TY - GEN A1 - Geyer, Thomas A1 - Schulz, Adrian A1 - Thürmer, Konrad A1 - Sarradj, Ennes A1 - Stapel, Jennifer T1 - Schallemission wasserwirtschaftlicher Anlagen T2 - Lärmbekämpfung Y1 - 2017 SN - 1436-4999 IS - 3 SP - 99 EP - 103 ER - TY - GEN A1 - Porteous, Ric A1 - Geyer, Thomas A1 - Moreau, Danielle J. A1 - Doolan, Con T1 - A correction method for acoustic source localisation in convex shear layer geometries T2 - Applied Acoustics Y1 - 2018 U6 - https://doi.org/10.1016/j.apacoust.2017.09.020 SN - 0003-682X VL - 130 SP - 128 EP - 132 ER - TY - CHAP A1 - Moreau, Danielle J. A1 - Geyer, Thomas A1 - Doolan, Con A1 - Sarradj, Ennes T1 - Influence of Camber on Wall-Mounted Finite Airfoil Tonal Noise Generation T2 - 4th Symposium on Fluid-Structure-Sound Interactions and Control, Tokio, 2017 Y1 - 2018 SN - 978-981-10-7542-1 SN - 978-981-10-7541-4 SP - 337 EP - 342 PB - Springer CY - Singapore ER - TY - GEN A1 - Geyer, Thomas A1 - Poppe, Willi A1 - Sarradj, Ennes T1 - Measurement of flow noise generation and pressure loss of nets and screens T2 - Applied Acoustics Y1 - 2018 U6 - https://doi.org/10.1016/j.apacoust.2018.01.008 SN - 0003-682X VL - 134 SP - 69 EP - 74 ER - TY - CHAP A1 - Jekosch, Simon A1 - Sarradj, Ennes A1 - Herold, Gert A1 - Geyer, Thomas T1 - Comparison of different solvers for general inverse beamforming algorithms for highresolution aeroacoustic source characterization T2 - 7th Berlin Beamforming Conference, BeBeC Y1 - 2018 UR - http://www.bebec.eu/Downloads/BeBeC2018/Papers/BeBeC-2018-D08.pdf ER - TY - CHAP A1 - Lucius, Andreas A1 - Hütter, Simon A1 - Dietrich, Philipp A1 - Schneider, Marc A1 - Lehmann, Marius A1 - Geyer, Thomas T1 - Experimental and Numerical Investigation of Axial Fan Aeroacoustics at Disturbed Inflow Conditions T2 - Fan 2018, International Conference on Fan Noise, Aerodynamics, Applications and Systems, Darmstadt 2018 Y1 - 2018 N1 - CD-ROM PB - CETIAT CY - Villeurbanne, France ER - TY - CHAP A1 - Kisler, Roman A1 - Materne, Daniel A1 - Geyer, Thomas A1 - Sarradj, Ennes T1 - Modularer Versuchsstand zur Charakterisierung von Plattenschalldämpfern T2 - Fortschritte der Akustik - DAGA 2018, 44. Jahrestagung für Akustik, 19.-22. März 2018 in München Y1 - 2018 UR - https://www-docs.b-tu.de/fg-akustik/public/veroeffentlichungen/kisler_versuchsstand_daga2018.pdf SP - 441 EP - 444 PB - Deutsche Gesellschaft für Akustik CY - Berlin ER - TY - CHAP A1 - Schneehagen, Erik W. A1 - Sarradj, Ennes A1 - Geyer, Thomas T1 - Numerische Simulation des Strömungsgeräusches eines wandbündigen Zylinders T2 - Fortschritte der Akustik - DAGA 2018, 44. Jahrestagung für Akustik, 19.-22. März 2018 in München Y1 - 2018 UR - https://www-docs.b-tu.de/fg-akustik/public/veroeffentlichungen/schneehagen_zylinder_daga2018.pdf SP - 1001 EP - 1004 PB - Deutsche Gesellschaft für Akustik CY - Berlin ER - TY - CHAP A1 - Sarradj, Ennes A1 - Herold, Gert A1 - Geyer, Thomas T1 - Vergleich verschiedener Mikrofonarray-Verfahren anhand synthetischer Daten T2 - Fortschritte der Akustik - DAGA 2018, 44. Jahrestagung für Akustik, 19.-22. März 2018 in München Y1 - 2018 UR - https://www-docs.b-tu.de/fg-akustik/public/veroeffentlichungen/sarradj_mikrofonarrayverfahren_daga2018.pdf SP - 1391 EP - 1394 PB - Deutsche Gesellschaft für Akustik CY - Berlin ER - TY - CHAP A1 - Geyer, Thomas A1 - Moreau, Danielle J. A1 - Sarradj, Ennes A1 - Doolan, Con T1 - Zur Schallentstehung an dreidimensionalen wandgebundenen Tragflügelprofilen T2 - Fortschritte der Akustik - DAGA 2018, 44. Jahrestagung für Akustik, 19.-22. März 2018 in München Y1 - 2018 UR - https://www-docs.b-tu.de/fg-akustik/public/veroeffentlichungen/geyer_wandgebundeneprofile_daga2018.pdf SP - 1587 EP - 1590 PB - Deutsche Gesellschaft für Akustik CY - Berlin ER - TY - CHAP A1 - Geyer, Thomas ED - Rottengruber, Hermann ED - Henze, Wilfried ED - Luft, Tommy T1 - Aeroakustische Schallquellen an Motoren und Aggregaten – Grundlagen und Möglichkeiten zur Minderung T2 - Motor- und Aggregate-Akustik, 10. Magdeburger Symposium N2 - Neben mechanischen und thermodynamischen Schallquellen kann es in Motoren und Aggregaten auch zu einer Entstehung von Lärm durch Strömungen kommen. Ein wichtiges Beispiel dafür ist die aerodynamische Schallentstehung an umströmten Festkörpern, wie sie an zur Kühlung benötigten Lüftern auftreten kann. Im vorliegenden Beitrag sollen zuerst grundlegende Mechanismen der Schallentstehung an umströmten Tragflügeln erläutert und die maßgeblichen Einflussparameter spezifiziert werden. Das geschieht mit Hilfe einfacher Schallvorhersagemodelle und umfasst sowohl die Schallentstehung in einer turbulenten Strömung sowie die Schallentstehung in einer quasi laminaren Strömung durch die profileigene Grenzschicht. Für beide Fälle lassen sich aus den Berechnungen bereits erste konstruktive Empfehlungen für eine möglichst effektive Lärmminderung ableiten. In einem zweiten Schritt werden zusätzlich Beispiele zur Minderung des strömungsmechanisch erzeugten Schalls durch eine Modifikation der Tragflügel aufgeführt, die auf systematische Untersuchungen in einem aeroakustischen Windkanal zurückgehen. Das beinhaltet so wohl den Einsatz einer sinusförmigen Zähnelung sowie eine Modifikation des Tragflügels mit porösen Materialien. Y1 - 2018 UR - https://opendata.uni-halle.de//handle/1981185920/13473 SN - 978-3-944722-72-6 U6 - https://doi.org/10.25673/13410 SP - 185 EP - 206 CY - Magdeburg ER - TY - GEN A1 - Moreau, Danielle J. A1 - Geyer, Thomas A1 - Doolan, Con A1 - Sarradj, Ennes T1 - Surface curvature effects on the tonal noise of a wall-mounted finite airfoil T2 - The Journal of the Acoustical Society of America N2 - This paper is concerned with the influence of camber on the noise of a wall-mounted finite airfoil with natural