Aeroacoustic Study of the Interaction of a Rotating Blade with a Batchelor Vortex

The aeroacoustic response of the orthogonal interaction of a rotating blade with an isolated Batchelor vortex is studied by means of numerical simulation. The relative influence of the vortex tangential and axial velocity on the blade aerodynamics and on the acoustics radiated in the far-field is analyzed by comparing the interaction with a Batchelor vortex to the interactions considering the vortex tangential or axial velocity components. Analyses show that the vortex tangential velocity contributes mostly to the noise level at low frequencies, whereas the vortex axial velocity is responsible for the contribution at high frequencies. For the range of frequencies in between, the interaction noise results from constructive interferences of the noise radiated separately by each velocity component of the vortex.

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“…The numerical setup, described hereafter, relies on a methodology developed in previous papers [26][27][28].…”

Section: Numerical Experimentsmentioning

confidence: 99%

Aeroacoustic Study of the Interaction of a Rotating Blade with a Batchelor Vortex

Zehner¹,

Falissard²,

Gloerfelt

2016

22nd AIAA/CEAS Aeroacoustics Conference

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“…The numerical setup is derived from the one used in a previous study to analyze the aeroacoustic response of a rotating blade interacting with a Batchelor vortex for an impingement located at 90% of the blade span [23]. It consists in a single blade of external radius R 0 = 1 m, of inner radius R root = 0.2 m, with NACA 0002 airfoil section of chord C = 0.2 m, rotating with a tip Mach number M 0 = 0.65 within a coaxial flow of upstream Mach number M ∞ = 0.25, as sketched in Fig.…”

Section: Setup Of the Numerical Experimentsmentioning

confidence: 99%

“…In fact, the blade rotation, the rotor advance ratio, and the location of the interaction on the blade influence strongly the blade aeroacoustic response to the interaction. These parameters have started to be accounted for in recent studies launched to better understand and characterize OBVI [20][21][22][23][24][25] in the context of open rotors and to improve the reliability of fast prediction methods [26][27][28].…”

Section: Introductionmentioning

confidence: 99%

“…They found that blade torque fluctuation increases as the interaction occurs closer to the blade tip and deduced that maximum torque fluctuation is obtained for an impingement at the blade tip. Zehner et al [23] focused on the relative influence of vortex axial and tangential velocities on the aerodynamic and acoustic response of the blade during the interaction. They showed that the vortex tangential velocity is responsible for the low-frequency content of the thrust fluctuation and noise radiation, whereas the axial velocity deficit in the vortex core accounts for the high-frequency content, with some constructive interference mechanism in between.…”

Section: Introductionmentioning

confidence: 99%

“…The dimensionless parameters characterizing the vortex response [2] are the same as in Ref. [23], resulting in a subcritical interaction in the weak-vortex regime where the cutting of the vortex by the blade does not alter significantly the vortex structure. For this type of interaction, Liu and Marshall [16] have demonstrated that the physical mechanisms governing the cutting process are mostly inviscid, and that the flow physics is not particularly sensitive to Reynolds number.…”

Section: Introductionmentioning

confidence: 99%

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Spatial development of trailing vortices behind a delta wing, in and out of ground effect

Morris

Williamson

2020

Exp Fluids

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In this research, we study the dynamics of vortex pairs both in and out of ground effect. Trailing vortices are generated by towing a 75 • leading-edge sweep-angle delta wing in an XY-towing tank, at 15 • angle of attack. As the delta wing is towed, it generates a spatially developing vortex pair with the axial (streamwise) flow in the vortex cores. Particle image velocimetry is used to determine the transverse velocity field, and the vortex pair is found to be well-characterized by the superposition of two Lamb-Oseen vortices. The axial flow is captured using a longitudinal light sheet. To ensure we capture the vortex core, a technique is used wherein the light sheet is set such that it is slightly oblique to the length of the vortex. Using this technique allows the axial flow to be measured in the vortex core more than 20 chord-lengths downstream of the delta wing, capturing data at a resolution as close as 0.03 chord-lengths apart. This technique is unaffected by displacements of the vortex core, allowing us to analyze the axial flow profile both in and out of ground effect. A Gaussian velocity profile with a wake-like velocity deficit (flow upstream) is observed in the far-wake of the delta wing in both cases. We also trigger the long-wavelength instability (

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Aeroacoustic Study of the Interaction of a Rotating Blade with a Batchelor Vortex

Cited by 11 publications

References 34 publications

Aeroacoustic Study of the Interaction of a Rotating Blade with a Batchelor Vortex

Aeroacoustic Study of the Interaction of a Rotating Blade with a Batchelor Vortex

Vortex Model and Blade Span Influence on Orthogonal Blade-Vortex Interaction Noise

Spatial development of trailing vortices behind a delta wing, in and out of ground effect

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