Acoustic Wave Radiation Research Articles

Experimental research on the horizontally getting together behaviors of acoustically manipulated bi-particle

This study aims at the controllability of acoustically manipulated non-contact aggregation of bi-particle. Based on the acoustic wave radiation model of the transducer and the acoustic wave interference theory, the mathematical model between the spatial levitation point and the phase of the phased array ultrasonic array unit is established. A double-sided phased array test system was developed and the phase calculation algorithm for independently manipulating bi-particle was optimized. The algorithm is capable of independently distributing the energy applied to each levitation point. Through simulation and experiment, the horizontally aggregation characteristics of two levitated particles are investigated, and a interesting relationship between particles aggregation and standing wave phase difference is revealed, which follows the law of “attraction in the same phase but repulsion in the opposite phase”. By adjusting the tilt angle of the standing wave acoustic trap, the critical distance when particles to accelerate and collision is sharply reduced from 1.5λ to 0.5λ, which provides a new perspective and potential application path for acoustic manipulation technology.

An efficient hybrid collocation scheme for vibro-acoustic analysis of the underwater functionally graded structures in the shallow ocean

In this paper, a novel hybrid collocation scheme based on the generalized finite difference method (GFDM) and the Burton–Miller singular boundary method (BMSBM) is developed to study the vibration and acoustic radiation characteristics of an underwater functionally graded (FG) structure immersed in the shallow ocean. By utilizing the individual strengths of both methods, the GFDM is adopted for the vibration analysis of the FG structures, while the BMSBM is applied for the acoustic wave radiation analysis. Numerical examples verify the accuracy and efficiency of the proposed hybrid collocation scheme for the natural frequency and acoustic radiation behavior of the underwater structures consisting of the functionally graded materials (FGMs). The influences of the material parameters, structural geometries and shallow ocean environment on the natural frequencies of the structural vibration and the underwater acoustic wave radiation field are investigated in detail. Numerical study shows that the variation trend of the natural frequencies of the structural vibration is consistent with that of the resonance peak frequencies of the underwater acoustic radiation field. The present results may provide valuable references for the design and application of underwater marine structures consisting of the FGMs.

Acoustic wave radiation from a coaxial pipe with partial lining and inner perforated screen

In this study, the analysis of sound waves from a coaxial pipe with a perforated screen and a partial acoustic absorbing lining is investigated. The geometry under consideration consists of an infinite pipe placed in a semi-infinite cylindrical pipe such that the inner surface of the outer pipe is covered with a partial acoustic absorbing lining. Because of the partial lining, the solution is obtained with both the Jones’ method and the Mode-Matching method. The effects of the problem parameters such as perforated screen and partial lining on the radiation phenomenon are presented.

Periodic Tubular Structures and Phononic Crystals towards High-Q Liquid Ultrasonic Inline Sensors for Pipes

The article focuses on a high-resolution ultrasound sensor for real-time monitoring of liquid analytes in cylindrical pipes, tubes, or capillaries. The development of such a sensor faces the challenges of acoustic energy losses, including dissipation at liquid/solid interface and acoustic wave radiation along the pipe. Furthermore, we consider acoustic resonant mode coupling and mode conversion. We show how the concept of phononic crystals can be applied to solve these problems and achieve the maximum theoretically possible Q-factor for resonant ultrasonic sensors. We propose an approach for excitation and measurement of an isolated radial resonant mode with minimal internal losses. The acoustic energy is effectively localized in a narrow probing area due to the introduction of periodically arranged sectioned rings around the tube. We present a sensor design concept, which optimizes the coupling between the tubular resonator and external piezoelectric transducers. We introduce a 2D-phononic crystal in the probing region for this purpose. The Q-factor of the proposed structures show the high prospects for phononic crystal pipe sensors.

