A1 - Kirschner, Daniel A1 - Neef, Matthias A1 - Adam, Mario ED - The International Centre for Sustainable Development of Energy, Water and Environment Systems, T1 - EnergiBUS4home – Sustainable energy resourcing in low-energy buildings T2 - 12th Conference on Sustainable Development of Energy, Water and Environment Systems, 04.-08.10.2017, Dubrovnik KW - energiBUS4home Y1 - 2017 ER - TY - JOUR A1 - Frank, Lena A1 - Rödder, Maximilian A1 - Neef, Matthias A1 - Adam, Mario T1 - Heating, Ventilation, Domestic Appliances – an Energy Integrated System Concept for the Household of the Future JF - Energy Y1 - 2021 U6 - https://doi.org/10.1016/j.energy.2021.121303 SN - 0360-5442 VL - 234 PB - Elsevier ER - TY - CHAP A1 - Dubberke, Frithjof H. A1 - Priebe, Klaus-Peter A1 - Vrabec, Jadran A1 - Neef, Matthias A1 - Rödder, Maximilian T1 - Thermodynamic simulation and experimental validation of a cascaded two-stage organic Rankine cycle T2 - ASME ORC 2015, Brussels KW - simulation Y1 - 2015 CY - Brussels ER - TY - CHAP A1 - Helm, Peter A1 - Spliethoff, Hartmut A1 - Neef, Matthias T1 - Closing the Gap: Measuring Bristle Blow Down of Brush Seals T2 - 19 th International Conference on Fluid Sealing, Poitiers Y1 - 2007 CY - Poitiers ER - TY - CHAP A1 - Neef, Matthias A1 - Hepermann, Florian A1 - Sürken, Norbert A1 - Schettel, Joachim T1 - Brush Seal Porosity Modeling: Applicability and Limitations T2 - ETC7 – 7th Conference on Turbomachinery, Athens Y1 - 2007 CY - Athens ER - TY - CHAP A1 - Neef, Matthias A1 - Hummel, Dietrich T1 - Euler solutions for a finite-span flapping wing T2 - "Fixed, flapping and rotary wing vehicles at very low Reynolds numbers, Notre Dame, Indiana, USA Y1 - 2000 ER - TY - JOUR A1 - Baier, André A1 - Neef, Matthias T1 - Studierende lehren und lernen sozial-ökologische Verantwortung JF - Die Neue Hochschule KW - Verantwortung Y1 - 2019 VL - 60 IS - 5 SP - 8 EP - 11 ER - TY - CHAP A1 - Neef, Matthias A1 - Fussenecker, Claudia A1 - Niemann, Jörg A1 - Zielke, Thomas ED - Clark, Robin ED - Munkebo Hussmann, Peter ED - Järvinen, Hannu-Matti T1 - Publish your undergraduate research! A mandatory course for master students in engineering T2 - Creativity, innovation and entrepreneurship for engineering education excellence : proceedings of the 46th SEFI Annual Conference 2018, Copenhagen, Denmark N2 - Undergraduate students in engineering often have little exposure to the world of scientific publishing and the culture of sharing research work. While the beneficial exchange between research and teaching is well promoted, while the benefits of conference participation for students have already been surveyed and while courses on scientific writing are readily available, the concept of mini-conferences as part of the curriculum combines all three aspects into one. Therefore, the course "Engineering Conferences" was developed and installed as a mandatory part of a master program for engineering students. The idea is to go beyond simply teaching the standards of academic writing and skills for using scientific publications. By using a learner-centered approach, the students are engaged in typical activities around an active attendance of a real conference. Based on their bachelor thesis, they write a paper complying with common academic standards, submit the paper and review submissions of their fellow students. They also produce a poster and defend their work in a poster session held publicly on campus. This contribution is based on the experience from the first four terms teaching the course. It explains the didactic rationale behind the concept and individual teaching modules, it comprises the collection of useful resources for teaching and organizing scientific publishing and it includes the consequences drawn from course evaluation results. Y1 - 2018 SN - 978-2-87352-016-8 PB - SEFI - Société Européenne pour la Formation des Ingénieurs CY - Brussels ER - TY - CHAP A1 - Neef, Matthias T1 - Innerstädtische Nutzung von Kleinwindkraftanlagen: Potentiale und Hürden T2 - Mülheimer Initiative für Klimaschutz, 06.05.2013 Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-21017 CY - Mülheim an der Ruhr ER - TY - THES A1 - Neef, Matthias T1 - Analyse des Schlagfluges durch numerische Strömungsberechnung N2 - 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. N2 - The three-dimensional viscous flow around a flapping wing is calculated by means of a finite volume code. The invoked motion parameters are comparable with the conditions in cruising flight of large birds. For the described application the numerical procedure is extended by implementing a method for realisation of arbitrary periodic motions. The verification is obtained by comparison with analytical, numerical and experimental results