Generic Wind Tunnel Study on Side Edge Noise

Drobietz, Roger; Borchers, I. U.

doi:10.2514/6.2006-2509

Cited by 4 publications

(6 citation statements)

References 7 publications

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“…The flap noise is generated by complex three-dimensional vortices (Figure 3): due to static pressure difference between suction and pressure surfaces of the flap, a primary vortex develops at the lower edge from the pressure to the suction side of the flap, near its leading edge; for the same reason, a secondary vortex develops from the flap upper edge to its suction side (MACARAEG, 1998;DROBIETZ;BORCHERS, 2006;DOBRZYNSKI, 2010). The lower vortices are continuously fed by the shear layer instabilities and are drawn by the flow to the upper surface, where both these vortices are merged and then separate from the pressure side at some position around 70% flap chord (MACARAEG, 1998;DROBIETZ;BORCHERS, 2006;DOBRZYNSKI, 2010). So, the flap side edge noise is a composition of classical leading edge noise mechanisms, pressure fluctuations caused by vortex breakdown, interaction between vortices and surfaces or edges and accelerated free turbulence in the vortex flow (DROBIETZ;BORCHERS, 2006;DOBRZYNSKI, 2010;ROSSIGNOL, 2013).…”

Section: Flap Noisementioning

confidence: 99%

“…The lower vortices are continuously fed by the shear layer instabilities and are drawn by the flow to the upper surface, where both these vortices are merged and then separate from the pressure side at some position around 70% flap chord (MACARAEG, 1998;DROBIETZ;BORCHERS, 2006;DOBRZYNSKI, 2010). So, the flap side edge noise is a composition of classical leading edge noise mechanisms, pressure fluctuations caused by vortex breakdown, interaction between vortices and surfaces or edges and accelerated free turbulence in the vortex flow (DROBIETZ;BORCHERS, 2006;DOBRZYNSKI, 2010;ROSSIGNOL, 2013). Therefore, flap side edge is mainly a broadband noise source where unsteady vorticity fluctuations from pressure side shear layer interacting with the upper tip edge produce mid-to-high frequencies, and vortex interaction with suction side surface after vortex merging produces low-to-mid frequencies (DROBIETZ;BORCHERS, 2006;ROSSIGNOL, 2013).…”

Section: Flap Noisementioning

confidence: 99%

“…So, the flap side edge noise is a composition of classical leading edge noise mechanisms, pressure fluctuations caused by vortex breakdown, interaction between vortices and surfaces or edges and accelerated free turbulence in the vortex flow (DROBIETZ;BORCHERS, 2006;DOBRZYNSKI, 2010;ROSSIGNOL, 2013). Therefore, flap side edge is mainly a broadband noise source where unsteady vorticity fluctuations from pressure side shear layer interacting with the upper tip edge produce mid-to-high frequencies, and vortex interaction with suction side surface after vortex merging produces low-to-mid frequencies (DROBIETZ;BORCHERS, 2006;ROSSIGNOL, 2013). According to Li and Liu (2017), besides this side edge noise mechanism, flap noise is also generated by interactions between the main element shear layer produced at the flap housing and the turbulent flow, flow separation, vortex shedding and mixing layer formed over the flap (Figure 4).…”

Section: Flap Noisementioning

confidence: 99%

“…This approach of combining computational and experimental studies is a broadly used tool for understanding complex aeroacoustic problems. Drobietz and Borchers (2006) highlights that this complexity of high lift aerodynamics and noise generation mechanisms creates a difficulty in understanding and implementing scaling of the noise solutions developed.…”