Numerical analyses of nonlinear acoustic wave radiation behaviors of vibrational objects immersed in infinite fluid

This paper is concerned with numerical analyses of radiated sound behaviors of dynamic systems containing nonlinear vibrational objects immersed in a compressible and inviscid fluid of infinite extent. The vibrational solids are modelled by the Lagrangian description of motion, while the fluid surrounding the vibrational objects is formulated by the two-dimensional linearized Euler equations (LEEs). The nonlinear dynamic responses of the vibrational solids are computed by both the harmonic balance method (HBM) and direct time integration method. A fourth-order dispersion-relation-preserving (DRP) scheme is implemented on a fixed Cartesian grid to solve the governing equations of the fluid. A constrained moving least-squares sharp-interface immersed boundary method is adopted to impose the compatibility conditions on the common boundaries of the vibrational objects and the fluid. Selective filters are employed to suppress the spurious short waves appearing in numerical computations. Several numerical tests are carried out to confirm the validity of the developed vibro-acoustic coupling computational model by comparing the present solutions with the exact solutions. Nonlinear acoustic wave responses of vibrational objects with smooth and non-smooth nonlinearities are examined, including rigid cylinder-shaped oscillators resting on nonlinear mounts, ellipse-shaped objects suspended on nonlinear torsional springs, and rigid isolators with frictions and clearances. It is found that for vibrational objects containing nonlinearities, the amplitude-frequency responses of radiated sound pressure exhibit shifting resonance frequencies, secondary resonances and jump phenomenon. The intermittent collisions of the vibrational objects with clearances can result in abrupt fluctuations and distortions of the radiated acoustic waves in fluid. In addition, the radiation efficiency of high-order harmonics of nonlinear acoustic waves induced by stick/slip transitions of friction interfaces can reach to maximum with the friction coefficient.

Piecewise assembled acoustic arrays based on reconfigurable tessellated structures.

Physically reconfigurable, tessellated acoustic arrays inspired by origami structures have recently been leveraged to adaptively guide acoustic energy. Yet, the prior work only examined tessellated arrays composed from uniform folding patterns, so that the limited folding-induced shape change prohibits broad acoustic field tailoring. To explore a wider range of opportunities by origami-inspired acoustic arrays, here, piecewise geometries are assembled from multiple folding patterns so that acoustic transducer elements are reconfigured in more intricate ways upon array folding. An analytical model of assembled geometries and resulting acoustic wave radiation from the oscillating facets is formulated. Using the theoretical tool, parametric investigations are undertaken to study the adaptation of acoustic energy transmission caused by folding and modularity of the array assembly. A proof-of-concept specimen is fabricated and experiments are conducted to validate the theoretical model and to investigate the efficacy of the piecewise acoustic array concept. The total findings reveal that the assembly of tessellated acoustic arrays may emulate the wave radiation emitted by ideal acoustic sources of intricate shapes. Moreover, by exploitation of origami folding actions, the shape adaptations of the proposed arrays permit straightforward wave guiding opportunities for diverse application needs.