boundary layer transition. Tonal noise measurements taken in an aeroacoustic wind tunnel are presented for airfoils with aspect ratio of 2, NACAxx12 profile and camber between 0 and 6% at 40% chord. The results show camber is an important parameter that determines the operating conditions for which acoustic tone generation occurs and the number and intensity of the tones produced. Airfoils with 0%–2% camber have an acoustic signature that is dominated by a high amplitude primary tone, whereas the spectra of airfoils with higher camber of 4%–6% feature a more pronounced side tone structure. Tonal noise production does not collapse with lift coefficient, demonstrating that the local flow conditions influence the noise source. Tonal noise production is explained in terms of changes to mean flow topology, namely the location of flow separation, which is linked to tonal noise generation. Scaling of airfoil tonal noise is found to vary with angle of attack and pressure gradient. Empirical scaling laws for the primary tone frequency dependence on velocity are also derived for the cambered airfoils. Y1 - 2018 U6 - https://doi.org/10.1121/1.5040981 SN - 1520-8524 VL - 143 IS - 6 SP - 3460 EP - 3473 ER - TY - GEN A1 - Geyer, Thomas A1 - Moreau, Danielle J. A1 - Giesler, Jens A1 - Hall, Philipp A1 - Sarradj, Ennes A1 - Doolan, Con T1 - Measurement of the noise generated by wall-mounted airfoils of different thickness T2 - 24th AIAA/CEAS Aeroacoustics Conference 2018, Atlanta, USA, 25 June - 29 June 2018, (AIAA 2018-3796) Y1 - 2018 UR - https://arc.aiaa.org/doi/abs/10.2514/6.2018-3796 SN - 978-1-62410-560-9 PB - AIAA CY - Reston, Va ER - TY - GEN A1 - Geyer, Thomas A1 - Sharma, Sparsh A1 - Sarradj, Ennes T1 - Detached Eddy Simulation of the Flow Noise Generation of Cylinders with Porous Cover T2 - 24th AIAA/CEAS Aeroacoustics Conference 2018, Atlanta, USA, 25 June - 29 June 2018, (AIAA 2018-3472) Y1 - 2018 UR - https://arc.aiaa.org/doi/abs/10.2514/6.2018-3472 SN - 978-1-62410-560-9 PB - AIAA CY - Reston, Va ER - TY - GEN A1 - Biedermann, Till A1 - Czeckay, Pasquale A1 - Geyer, Thomas A1 - Kameier, Frank A1 - Paschereit, Christian Oliver T1 - Noise Source Identification of Aerofoils Subjected to Leading Edge Serrations using Phased Array Beamforming T2 - 24th AIAA/CEAS Aeroacoustics Conference 2018, Atlanta, USA, 25 June - 29 June 2018, (AIAA 2018-3794) Y1 - 2018 UR - https://arc.aiaa.org/doi/abs/10.2514/6.2018-3794 SN - 978-1-62410-560-9 PB - AIAA CY - Reston, Va ER - TY - CHAP A1 - Talboys, Edward A1 - Geyer, Thomas A1 - Brücker, Christoph T1 - The Aerodynamic And Aeroacoustic Effect Of Passive High Frequency Oscillating Trailing Edge Flaplets T2 - IUTAM Symposium on Critical flow dynamics involving moving/deformable structures with design applications, Santorini, Greece, 2018 Y1 - 2018 ER - TY - GEN A1 - Çaldichoury, Iñaki A1 - Souli, Mhamed A1 - Sarradj, Ennes A1 - Geyer, Thomas A1 - Del Pin, Facundo T1 - Numerical investigation of flow around hairy flaps cylinder using FSI Capabilities T2 - The International journal of multiphysics Y1 - 2018 SN - 2048-3961 SN - 1750-9548 VL - 12 IS - 2 SP - 189 EP - 208 ER - TY - CHAP A1 - Geyer, Thomas A1 - Sarradj, Ennes T1 - Noise reduction and aerodynamics of airfoils with porous trailing edges T2 - INTER-NOISE 2018, the 47th International Congress and Exposition on Noise Control Engineering, Chicago, Illinois, USA Y1 - 2018 UR - https://www-docs.b-tu.de/fg-akustik/public/veroeffentlichungen/geyer_porousTE_internoise2018.pdf ER - TY - CHAP A1 - Sharma, Sparsh A1 - Geyer, Thomas A1 - Sarradj, Ennes T1 - Time Domain Boundary Element Method for the Leading-Edge Noise subjected to Linear Vorticity T2 - INTER-NOISE 2018, the 47th International Congress and Exposition on Noise Control Engineering, Chicago, Illinois, USA Y1 - 2018 UR - https://www-docs.b-tu.de/fg-akustik/public/veroeffentlichungen/sharma_bem_internoise2018.pdf ER - TY - GEN A1 - Geyer, Thomas A1 - Lucius, Andreas A1 - Schrödter, Marcus A1 - Schneider, Marc A1 - Sarradj, Ennes T1 - Reduction of Turbulence Interaction Noise Through Airfoils With Perforated Leading Edges T2 - Acta Acustica united with Acustica Y1 - 2019 U6 - https://doi.org/10.3813/AAA.919292 SN - 1610-1928 SN - 1436-7947 VL - 105 IS - 1 SP - 109 EP - 122 ER - TY - GEN A1 - Geyer, Thomas A1 - Kamps, Laura A1 - Sarradj, Ennes A1 - Brücker, Christoph T1 - Vortex Shedding and Modal Behavior of a Circular Cylinder Equipped with Flexible Flaps T2 - Acta Acustica united with Acustica Y1 - 2019 U6 - https://doi.org/10.3813/aaa.919301 SN - 1610-1928 SN - 1436-7947 VL - 105 IS - 1 SP - 210 EP - 219 ER - TY - GEN A1 - Henke, Anna-Sophia A1 - Noack, Martin A1 - Geyer, Thomas A1 - Heinrich, Christoph Rocky A1 - Beirow, Bernd A1 - Sarradj, Ennes A1 - Kühhorn, Arnold T1 - Calculation of the Modal Behavior of Structured Sheet Metal T2 - International Journal of Lightweight Materials and Manufacture Y1 - 2019 U6 - https://doi.org/10.1016/j.ijlmm.2019.01.004 SN - 2588-8404 ER - TY - GEN A1 - Lucius, Andreas A1 - Dietrich, Philipp A1 - Lehmann, Marius A1 - Schneider, Marc A1 - Geyer, Thomas T1 - Schallquellenlokalisation aus CAA Simulationen von Ventilatorflügeln mit Hilfe von Mikrofon-Array Techniken T2 - Fortschritte der Akustik - DAGA 2019, 45. Jahrestagung für Akustik, 18.