@article{WendelKaramanakosGebhardtetal.2021, author = {Wendel, Sebastian and Karamanakos, Petros and Gebhardt, Philipp and Dietz, Armin and Kennel, Ralph}, title = {Flux Linkage-Based Direct Model Predictive Current Control for Synchronous Machines}, series = {IEEE Transactions on Power Electronics}, volume = {36}, journal = {IEEE Transactions on Power Electronics}, number = {12}, publisher = {Institute of Electrical and Electronics Engineers (IEEE)}, issn = {0885-8993}, doi = {10.1109/tpel.2021.3083657}, pages = {14237 -- 14256}, year = {2021}, abstract = {This article presents a flux linkage-based direct model predictive current control approach that achieves favorable performance both during steady-state and transient operation. The former is achieved by computing the optimal time instants at which a new switch position is applied to the converter. To this end, the future current behavior is not computed based on the machine inductances or inductance look-up tables; instead, flux linkage maps are utilized to predict the trajectory of the magnetic flux linkage, and subsequently of the current. This is advantageous for electric drives with noticeable magnetic nonlinearity in terms of saturation and/or cross-coupling effects. Hence, by using flux linkage maps in the prediction process, the evolution of the stator current can be calculated more accurately, enabling the controller to make better switching decisions. Moreover, the discussed predictive controller exhibits excellent dynamic performance owing to its direct control nature, i.e., the control and modulation tasks are performed in one computational stage rendering a dedicated modulation stage redundant. Three different drive systems based on permanent magnet synchronous motors are examined to demonstrate the effectiveness of the presented control approach.}, language = {en} } @article{DietzDiTommasoMarignettietal.2020, author = {Dietz, Armin and Di Tommaso, Antonino Oscar and Marignetti, Fabrizio and Miceli, Rosario and Nevoloso, Claudio}, title = {Enhanced Flexible Algorithm for the Optimization of Slot Filling Factors in Electrical Machines}, series = {Energies}, volume = {13}, journal = {Energies}, number = {5}, publisher = {MDPI AG}, issn = {1996-1073}, doi = {10.3390/en13051041}, pages = {21}, year = {2020}, abstract = {The continuous development in the field of industrial automation and electric mobility has led to the need for more efficient electrical machines with a high power density. The improvement of electrical machines' slot filling factors is one of the measures to satisfy these requirements. In recent years, this topic has aroused greater interest in the industrial sector, since the evolution of the winding technological manufacturing processes allows an economically sustainable realization of ordered winding arrangements, rather than random ones. Moreover, the manufacture of electrical machines' windings must be preceded by an accurate design phase in which it is possible to evaluate the maximum slot filling factor obtainable for a given wire shape and for its dimensions. For this purpose, this paper presents an algorithmic approach for the evaluation of maximum slot filling factors in electrical machines under an ideal geometric premise. In particular, this algorithm has a greater degree of flexibility with respect to the algorithm approaches found in the literature, since the study has been extended to round, rectangular and hexagonal wire sections. Furthermore, the slot filling factor calculation was carried out both for standard and non-standard slots. The algorithmic approach proposed can be considered as an additional useful tool for the fast design of electrical machine windings.}, language = {en} } @article{Hess2023, author = {Heß, Max}, title = {Wave runup and wave deflection within the freebord design at dams}, series = {WASSERWIRTSCHAFT}, volume = {113}, journal = {WASSERWIRTSCHAFT}, number = {6}, publisher = {Springer Science and Business Media LLC}, issn = {0043-0978}, doi = {10.1007/s35147-023-1827-1}, pages = {72 -- 75}, year = {2023}, abstract = {The wave overtopping in context with the freebord design at dams is generally not accepted. With the implementation of independent investigations, the prognostic capability of numerical methods regarding the wave run-up and wave deflection processes on dam embankments with and without wave deflectors was verified. Furthermore, a dimensioning concept was developed that is based on data sets obtained by means of calibrated hydrodynamic-numerical models to estimate the required size of deflection structures.