ВОЛНОВОЙ ПАРАМЕТР КАК КРИТЕРИЙ В ОСНОВЕ МЕТОДА ИССЛЕДОВАНИЯ АКУСТИЧЕСКИХ ИСТОЧНИКОВ ПРИ СТАРТЕ РАКЕТ

The purpose of this work is to develop a method for determining the types of acoustic sources of radiation and their acoustic fields during the space rockets launch in the first seconds based on the wave parameter values. The main noise source during the space rocket launch is its propulsion system (PS). The cross-section of the nozzle is taken as the oscillation source. The theory of siren sound emission is based on the acoustic power calculation of a jet as a volume sound radiator or a radiator with a space velocity. In the model of a volumetric spherical radiator, the front of a spherical wave is a spherical surface, and the sound rays, according to the definition of the wave front, coincide with the radii of the sphere. As a result of the divergence of waves, the sound intensity decreases with distance from the source. The present work has a prospective character for clarifying the nature of the acoustic fields and for calculating the noise levels from the space rocket launch when designing the cosmodromes. In the requirements for the construction of such structures, the noise impact on the environment of infrasound radiation upon launching launch vehicles is identified. A method for determining the types of acoustic radiation sources during the space rocket launch and their acoustic fields has been developed. The method makes it possible to develop physical models of acoustic fields and apply known mathematical models to calculating their characteristics. The method is applicable for the study of acoustic emissions in the first seconds of the space rocket launch based on the determination of the wave parameter kR and allows us to provide valid data on the levels of sound pressure, intensity and acoustic power at specific points of airspace around the PS in the first seconds of the launch. The character of the acoustic wave radiation from a hole in a specific size gas flue has been studied. To calculate the acoustic characteristics, an algorithm and a program on Java programming language have been developed. Two models of acoustic field generation in the environment are described during the work of a rocket as a plane radiator and spherical waves, depending on the value of the wave parameter kR. A technique for calculating the noise of a remote control in the range for the first 1.5-4 seconds of the space rocket start time is developed

A New Numerical Method for Solving the Acoustic Radiation Problem

A numerical method of solving the problem of acoustic wave radiation in the presence of a rigid scatterer is described. It combines the finite element method and the boundary algebraic equations. In the proposed method, the exterior domain around the scatterer is discretized, so that there appear an infinite domain with regular discretization and a relatively small layer with irregular mesh. For the infinite regular mesh, the boundary algebraic equation method is used with spurious resonance suppression according to Burton and Miller. In the thin layer with irregular mesh, the finite element method is used. The proposed method is characterized by simple implementation, fair accuracy, and absence of spurious resonances.

Realization of manipulating acoustic surface waves radiation direction with rectangular-groove structure

Acoustic surface waves (ASWs) can be generated through a one-dimensional array of grooves. Sound can be collimated by ASWs. However, in previous studies, the groove period and grating period have been the same. In this work, we propose a structure where the groove period is different from the grating period, and collimates sound waves with very small side lobes. The structure can alter the acoustic wave radiation direction by manipulating ASWs and the relationship between the radiation direction and the frequency for different groove depths are investigated. Furthermore the incident direction of the sound wave, which can be coupled into ASWs, can be manipulated by changing the period of rectangular grating. We theoretically illustrate the physical mechanism of controlling the ASW radiation direction by wave-number analysis. These theoretical predictions are verified using numerical simulations. Using this proposed structure, we can manipulate the ASW radiation direction, which is very important for practical applications of directional acoustic propagation.

A new microvalve controlled by surface acoustic wave

ABSTRACTA new microvalve controlled by surface acoustic wave was presented. A shape memory alloy (SMA) with plastic sheet was integrated into a printed circuit board by way of small copper pipe. A 128°-YX LiNbO3 piezoelectric substrate was under the SMA wire with small gap. A polydimethylsiloxane (PDMS) microchannel was squeezed by the extension of the heated SMA wire due to surface acoustic wave radiation. The microvalve state was then changed. Experimental results show that the switching-off time of the microvalve is 39.533 s at 28.5 dBm electric signal power. The variation of SMA size during expansion is theoretically calculated.

Directive and focused acoustic wave radiation by tessellated transducers with folded curvatures

Guiding radiated acoustic energy from transducer arrays to arbitrary points in space requires fine control over contributions of sound provided to the point from each transducer constituent. Recent research has revealed advantages of mechanically reconfiguring array constituents along the folding patterns of an origami-inspired tessellation, in comparison to digitally processing signals sent to each element in a fixed configuration. To date, this concept of acoustic beamfolding has exemplified that far field wave radiation may be adapted by orders of magnitude to a point according to the folding of a Miura-ori tessellated array when the array constituents are driven by the same signal. This research investigates a new level of adaptive acoustic energy delivery from foldable arrays through study of tessellated transducers that adopt folded curvatures, thus introducing opportunity for near field energy focusing alongside far field directionality. The outcomes of these computational and experimental efforts plainly reveal that foldable, tessellated transducers that curve upon folding empower straightforward means for the fine, real-time control needed to beam and focus sound to points in space. Discussions are provided on the potentials and limitations of the current tessellations considered, and means for future studies to build upon the new understanding.

