Wavelet Analysis of a Blade Tip-Leakage Flow

Boudet, Jérôme; Jacob, Marc C.; Caro, Joëlle; Jondeau, Emmanuel; Li, Bo

doi:10.2514/1.j056703

Cited by 7 publications

(4 citation statements)

References 16 publications

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“…11 of [1] by scaling the latter using the Strouhal number. In both tests, a dipole-like directivity attributed to TE noise can be observed for St= [1][2][3][4][5][6], which is stronger in the suction side possibly due to a thicker boundary layer. However, no symmetry between the pressure side and suction side can be observed at higher frequencies, showing a discrepancy with the results in [1] and stronger radiation of the gap sources towards the pressure side in this instance.…”

Section: Noise Localisation and Extractionmentioning

confidence: 88%

“…12c-12e. An increase of noise followed by saturation is observed in the first frequency range (f= [2][3][4][5][6] kHz). This is what the authors expected: a higher velocity of the cross-flow and a consequent noise rise until the gap size is big enough such that it behaves as a free tip vortex.…”

Section: Noise Localisation and Extractionmentioning

confidence: 99%

“…The pressure difference between the suction side and the pressure side of the fan blades creates a jet-like flow through the tip gap that rolls up into a tip leakage vortex (TLV). The main source mechanism of tip gap noise is attributed to the interaction of the turbulent structures in the jet-like cross-flow with the blade tip suction side edge and the scattering by the tip edge and/or the trailing edge of the unsteady perturbations induced by the tip vortex [1][2][3]. Recent LES simulations of the experimental set-up tested in [1,2] have shown agreement with the experiments and identified the former noise mechanism as dominant by means of an acoustic decomposition [4].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Aeroacoustic Assessment of Performance of Overtip Liners in Reducing Airfoil Noise

et al. 2021

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The reduction of fan broadband noise in the next generation of Ultra-High By-pass-Ratio (UHBR) engines remains a key technology challenge for the foreseeable future. The Over-Tip-Rotor (OTR) liner concept has been studied as a technology with the potential to further reduce fan noise and significant noise reductions have been measured. This paper describes a fundamental experimental evaluation that represents the Over-Tip-Rotor liner as a static airfoil with its tip located over a flat plate containing a flush-mounted lined insert and separated from the airfoil tip by a small gap. Differences in measured far-field sound spectra and in source power estimates derived from post-processed spiral array data have shown broadband gap noise reductions of 5-10 dB, even in the absence of a tip gap. Over-tip liners are found to suppress noise sources when located in the immediate vicinity, irrespective of the generation mechanism, mainly due to back-reaction effects on the source. An analytical prediction model for the over-tip liner noise reduction, based on a point source located over an infinite lined plane, is evaluated and compared with the experimental data. The model captures the back-reaction effects and provides qualitative agreement with the measured data, including the variation of noise reduction with increasing gap size.

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Section: Noise Localisation and Extractionmentioning

confidence: 88%

Section: Noise Localisation and Extractionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Aeroacoustic Assessment of Performance of Overtip Liners in Reducing Airfoil Noise

et al. 2021

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“…On probe B, the hump around 1.3 kHz characterises the pressure fluctuations induced by the detachment of the tip leakage flow on the airfoil pressure side-tip corner. A broadband hump is observed instead of a tonal peak because of the intermittency of the phenomenon [32]. The LES is able to well retrieve the hump at 1.3 kHz.…”

Section: Spectral Signature Of the Tip Leakage Flowmentioning

confidence: 93%

Numerical Prediction of the Aerodynamics and Acoustics of a Tip Leakage Flow Using Large-Eddy Simulation

Lamidel

Daviller

Roger

et al. 2021

IJTPP

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A Large-Eddy Simulation of the tip leakage flow of a single airfoil is carried out. The configuration consists of a non-rotating, isolated airfoil between two horizontal plates with a gap of 10 mm between the tip of the airfoil and the lower plate. The Mach number of the incoming flow is 0.2, and the Reynolds number based on the chord is 9.3 × 105. The objective of the present study is to investigate the best way to compute both the aerodynamics and acoustics of the tip leakage flow. In particular, the importance of the inflow conditions on the prediction of the tip leakage vortex and the airfoil loading is underlined. On the other hand, the complex structure of the tip leakage vortex and its convection along the airfoil was recovered due to the use of a mesh adaptation based on the dissipation of the kinetic energy. Finally, the ability of the wall law to model the flow in the tip leakage flow region was proven in terms of wall pressure fluctuations and acoustics in the far-field.

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The effects of stator-rotor interaction on unsteady characteristics of turbine tip leakage flow

Wang

Xuan

Han

2023

Aerospace Science and Technology

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Wavelet Analysis of a Blade Tip-Leakage Flow

Cited by 7 publications

References 16 publications

Aeroacoustic Assessment of Performance of Overtip Liners in Reducing Airfoil Noise

Aeroacoustic Assessment of Performance of Overtip Liners in Reducing Airfoil Noise

Numerical Prediction of the Aerodynamics and Acoustics of a Tip Leakage Flow Using Large-Eddy Simulation

The effects of stator-rotor interaction on unsteady characteristics of turbine tip leakage flow

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