}, language = {de} } @article{KuglerAumuellerKrcmaretal.2022, author = {Kugler, Felix and Aum{\"u}ller, Jessica and Krcmar, Wolfgang and Teipel, Ulrich}, title = {Construction and Demolition Residuals as Raw Materials for the Production of Novel Geopolymer Building Materials}, series = {Crystals}, volume = {12}, journal = {Crystals}, number = {5}, publisher = {MDPI AG}, issn = {2073-4352}, doi = {10.3390/cryst12050678}, year = {2022}, abstract = {The increasing number of new construction projects requiring high-quality building products, which, in turn, emit enormous amounts of CO2, runs counter to European and global climate goals. The increasing occupation of valuable landfill space is also an ecological problem. To meet these challenges without having to lower living standards, more ecological building materials should be used in the future. Geopolymers or alkali-activated materials, which, unlike conventional building materials, can be produced and used without a prior burning or calcination process, offer a comparatively low-CO2 alternative. Significant CO2 emissions can already be saved by using this technology. The aim of this work is to investigate whether geopolymers can also be produced from construction and demolition residuals generated by the construction industry in order to counteract the problem of the increasing use of landfill space and, at the same time, to further reduce greenhouse gas emissions in the production of building materials. For this purpose, various residual materials from the construction and demolition industry are investigated by means of XRF, XRD, and IR spectroscopy for their setting behavior by alkaline activation. At the same time, the characteristic values of compressive strength, flexural strength, bulk density, and thermal conductivity, which are important for building materials, are determined in order to test the possible applications of the resulting materials as building materials.}, language = {en} } @article{KuglerFehnSandneretal.2022, author = {Kugler, Felix and Fehn, Thomas and Sandner, Maximilian and Krcmar, Wolfgang and Teipel, Ulrich}, title = {Microstructural and mechanical properties of geopolymers based on brick scrap and fly ash}, series = {International Journal of Ceramic Engineering \& Science}, volume = {4}, journal = {International Journal of Ceramic Engineering \& Science}, number = {2}, publisher = {Wiley}, issn = {2578-3270}, doi = {10.1002/ces2.10120}, pages = {92 -- 101}, year = {2022}, abstract = {In the present work, the influence of increasing brick scrap additions on the setting behavior and material properties of fly ash-based geopolymers is investigated. The geopolymers produced are tested for their compressive strengths, bulk densities, and thermal conductivities, among other properties. Both the starting materials and the produced geopolymers are also investigated by infrared spectroscopy, X-ray diffraction analysis, and scanning electron microscopy to show the relationship between the solidification behavior and the resulting material properties. The investigations show that brick scrap is very suitable as a matrix material for geopolymer production. Increasing brick scrap additions lead, among other things, to a reduction in bulk density, thermal conductivity and compressive strength.