One-dimensional acoustic waves in retarding structures with propagation velocity tending to zero

A model, presented in a previous paper [J. App. Phys. 108 (2010) 074910], describing the modes coupling due to scattering on small one-dimensional irregularities (parallel ridges) of the surface of isotropic solid plates, when shear horizontal waves polarized along the ridges propagate perpendicularly to them, appears to be a convenient tool to tackle the effects of the shape profile of the ridges (including the depth and the slope). Being concerned by the use of this analytical approach not utilised until now, several results, yet typical of applications, are presented below and compared with some experimental and numerical results, even analytical results (from an alternative analytical model for particular cases). These comparisons permit to highlight the effects of spatial periodicities of the ridges and show that the method could provide information on geometrical parameters characterising the profile of the roughness, which could be of interest when other methods like optical methods cannot be used.

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Standing Waves in One-Dimensional Resonator Containing an Ideal Isothermal Gas Affected by the Constant Mass Force

Archives of Acoustics ◽

10.1515/aoa-2017-0029 ◽

2017 ◽

Vol 42 (2) ◽

pp. 263-271

Author(s):

Anna Perelomova

Keyword(s):

Boundary Conditions ◽

Acoustic Waves ◽

Standing Waves ◽

Ideal Gas ◽

Excess Pressure ◽

Mass Force ◽

Constant Mass ◽

Total Field ◽

One Dimensional ◽

Isothermal Gas

Abstract The study is devoted to standing acoustic waves in one-dimensional planar resonator which containing an ideal gas. A gas is affected by the constant mass force. Two types of physically justified boundary conditions are considered: zero velocity or zero excess pressure at both boundaries. The variety of nodal and antinodal points is determined. The conclusion is that the nodes of pressure and antinodes of velocity do not longer coincide, as well as antinodes of pressure and nodes of velocity. The entropy mode may contribute to the total field in a resonator. It is no longer isobaric, in contrast to the case when the external force is absent. Examples of perturbations inherent to the entropy mode in the volume of a resonator are discussed.

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Combustion Technology for Low-Emissions Gas-Turbines:Selected Phenomena Beyond NOx

Journal of Energy Resources Technology ◽

10.1115/1.2793862 ◽

1996 ◽

Vol 118 (3) ◽

pp. 193-200 ◽

Cited By ~ 7

Author(s):

S. M. Correa ◽

A. J. Dean ◽

I. Z. Hu

Keyword(s):

Acoustic Waves ◽

Liquid Fuel ◽

Carbon Deposition ◽

Surface Composition ◽

Dimensional System ◽

Pressure Oscillations ◽

Nox Formation ◽

Fuel Injectors ◽

One Dimensional ◽

Combustion Technology

Since recent reviews cover the issues in NOx formation under gas-turbine canditions, and since regulations essentially dictate use of the premixed mode of combustion for minimum NOx, this review concentrates on phenomena that can arise in premixed combustion. Specifically, 1) the initial unmixedness in a fuel-air premixer has been shown to make overall lean mixtures autoignite sooner than might be expected based on the overall fuel-air ratio, because the richer portions of the mixture lead the process;2) combustion pressure oscillations caused by the interplay between acoustic waves and unsteady heat release in a one-dimensional system can be calculated in good accordance with measured data, and set the stage for multi-dimensional CFD;3) carbon deposition arising from the flow of liquid fuel over metal surfaces such as found in fuel injectors and swirl cups has been described as a function of temperature and of surface composition; and 4) quenching and subsequent emissions of carbon monoxide can be minimized by preservation of a boundary-layer rather than an impingement type of flow over combustor liners.

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Quantized current in one-dimensional channel induced by surface acoustic waves

Physica B Condensed Matter ◽

10.1016/s0921-4526(98)00086-6 ◽

1998 ◽

Vol 249-251 ◽

pp. 140-146 ◽

Cited By ~ 33

Author(s):

V.I. Talyanskii ◽

J.M. Shilton ◽

J. Cunningham ◽

M. Pepper ◽

C.J.B. Ford ◽

...

Keyword(s):

Acoustic Waves ◽

Surface Acoustic Waves ◽

One Dimensional

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An Acoustic-Microwave Method for the Study of the Mechanical Influence of Moisture Content in Materials

Journal of Applied Mechanics ◽

10.1115/1.1545783 ◽

2003 ◽

Vol 70 (2) ◽

pp. 268-274 ◽

Cited By ~ 2

Author(s):

C. Bacon ◽

E. Guilliorit ◽

B. Hosten

Keyword(s):

Moisture Content ◽

Acoustic Waves ◽

Viscoelastic Properties ◽

Medium Density Fiberboard ◽

Microwave Method ◽

One Dimensional ◽

Electromagnetic Absorption ◽

Absorbing Materials ◽

Viscoelastic Characteristics ◽

Mechanical Influence

A one-dimensional theoretical model is developed to predict the acoustic waves generated by rapid thermal expansion caused by electromagnetic microwave absorption in viscoelastic rods. The theoretical acceleration at the end of the irradiated rod is predicted. The comparison between the experimental and the theoretical accelerations leads to the evaluation of viscoelastic characteristics. Parameters related to the electromagnetic absorption can be also obtained. A procedure to find approximate values of the different parameters is developed. Since it is considered in the model that the distribution of the temperature rise along the rod is exponential, very absorbing materials can be tested. Consequently, the influence of the moisture content on viscoelastic properties of a porous material can be investigated. The method is applied to study the influence of the moisture content on viscoelastic characteristics of medium density fiberboard materials.

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