-21. März 2019 in Rostock N2 - Die CAA Simulation stellt ein wertvolles Hilfsmittel zum Verständnis aeroakustischer Phänomene in Ventilatoren dar. Im Rahmen der Simulation werden große Mengen transienter Daten erzeugt, die ausgewertet werden müssen. Neben den Akustikergebnissen an geeigneten Mikrofonpositionen sind die transienten Daten aller Strömungsgrößen im Nahfeld verfügbar. Frequenzgefilterte Visualisierungen sowohl der Druckfluktuationen auf der Oberfläche des Flügels als auch der akustischen Quellterme haben in den untersuchten Fällen nicht verlässlich die relevanten Orte der Schallentstehung gezeigt. Bedingt durch Interferenzen im Nahfeld werden nicht alle Fluktuationen auf der Oberfläche als Schall abgestrahlt. Der Einsatz von Mikrofon-Array Techniken zur Schallquellenlokalisation hat sich dagegen als eine sehr gut geeignete Methode herausgestellt. Für einen stehenden und einen rotierenden Flügel wurden experimentell vorhandene Arrays in Simulationsmodellen nachgebaut. Die Akustik im Fernfeld wurde über die FW-H Gleichung bestimmt. Es zeigen sich in beiden Fällen ähnliche Quellverteilung und Quellstärke in Experiment und Simulation. Zusätzlich bietet die Simulation den Vorteil, ohne wesentlichen Mehraufwand beliebig viele frei positionierbare Mikrofone nutzen zu können. Die Ergebnisse zeigen, dass sich der Nachteil der sehr kurzen physikalischen Zeit einer Simulation durch diesen Freiheitsgrad ausgleichen lässt. Die Analyse ist nicht nur im Hinblick auf physikalische Schallquellen hilfreich, sondern kann auch zur Lokalisierung von numerischem Störschall genutzt werden. Y1 - 2019 UR - https://www.dega-akustik.de/publikationen/tagungsbaende/verzeichnisse/ ER - TY - GEN A1 - Geyer, Thomas A1 - Karijasevic, Benjamin T1 - Untersuchung der tonalen Schallentstehung umströmter Tragflügelprofile T2 - Fortschritte der Akustik - DAGA 2019, 45. Jahrestagung für Akustik, 18.-21. März 2019 in Rostock N2 - Bildet sich bei der Umströmung eines Tragflügel- oder Schaufelprofils auf dessen Oberfläche eine laminare Grenzschicht aus, so kommt es zu einer stark tonalen Schallentstehung. Diese äußert sich durch eine sehr charakteristische spektrale Struktur, die sich aus deutlichen Haupttönen und weiteren kleineren Nebenmaxima zusammensetzt. Dieser Schallentstehungsmechanismus tritt meist bei niedrigen Strömungsgeschwindigkeiten und Tragflügelnmit vergleichsweise geringer Sehnenlänge auf, was in der Praxis vor allem bei Kompressoren, kleinen Lüftern, Mikrowindanlagen, U-Booten und kleinen unbemannten Luftfahrzeugen vorkommt. Im Beitrag werden die Ergebnisse einer Untersuchung an drei NACA0012-Tragflügelmodellenmit unterschiedlicher Sehnenlänge (100 mm, 150 mm und 200 mm) vorgestellt, die im aeroakustischen Windkanal der Brandenburgischen Technischen Universität durchgeführtwurde. Dabei soll vor allem der Einfluss der Strömungsgeschwindigkeit und der Sehnenlänge, aber auch der des Anstellwinkels, auf die tonalen Charakteristiken dargestellt werden. Y1 - 2019 UR - https://www.dega-akustik.de/publikationen/tagungsbaende/verzeichnisse/ ER - TY - GEN A1 - Geyer, Thomas A1 - Sarradj, Ennes T1 - Self Noise Reduction and Aerodynamics of Airfoils With Porous Trailing Edges T2 - Acoustics Y1 - 2019 U6 - https://doi.org/10.3390/acoustics1020022 SN - 2624-599X VL - 1 IS - 2 SP - 393 EP - 409 ER - TY - GEN A1 - Sharma, Sparsh A1 - Geyer, Thomas A1 - Sarradj, Ennes A1 - Schmidt, Heiko T1 - Numerical investigation of noise generation by rod-airfoil configuration using DES (SU2) and the FW-H analogy T2 - 25th AIAA/CEAS Aeroacoustics Conference 2019, Delft, The Netherlands, 20 - 24 May 2019, (AIAA 2019-2400) KW - airfoil noise KW - computational aeroacoustics KW - cylinder noise KW - detached eddy simulatio KW - ffowcs-williams hawkings KW - rod-airfoil Y1 - 2019 UR - https://arc.aiaa.org/doi/10.2514/6.2019-2400 U6 - https://doi.org/10.2514/6.2019-2400 SP - 1 EP - 17 ER - TY - GEN A1 - Geyer, Thomas A1 - Al-Shuga, Nazar T1 - Reduction of vortex shedding noise from finite, wall-mounted, circular cylinders using porous material T2 - 25th AIAA/CEAS Aeroacoustics Conference 2019, Delft, The Netherlands, 20 - 24 May 2019, (AIAA 2019-2400) Y1 - 2019 U6 - https://doi.org/10.2514/6.2019-2695 ER - TY - GEN A1 - Biedermann, Till A1 - Czeckay, Pasquale A1 - Geyer, Thomas A1 - Kameier, Frank A1 - Paschereit, Christian Oliver T1 - Effect of Inflow Conditions on the Noise Reduction Through Leading Edge Serrations T2 - AIAA Journal Y1 - 2019 U6 - https://doi.org/10.2514/1.J057831 SN - 1533-385X VL - 57 IS - 9 ER - TY - GEN A1 - Talboys, Edward A1 - Geyer, Thomas A1 - Prüfer, Florian A1 - Brücker, Christoph T1 - The aeroacoustic effect of different inter-spaced self-oscillating passive trailing edge flaplets T2 - 5th Symposium on Fluid-Structure-Sound Interactions and Control N2 - An aeroacoustic investigating looking into the effect of changing theinter-spacing of passive self-oscillating trailing edge flaplets has been carried outusing a NACA0012 aerofoil. Clear differences can be observed between each ofthe inter-spacing cases. Where a reduction in low frequency noise, an increase inhigh frequency noise and a reduction in turbulence intensity in the wake can beseen for each case. As the inter-spacing is reduced, the differences become moreprominent when compared to the reference aerofoil. KW - Passive oscillators, aeroacoustics, trailing edge flaplets, fluid structure interaction Y1 - 2019 UR - http://smartwing.org/FSSIC2019/FULL_PAPERS/51-The%20aeroacoustic%20effect%20of%20different%20inter-spaced%20self-oscillating%20passive%20trailing%20edge%20flaplets.pdf ER - TY - GEN A1 - Geyer, Thomas A1 - Peschel, Richard T1 - The effect of flow-permeable material on the flow field and the aerodynamic noise of cylinders T2 - 23rd International Congress on Acoustics, Aachen, Germany Y1 - 2019 UR - http://pub.dega-akustik.de/ICA2019/data/articles/000101.pdf SP - 5365 EP - 5372 ER - TY - GEN A1 - Lucius, Andreas A1 - Schneider, Marc A1 - Schweitzer-De Bortoli, Stefan A1 - Gerhard, Tom A1 - Geyer, Thomas T1 - Aeroacoustic simulation and experimental validation of sound emission of an axial fan applied in a heat pump T2 - 23rd International Congress