The attenuation of poly(dimethylsiloxane) film to surface acoustic wave on a piezoelectric substrate

ABSTRACTThe attenuation characteristics of poly(dimethylsiloxane) (PDMS) film to surface acoustic wave was studied. An interdigital transducer with 27.7 MHz center frequency was fabricated on a 1280 yx-LiNbO3 substrate using microelectric technology. PDMS film with different thickness was coated on the piezoelectric substrate. Paraffin oil was pipetted on the PDMS film and heated by surface acoustic wave radiation. The temperature of the paraffin oil was measured by a temperature measuring meters. Then, the energy radiated into the paraffin oil per unit time was calculated. Comparison to SAW without the attenuation of PDMS film, the attenuation of SAW is 12.6%, 31.6% and 38% respectively, when the thickness of the PDMS film is 50μm, 100μm or 150μm.

Acoustic wavefield and Mach wave radiation of flashing arcs in strombolian explosion measured by image luminance

AbstractExplosive activity often generates visible flashing arcs in the volcanic plume considered as the evidence of the shock‐front propagation induced by supersonic dynamics. High‐speed image processing is used to visualize the pressure wavefield associated with flashing arcs observed in strombolian explosions. Image luminance is converted in virtual acoustic signal compatible with the signal recorded by pressure transducer. Luminance variations are moving with a spherical front at a 344.7 m/s velocity. Flashing arcs travel at the sound speed already 14 m above the vent and are not necessarily the evidence of a supersonic explosive dynamics. However, seconds later, the velocity of small fragments increases, and the spherical acousto‐luminance wavefront becomes planar recalling the Mach wave radiation generated by large scale turbulence in high‐speed jet. This planar wavefront forms a Mach angle of 55° with the explosive jet axis, suggesting an explosive dynamics moving at Mo = 1.22 Mach number.

Design of a phased array for the generation of adaptive radiation force along a path surrounding a breast lesion for dynamic ultrasound elastography imaging

This work demonstrates, with numerical simulations, the potential of an octagonal probe for the generation of radiation forces in a set of points following a path surrounding a breast lesion in the context of dynamic ultrasound elastography imaging. Because of the in-going wave adaptive focusing strategy, the proposed method is adapted to induce shear wave fronts to interact optimally with complex lesions. Transducer elements were based on 1-3 piezocomposite material. Three-dimensional simulations combining the finite element method and boundary element method with periodic boundary conditions in the elevation direction were used to predict acoustic wave radiation in a targeted region of interest. The coupling factor of the piezocomposite material and the radiated power of the transducer were optimized. The transducer's electrical impedance was targeted to 50 Ω. The probe was simulated by assembling the designed transducer elements to build an octagonal phased-array with 256 elements on each edge (for a total of 2048 elements). The central frequency is 4.54 MHz; simulated transducer elements are able to deliver enough power and can generate the radiation force with a relatively low level of voltage excitation. Using dynamic transmitter beamforming techniques, the radiation force along a path and resulting acoustic pattern in the breast were simulated assuming a linear isotropic medium. Magnitude and orientation of the acoustic intensity (radiation force) at any point of a generation path could be controlled for the case of an example representing a heterogeneous medium with an embedded soft mechanical inclusion.

Surface Acoustic Wave Enhancing Drop-Drop Microextraction with an Original Position Loop for Stabilizing Drops

A surface acoustic wave based drop-drop microextraction, in which an original position loop is used for stabilizing drops, is proposed. An interdigital transducer with 27.5 MHz center frequency was fabricated on a 128° yx-LiNbO3 piezoelectric substrate for exciting surface acoustic wave. Mass transfer of extractive matter between two liquid phases was enhanced due to acoustic streaming caused by radiation of surface acoustic wave. An original position loop, which was used to prevent extraction liquid from movement along the surface of piezoelectric substrate, was fixed on the substrate with 1 mm gap. An ionic liquid and an organic dye (acid green-25) solution were used for extraction experiments. Results show that the extraction time is greatly decreased due to surface acoustic wave radiation, and extraction process can be finished within two minutes at 30.0 dBm RF signal power.

