Active Suppression of Buffeting at the Audi AAWT: Operational Experiences and Enhancements of the Control Scheme

Evert, Fabian; Miehling, Hans

doi:10.4271/2004-01-0804

Cited by 13 publications

(13 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…According to the above mentioned hypothetical mechanisms, the shedding of large-scale vortices in the jet shear layer and its interaction with the collector play an important role in studying the mechanisms of buffeting. In fact, the use of vortex generators and other methods can indeed suppress low-frequency buffeting by destroying the ordinality of large-scale vortices (Evert et al, 2004). However, it generates high-frequency noise, which is unacceptable in aeroacoustics automotive wind tunnels.…”

Section: Introductionmentioning

confidence: 99%

“…This passive method also has an effect on the axial static pressure gradient (Wickern et al, 2000). Some wind tunnels adopt active control methods to control low-frequency buffeting, such as Audi's ARC (Active Resonance Control) system, but the active maintenance means have higher maintenance costs in the later period, which limits the application of this control method in wind tunnels (Evert et al, 2004). The principle based on the active control method is also the destructive vorticity ordering.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

On the Low Frequency Pressure Fluctuation in a 3/4 Open Jet Automotive Wind Tunnel

Jia

Zhu

Bao

et al. 2019

JAFM

View full text Add to dashboard Cite

In the present research, a possible generation mechanism of low-frequency buffeting phenomenon based on a 1:15 open jet automotive wind tunnel was investigated. Evolution of vortex structures and pressure field in the plenum chamber have been visualized and analyzed by Large-eddy simulation (LES). It is shown that the low frequency pressure fluctuation is caused by the largescale structures and their interaction. Multiple proper orthogonal decomposition was adopted to analyze the flow field in the plenum chamber. The characteristic frequencies of the vortex-rings after pairing is the same as the dominant resonance of buffeting at this wind velocity.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

On the Low Frequency Pressure Fluctuation in a 3/4 Open Jet Automotive Wind Tunnel

Jia

Zhu

Bao

et al. 2019

JAFM

View full text Add to dashboard Cite

show abstract

“…the shear layer instability), or an active damping of the acoustic resonant modes of the wind tunnel. The later was successfully implemented in the Audi Aeroacoustic Wind Tunnel (Evert and Miehling, 2004) but needs considerable effort to be efficient for each operational configuration.…”

Section: Attenuatorsmentioning

confidence: 99%

Reduction of 3/4 open jet low-frequency fluctuations in the S2A wind tunnel

Amandolèse

Vartanian²

2010

Journal of Wind Engineering and Industrial Aerodynamics

View full text Add to dashboard Cite

“…A similar model is presented by Evert [13]. It is based on the assumption that in order to excite the acoustic resonance there must be an appropriate phase relation between the vortex leaving the nozzle and the excitation of the acoustic wave when the vortex hits the collector.…”

Section: New Modelsmentioning

confidence: 99%

“…Because modifications to the collector usually also affect the pressure distribution in the test section, it can be quite a laborious job to find a geometry with good flow quality and sufficient reduction of buffeting. The Audi active system is very efficient but it is rather expensive and it requires a sophisticated control scheme [13].…”

Section: Means Of Controlmentioning

confidence: 99%

Suppression of Wind Tunnel Buffeting by Active Flow Control

Heesen¹,

Höpfer²

2004

SAE Technical Paper Series

View full text Add to dashboard Cite

A well-known problem with open-jet wind tunnels are low-frequency pulsations, which affect the flow quality and thus the quality of the measured data. This so-called wind tunnel buffeting is caused by large-scale vortices in the shear layer, which excite acoustic resonant modes of the wind tunnel circuit. This paper presents a novel approach to control lowfrequency pulsations by means of active flow control at the nozzle exit. The final setup consists of oscillated flaps which are actuated by electrodynamic shakers. Single-frequency sinusoidal signals and band-limited random signals were used for excitation. The oscillated flaps prevent the synchronization of vortex shedding with acoustic resonance by generating forced perturbations in the shear layer at a frequency that is different from the acoustic resonance. The flaps-which were named FKFS-flaps by the authors-were installed at the IVK 1:4 model-scale wind tunnel. Experimental results from an ongoing experimental study are presented showing the reduction of low-frequency pulsations and the influence of the flaps on pressure distribution and force measurements. The small space requirements of the FKFS-flaps allows retrofit of existing wind tunnels without major modifications to the tunnel. The installation cost is considerably lower than that of other active systems. Very simple open-loop control is used, which is easier to implement and more stable than a closed-loop system.

show abstract

Active Suppression of Buffeting at the Audi AAWT: Operational Experiences and Enhancements of the Control Scheme

Cited by 13 publications

References 3 publications

On the Low Frequency Pressure Fluctuation in a 3/4 Open Jet Automotive Wind Tunnel

On the Low Frequency Pressure Fluctuation in a 3/4 Open Jet Automotive Wind Tunnel

Reduction of 3/4 open jet low-frequency fluctuations in the S2A wind tunnel

Suppression of Wind Tunnel Buffeting by Active Flow Control

Contact Info

Product

Resources

About