on Acoustics, Aachen, Germany Y1 - 2019 UR - http://pub.dega-akustik.de/ICA2019/data/articles/001077.pdf SP - 1851 EP - 1858 ER - TY - GEN A1 - Talboys, Edward A1 - Geyer, Thomas A1 - Brücker, Christoph T1 - Influence of self-oscillating trailing edge flaplets on turbulent boundary layer - trailing edge noise T2 - 23rd International Congress on Acoustics, Aachen, Germany Y1 - 2019 UR - http://pub.dega-akustik.de/ICA2019/data/articles/001276.pdf SP - 588 EP - 595 ER - TY - GEN A1 - Talboys, Edward A1 - Geyer, Thomas A1 - Brücker, Christoph T1 - An aeroacoustic investigation into the effect of self-oscillating trailing edge flaplets T2 - Journal of Fluids and Structures Y1 - 2019 U6 - https://doi.org/10.1016/j.jfluidstructs.2019.02.014 SN - 1095-8622 SN - 0889-9746 VL - 91 ER - TY - CHAP A1 - Moreau, Danielle J. A1 - Geyer, Thomas A1 - Doolan, Con A1 - Sarradj, Ennes ED - Zhou, Yu ED - Kimura, Motoaki ED - Peng, Guoyi ED - Lucey, A. D. ED - Huang, Lixi T1 - Influence of Camber on Wall-Mounted Finite Airfoil Tonal Noise Generation T2 - Fluid-Structure-Sound Interactions and Control Proceedings of the 4th Symposium on Fluid-Structure-Sound Interactions and Control Y1 - 2019 SN - 978-981-10-7541-4 SN - 978-981-10-7542-1 U6 - https://doi.org/10.1007/978-981-10-7542-1_51 SP - 337 EP - 342 PB - Springer CY - Singapore ER - TY - GEN A1 - Zhang, Tingyi A1 - Moreau, Danielle J. A1 - Geyer, Thomas A1 - Fischer, Jeoffrey A1 - Doolan, Con T1 - Dataset on tip vortex formation noise produced by wall-mounted finite airfoils with flat and rounded tip geometries T2 - Data in Brief Y1 - 2020 U6 - https://doi.org/10.1016/j.dib.2019.105058 SN - 2352-3409 VL - 28 ER - TY - GEN A1 - Zhang, Tingyi A1 - Moreau, Danielle J. A1 - Geyer, Thomas A1 - Fischer, Jeoffrey A1 - Doolan, Con T1 - Dataset on tip vortex formation noise produced by wall-mounted finite airfoils with sinusoidal and porous tip geometries T2 - Data in Brief Y1 - 2020 U6 - https://doi.org/10.1016/j.dib.2020.105471 SN - 2352-3409 VL - 30 ER - TY - GEN A1 - Geyer, Thomas A1 - Wasala, Sahan A1 - Sarradj, Ennes T1 - Experimental Study of Airfoil Leading Edge Combs for Turbulence Interaction Noise Reduction T2 - Acoustics Y1 - 2020 U6 - https://doi.org/10.3390/acoustics2020014 SN - 2624-599X VL - 2 IS - 2 SP - 207 EP - 223 ER - TY - GEN A1 - Geyer, Thomas T1 - Vortex Shedding Noise from Finite, Wall-Mounted, Circular Cylinders Modified with Porous Material T2 - AIAA Journal Y1 - 2020 U6 - https://doi.org/10.2514/1.J058877 SN - 1533-385X VL - 58 IS - 5 SP - 2014 EP - 2028 ER - TY - GEN A1 - Geyer, Thomas T1 - Measurement of the Turbulence Interaction Noise Generated by Flat Plates with Perforated Leading Edges T2 - 26th AIAA/CEAS Aeroacoustics Conference 2020, Virtual Event, 14 - 19 June 2020, virtual event Y1 - 2020 U6 - https://doi.org/10.2514/6.2020-2576 ER - TY - GEN A1 - Arcondoulis, Elias A1 - Liu, Yu A1 - Geyer, Thomas A1 - Sedaghatizadeh, Nima A1 - Arjomandi, Maziar T1 - Aeroacoustic performance of cylinders with a circumferential varying porous coating T2 - 26th AIAA/CEAS Aeroacoustics Conference 2020, Virtual Event, 14 - 19 June 2020, virtual event Y1 - 2020 U6 - https://doi.org/10.2514/6.2020-2527 ER - TY - GEN A1 - Ocker, Christof A1 - Geyer, Thomas A1 - Czwielong, Felix A1 - Krömer, Florian A1 - Becker, Stefan A1 - Merkel, Markus A1 - Pannert, Wolfram T1 - Experimental Investigation of the Impact of 3D-Metal-Printed Perforated Leading Edges on Airfoil and Axial Fan Noise T2 - 26th AIAA/CEAS Aeroacoustics Conference, Virtual Event, 14 - 19 June 2020, virtual event Y1 - 2020 U6 - https://doi.org/10.2514/6.2020-2529 ER - TY - GEN A1 - Geyer, Thomas T1 - Experimental evaluation of cylinder vortex shedding noise reduction using porous material T2 - Experiments in Fluids N2 - The tonal noise generation of a circular cylinder in a uniform flow is an important source of aerodynamic noise. It can be found at parts of the landing gear of airplanes, at pantographs of trains, at antennas and basically all other protruding parts of vehicles. This noise is due to the periodic shedding of vortices along the cylinder span. One method to reduce this noise is the use of flow permeable covers around the cylinders. In the present study, measurements were performed in an aeroacoustic wind tunnel on a large set of porous covered cylinders. In addition to varying the porous material, which is characterized by its air flow resistivity and its porosity, the thickness of the porous layer was varied as well. The measurements were performed at Reynolds numbers between 14,000 and 103,000 using microphones located in the acoustic far field. It was found that the porous covers lead to a notable narrowing of the vortex shedding tonal peak in the sound pressure level spectra, an effect that increases with increasing porosity and thickness and decreasing air flow resistivity of the porous layer. Based on the large set of experimental data, basic trends were derived for the estimation of the vortex shedding Strouhal number and the reduction in the energy in the vortex shedding peak using the method of linear regression. Constant temperature anemometry measurements in the wake of selected cylinders basically showed a similar narrowing of the vortex shedding peak in the spectra of the turbulent velocity fluctuations. In addition, the measurement of wake profiles showed a reduction in the mean velocity and the turbulence in the wake as well as a widening of the wake region, while an analysis of the spanwise coherence revealed that the cause of the overall noise reduction is not a breakup of spanwise turbulent structures. Rather, the results imply that viscous damping of turbulent flow pressure amplitudes by the porous material strongly contributes to the noise reduction. Y1 - 2020 U6 - https://doi.org/10.1007/s00348-020-02972-0 SN - 0723-4864 SN - 1432-1114 VL - 61 IS - 7 ER - TY - GEN A1 - Geyer, Thomas A1 - Moreau, Danielle J. A1 - Zhang, Tingyi A1 - Schneehagen, Erik W. A1 - Ding, Yuchen T1 - Experimental investigation of novel, low-noise turbine blade tip designs T2 - Fortschritte der Akustik - DAGA, 46. Jahrestagung für Akustik, 16.