Time-resolved and volumetric PIV measurements of a transitional separation bubble on an SD7003 airfoil

Burgmann, Sebastian; Dannemann, J.; Schröder, Wolfgang

doi:10.1007/s00348-007-0421-0

Cited by 98 publications

(65 citation statements)

References 20 publications

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“…These results are supported by recent studies from, e.g. Burgmann et al (2007), Hain and Kähler (2005) and Zhang et al (2008) who have applied time-resolved planar or stereo scanning PIV in order to gain insight into the temporal development and 3D spatial formation of a LSB on a SD7003 aerofoil, as well as the behaviour of the vortices formed in the shear layer. In their analysis the choice for this specific aerofoil was motivated by the well-developed laminar separation bubble on its suction side.…”

Section: Introductionsupporting

confidence: 80%

“…Literature has shown that the vortex roll-up and shedding occur in the downstream part of the LSB (Burgmann et al 2007;Burgmann and Schröder 2008). Therefore, the area of interest to be observed during tomographic experiments was selected on the basis of the observations obtained from the planar TR-PIV measurements.…”

Section: Tomographic Piv Configurationmentioning

confidence: 99%

“…In their analysis the choice for this specific aerofoil was motivated by the well-developed laminar separation bubble on its suction side. Burgmann et al (2007) observed that in the process towards reattachment, the K-H instabilities lead to a smooth transition of the LSB, inducing a two-dimensional spanwise vortex roll-up of the separated shear layer. As the two-dimensional rollers entrain fluid from the outer flow and move downstream, they shed from the shear layer and undergo a deformation process into c-shaped vortices, which evolve to arch-like Λ-structures and eventually breakdown into turbulence, showing hairpin-like structures.…”

Section: Introductionmentioning

confidence: 99%

“…Due to its turbulent nature this reattachment was found to be an unsteady process, where the vortex formation frequency corresponds to the K-H instability frequency (Burgmann et al 2007), causing a streamwise and vertical flapping motion of the shear layer close to reattachment (Zhang et al 2008).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Dynamic pitching effect on a laminar separation bubble

et al. 2015

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Section: Introductionsupporting

confidence: 80%

Section: Tomographic Piv Configurationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Dynamic pitching effect on a laminar separation bubble

et al. 2015

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“…This kind of separation is called the "long bubble", and its extent quickly increases as angles of attack increase until the presence of the deep stall at high angle of attack. At the downstream end of the transitional separation bubble, a large-scale vortex detaches from the bubble and moves further downstream, as depicted by Burgmann et al [18]. Simultaneously, the similar evolution is also shown on the lower surface.…”

Section: Instantaneous Flow Fieldsupporting

confidence: 60%

Noise Generation of a Bionic Airfoil Based on Owl Wings

2017

MATEC Web Conf.

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Abstract.A bionic airfoil is used to investigate a preliminary understanding of the noise mechanism generated by the flow around the owl wing. The flow indicates a transitional separation bubble on the surface and the turbulent boundary layer reattaches at the downstream end of the bubble. This causes turbulent boundary layer trailing-edge scattering noise corresponding to the broadband noise of owl wings at low Reynolds numbers. Furthermore, a large-scale vortex detaches from the bubble and then drifts downstream. Thus, a tone will be generated by the vortex shedding. However, the computations of the acoustic field for both cases, where the on-body data surface and the off-body data surface are used respectively, predominantly verify the broadband nature of the noise that well agrees with the noise scattering caused by the turbulent boundary layer passing by the sharp trailing edge. Furthermore, the significant decrease of the spectra around 2k Hz is consistent with that of silent owl wings. This fact suggests that the numerical simulations are capturing the basic physical mechanism responsible for the noise radiated by the natural owl wing. This might be able to provide a reference for engineering applications of the owl technology.

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Time-Resolved Two- and Three-Dimensional Measurements of Transitional Separation Bubbles

Burgmann

Schröder

2009

Notes on Numerical Fluid Mechanics and Multidisciplinary Design

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Abstract. Advanced methods of the Particle-Image Velocimetry (PIV) technique such as Time-Resolved and Stereo-Scanning PIV have been applied to investigate the separation bubbles on top of a finite circular cylinder and on the suction side of an SD7003 airfoil. A kind of three-dimensional vortex-shedding mechanism associated with the inviscid Kelvin-Helmholtz-instability has been identified to govern the flow field in both cases. The time-averaged velocity distribution is strongly affected by these vortex cascades although the unsteadiness of the bubbles due to the band of frequencies in the spectra of the vortex-shedding mechanism is hidden. Several analyzing methods are used and/or developed and the capabilities of more sophisticated experimental investigations of the three-dimensional flow field associated with separation bubbles are outlined.

show abstract

Time-resolved and volumetric PIV measurements of a transitional separation bubble on an SD7003 airfoil

Cited by 98 publications

References 20 publications

Dynamic pitching effect on a laminar separation bubble

Dynamic pitching effect on a laminar separation bubble

Noise Generation of a Bionic Airfoil Based on Owl Wings

Time-Resolved Two- and Three-Dimensional Measurements of Transitional Separation Bubbles

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