}, language = {en} } @article{KuglerKarrerKrcmaretal.2022, author = {Kugler, Felix and Karrer, J{\"o}rg and Krcmar, Wolfgang and Teipel, Ulrich}, title = {Setting behavior and mechanical properties of concrete rubble fly ash geopolymers}, series = {Open Ceramics}, volume = {11}, journal = {Open Ceramics}, publisher = {Elsevier BV}, issn = {2666-5395}, doi = {10.1016/j.oceram.2022.100286}, pages = {11}, year = {2022}, abstract = {Due to concerns about the very high primary raw material consumption and CO2 emissions of the economically important construction sector, the demand for "green" binders is growing. One option that is receiving particular attention is the material class of "geopolymers", which could be used as a substitute for Portland cement. This new group of binders not only exhibits improved mechanical properties, but is also characterized by particularly low carbon dioxide emissions in the course of its production. This work focuses on the influence of concrete rubble on the setting behavior and microstructural properties of fly ash-based geopolymers. In the course of the investigations, the manufactured geopolymer samples are examined for the material parameters relevant to building materials, namely compressive strength, raw density and thermal conductivity. The setting behavior and the forming structures are investigated by infrared spectroscopy, X-ray diffraction analysis and scanning electron microscopy. The present work is intended to contribute to the development of a suitable recycling strategy for the material recycling of concrete rubble in novel substitute construction materials, the geopolymers.}, language = {en} } @article{FehnKuglerTuebkeetal.2021, author = {Fehn, Thomas and Kugler, Felix and T{\"u}bke, Beatrice and Schweppe, Rainer and Mebert, Phillip and Krcmar, Wolfgang and Teipel, Ulrich}, title = {Charakterisierung und St{\"o}rstoffanalyse von r{\"u}ckgewonnenen Stoffstr{\"o}men aus W{\"a}rmed{\"a}mmverbundsystemen}, series = {Chemie Ingenieur Technik}, volume = {93}, journal = {Chemie Ingenieur Technik}, number = {5}, publisher = {Wiley}, issn = {0009-286X}, doi = {10.1002/cite.202000215}, pages = {771 -- 780}, year = {2021}, abstract = {Aufgrund steigender energetischer Anforderungen ist der Anteil an verbauten W{\"a}rmed{\"a}mmverbundsystemen (WDVS) in den vergangenen 50 Jahren deutlich gestiegen. Trotz der Langlebigkeit dieser Systeme fallen zunehmend WDVS-Abf{\"a}lle an, deren Nutzungsphase beendet ist. Aufgrund der komplexen Bauweise sowie einer Vielzahl an unterschiedlich verbauten Materialien der vergangenen Generationen bestehen viele Unsicherheiten und Probleme bei der sortenreinen und schadstoffarmen Aufbereitung solcher Systeme. Im Rahmen der vorliegenden Arbeit wurde ein Aufbereitungsverfahren f{\"u}r WDVS entwickelt. Damit gelingt eine weitestgehende R{\"u}ckgewinnung verwertbarer Werkstofffraktionen. Diese wurden auf etwaige St{\"o}r- und Schadstoffe wie Flammschutzmittel sowie auf deren Reinheit untersucht.}, language = {de} } @article{GumpertJanssenBrabecetal.2023, author = {Gumpert, Fabian and Janßen, Annika and Brabec, Christoph J. and Egelhaaf, Hans-Joachim and Lohbreier, Jan and Distler, Andreas}, title = {Predicting layer thicknesses by numerical simulation for meniscus-guided coating of organic photovoltaics}, series = {Engineering Applications of Computational Fluid Mechanics}, volume = {17}, journal = {Engineering Applications of Computational Fluid Mechanics}, number = {1}, publisher = {Informa UK Limited}, issn = {1994-2060}, doi = {10.1080/19942060.2023.2242455}, year = {2023}, abstract = {To achieve maximum efficiency in organic photovoltaics (OPV), functional layers with uniform and exactly predefined thickness are required. An in-depth understanding of the coating process is therefore crucial for an accurate process control. In this paper, the meniscus-guided blade coating process, which is the most commonly used process for the manufacturing of organic electronics, is investigated by experimental and numerical methods. A computational fluid dynamics (CFD) model is created to simulate the coating behaviour of P3HT:O IDTBR, an industrial state-of-the-art active material system used in OPV, and its results' independence of numerical parameters is ensured. In particular, the influence of the coating velocity and the initially injected fluid volume on the resulting wet film thickness is studied. The developed CFD analysis is able to reproduce the experimental results with very high accuracy. It is found that the film thickness follows a power law dependence on the velocity (˜v 2/3) and a linear dependence on the ink volume (˜V). Accordingly, an analytical expression based on our theoretical considerations is presented, which predicts the wet film thickness as a function of the coating velocity and the ink volume only based on easily accessible ink properties. Consequently, this CFD model can effectively substitute time-consuming and expensive experiments, which currently have to be performed manually in the laboratory for a multitude of novel material systems, and thus supports highly accelerated material research. Moreover, the results of this work can be used to achieve homogeneous large-area coatings by utilising accelerated blade coating.}, language = {en} } @article{BasuGumpertLohbreieretal.2024, author = {Basu, Robin and Gumpert, Fabian and Lohbreier, Jan and Morin, Pierre-Olivier and Vohra, Varun and Liu, Yang and Zhou, Yinhua and Brabec, Christoph J. and Egelhaaf, Hans-Joachim and Distler, Andreas}, title = {Large-area organic photovoltaic modules with 14.5\% certified world record efficiency}, series = {Joule}, volume = {8}, journal = {Joule}, number = {4}, publisher = {Elsevier BV}, issn = {2542-4351}, doi = {10.1016/j.joule.2024.02.016}, pages = {970 -- 978}, year = {2024}, abstract = {Organic photovoltaics (OPVs) have experienced a significant increase in power conversion efficiency (PCE) recently, now approaching 20\% on small-cell level. Since the efficiencies on the module level are still substantially lower, focused upscaling research is necessary to reduce the gap between cells and modules. In this work, we present the upscaling of PM6:Y6-C12:PC 61 BM-based devices, processed in ambient air from non-halogenated solvents, from small-area cells to large-area modules with barely any performance loss. Supported by computational fluid dynamics simulations, an acceler- ated blade coating process that enables homogeneous coatings with <5\% thickness deviation over 200 cm 2 is developed. Additional finite element method simulations are used to optimize the module layout and minimize the inevitable losses caused by electrode resistances and inactive interconnect areas to 1.9\% and 3.5\%, respectively. Finally, a 204-cm 2 OPV module with a certified PCE of 14.5\% (15.0\% on active area) is fabricated, which constitutes the new world record.}, language = {en} } @article{GumpertJanssenBasuetal.2024, author = {Gumpert, Fabian and Janßen, Annika and Basu, Robin and Brabec, Christoph J. and Egelhaaf, Hans-Joachim and Lohbreier, Jan and Distler, Andreas}, title = {On the theoretical framework for meniscus-guided manufacturing of large-area OPV modules}, series = {Progress in Organic Coatings}, volume = {192}, journal = {Progress in Organic Coatings}, publisher = {Elsevier BV}, issn = {0300-9440}, doi = {10.1016/j.porgcoat.2024.108505}, pages = {10}, year = {2024}, abstract = {Although the formation of plasma electrolytic oxidation (PEO) coatings on aluminum alloys can significantly enhance their service life, they may still suffer from corrosion damage when exposed to harsh environments with strong corrosivity for a long time. In this work, chitosan (CS) was dissolved in four acids, i.e. hydrochloric acid (HCl), citric acid (CA), lactic acid (LA), and acetic acid (HAc), and deposited onto the PEO-coated 5052 aluminum alloy using dip coating method. Scanning electron microscope (SEM), energy dispersive spectrometer (EDS), atomic force microscope (AFM), contact angle (CA) meter, grazing incidence X-ray diffraction (GIXRD), Fourier transform infrared spectrometer (FTIR), and electrochemical workstation system were used to explore the enhancement of the corrosion resistance of PEO-coated 5052 aluminum alloy by application of CS film prepared in different solvent acids. The results showed that the interactions between chitosan and acid ions affects the uniformity, hydrophobicity, thickness and surface roughness of the CS/PEO coating. The HAc-CS/PEO coating had the lowest surface roughness of 32.4 ± 3.9 nm, the largest contact angle of 85.7 ± 2.0◦, and the thickest CS film of 20 μm, which significantly improved corrosion resistance of PEO-coated aluminum alloy.