-19. März 2020 in Hannover Y1 - 2020 UR - https://www-docs.b-tu.de/fg-akustik/public/veroeffentlichungen/geyer_noveltip_daga2020.pdf ER - TY - GEN A1 - Mai, Christopher A1 - Henke, Anna-Sophia A1 - Geyer, Thomas T1 - Numerische Untersuchung der Schalldämpfung von Absorptionsschalldämpfern unterschiedlicher Querschnittsform T2 - Fortschritte der Akustik - DAGA, 46. Jahrestagung für Akustik, 16.-19. März 2020 in Hannover Y1 - 2020 UR - https://www-docs.b-tu.de/fg-akustik/public/veroeffentlichungen/mai_schalldaempfer_daga2020.pdf ER - TY - GEN A1 - Ayton, Lorna A1 - Colbrook, Matthew A1 - Geyer, Thomas A1 - Chaitanya, Paruchuri A1 - Sarradj, Ennes T1 - Reducing aerofoil–turbulence interaction noise through chordwise-varying porosity T2 - Journal of Fluid Mechanics Y1 - 2020 U6 - https://doi.org/10.1017/jfm.2020.746 SN - 1469-7645 VL - 906 SP - A1 EP - A28 ER - TY - GEN A1 - Arcondoulis, Elias A1 - Liu, Yu A1 - Geyer, Thomas T1 - An aeroacoustic investigation of circumferential and spanwise varying structured porous coated cylinders T2 - AIAA Scitech 2021 Forum Y1 - 2021 U6 - https://doi.org/10.2514/6.2021-0816 ER - TY - GEN A1 - Sharma, Sparsh A1 - Geyer, Thomas A1 - Giesler, Jens T1 - Effect of geometric parameters on the noise generated by rod-airfoil configuration T2 - Applied Acoustics Y1 - 2021 U6 - https://doi.org/10.1016/j.apacoust.2021.107908 SN - 0003-682X VL - 177 ER - TY - GEN A1 - Talboys, Edward A1 - Geyer, Thomas A1 - Prüfer, Florian A1 - Brücker, Christoph T1 - A parametric study of the effect of self-oscillating trailing-edge flaplets on aerofoil self-noise T2 - Applied Acoustics Y1 - 2021 U6 - https://doi.org/10.1016/j.apacoust.2020.107907 SN - 0003-682X VL - 177 ER - TY - CHAP A1 - Talboys, Edward A1 - Geyer, Thomas A1 - Brücker, Christoph ED - Braza, Marianna ED - Hourigan, Kerry ED - Triantafyllou, Michael T1 - The Aerodynamic and Aeroacoustic Effect of Passive High Frequency Oscillating Trailing Edge Flaplets T2 - Advances in Critical Flow Dynamics Involving Moving/Deformable Structures with Design Applications Y1 - 2021 SN - 978-3-030-55593-1 SN - 978-3-030-55596-2 U6 - https://doi.org/10.1007/978-3-030-55594-8_34 SN - 1612-2909 SN - 1860-0824 SP - 413 EP - 425 PB - Springer CY - Cham, Schweiz ER - TY - GEN A1 - Arcondoulis, Elias A1 - Geyer, Thomas A1 - Liu, Yu T1 - An investigation of wake flows produced by asymmetrically structured porous coated cylinders T2 - Physics of Fluids Y1 - 2021 UR - https://aip.scitation.org/doi/full/10.1063/5.0042496 U6 - https://doi.org/10.1063/5.0042496 SN - 1089-7666 VL - 33 IS - 3 ER - TY - GEN A1 - Geyer, Thomas A1 - Moreau, Danielle J. T1 - A study of the effect of airfoil thickness on the tonal noise generation of finite, wall-mounted airfoils T2 - Aerospace Science and Technology Y1 - 2021 U6 - https://doi.org/10.1016/j.ast.2021.106768 SN - 1270-9638 ER - TY - GEN A1 - Schneehagen, Erik W. A1 - Geyer, Thomas A1 - Sarradj, Ennes A1 - Moreau, Danielle J. T1 - Aeroacoustic noise reduction by application of end plates on wall‑mounted finite airfoils T2 - Experiments in Fluids Y1 - 2021 U6 - https://doi.org/10.1007/s00348-021-03204-9 SN - 0723-4864 SN - 1432-1114 VL - 62 IS - 5 ER - TY - GEN A1 - Ding, Yuchen A1 - Zhang, Tingyi A1 - Geyer, Thomas A1 - Silva, Charitha de A1 - Doolan, Con A1 - Moreau, Danielle J. T1 - Experimental Investigation of the Flow Characteristics and Noise Generation at the Wing–Wall Junction T2 - Journal of Aerospace Engineering Y1 - 2021 UR - https://ascelibrary.org/doi/abs/10.1061/%28ASCE%29AS.1943-5525.0001303 U6 - https://doi.org/10.1061/(ASCE)AS.1943-5525.0001303 VL - 34 IS - 5 ER - TY - GEN A1 - Geyer, Thomas A1 - Fritzsche, Christoph A1 - Sarradj, Ennes A1 - Wagner, Hermann T1 - Der leise Flug der Eule T2 - Akustik Journal Y1 - 2021 UR - https://www.dega-akustik.de/fileadmin/dega-akustik.de/publikationen/akustik-journal/21-02/akustik_journal_2021_02_online.pdf VL - 2021 IS - 2 SP - 9 EP - 17 ER - TY - GEN A1 - Liu, Yu A1 - Geyer, Thomas A1 - Lu, Zhenbo T1 - Source Mechanisms and Control Methods for Aerodynamic Noise T2 - Journal of Aerospace Engineering Y1 - 2021 UR - https://ascelibrary.org/doi/10.1061/%28ASCE%29AS.1943-5525.0001351 U6 - https://doi.org/10.1061/(ASCE)AS.1943-5525.0001351 SN - 1943-5525 VL - 34 IS - 6 ER - TY - GEN A1 - Ocker, Christof A1 - Geyer, Thomas A1 - Czwielong, Felix A1 - Krömer, Florian A1 - Pannert, Wolfram A1 - Merkel, Markus A1 - Becker, Stefan T1 - Permeable Leading Edges for Airfoil and Fan Noise Reduction in Disturbed Inflow T2 - AIAA Journal Y1 - 2021 UR - https://arc.aiaa.org/doi/10.2514/1.J060396 U6 - https://doi.org/10.2514/1.J060396 SN - 1533-385X VL - 59 IS - 12 SP - 4969 EP - 4986 ER - TY - GEN A1 - Ayton, Lorna A1 - Colbrook, Matthew A1 - Geyer, Thomas A1 - Chaitanya, Paruchuri A1 - Sarradj, Ennes T1 - Modelling chordwise-varying porosity to reduce aerofoil-turbulence interaction noise T2 - 27th AIAA/CEAS Aeroacoustics Conference 2021, Virtual Event, August 2 - 6 2021 Y1 - 2021 U6 - https://doi.org/10.2514/6.2021-2190 ER - TY - GEN A1 - Geyer, Thomas A1 - Arcondoulis, Elias A1 - Liu, Yu T1 - Experimental Investigation of Noise Generation by Porous Coated Tandem Cylinder Configurations T2 - 27th AIAA/CEAS Aeroacoustics Conference 2021, Virtual Event, August 2 - 6 2021 Y1 - 2021 U6 - https://doi.org/10.2514/6.2021-2266 ER - TY - GEN A1 - Ocker, Christof A1 - Czwielong, Felix A1 - Geyer, Thomas A1 - Chaitanya, Paruchuri A1 - Merkel, Markus A1 - Becker, Stefan T1 - Permeable Structures for Leading Edge Noise Reduction T2 - 27th AIAA/CEAS Aeroacoustics Conference 2021, Virtual Event, August 2 - 6 2021 Y1 - 2021 U6 - https://doi.org/10.2514/6.2021-2192 ER - TY - GEN A1 - Sharma, Sparsh A1 - Geyer, Thomas A1 - Sarradj, Ennes A1 - Schmidt, Heiko T1 - Experimental validation of a lower-order model for leading-edge noise based on vortex method T2 - 27th AIAA/CEAS Aeroacoustics Conference 2021, Virtual Event, August 2 - 6 2021 Y1 - 2021 U6 - https://doi.org/10.2514/6.2021-2250 ER - TY - GEN A1 - Geyer, Thomas A1 - Mai, Christopher A1 - Henke, Anna-Sophia T1 - Numerical analysis of the transmission loss of dissipative mufflers with polygonal cross-section T2 - INTER-NOISE and NOISE-CON Congress and Conference Proceedings Y1 - 2021 UR - https://www.ingentaconnect.com/content/ince/incecp/2021/00000263/00000003/art00016;jsessionid=8bh6jb49nteeg.x-ic-live-01 U6 - https://doi.org/10.3397/IN-2021-2308 SN - 0736-2935 SP - 2949 EP - 3943 ER - TY - GEN A1 - Zhang, Tingyi A1 - Geyer, Thomas A1 - Silva, Charitha de A1 - Fischer, Jeoffrey A1 - Doolan, Con A1 - Moreau, Danielle J. T1 - Experimental Investigation of Tip Vortex Formation Noise Produced by Wall-Mounted Finite Airfoils T2 - Journal of Aerospace Engineering Y1 - 2021 UR - https://ascelibrary.org/doi/10.1061/%28ASCE%29AS.1943-5525.0001315 U6 - https://doi.org/10.1061/(ASCE)AS.1943-5525.0001315 SN - 1943-5525 VL - 34 IS - 6 ER - TY - GEN A1 - Geyer, Thomas A1 - Sharma, Sparsh A1 - Calisci, Baran T1 - Schallminderung an einer umströmten Tandem-Zylinder-Anordnung durch poröses Material T2 - Fortschritte der Akustik - DAGA, 47. Jahrestagung für Akustik, 15.-18. August 2020 in Wien Y1 - 2021 UR - https://www.researchgate.net/publication/355145151_Schallminderung_an_einer_umstromten_Tandem-Zylinder-Anordnung_durch_poroses_Material SP - 1505 EP - 1508 ER - TY - GEN A1 - Ocker, Christof A1 - Czwielong, Felix A1 - Geyer, Thomas A1 - Merkel, Markus A1 - Becker, Stefan T1 - Strukturierte Porosität zur Lärmminderung von Axialventilatoren T2 - Fortschritte der Akustik - DAGA, 47. Jahrestagung für Akustik, 15.-18. August 2020 in Wien Y1 - 2021 UR - https://www.researchgate.net/publication/355145190_Strukturierte_Porositat_zur_Larmminderung_von_Axialventilatoren SP - 1512 EP - 1515 ER - TY - GEN A1 - Arcondoulis, Elias A1 - Geyer, Thomas A1 - Liu, Yu T1 - An acoustic investigation of non-uniformly structured porous coated cylinders in uniform flow T2 - The Journal of the Acoustical Society of America Y1 - 2021 UR - https://asa.scitation.org/doi/full/10.1121/10.0005886 U6 - https://doi.org/10.1121/10.0005886 SN - 1520-8524 VL - 150 SP - 1231 EP - 1242 ER - TY - GEN A1 - Geyer, Thomas T1 - Experimental Investigation of Flow and Noise Control by Porous Coated Tandem Cylinder Configurations T2 - AIAA Journal Y1 - 2022 UR - https://arc.aiaa.org/doi/10.2514/1.J061180 U6 - https://doi.org/10.2514/1.J061180 SN - 1533-385X VL - 60 IS - 7 ER - TY - GEN A1 - Geyer, Thomas T1 - Effect of a porous coating on the vortex shedding noise of a cylinder in turbulent flow T2 - Applied Acoustics Y1 - 2022 UR - https://www.sciencedirect.com/science/article/pii/S0003682X22002080?via%3Dihub U6 - https://doi.org/10.1016/j.apacoust.2022.108834 SN - 0003-682X VL - 195 ER - TY - GEN A1 - Geyer, Thomas A1 - Sarradj, Ennes T1 - Aerodynamische Schallentstehung durchströmter Netze T2 - Fortschritte der Akustik - DAGA, 48. Jahrestagung für Akustik, 21. - 24. März 2022 Y1 - 2022 UR - https://pub.dega-akustik.de/DAGA_2022/data/articles/000133.pdf UR - https://www.daga2022.de/programm SP - 109 ER - TY - GEN A1 - Shokri, Majid A1 - Lucius, Andreas A1 - Schneider, Marc A1 - Geyer, Thomas T1 - Aeroacoustics of tandem cylinders in crossflow – application to fan guard grills T2 - Fortschritte der Akustik - DAGA, 48. Jahrestagung für Akustik, 21. - 24. März 2022 Y1 - 2022 UR - https://pub.dega-akustik.de/DAGA_2022/data/articles/000151.pdf UR - https://www.daga2022.de/programm SP - 110 ER - TY - GEN A1 - Sharma, Sparsh A1 - Geyer, Thomas A1 - Arcondoulis, Elias T1 - Effect of Coating Thickness on Aerodynamic Noise Reduction by Porous-Coated Cylinders T2 - 28th AIAA/CEAS Aeroacoustics Conference 2022, Southampton, UK, 14 - 18 June 2021 Y1 - 2022 U6 - https://doi.org/10.2514/6.2022-2889 ER - TY - GEN A1 - Sharma, Sparsh A1 - Geyer, Thomas T1 - Numerical Investigation of Aerodynamic Noise Generation by Porous-Coated Staggered Cylinders T2 - 28th AIAA/CEAS Aeroacoustics Conference 2019, Southampton, UK, 14 - 18 June 2022 Y1 - 2022 U6 - https://doi.org/10.2514/6.2022-2890 ER - TY - GEN A1 - Geyer, Thomas A1 - Enghardt, Lars T1 - Noise generation by two staggered circular cylinders of equal diameter in cross-flow T2 - 28th AIAA/CEAS Aeroacoustics Conference 2019, Southampton, UK, 14 - 18 June 2022 Y1 - 2022 U6 - https://doi.org/10.2514/6.2022-3093 ER - TY - GEN A1 - Palleja-Cabre, Sergi A1 - Chaitanya, Paruchuri A1 - Joseph, Phillip A1 - Kim, Jae-Wook A1 - Priddin, Matthew A1 - Ayton, Lorna A1 - Geyer, Thomas A1 - Chong, Tze Pei T1 - Downstream porosity for the reduction of turbulence-aerofoil interaction noise T2 - Journal of Sound and Vibration Y1 - 2022 U6 - https://doi.org/10.1016/j.jsv.2022.117324 SN - 0022-460X ER - TY - GEN A1 - Schneehagen, Erik W. A1 - Geyer, Thomas A1 - Sarradj, Ennes T1 - Reduzierung des Eigengeräuschs von Tragflügeln durch Seitenplatten T2 - Fortschritte der Akustik - DAGA, 48. Jahrestagung für Akustik Y1 - 2022 UR - https://pub.dega-akustik.de/DAGA_2022/data/articles/000189.pdf ER - TY - GEN A1 - Lucius, Andreas A1 - Geyer, Thomas A1 - Dietrich, Philipp A1 - Dietrich, Marc A1 - Ruck, Richard