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 -