from existing literature. With the verified method the instationary quantities such as pressure and velocity are known in the vicinity of the wing. This also yields the time averaged values such as thrust and propulsive efficiency of the flapping wing propulsion. Additionally, the interaction between longitudinal and transverse vortices in the wake of the flapping wing is investigated. A dominant influence of the oscillating tip vortices due to the finite span can be seen, while the starting and stopping vortices due to the wing motion appear almost negligible in the cruising flight of large birds. Y1 - 2002 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:084-14501 UR - http://www.digibib.tu-bs.de/?docid=00001361 VL - ZLR-Forschungsbericht, 2 ER - TY - CHAP A1 - Helm, Peter A1 - Pugachev, Alexander A1 - Neef, Matthias T1 - Breaking the Swirl With Brush Seals: Numerical Modeling and Experimental Evidence T2 - Proceedings of the ASME Turbo Expo 2008 : presented at the 2008 ASME Turbo Expo, June 9 - 13, 2008, Berlin, Germany N2 - Striving for smaller losses in turbomachinery has led to many advancements in the design of seals. Modern sealing concepts such as brush seals hold a great potential to increase the efficiency of both flight engines and stationary turbines. At the same time, in order to maintain stable operating conditions of the rotor, swirl-induced forces must be kept at a minimum in the sealing channels. Therefore, the influence of the permeable and flexible bristle pack of brush seals on the flow around the rotor surface must be known. In this paper the swirl flow in the cavities of two different seal geometries is studied experimentally and numerically. A conventional three-tooth labyrinth serves as a reference. A second seal arrangement with a bristle pack upstream of two teeth is compared with the reference labyrinth. The swirl is evaluated experimentally from total and static pressure measurements in various axial and circumferential positions. Additionally, the axial swirl distribution is calculated using computational fluid dynamics (CFD). Here, the numerical model of the brush seal is based on the porous medium approach and is calibrated using the experimental values of the leakage and the bristle clearance by adjusting the thickness of the bristle pack. The calibrated CFD model is then used to study the impact of the brush seal on the swirl component of the sealing flow. The observed significant decrease of the swirl by the brush seal shows good agreement with the experimental data. The impact of changes in bristle pack clearance on the swirl is also investigated and compared with experimental evidence. The aim is to show that the brush seals have a natural tendency to interrupt seal swirl. They can therefore be used for swirl control in order to create a beneficial impact on the dynamic stability of turbomachines. Y1 - 2008 SN - 978-0-7918-4314-7 U6 - https://doi.org/10.1115/GT2008-50257 VL - 4 SP - 1387 EP - 1396 PB - ASME CY - New York ER - TY - CHAP A1 - Neef, Matthias A1 - Sulda, Erik A1 - Sürken, Norbert A1 - Walkenhorst, Jan T1 - Design Features and Performance Details of Brush Seals for Turbine Applications T2 - Proceedings of the ASME Turbo Expo 2006 : presented at the 2006 ASME Turbo Expo, May 6 - 11, 2006, Barcelona, Spain N2 - 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. Y1 - 2006 SN - 0-7918-4238-X U6 - https://doi.org/10.1115/GT2006-90404 VL - 3 SP - 1385 EP - 1392 PB - ASME CY - New York ER - TY - CHAP A1 - Hurd, Paul A1 - Truckenmueller, Frank A1 - Thamm, Norbert A1 - Pollak, Helmut A1 - Neef, Matthias A1 - Deckers, Mathias T1 - Modern Reaction HP/IP Turbine Technology Advances and Experiences T2 - Proceedings of the ASME Power Conference - 2005 : includes papers from the 2005 International Conference on Power Engineering (ICOPE) ; presented at the 2005 ASME Power Conference, April 5 - 7, 2005, Chicago, Illinois, USA Y1 - 2005 UR - https://asmedigitalcollection.asme.org/POWER/proceedings/POWER2005/41820/425/311927 SN - 0-7918-4182-0 U6 - https://doi.org/10.1115/PWR2005-50085 SP - 425 EP - 435 PB - ASME CY - New York ER - TY - CHAP A1 - Völker, Lutz A1 - Casey, Michael A1 - Neef, Matthias A1 - Stüer, Heinrich T1 - The Flow Field and Performance of a Model Low Pressure Steam Turbine T2 - 6th European Conference on Turbomachinery - Fluid Dynamics and Thermodynamics : conference proceedings; 7-11 March 2005, Lille, France N2 - A 3-stage model of a low pressure steam turbine has been equipped with extensive instrumentation to assess aerodynamic performance and for validation of numerical methods. Emphasis was placed on detailed measurements at the inlet and exit of the last stage guide vane. Two configurations were examined – the first used a