On the possible mechanism of the jet noise intensification near a wing

Bychkov, O. P.; Faranosov, G. A.

doi:10.1134/s1063771014060050

Cited by 25 publications

(12 citation statements)

References 22 publications

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“…This linear dependence is in an agreement with theoretical predictions and seems to validate the mechanism of noise generation and intensification proposed in [9]. It has also been experimentally shown that core flow velocity does not noticeably affect JFI noise, which is determined by bypass flow velocity (high-frequency region) and coflow velocity (low-frequency region).…”

Section: Discussionsupporting

confidence: 81%

“…For subsonic jets, they result primarily in pressure pulsations exponentially decaying in the sideline direction with only a small fraction of acoustic energy radiating in the far field. When the wing trailing edge is placed in the jet nearfield, the non-radiating hydrodynamic pulsations are diffracted into acoustic waves thus significantly intensifying far field noise [3,9].…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…A possible mechanism of jet noise intensification when the jet is located near a wing has been proposed in [3,9] and can be described as follows. The wing trailing edge lies in the jet near field where hydrodynamic nonradiating pressure pulsations dominate.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

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A parametric experimental study of jet-flap interaction noise for a realistic small-scale swept wing model

Belyaev¹,

Faranosov²,

Ostrikov³

et al. 2015

21st AIAA/CEAS Aeroacoustics Conference

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An experimental study of jet-flap interaction (JFI) noise has been carried out for a realistic small-scale model of the swept wing with an installed dual-stream nozzle. The effect of flap deflection angle on JFI noise has been a major objective of the investigation. It has been found that the flap deflection angle exerts a significant effect on JFI noise in the midfrequency range, so that JFI noise is basically a linear function (in dB) of the flap angle, while for high frequencies JFI noise seems to be independent of flap deflection angle. This linear dependence of noise on flap angle is in agreement with theoretical predictions. The effects of other parameters, such as the velocities of core flow, bypass flow, and coflow have also been studied. It has been shown that core flow velocity does not noticeably influence JFI noise, whereas bypass flow and coflow velocities have a strong effect on noise in the highfrequency and low-frequency ranges, respectively.

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Section: Discussionsupporting

confidence: 81%

Section: Theoretical Backgroundmentioning

confidence: 99%

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A parametric experimental study of jet-flap interaction noise for a realistic small-scale swept wing model

Belyaev¹,

Faranosov²,

Ostrikov³

et al. 2015

21st AIAA/CEAS Aeroacoustics Conference

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“…It is worth noting that the trailing-edge scattering mechanism of the hydrodynamic field has been suggested in several earlier works, for example those of Lawrence et al (2011) and Bychkov & Faranosov (2014). However, the term of hydrodynamic field is not always same as the evanescent wave mentioned here, for both non-linear and linear regions of hydrodynamic field exist.…”

Section: Near-field Scatteringmentioning

confidence: 75%

“…Due to the presence of the flat plate, we switch back to the Cartesian coordinates defined in figure 2 again. When the flat plate is sufficiently far away from the jet axis, for example the perpendicular distance between the plate and the jet axis is greater than 2D, little change of the flow occurs due to the presence of the plate and therefore the near-field evanescent waves, originating from hydrodynamic instability waves, can be found to be virtually same as that for an isolated jet (Bychkov & Faranosov 2014). We can thus use the evanescent wave field for an isolated jet as the incident evanescent field for an installed jet.…”

Section: Near-field Pressure Scatteringmentioning

confidence: 99%

Prediction of installed jet noise

2016

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A semi-analytical model for installed jet noise is proposed in this paper. We argue and conclude that there exist two distinct sound source mechanisms for installed jet noise and the model is therefore composed of two parts to account for these different sound source mechanisms. Lighthill's acoustic analogy and a fourth-order space-time correlation model for Lighthill stress tensor are used to model the sound induced by the equivalent turbulent quadrupole sources, while the trailing-edge scattering of near-field evanescent instability waves are modelled using Amiet's approach. A non-zero ambient mean flow is taken into account. It is found that, when the rigid surface is not so close to the jet as to affect the turbulent flow field, the trailing-edge scattering of near-field evanescent waves dominates the low frequency amplification of installed jet noise in the far-field. The high-frequency noise enhancement on the reflected side is due to the surface reflection effect. The model agrees well with experimental results at different observer angles apart from deviations caused by mean-flow refraction effect at high frequencies at low observer angles.

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