Experimental validation of numerical simulations for an acoustic liner in grazing flow: Self-noise and added drag

Tam, Christopher K. W.; Pastouchenko, Nikolai; Jones, Michael G.; Watson, William

doi:10.1016/j.jsv.2014.02.019

Cited by 71 publications

(30 citation statements)

References 28 publications

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“…As table 1 shows, several parameters were estimated from both experimental and simulation datasets and found to have differences less than 10 %. Other than to ensure grid convergence, no attempts were made to assess the sensitivity of the RANS predictions to the particular model chosen; the present results are similar to those found in Tam et al (2014) using an entirely different method. The RANS results provide confidence that the basic thermodynamic state and flow field throughout the GFIT are sufficiently characterized to permit the detailed direct numerical simulations to proceed.…”

Section: Rans-based Duct Flow Simulationsupporting

confidence: 63%

“…Recent work by Tam et al (2014) focused on creating a two-dimensional model of the NASA Langley grazing flow impedance tube (GFIT) fitted with an eight-orifice slit liner. Care was taken to match, as much as possible, the spatially developing flow within the GFIT through a tuned eddy viscosity and grazing acoustic incidence along the duct; in addition, a slit liner was manufactured to match the computational model.…”

Section: Literature Reviewmentioning

confidence: 99%

“…The recent paper by Tam et al (2014) estimated the drag change due to their slit liner by counting the rotational kinetic energy bound to vortices shed per unit time; that method is not useful for turbulent flows with distributed vorticity. More recently experimental methods are being developed to estimate liner drag from in situ flow measurements Gerhold, Brown & Jasinski 2016); both studies indicate liners cause increased drag.…”

Section: Drag Analysismentioning

confidence: 99%

“…The GFIT is a 2 × 2.5 rectangular cross-section duct with grazing acoustic waves that have been influenced by the duct flow while the simulations assume an infinitely large facesheet with normal acoustic incidence. It is unknown how important these differences are but the results of Tam et al (2014), which include duct effects and grazing incidence, suggest they are not dominant. In addition to the physical differences in the experimental setup and conditions it is important to mention that the impedance eduction methods are also different.…”

Section: Surface Dragmentioning

confidence: 99%

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Numerical investigation of a honeycomb liner grazed by laminar and turbulent boundary layers

Zhang

Bodony

2016

J. Fluid Mech.

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Direct numerical simulations are used to study the interaction of a cavity-backed circular orifice with grazing laminar and turbulent boundary layers and incident sound waves. The flow conditions and geometry are representative of single degree-of-freedom acoustic liners applied in the inlet and exhaust ducts of aircraft engines and are the same as those from experiments conducted at NASA Langley. The simulations identify the fluid mechanics of how the sound field and state of the grazing boundary layer impact the in-orifice flow and suggest a simple flow analogy that enables scaling estimates. From the scaling estimates the simulations are then used to develop reduced-order models for the in-orifice flow and a time-domain impedance model is constructed. The liner is found to increase drag at all conditions studied by an amount that increases with the incident sound pressure amplitude.

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Section: Rans-based Duct Flow Simulationsupporting

confidence: 63%

Section: Literature Reviewmentioning

confidence: 99%

Section: Drag Analysismentioning

confidence: 99%

Section: Surface Dragmentioning

confidence: 99%

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Numerical investigation of a honeycomb liner grazed by laminar and turbulent boundary layers

Zhang

Bodony

2016

J. Fluid Mech.

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“…[5][6][7] For example, grazing-incidence sound waves at different sound pressure levels (SPL) have been used to excite a resonator in the presence of a low Mach number grazing flow. [8,9] It was observed that at low SPLs, the presence of the flow over the orifice increases the resistance of the resonator. With increased SPL the structure of the vortices within the shear layer over the orifice is also altered and dissipated more quickly.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the turbulent boundary layer in the vicinity of a self-excited cylindrical Helmholtz resonator

Ghanadi

Arjomandi

Cazzolato

et al. 2015

Journal of Turbulence

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This study investigates the changes in the structure of a turbulent boundary layer downstream of a flow-excited Helmholtz resonator. To this end, a fully developed turbulent boundary layer over a resonator mounted flush with a flat plate was simulated by implementing a large eddy simulation (LES). To assist in understanding the effect of the resonator on the flow structure, a sensitivity study was undertaken by changing the main geometrical parameters of the resonator. The results demonstrated that when the boundary layer thickness equals the orifice length, the cross-stream component of velocity fluctuations penetrates the boundary layer, resulting in a reduction of the turbulence intensity by up to 12%. Therefore, it is concluded that a Helmholtz resonator has the potential to reduce the instabilities within the boundary layer. These investigations also assist in identifying the optimal parameters to delay turbulence events within the grazing flow using Helmholtz resonators.

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Lattice Boltzmann simulation on the flow behaviour associated with Helmholtz cavity-backed acoustic liners

Heng

Thanapal

Chan

et al. 2020

J Vis

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Noise from jet engines can be reduced by means of a Helmholtz cavity configuration. The resonance that occurs when a flow passes the neck of the Helmholtz resonator will dissipate acoustical energy. The mechanism for such dissipation is mainly due to the vortex shedding that occurs at the neck of the resonator where the vortex structures absorb acoustical energy and subsequently dissipate through viscous effects. In this work, numerical simulations utilizing the Lattice Boltzmann method is used to aid in visualizing the flow behaviour that is associated with Helmholtz cavity-backed acoustic liners. In both experiments and numerical simulations, the 1-neck cavity is found to result in an amplification of an applied acoustic source. For a 4-neck cavity, the configuration is able to achieve acoustic pressure reductions. Differences in the flow behaviour of the 1-neck and 4-neck cavities are detailed in this work. Results show that stronger vortex shedding that occurs in the 4-neck cavity configuration could explain the increased effectiveness of a Helmholtz cavity-backed acoustic liner.

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Experimental validation of numerical simulations for an acoustic liner in grazing flow: Self-noise and added drag

Cited by 71 publications

References 28 publications

Numerical investigation of a honeycomb liner grazed by laminar and turbulent boundary layers

Numerical investigation of a honeycomb liner grazed by laminar and turbulent boundary layers

Analysis of the turbulent boundary layer in the vicinity of a self-excited cylindrical Helmholtz resonator

Lattice Boltzmann simulation on the flow behaviour associated with Helmholtz cavity-backed acoustic liners

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