guide vane with lean in the last stage and a the second used a guide vane combining both lean and sweep. The experimental results from the two configurations have been compared with data from various design methods, ranging from through-flow to 3D multistage viscous simulations with mixing planes. Despite the challenges in modelling complex rotating blades in a wet steam environment, good agreement between the numerical and experimental results was obtained, and the new stator vane combining lean and sweep achieved the desired increase in reaction at the hub section. Y1 - 2005 CY - Lille ER - TY - CHAP A1 - Windte, Jan A1 - Radespiel, Rolf A1 - Neef, Matthias ED - Kroll, Norbert ED - Fassbender, Jens K. T1 - Aerodynamic Analysis of Flapping Airfoil Propulsion at Low Reynolds Numbers T2 - MEGAFLOW - Numerical Flow Simulation for Aircraft Design KW - Lift Curve KW - Chord Length KW - Pitch Motion KW - Laminar Separation Bubble KW - Combine Motion Y1 - 2005 SN - 978-3-540-24383-0 U6 - https://doi.org/10.1007/3-540-32382-1_21 VL - NNFM, 89 SP - 299 EP - 313 PB - Springer-Verlag CY - Berlin, Heidelberg ER - TY - CHAP A1 - Neef, Matthias A1 - Hummel, D. ED - Krause, Egon ED - Jäger, Willi T1 - Euler and Navier-Stokes Solutions for Flapping Wing Propulsion T2 - High Performance Computing in Science and Engineering ’01 KW - Wing Motion KW - Computational Fluid Dynamics KW - High Performance Computing KW - Thrust Coefficient Y1 - 2002 SN - 978-3-642-62719-4 U6 - https://doi.org/10.1007/978-3-642-56034-7_37 VL - 30 SP - 386 EP - 395 PB - Springer CY - Berlin ER - TY - CHAP A1 - Neef, Matthias A1 - Hummel, Dietrich ED - Mueller, Thomas J. T1 - Euler Solutions for a Finite-Span Flapping Wing T2 - Fixed and Flapping Wing Aerodynamics for Micro Air Vehicle Applications Y1 - 2001 SN - 978-1-56347-517-7 U6 - https://doi.org/10.2514/5.9781600866654.0429.0451 VL - 16 SP - 429 EP - 451 PB - American Institute of Aeronautics and Astronautics CY - Reston, VA ER - TY - JOUR A1 - Neef, Matthias A1 - Fritzen, J. P. A1 - Schumacher, G. T1 - Evaluation of mount loads in dynamic testing of a jet engine JF - Mechanical Systems and Signal Processing N2 - In the dynamic testing of jet engines the evaluation of loads on the mount structure is vital for comparison with finite element calculations of such testing. Measuring these loads with the help of strain gauges applied to the structure becomes difficult if the mount is overdetermined and thus not every strain gauge can be assigned to a single load direction. In this study, the overdetermined mount structure of the BR715 engine was examined at one of the three mounting points between the Boeing 717 airframe and the engine, where loads in five directions were reacted. Firstly, the dependence of five measured strains upon known static load conditions at the mounting point had to be determined. For this purpose a static calibration test was carried out where defined forces and moments in known directions were applied to the structure while the output from five strain gauges was measured accordingly. The result was the desired relationship between loads and strains in terms of a matrix, which yields the corresponding load condition of the examined mounting point if multiplied with a set of strains. The same calibration procedure was carried out with a finite element model of the mount, where direct comparison to dynamic load results from the model itself was possible. With this model the validity of the above method was shown as well as possible errors which may occur while evaluating dynamic test results. The method was found to give satisfactory results even for dynamic loading, although some inertia forces disturb the signals in dynamic testing. Finally, the results from an actual dynamic engine test were processed into loads and then compared to the simulated loads from a finite element model of the engine. Good agreement was found and the indication of any remaining discrepancies was used to update the model for an even better representation of the dynamic test loads. Y1 - 2003 UR - http://www.sciencedirect.com/science/article/pii/S0888327001914050 U6 - https://doi.org/10.1006/mssp.2001.1405 VL - 17 IS - 3 SP - 665 EP - 681 PB - Elsevier ER - TY - CHAP A1 - Jones, Kevin A1 - Castro, Breno A1 - Mahmoud, Osama A1 - Pollard, S. A1 - Platzer, Max A1 - Neef, Matthias A1 - Gonet, K. A1 - Hummel, D. T1 - A collaborative numerical and experimental investigation of flapping-wing propulsion T2 - 40th AIAA Aerospace Sciences Meeting & Exhibit N2 - 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. Y1 - 2002 UR - http://arc.aiaa.org/doi/book/10.2514/MASM02 U6 - https://doi.org/10.2514/6.2002-706 PB - American Institute of Aeronautics and Astronautics CY - Reston, Virigina ER -