}, language = {en} } @inproceedings{GumpertVamboltSchmidtetal.2024, author = {Gumpert, Fabian and Vambolt, Eugen and Schmidt, Michael and Fromme, Lars and Dietz, Armin and Lohbreier, Jan}, title = {Physics-Informed Neural Networks to predict the Power Transmission of Electric Road Systems}, series = {2024 1st International Conference on Production Technologies and Systems for E-Mobility (EPTS)}, booktitle = {2024 1st International Conference on Production Technologies and Systems for E-Mobility (EPTS)}, publisher = {IEEE}, doi = {10.1109/EPTS61482.2024.10586741}, pages = {1 -- 7}, year = {2024}, language = {en} } @article{MoeldnerHentschelCarstensen2024, author = {M{\"o}ldner, Fabian and Hentschel, Bernd and Carstensen, Dirk}, title = {Ice-Jam Investigations along the Oder River Based on Satellite and UAV Data}, series = {Water}, volume = {16}, journal = {Water}, number = {10}, publisher = {MDPI AG}, issn = {2073-4441}, doi = {10.3390/w16101323}, pages = {23}, year = {2024}, abstract = {The Oder River, situated along the border between Poland and Germany, is regularly affected by ice-jam events and their associated hazards, such as a sudden rise in water level and the endangerment to flood-protection infrastructure. The existing databases on past ice-jam events lack substantial information considering ice formation, blockage origins or the spatiotemporal evolution of the ice cover needed for a comprehensive understanding of relevant ice processes. Within this study, the evaluation of satellite and Uncrewed Aerial Vehicle (UAV) data was carried out in order to analyze the capabilities of enhancing river ice information in the study area. Satellite imagery was proven to be a valuable source of investigating ice-jam phenomena on all scales, leading to the identification of initial ice-jam locations, surveying spatiotemporal ice cover evolution or monitoring the maximum ice-cover extent. A simplified approach for river ice classification of satellite radar data using the K-Means Cluster Analysis is introduced, enabling the differentiation between river ice formations. Based on UAV data taken in this study, workflows were presented, allowing for measurements of ice floe velocities and the localization of flooded and ice-covered flow control structures.}, language = {en} } @article{SchefflerModerSchrageetal.2023, author = {Scheffler, Holger and Moder, Michael and Schrage, Nico and Lippert, Kaj and Heß, Max and Rostan, Fabian and Carstensen, Dirk and K{\"o}hler, Albrecht and Schaarschmidt, Lars}, title = {Zusammenwirken von Planung und hydraulischer Untersuchung am HRB Weilers/Bracht}, series = {WASSERWIRTSCHAFT}, volume = {113}, journal = {WASSERWIRTSCHAFT}, number = {6}, publisher = {Springer Science and Business Media LLC}, issn = {0043-0978}, doi = {10.1007/s35147-023-1833-3}, pages = {44 -- 47}, year = {2023}, abstract = {Der Neubau eines Hochwasserr{\"u}ckhaltebeckens (HRB) erfordert umfangreiche hydraulische Untersuchungen. M{\"o}glichkeiten zur {\"U}berpr{\"u}fung und Optimierung einer wasserbaulichen Planung sind sowohl der physikalische Modellversuch als auch eine hydrodynamisch-numerische Str{\"o}mungsmodellierung. Fragestellungen zur Wirkungsweise und zu den Wechselwirkungen der Betriebseinrichtung eines HRB k{\"o}nnen so beantwortet werden. Der vorliegende Beitrag beschreibt das Zusammenwirken von Planung und hydraulischen Untersuchungen am Neubauprojekt HRB Weilers/Bracht in Hessen.}, language = {de} } @inproceedings{GerstnerMaerzDietz2020, author = {Gerstner, Michael and Maerz, Martin and Dietz, Armin}, title = {Design of a Wide Input Voltage Range Current-Fed DC/DC Converter Within a Reduced Duty-Cycle Range}, series = {2020 22nd European Conference on Power Electronics and Applications (EPE'20 ECCE Europe)}, booktitle = {2020 22nd European Conference on Power Electronics and Applications (EPE'20 ECCE Europe)}, publisher = {IEEE}, doi = {10.23919/epe20ecceeurope43536.2020.9215825}, pages = {10}, year = {2020}, abstract = {A design of a current-fed push-pull converter for wide input voltage ranges within a reduced duty-cycle range is presented. Based on the converter conversion ratios of three different clamping configurations, the potential of the input clamping is shown analytical, simulative and by measurements. A differentiation is made between the four possible operating modes, which can be distinguished in the control of the semiconductors and the magnetomotive force in the reactor. By optimizing the turn ratios of both transformers, the wide input voltage range capability of the input clamped current-fed push-pull converter was improved, which has been proved by measurements on a real prototype.