Interaction Of Acoustic Waves Research Articles

Oscillatory Pressure Effect on Mean Burning Rates of Solid Propellant Combustion at Low Frequency Conditions

AbstractThe investigation on acoustic pressure oscillation effect on the mean burning rate of solid propellant combustion under quasi and unsteady conditions has been carried out at elevated pressures typical of rocket operation. Experiments were conducted in the window bomb test facility to measure mean burning rate for the mean chamber pressure ranging from 1 to 7 MPa. This analysis facilitates current understanding regarding the mean burning rate variation due to the acoustic wave interaction with propellant flame complexes. The present work is focused on low frequency combustion instability and characterization of the long rocket motor configurations. The window bomb is connected with an exclusively designed rotating valve for the generation of acoustic pressure oscillations at selected mean chamber pressures and the corresponding frequency of operations. Two kinds of ammonium perchlorate/hydroxyl terminated poly butadiene (AP/HTPB) based composite propellants, one with aluminium, and the other without aluminium were considered. Experiments were conducted at the excited frequency of 140 Hz with different excited acoustic pressure amplitudes. This experimental setup facility has the provision of visual observation during propellant combustion using optical methods. The performance of the rotating valve was competent over the tested conditions. These studies reveal that the acoustic pressure amplitudes significantly enhance the mean burning rate of the solid propellants. The response of the aluminized propellants to the excited acoustic oscillations was relatively prominent as compared to that of its non‐aluminized counterparts. The results obtained are extremely useful in combustion instability characteristics of large scale rocket motors.

Влияние конфигурации и материала встречно-штыревых преобразователей на возбуждение поверхностных и псевдоповерхностных акустических волн в подложках ниобата лития

The excitation, distribution, and interaction of surface acoustic waves (SAW) and pseudo surface acoustic waves (PSAW) in a X-cut lithium niobate substrates were investigated. The resonant excitation frequencies, the wave distribution velocities and the dispersion characteristics were determined for each of the wave types. The influence of the interdigital transducer (IDT) material on the excitation efficiency and the interaction between investigated wave types was found out. The interdigital transducer material and configuration requirements for integrated acousto-optic devices were determined.

Interaction of Acoustic Waves in The Media with Quadratically Bimodular Nonlinearity

We obtain the quadratically bimodular equation of state for a rod with cracks on the basis of a model of the crack as an elastic contact of rough surfaces of solids. The perturbation method is used to theoretically study the propagation and interaction of collinear longitudinal elastic (strong low-frequency and weak high-frequency) waves in such media. Expressions for the amplitudes of the secondary waves, namely, the second and the fourth harmonics of the strong wave, the second harmonic of the weak wave, and the combination-frequency waves are obtained.

Guided acoustic wave interaction with flanged junctions in water-filled steel pipelines.

The interactions of guided acoustic waves with pipelines and associated components has become a topic of interest due to their application in water pipeline condition assessment. In this paper, guided acoustic wave interactions with flanged junctions in a water-filled pipeline are investigated by an analytical model and experimental measurements. In the model, axial wavenumbers, displacement, and stress profiles of the main pipeline and flange junction components are calculated by an existing cylindrical waveguide analytical model. These components are then concatenated together using mode matching to determine the overall theoretical characteristics. Experiments with a flanged water-filled steel pipeline are carried out to verify model predictions. Transmitted signals are acquired using acoustic transducers uniformly spaced along the pipeline axis to separate individual modes and extract mode amplitudes. Transmission losses are estimated by comparing the extracted amplitudes in a pipeline with and without the flanged junction. Both theoretical predictions and experimental results indicate that the flanged junction interacts with pipeline wall dominant modes by transforming them into waterborne modes and as a result guides acoustic power into the water medium. The flange is shown to cause a small transmission loss in waterborne modes as compared to the pipeline without flanges.

Nonlinear X-wave ultrasound imaging of acoustic biomolecules.