T1 - Experimentelle und numerische Untersuchungen eines Tragflügelprofils unter gestörten Zuströmbedingungen T2 - Fortschritte der Akustik - DAGA, 48. Jahrestagung für Akustik Y1 - 2022 UR - https://app2022.daga-tagung.de/konferenz?article=49 ER - TY - GEN A1 - Czwielong, Felix A1 - Berchtenbreiter, Benedikt A1 - Ocker, Christof A1 - Geyer, Thomas A1 - Stockmeier, Gabriel A1 - Merkel, Markus A1 - Becker, Stefan T1 - On the Application and Limitations of Sound-Absorbing Materials for Axial Fan Blades T2 - FAN 2022 – International Conference on Fan Noise, Aerodynamics, Applications and Systems Y1 - 2022 UR - https://tuprints.ulb.tu-darmstadt.de/21725/1/fp-44-CZWIELONG.pdf ER - TY - GEN A1 - Schneehagen, Erik W. A1 - Geyer, Thomas A1 - Sarradj, Ennes T1 - Influence of end plate placement on the reduction of airfoil tip vortex formation noise T2 - Acta Acustica Y1 - 2022 UR - https://acta-acustica.edpsciences.org/articles/aacus/full_html/2022/01/aacus220025/aacus220025.html U6 - https://doi.org/10.1051/aacus/2022053 SN - 2681-4617 VL - 6 SP - 1 EP - 14 ER - TY - GEN A1 - Sharma, Sparsh A1 - Geyer, Thomas A1 - Arcondoulis, Elias T1 - On the influence of porous coating thickness and permeability on passive flow and noise control of cylinders T2 - Journal of Sound and Vibration Y1 - 2023 UR - https://www.sciencedirect.com/science/article/pii/S0022460X23000135?via%3Dihub U6 - https://doi.org/10.1016/j.jsv.2023.117563 ER - TY - GEN A1 - Geyer, Thomas A1 - Schneehagen, Erik W. A1 - Herold, Gert A1 - Zhang, Tingyi A1 - Moreau, Danielle J. T1 - Reduction of rotor aerodynamic noise using porous blade tips T2 - Fortschritte der Akustik - DAGA, 50. Jahrestagung für Akustik N2 - Motivated by promising results from experiments on the noise reduction performance of finite wall-mounted airfoils with a porous tip in an aeroacoustic wind tunnel, corresponding measurements were performed in a dedicated rotor test rig. This rig features a 3 kW direct-drive electric motor with three rotor blades of 1.1 m diameter. In the experiments, a variety of different tip modifications was tested regarding their noise reducing performance, including different porous materials that were manufactured using rapid prototyping. Acoustic measurements were performed at different rotationals speeds and blade angles using a ring-shaped microphone array consisting of 60 evenly spaced microphones. The rotational speed was measured using a laser sensor. Different beamforming algorithms were used in post-processing to help analyzing the data. The results show that porous tips can lead to a notable noise reduction at low frequencies, but a small penalty at medium and high frequencies which may be due to the surface roughness of the porous tips. This trend seems more severe for lower blade angles than for higher ones. These findings agree well with those obtained from the previous wind tunnel measurements. Y1 - 2024 UR - https://pub.dega-akustik.de/DAGA_2024/konferenz?article=471 ER - TY - GEN A1 - Kara, Emre A1 - Henke, Anna-Sophia A1 - Geyer, Thomas T1 - Konzeption und Inbetriebnahme eines kleinen Messaufbaus für Freistrahllärm T2 - Fortschritte der Akustik - DAGA, 49. Jahrestagung für Akustik Y1 - 2023 UR - https://pub.dega-akustik.de/DAGA_2023/data/index.html ER - TY - GEN A1 - Geyer, Thomas A1 - Enghardt, Lars T1 - Minderung von turbulenzinduziertem Schall an Lüftern durch perforierte Blattvorderkanten T2 - Fortschritte der Akustik - DAGA, 49. Jahrestagung für Akustik Y1 - 2023 UR - https://pub.dega-akustik.de/DAGA_2023/data/index.html ER - TY - GEN A1 - Geyer, Thomas A1 - Velpula, Rishi A1 - Sharma, Sparsh T1 - Experimental Investigation of Tonal Noise Radiation from Trapezoidal Cylinders in Cross-Flow T2 - AIAA AVIATION 2023 Forum, 12-16 June 2023, San Diego, CA and Online Y1 - 2023 U6 - https://doi.org/10.2514/6.2023-3496 ER - TY - GEN A1 - Kershner, John A1 - Jaworski, Justin A1 - Geyer, Thomas T1 - Experimental study of trailing-edge bluntness noise reduction by porous plates T2 - AIAA AVIATION 2023 Forum, 12-16 June 2023, San Diego, CA and Online Y1 - 2023 U6 - https://doi.org/10.2514/6.2023-4284 ER - TY - GEN A1 - Geyer, Thomas A1 - Enghardt, Lars T1 - Experimental Evaluation of the Turbulence Interaction Noise Reduction by Flat Plates with Perforated Leading Edges T2 - AIAA AVIATION 2023 Forum, 12-16 June 2023 Y1 - 2023 U6 - https://doi.org/10.2514/6.2023-4287 ER - TY - GEN A1 - Kershner, John A1 - Geyer, Thomas A1 - Jaworski, Justin T1 - Setup for experimental study of porous plate acoustics and local flow features T2 - Fortschritte der Akustik - DAGA, 49. Jahrestagung für Akustik Y1 - 2023 UR - https://pub.dega-akustik.de/DAGA_2023/data/articles/000077.pdf SP - 530 EP - 533 ER - TY - GEN A1 - Lyu, Benshuai A1 - Xu, Jiali A1 - Geyer, Thomas A1 - Paruchuri, Chaitanya A1 - Ye, Qingqing A1 - Cui, Jiahuan A1 - Ayton, Lorna T1 - Experimental investigation into the acoustical superiority of ogee serrations in reducing leading edge noise T2 - Applied Acoustics Y1 - 2024 UR - https://www.sciencedirect.com/science/article/pii/S0003682X23005200 U6 - https://doi.org/10.1016/j.apacoust.2023.109722 SN - 1872-910X SN - 0003-682X VL - 216 ER - TY - GEN A1 - Abromeit, Paul A1 - Raghuram, Priyanka A1 - Geyer, Thomas Fritz A1 - Enghardt, Lars ED - DEGA e.V., T1 - Investigation on aerodynamic noise generated by porous coated, staggered tandem cylinders T2 - Proceedings of DAS|DAGA 2025 : 51st Annual Meeting on Acoustics, March 17-20, 2025, Copenhagen N2 - The aerodynamic noise generated by the landing gear of an aircraft or the protective guard grille of a fan is often studied by a tandem cylinder configuration, modeling the interaction between main strut and hydraulic lines and the rods of the