Section: Flap Noisementioning

confidence: 99%

“…Most of the solutions to the flap side edge noise are based on passive flow control, such as fences (DOBRZYNSKI; POTT-POLLENSKE, 2001;GUO;JOSHI, 2003;DROBI-ETZ;BORCHERS, 2006;KOPIEV;ZAYTSEV;BELYAEV, 2016) to reduce shear layer instabilities and avoid vortex merging; transparent edge replacements (foam, porosities and brushes) to reduce surface radiation efficiency and dissipate intruding turbulences (DROBIETZ;BORCHERS, 2006;DOBRZYNSKI, 2010;KHORRAMI et al, 2016); trailing edge serrations to reduce interaction of merged vortex with trailing edge (DROBIETZ; BORCHERS, 2006) and flexible link between flap edge and main element for a soft geometry transition (KHORRAMI et al, 2016). Active flow control, though, is proposed by some research groups from the University of Notre Dame and the University of Southampton (YONG; XUNNIAN; DEJIU, 2013).…”

Section: Flap Noisementioning

confidence: 99%

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Dielectric barrier discharge plasma actuators applied to high-lift devices for aerodynamic noise reduction

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scholarships were essential for the realization of this project. To Prof. Dr. Fernando Martini Catalano, for the friendship, support, knowledge and experience shared with me throughout all these years, either as teacher when I was an undergraduate student, either as a supervisor during the execution of the research, or as my supervisor during my teaching internship. To Prof. Dr. José Antônio Garcia Croce, who kindly gave his massive contribution in the implementation and maintenance of the high voltage high frequency AC power supply, without which the experiments of this research could not have been carried out. To the technicians José Claudio Pinto de Azevedo, Mário Sbampato and Osnan Ignacio Faria, for their friendship, solicitude, aid and shared knowledge in the manufacture, assembly, maintenance and operation of the necessary equipment for the experiments. To Gisele Aparecida Poppi Lavadeci, secretary of the Department of Aeronautical Engineering, who was always available to assist me with the bureaucracies, printings or just to talk and take a coffee. To the São Carlos School of Engineering Library staff, for checking the typesetting and the referencing style. To my friends and laboratory colleagues, the engineers

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Section: Flap Noisementioning

confidence: 99%

Section: Flap Noisementioning

confidence: 99%

Section: Flap Noisementioning

confidence: 99%

Section: Flap Noisementioning

confidence: 99%

Section: Flap Noisementioning

confidence: 99%

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Dielectric barrier discharge plasma actuators applied to high-lift devices for aerodynamic noise reduction

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Effect of a Variable-Bend Slat on Tones Due to the Cove’s Self-Excited Oscillation

Liu

Guo

et al. 2021

J. Aerosp. Eng.

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Specification of Porous Materials for Low-Noise Trailing-Edge Applications

Herr

Rossignol

Delfs

et al. 2014

20th AIAA/CEAS Aeroacoustics Conference

114

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Systematic testing of the microstructural and aeroacoustic properties of porous metals applicable as low-noise trailing-edge (TE) treatments has been initiated within the Collaborative Research Center SFB 880-Fundamentals of High-Lift for Future Civil Aircraft. Generic TE noise experiments were performed at Re = 0.8 × 10 6 to 1.2 × 10 6 in DLR's open-jet AWB facility. Complementary flow measurements in the closed test section MUB wind-tunnel of the TU Braunschweig served to quantify the induced aerodynamic effects. The presented database forms part of an ongoing cumulative effort, combining experimental and numerical methods, to gain a deeper understanding of the prevalent TE noise reduction mechanisms. For the large variety of porous materials tested herein a clear dependence of the achieved broadband noise reduction (reaching 2-6 dB at maximum) on the flow resistivity was identified. Basic design recommendations for material resistivity and pore sizes, the latter to minimize high-frequency self-noise contributions, were deduced for low-noise TE applications. An acoustic nearfield pressure release across the porous region, adversely coupled with a loss in lift performance for porous TE replacements, appears as the major noise-reduction requirement.

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Generic Wind Tunnel Study on Side Edge Noise

Cited by 4 publications

References 7 publications

Dielectric barrier discharge plasma actuators applied to high-lift devices for aerodynamic noise reduction

Dielectric barrier discharge plasma actuators applied to high-lift devices for aerodynamic noise reduction

Effect of a Variable-Bend Slat on Tones Due to the Cove’s Self-Excited Oscillation

Specification of Porous Materials for Low-Noise Trailing-Edge Applications

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