@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}, doi = {10.1115/1.4048599}, year = {2020}, language = {en} } @article{AlSadawiBiedermannFritsche2021, author = {Al-Sadawi, L. and Biedermann, Till M. and Fritsche, M.}, title = {Passive Control of Vortex Shedding Noise of Circular Cylinders by Passive Air-Jet Blowing}, series = {Journal of Aerospace Engineering}, volume = {34}, journal = {Journal of Aerospace Engineering}, number = {5}, publisher = {American Society of Civil Engineers (ASCE)}, issn = {0893-1321}, doi = {10.1061/(asce)as.1943-5525.0001301}, year = {2021}, language = {en} } @article{BiedermannCzeckayGeyeretal.2019, author = {Biedermann, Till M. and Czeckay, Pasquale and Geyer, Thomas F. and Kameier, Frank and Paschereit, Christian O.}, title = {Effect of Inflow Conditions on the Noise Reduction Through Leading Edge Serrations}, series = {AIAA Journal}, volume = {57}, journal = {AIAA Journal}, number = {9}, publisher = {ARC}, issn = {1533-385X}, doi = {10.2514/1.j057831}, pages = {4104 -- 4109}, year = {2019}, language = {en} } @article{BiedermannKameierPaschereit2019, author = {Biedermann, Till M. and Kameier, F. and Paschereit, C. O.}, title = {Successive Aeroacoustic Transfer of Leading Edge Serrations From Single Airfoil to Low-Pressure Fan Application}, series = {Journal of Engineering for Gas Turbines and Power}, volume = {141}, journal = {Journal of Engineering for Gas Turbines and Power}, number = {10}, publisher = {ASME}, doi = {10.1115/1.4044362}, year = {2019}, language = {en} } @article{BiedermannReichKameieretal.2019, author = {Biedermann, Till M. and Reich, Marius and Kameier, Frank and Adam, Mario}, title = {Assessment of statistical sampling methods and approximation models applied to aeroacoustic and vibroacoustic problems}, series = {Advances in Aircraft and Spacecraft Science}, volume = {6}, journal = {Advances in Aircraft and Spacecraft Science}, number = {6}, publisher = {Techno Press}, issn = {2287-528X}, doi = {10.12989/aas.2019.6.6.531}, pages = {529 -- 550}, year = {2019}, language = {en} } @article{BiedermannChongKameieretal.2017, author = {Biedermann, Till M. and Chong, Tze Pei and Kameier, Frank and Paschereit, Christian O.}, title = {Statistical-Empirical Modeling of Airfoil Noise Subjected to Leading-Edge Serrations}, series = {AIAA Journal}, volume = {55}, journal = {AIAA Journal}, number = {9}, publisher = {ARC}, doi = {10.2514/1.j055633}, pages = {3128 -- 3142}, year = {2017}, language = {en} } @phdthesis{Biedermann2019, author = {Biedermann, Till M.}, title = {Aeroacoustic transfer of leading edge serrations from single aerofoils to low-pressure fan applications}, publisher = {Technische Universit{\"a}t Berlin}, address = {Berlin}, organization = {Technische Univerit{\"a}t Berlin}, doi = {10.14279/depositonce-9075}, school = {Hochschule D{\"u}sseldorf}, pages = {221}, year = {2019}, abstract = {Leading edge serrations are well-known for their aeroacoustic potential in reducing aerofoil-turbulence interaction noise and are also associated with certain aerodynamic advantages. To prepare leading edge serrations for industrial application, two obstacles remain to be addressed. First is a combined analysis of the aeroacoustic and the aerodynamic performance of leading edge serrations to develop optimum designs. Second is the need to examine the transferability of the known effects of leading edge serrations from a single aerofoil to full rotors, which are considered to be the final area of application. This thesis aims to assist in the transfer of a well-investigated aerofoil with serrated leading edges from the rigid to the rotating domain. With this purpose, a single aerofoil type is selected and thoroughly analysed, experimentally and numerically, to generate a reliable data basis for aerodynamic performance and noise reduction capability. Aside from gathering information on the overall performance, the spatial distribution of the noise sources is localised, and the spectral composition of the noise reduction is found to follow a clearly defined scaling law. Aerodynamically, generated vortices are found to be responsible for a complex three-dimensional separation mechanism of the leading edge serrations, causing a delay of stall. The generated data basis is then used to design low-pressure axial fans of minimum complexity by keeping the initially chosen aerofoil type. The experimentally identified noise reduction mechanisms for the serrated axial fans are found to be more diverse than the single aerofoil and highly dependent on the inflow conditions and the operation point of the fan. A highly similar pattern for the spectral scaling of the noise reduction supports the finding that at optimum operation conditions, the previously identified noise reduction mechanisms for the single aerofoils are transferable to the rotating domain. On the other hand, additional aerodynamic mechanisms are found to dominate the noise reduction for the instability region of the fan, also contributing to reduced blade-to-blade interaction effects. Moreover, the blade-tip leakage flow is altered by delaying the development of coherent structures. The next step towards a more general description of the aeroacoustic and aerodynamic dependencies is developing a comprehensive model based on artificial neural networks. This model allows a combined analysis of the aerodynamic and acoustic performance of rotors with serrated leading edges and shows an accurate prediction of the overall performance and the spectral composition of the radiated noise. It also enables the development of multi-objective optima for serration designs and motivates further studies into the generalisability of the observed trends. Furthermore, the developed model represents a feasible tool to create tailored serration designs for maximum efficiency in both aeroacoustics and aerodynamics, contributing to the development of future low-noise fans and rotating machinery.