}, language = {en} } @inproceedings{RabensteinDietzParspour2020, author = {Rabenstein, Lukas and Dietz, Armin and Parspour, Nejila}, title = {Design Concept of a Wound Field Transverse Flux Machine using Soft Magnetic Composite Claw-Poles}, series = {2020 10th International Electric Drives Production Conference (EDPC)}, booktitle = {2020 10th International Electric Drives Production Conference (EDPC)}, publisher = {IEEE}, doi = {10.1109/edpc51184.2020.9388176}, pages = {5}, year = {2020}, abstract = {This paper presents the machine concept of a wound field transverse flux machine (WFTFM). In contrast to permanent magnet transverse flux machines (PMTFM), here the magneto motive force (mmf) of the rotor is generated by a current. The magnetic circuit of the WFTFM is made of soft magnetic composite (SMC) and is designed as claw-poles. Thus the magnetic circuit consists of only a few components. Together with the simple ring coils in stator and rotor, the WFTFM offers advantages in the production of electrical machines. The basic structure of the machine and a first design is described here. The results generated by numerical three-dimensional finite element analysis (FEA) are compared with those of conventional machines.}, language = {en} } @inproceedings{RucciusPrellerMarzetal.2017, author = {Ruccius, Benjamin and Preller, Bastian and Marz, Martin and Wagner, Bernhard}, title = {An advanced control concept for modular multilevel converter using capacitor voltage estimation}, series = {2017 IEEE Southern Power Electronics Conference (SPEC)}, booktitle = {2017 IEEE Southern Power Electronics Conference (SPEC)}, publisher = {IEEE}, doi = {10.1109/SPEC.2017.8333590}, pages = {8}, year = {2017}, abstract = {An advanced control concept for a Modular Multilevel Converter (MMC) is presented in this paper. By using a Notch Filter and a Kalman Filter it is possible to reduce unwanted AC components within circulating currents in the MMC significantly. Subsequently the current stress and the conduction and switching losses in the semiconductors can be minimized. In the second part of this paper, approaches to estimate the capacitor voltages are presented. The observability is inverstigated theoretically and via simulations. A disadvantage of the MMC topology is the need of a complex and expensive communication system. While the submodule voltages are being estimated, the communication effort between the submodules and the main controller hardware is significantly reduced.}, language = {en} } @article{StockingerSchmid2023, author = {Stockinger, Volker and Schmid, Matthias}, title = {Hydraulischer Abgleich als Schl{\"u}ssel zur Energieeffizienz}, series = {BWK ENERGIE}, volume = {75}, journal = {BWK ENERGIE}, number = {3/4}, publisher = {VDI Fachmedien GmbH and Co. KG}, issn = {1618-193X}, doi = {10.37544/1618-193X-2023-3-4-48}, pages = {48 -- 52}, year = {2023}, abstract = {Im Forschungsvorhaben „+EQ-Net II" wird der Betrieb eines gemischt genutzten Geb{\"a}udes {\"u}ber ein mehrj{\"a}hriges Monitoring wissenschaftlich analysiert. Ziel ist es, Betriebsoptimierungspotenziale an der Anlagentechnik inklusive einer Großkollektoranlage zu heben. Aufgrund der Messdaten konnten bereits erhebliche Einsparpotenziale in der W{\"a}rmeverteilung aufgezeigt werden.}, language = {de} } @inproceedings{KrippnerFlade2020, author = {Krippner, Roland and Flade, F.