Rapid drop-to-drop liquid–liquid microextraction by help of surface acoustic wave

A novel drop-to-drop liquid–liquid microextraction method is presented, by which a liquid–liquid microextraction is greatly accelerated. A pair of interdigital transducers (IDTs) with 27.5MHz center frequency is fabricated on a 128° yx-LiNbO3 substrate. Once a RF signal is applied to an IDT, surface acoustic wave is generated and then radiated into drops to be extracted on the acoustic path. The surface acoustic wave radiation, leading to rapid movement of droplets in original position, enhances the microextraction. An ionic liquid and an organic dye aqueous solution are used for extraction experiments and extraction kinetics is studied using an image-based concentration measurement technique. Extraction experiments show that a drop-to-drop liquid–liquid microextraction process can be finished within 100s when the RF signal power applied to the IDT is 26.9dBm, and the extraction time is decreased with RF signal power applied to the IDT.

Acousto-optic interaction with leaky surface acoustic waves in Y-cut LiTaO3 crystals

The acousto-optic interaction with leaky surface acoustic wave radiation into the bulk of YX-cut LiTaO3 crystals has been investigated. The light incidence and diffraction angles corresponding to the strongest acousto-optic interaction were calculated and measured as functions of the acoustic wave frequency. The dependencies of the diffracted light intensity on the amplitude of radio-frequency voltage applied to the interdigital transducer (IDT) were studied. Our acousto-optic measurements revealed generation, by the IDTs, of slow shear bulk acoustic waves propagating at different angles depending on their frequency. A secondary acousto-optic interaction from the bulk waves radiated by the receiving IDT has been studied.

SAW excitation properties on YX-cut of CNGS and SNGS single crystals

The paper presents numerical results on conductances of surface acoustic wave interdigital transducers (IDTs) on YX-cut Ca(3)NbGa(3)Si(2)O(14) (CNGS) and Sr(3)NbGa(3)Si(2)O(14) (SNGS) single crystals. It is shown that there is a strong bulk acoustic wave radiation from IDTs on YX-cut of CNGS single crystal in contrast to that of SNGS single crystal.

Particle concentration via acoustically driven microcentrifugation: microPIV flow visualization and numerical modelling studies

Through confocal-like microparticle image velocimetry experiments, we reconstruct, for the first time, the three-dimensional flow field structure of the azimuthal fluid recirculation in a sessile drop induced by asymmetric surface acoustic wave radiation, which, in previous two-dimensional planar studies, has been shown to be a powerful mechanism for driving inertial microcentrifugation for micromixing and particle concentration. Supported through finite element simulations, these insights into the three-dimensional flow field provide valuable information on the mechanisms by which particles suspended in the flow collect in a stack at a central position on the substrate at the bottom of the drop once they are convected by the fluid to the bottom region via a helical spiral-like trajectory around the drop periphery. Once close to the substrate, the inward radial velocity then forces the particles into this central stagnation point where they are trapped by sedimentary forces, provided the convective force is insufficient to redisperse them along with the fluid up a central column and into the bulk of the drop.

Microfluidic Colloidal Island Formation and Erasure Induced by Surface Acoustic Wave Radiation

Spatiotemporal patterns form in many nonlinear physicochemical or biological systems. Although unusual, microfluidic systems are no exception. We observe such patterns to form by colloids along the free surface of a drop beneath which surface acoustic waves propagate, and propose fundamental mechanisms to elucidate their formation. With increasing excitation amplitude, the colloids first assemble into concentric rings and then cluster into islands due to a combination of capillarity and surface acceleration. As the excitation is further increased, fluid streaming commences within the drop, inducing a transient metastable state in which the system alternates between colloidal island formation on the quiescent drop surface and subsequent erasure due to local vortex generation.