}, language = {en} } @inproceedings{BiedermannReichKameieretal.2018, author = {Biedermann, Till M. and Reich, Marius and Kameier, Frank and Adam, Mario and Paschereit, C.}, title = {Assessment of Statistical Sampling Methods and Approximation Models Applied to Aeroacoustic and Vibroacoustic Problem}, series = {NOVEM - 6th conference on Noise and Vibration emerging methods, 07.-09.05.2018, Ibiza / Spain}, booktitle = {NOVEM - 6th conference on Noise and Vibration emerging methods, 07.-09.05.2018, Ibiza / Spain}, address = {Ibiza}, year = {2018}, language = {en} } @techreport{BiedermannKameier2018, author = {Biedermann, Till M. and Kameier, Frank}, title = {Konzeption eines praxisnahen Versuchsstandes zur Untersuchung von Leading Edge Serrations als Proof-of-Concept}, address = {D{\"u}sseldorf}, organization = {Hochschule D{\"u}sseldorf}, issn = {2625-3690}, doi = {10.20385/2625-3690/2018.2}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-12300}, pages = {26}, year = {2018}, abstract = {Der Einsatz von Leading Edge Serrations (gezackte Tragfl{\"a}chenvorderkanten) als Schallminderungsmaßnahme bei hochturbulenter Anstr{\"o}mung wurde bisher maßgeblich in Form von eben im Windkanal gelagerten, modifizierten Tragfl{\"u}geln untersucht. Diese Untersuchungen dienten der aeroakustischen Designoptimierung und der Identifikation von Wirkmechanismen anhand eines simplifizierten Systems. Das zuk{\"u}nftige Einsatzgebiet dieser neuartigen Modifikation wird im Bereich von Windenergieanlagen, Flugzeugtriebwerken und kontrarotierenden Rotoren der n{\"a}chsten Generation aber auch bei g{\"a}ngigen Axialverdichtern gesehen. Der Transfer der im ebenen System erhaltenen Erkenntnisse in Richtung einer rotierenden Applikation erfordert die Ber{\"u}cksichtigung einer Vielzahl an zus{\"a}tzlichen Einflussgr{\"o}ßen, welche die aerodynamische und aeroakustische Effizienz der Leading Edge Serrations in Form verst{\"a}rkender oder auch hemmender Effekte signifikant beeinflussen k{\"o}nnen. Im durchgef{\"u}hrten Projekt wurde untersucht, inwieweit sich diese durch Buckelwale und Eulen inspirierten Tragfl{\"a}chen auf rotierende Systeme {\"u}bertragen lassen, ohne Einbußen ihrer bereits best{\"a}tigten vorteilhaften aeroakustischen und aerodynamischen Eigenschaften zu erleiden. Von besonderem Interesse waren hier etwaige Einfl{\"u}sse der mit dem Radius variierenden Umfangsgeschwindigkeit sowie der im Praxisfall stark variierenden Anstr{\"o}mrichtungen und -zust{\"a}nde. In diesem Sinne wurde ein experimenteller Versuchsstand in Anlehnung an die DIN EN ISO 5136 zur simultanen Vermessungen der aeroakustischen und aerodynamischen Eigenschaften konzipiert. Ein eigens konzipierter Modellrotor in Form eines Axialverdichters erm{\"o}glichte einen flexiblen Austausch der Rotorbl{\"a}tter, was die M{\"o}glichkeit einer kosten- und zeitsparenden Variation der Rotorblattgeometrien bietet. Im Rahmen des Projektes konnten neben der Konzeption des Versuchsstandes im Rahmen einer experimentellen Proof-of-Concept Studie und einer umfangreichen Quantifizierung der Zustr{\"o}mbedingungen auch das Schallreduktionspotential der untersuchten Applikation im rotierenden System nachgewiesen werden. Eine Variation verschiedener aerodynamischer und geometrischer Einflussgr{\"o}ßen l{\"a}sst zudem allgemeing{\"u}ltige Aussagen bez{\"u}glich der zugrundeliegenden Abh{\"a}ngigkeiten zu. Zudem f{\"u}hrten parallele Untersuchungen mittels Array-Beamforming mit dem Ziel der Schallquellenlokalisationen zu wertvollen Transfererkenntnissen bez{\"u}glich des Einsatzes von Leading Edge Serrations im rotierenden System. Eine erste Untersuchung zur m{\"o}glichen Approximation der Wirkzusammenh{\"a}nge von Einfluss- und Zielgr{\"o}ßen wies ein hohes Potential zur komplexen Modellbildung mittels neuronaler Netze aus. Die gewonnenen Erkenntnisse tragen zu einem tieferen Verst{\"a}ndnis der zugrundeliegenden Wirkmechanismen von Leading Edge Serrations bei und unterst{\"u}tzten in der Definition weiterer verbleibender Forschungsl{\"u}cken, deren Erforschung im mittel- bis langfristigen Kontext einen Beitrag zu einer industriellen Verwertung dieser Applikation und somit zu einer Reduktion der L{\"a}rmbelastung der Bev{\"o}lkerung leistet.}, language = {de} } @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}, 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.}, subject = {L{\"a}rmschutz}, language = {en} }