mesh, respectively. Previous investigations have shown that the angle between the upstream and downstream cylinder has a great effect on the peak sound pressure level. The present study describes both acoustic and hot-wire measurements of a tandem cylinder configuration to investigate the flow field around the staggered cylinders and to evaluate the effects of porous coatings of the cylinders. A cylinder spacing of S = 4.7D was used, where D represents the diameter of the cylinders. Spacing and diameter of the cylinders are known to affect the flow behavior. The results show that increasing the angle up to a certain limit of 30° to 35° leads to complex interactions of the wake flows. For large angles, the interference between the two cylinders decreases. It can also be observed that porous materials with high permeability reduce the tonal noise better than materials with low permeability, effectively shifting the peak towards lower frequencies. Y1 - 2025 UR - https://pub.dega-akustik.de/DAS-DAGA_2025/files/upload/paper/165.pdf SN - 978-3-939296-23-2 U6 - https://doi.org/10.71568/dasdaga2025.165 SP - 521 EP - 524 PB - Deutsche Gesellschaft für Akustik e.V. CY - Berlin ER - TY - GEN A1 - Abromeit, Paul A1 - Geyer, Thomas A1 - Enghardt, Lars T1 - Aerodynamische Schallentstehung an zwei versetzt angeordneten Zylindern gleichen Durchmessers T2 - Fortschritte der Akustik - DAGA, 50. Jahrestagung für Akustik N2 - Die komplexe Umströmung von zwei versetzt angeordneten Zylindern ist in verschiedenen technischen Anwendungen, wie zum Beispiel dem Fahrwerk von Flugzeugen oder Schutzgittern von Ventilatoren, wiederzufinden. Obwohl es zahlreiche numerische und experimentelle Untersuchungen zu diesem Aufbau gibt, beschäftigen sich nur wenige davon mit der Schallentstehung. In der hier vorgestellten Untersuchung wurde die Schallentstehung einer Tandemzylinderanordnung bei verschiedenen Anstellwinkeln in einem kleinen akustischen Freistrahlwindkanal bei Reynolds-Zahlen (bezogen auf den Zylinderdurchmesser) zwischen 3.300 und 11.500 gemessen. Der Winkel zwischen den Zylindern wurde zwischen 0° und 90° in Schritten von 5° variiert. Die resultierenden Spektren der Schalldruckpegel zeigen auffällige tonale Merkmale und bei bestimmten Winkeln und Abständen zwischen den Zylindern konnte ein bistabiles Verhalten beobachtet werden. Dabei teilt sich das tonale Maximum des Spektrums in zwei Maxima auf und vereinigt sich bei höheren Anstellwinkeln wieder zu einem Maximum. Zum besseren Verständnis dieser Mechanismen wurden für verschiedene Anstellwinkel qualitative Strömungssimulationen durchgeführt. Y1 - 2024 UR - https://pub.dega-akustik.de/DAGA_2024/konferenz?article=589 ER - TY - GEN A1 - Geyer, Thomas Fritz A1 - Abromeit, Paul A1 - Prügel, Maximilian T1 - Noise generation by tandem cylinders of different diameter in cross-flow T2 - Proceedings of DAS|DAGA 2025 : 51st Annual Meeting on Acoustics, March 17-20, 2025, Copenhagen N2 - The noise generation by two circular cylinders placed in a tandem configuration is of large interest in aeroacoustic research, as it constitutes a simple model for technical applications like parts of the landing gear of aircraft or the protective guard grille of axial fans. The resulting tonal noise depends on parameters such as the diameter of the cylinders and their spacing, the angle between the cylinders with respect to the flow and the flow velocity and inflow turbulence parameters. In a recent study in a small aeroacoustic wind tunnel facility, the far-field noise generated by parallel tandem cylinders with different diameter was measured for various cylinder spacings, allowing for the analysis of the effect that the wake impingement of the upstream cylinder on the downstream cylinder has on the tonal noise. In the paper, results from these experiments are presented and discussed together with results from flow field measurements that enable a better understanding of the physical noise generation mechanisms. Y1 - 2025 UR - http://pub.dega-akustik.de/DAS-DAGA_2025/files/upload/paper/242.pdf SN - 978-3-939296-23-2 U6 - https://doi.org/10.71568/dasdaga2025.242 SP - 525 EP - 528 PB - Deutsche Gesellschaft für Akustik e.V. CY - Berlin ER - TY - GEN A1 - Geyer, Thomas A1 - Lucius, Andreas A1 - Schneider, Marc A1 - Enghardt, Lars T1 - Aerodynamic noise from circular cylinders under turbulent inflow conditions T2 - AIAA journal N2 - The aerodynamic noise generated by a circular cylinder in a subsonic crossflow is a classical problem in aeroacoustics, which has been investigated experimentally and numerically in the past. The presence of a turbulent inflow is known to have an effect on the generation of tonal noise due to vortex shedding, although the available experimental data are sparse. The present paper describes an experimental study on the noise generated by a set of circular cylinders in grid-generated turbulence conducted in an aeroacoustic wind tunnel facility. Acoustic measurements were performed using microphone array technology. The results show that the free stream turbulence broadens the spectral peak of the vortex shedding tones, especially for cylinders with a diameter that is small compared to the turbulent integral length scale. One key result of the study is that the turbulent inflow leads to an increase in the vortex shedding Strouhal number compared to the case with clean inflow as well as to an additional increase of the Strouhal number with Reynolds number. This trend can also be observed qualitatively in the velocity power spectral densities measured in the wake of a selected cylinder using hot-wire anemometry. Y1 - 2025 U6 - https://doi.org/10.2514/1.J064504 SN - 1533-385X VL - 63 IS - 8 SP - 3250 EP - 3260 PB - AIAA CY - Reston, Va. ER -