}, title = {Cleanvelope - Students concepts of refurbishment with solar energy and fa{\c{c}}ade greening}, series = {Proceedings of the ISES EuroSun 2020 Conference}, booktitle = {Proceedings of the ISES EuroSun 2020 Conference}, publisher = {International Solar Energy Society}, address = {Freiburg, Germany}, doi = {10.18086/eurosun.2020.01.11}, pages = {1 -- 12}, year = {2020}, language = {en} } @article{BiedermannHintzenKameier2022, author = {Biedermann, Till M. and Hintzen, Nils and Kameier, Frank}, title = {Aeroacoustic Interactions of Blade Skew and Leading Edge Serrations Applied to Low-Pressure Axial Fans}, series = {Journal of Engineering for Gas Turbines and Power}, volume = {144}, journal = {Journal of Engineering for Gas Turbines and Power}, number = {12}, publisher = {ASME International}, issn = {0742-4795}, doi = {10.1115/1.4055637}, pages = {12}, year = {2022}, abstract = {Leading edge serrations are well known for their ability to reduce turbulence-induced noise of single aerofoils while also providing aerodynamic advantages under certain operating conditions. Continuatively, applying leading edge serrations to rotating machinery such as axial fans proved the validity to generally transfer the obtained aeroacoustic benefits of single aerofoils. However, for the rotating applications the noise reduction potential highly depends on the point of operation. The current work aims at assessing the aeroacoustic effects of serrated leading edges under the increased geometrical complexity of the fan blades through blade skew. Therefore, the question is whether combining two potentially effective noise-reducing treatments through blade skew and leading edge serrations results in leveraging or obstructing effects. By varying the skew angle from 0 deg to 38 deg, four different prototypes of the fan impeller are tested experimentally in a test rig according to ISO 5136 and ISO 5801. All configurations are tested with original blades of straight leading edges plus five sets of serrations each, parameterised by the serration amplitude and the serrations wavelength. The intensity of the incoming turbulence ranges from 2.6\% to 12.1\%. The results obtained show the skewed blades to improve both the aerodynamic performance and the noise radiation after exceeding an initial skew angle, complemented by a significant onset of stall. Moreover, no contraindication between blade skew and serrated leading edges is encountered, showing the potential to further extend the noise reduction capabilities by combining effects of blade skew and leading edge treatment.}, language = {en} } @article{BiedermannReichPaschereit2020, author = {Biedermann, Till M. and Reich, M. and Paschereit, C. O.}, title = {Multi-Objective Modeling of Leading-Edge Serrations Applied to Low-Pressure Axial Fans}, series = {Journal of Engineering for Gas Turbines and Power}, volume = {142}, journal = {Journal of Engineering for Gas Turbines and Power}, number = {11}, publisher = {ASME International}, issn = {0742-4795}, doi = {10.1115/1.4048599}, pages = {13}, year = {2020}, abstract = {A novel modeling strategy is proposed which allows high-accuracy predictions of aerodynamic and aeroacoustic target values for a low-pressure axial fan, equipped with serrated leading edges. Inspired by machine learning processes, the sampling of the experimental space is realized by use of a Latin hypercube design plus a factorial design, providing highly diverse information on the analyzed system. The effects of four influencing parameters (IP) are tested, characterizing the inflow conditions as well as the serration geometry. A total of 65 target values in the time and frequency domains are defined and can be approximated with high accuracy by individual artificial neural networks. Furthermore, the validation of the model against fully independent test points within the experimental space yields a remarkable fit, even for the spectral distribution in 1/3-octave bands, proving the ability of the model to generalize. A metaheuristic multi-objective optimization approach provides two-dimensional Pareto optimal solutions for selected pairs of target values. This is particularly important for reconciling opposing trends, such as the noise reduction capability and aerodynamic performance. The chosen optimization strategy also allows for a customized design of serrated leading edges, tailored to the specific operating conditions of the axial fan.}, language = {en} }