Noise Generation of Blade–vortex Resonance

Leung, R. C. K.; So, R. M. C.

doi:10.1006/jsvi.2001.3575

Cited by 12 publications

(6 citation statements)

References 21 publications

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“…Vortices, though, are drastic simplifications of the real flows, and have been adapted extensively in the study of sound generation by turbulent flows in the presence of a solid object because of their simplicity such that analytical solutions can be obtained in some cases. Typical examples of these studies include Howe, 17 Obermeier 18 and the more recent work of Leung and So 19 and Tang and Lau. 20 In the present investigation, a vortex is chosen to represent a turbulent eddy, and the motion of a flexible boundary in an otherwise rigid plane under the actions of this vortex is calculated.…”

Section: Introductionmentioning

confidence: 97%

Acoustic radiation by vortex induced flexible wall vibration

Tang

Leung

et al. 2005

The Journal of the Acoustical Society of America

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Sound radiation due to unsteady interaction between an inviscid vortex ͑which models a turbulent eddy͒ and a finite length flexible boundary in a two-dimensional space is studied using potential theory and the matched asymptotic expansion technique. The Mach number of the vortex propagation is kept below 0.15. Results suggest that the monopole field created by the volumetric flow induced by the vibrating flexible boundary dominates the overall acoustic power radiation. The longitudinal dipole directly due to the transverse vortex acceleration is only important when the vortex is moving over the flexible boundary. The longitudinal dipole resulting from the boundary vibration gains slightly in importance in the strong vortex case, but the corresponding transverse dipole remains negligible for the cases considered in the present study. The two longitudinal dipoles give rise to biased radiation directivities on both sides of the flexible boundary.

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Section: Introductionmentioning

confidence: 97%

Acoustic radiation by vortex induced flexible wall vibration

Tang

Leung

et al. 2005

The Journal of the Acoustical Society of America

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“…DNS and LES are the common approaches for the direct method. A computational aeroacoustic (CAA) hybrid method comprises independent treatment of flow field and acoustic propagation field (Leung and So, 2001). It separates the nonlinear flow computation and linear acoustic propagation.…”

Section: Numerical Test Model and Methodologymentioning

confidence: 99%

“…(2005). Leung and So (2001) have found that strong loading noise is generated at the resonance condition. In their work, instead of using a flexible structure, a spring-loaded rigid airfoil is used to simulate the flexible blade and the vortical field is modeled by a series of vortices.…”

Section: Introductionmentioning

confidence: 99%

Influence of flow velocity and flexural rigidity on the flow induced vibration and acoustic characteristics of a flexible plate

Purohit

Darpe

Singh

2017

Journal of Vibration and Control

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A numerical investigation on the influence of structural flexibility and flow velocity on the flow-induced acoustic and vibration response of a plate is presented. Simulations are performed on a test geometry of rigid square bluff body with a trailing flexible plate in low Reynolds number flow stream. The focus of the study is to characterize the flow-induced vibration and associated aerodynamic far field sound radiation from a flexible structure in flow. The role of flow velocity and level of structural flexibility on the acoustic radiation is thoroughly investigated. A linearized Euler equation based computational aeroacoustic hybrid method and a surface source approach for coupling the flow and acoustic domains are implemented with a bi-directional fluid structure interaction. The vortex shedding frequency of the coupled fluid-structure system synchronizes with the fundamental frequency of the trailing plate and steady-state vibration of the plate is observed. The results indicate that the relation between vibration level and the flow velocity as well as structural flexibility is not linearly related. For a particular combination of flow velocity and plate stiffness, the coupled fluid-structure system shows the resonance condition. The observed resonance frequency is slightly different from the free vibration (natural) frequency of the plate. Computation of the acoustic shows that the magnitude and spectral nature of the far field sound depends on the amplitude of the vibration and a higher acoustic pressure and the sound rich in tones is observed at resonance condition.

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“…However, the interaction between the modified wake and the downstream plate received little or no attention. The numerical studies of So et al (1999), and Leung and So (2001) showed that, under excitation of an oncoming KVS, a rigid slender streamlined structure, be it an airfoil or a turbine blade, would exhibit aerodynamic resonance at which the aerodynamic response and sound generation are the highest. In addition, structural resonance would occur if the elasticity of the structure was taken into consideration.…”

Section: Introductionmentioning

confidence: 99%