The basic physics of sound waves enables ultrasound to visualize biological tissues with high spatial and temporal resolution. Recently, this capability was enhanced with the development of acoustic biomolecules - proteins with physical properties enabling them to scatter sound. The expression of these unique air-filled proteins, known as gas vesicles (GVs), in cells allows ultrasound to image cellular functions such as gene expression in vivo, providing ultrasound with its analog of optical fluorescent proteins. Acoustical methods for the in vivo detection of GVs are now required to maximize the impact of this technology in biology and medicine. We previously engineered GVs exhibiting a nonlinear scattering behavior in response to acoustic pressures above 300 kPa, and showed that amplitude-modulated (AM) ultrasound pulse sequences that both excite the linear and nonlinear GV scattering regimes were highly effective at distinguishing GVs from linear scatterers like soft biological tissues. Unfortunately, the in vivo specificity of AM ultrasound imaging is systematically compromised by the nonlinearity added by the GVs to propagating waves, resulting in strong image artifacts from linear scatterers downstream of GV inclusions. To address this issue, we present an imaging paradigm, cross-amplitude modulation (xAM), which relies on cross-propagating plane-wave transmissions of finite aperture X-waves to achieve quasi artifact-free in vivo imaging of GVs. The xAM method derives from counter-propagating wave interaction theory which predicts that, in media exhibiting quadratic elastic nonlinearity like biological tissue, the nonlinear interaction of counter-propagating acoustic waves is inefficient. By transmitting cross-propagating plane-waves, we minimize cumulative nonlinear interaction effects due to collinear wave propagation, while generating a transient wave-amplitude modulation at the two plane-waves' intersection. We show in both simulations and experiments that residual xAM nonlinearity due to wave propagation decreases as the plane-wave cross-propagation angle increases. We demonstrate in tissue-mimicking phantoms that imaging artifacts distal to GV inclusions decrease as the plane-wave cross-propagation angle opens, nearing complete extinction at angles above 16.5 degrees. Finally, we demonstrate that xAM enables highly specific in vivo imaging of GVs located in the gastrointestinal tract, a target of prime interest for future cellular imaging. These results advance the physical facet of the emerging field of biomolecular ultrasound, and are also relevant to synthetic ultrasound contrast agents.

Interaction of External Acoustic Waves - Confined Electrons - Internal Phonons in a Cylindrical Quantum Wire with an Infinite Potential in the Presence of an External Magnetic Field

Interaction of external acoustic waves - confined electrons - internal phonons in a cylindrical quantum wire with an infinite potential (CQWIP) has been theoretically studied via the quantum kinetic equation for electrons in the presence of an external magnetic field (EMF). The quantum kinetic equation for the distribution function of electrons interacting with internal and external acoustic phonons is obtained from the Heisenberg equation of motion and the model of CQWIP. The density of acoustomagnetoelectric (AME) current and the analytical expressions for the AME field in the CQWIP in the presence of the EMF are obtained. The theoretical results are numerically evaluated for the specific CQWIP of GaAs/GaAsAl. It is shown that the AME field strongly depends on the system temperature in both cases of the strong magnetic field and the weak magnetic field. However, the graph showing the relationship between the AME field and the system temperature has the peaks in case of the strong magnetic field. The reason may be due to movement of the electrons between the mini-bands. The AME field obtained in this work are then compared with those of bulk semiconductors, superlattices, quantum wells (QW) and rectangular quantum wire (RQW).

Picosecond opto-acoustics for the remote ultrasonography of single cells

Picosecond ultrasonics (PU) is a technique that offers the possibility to generate and detect acoustic waves remotely with an unequalled frequency bandwidth. After decades of developments and applications for researches in solid-state physics, a vast application field was recently demonstrated for PU in biology and medicine. The technique allows imaging single cells with a lateral resolution limited by optics and with the mechanical properties as the contrast mechanism. The opto-acoustic images can reveal the structure of the cell nucleus, the fine details of the actin network and of the adhesion pattern. In addition to imaging capabilities, quantitative analysis of the interaction of the GHz acoustic waves with the complex cell medium provides information on the cell nanostructure. For instances, the standard deviation of impedance data we measured for single nuclei revealed differences between different cell types arising from the multiplicity of local chromatin conformations within the nucleus. Moreover, the distribution of the cell-substrate interface stiffness we identified allowed us to separate the contribution of passive and active adhesion processes. The technique allows thus gaining new insights into cell mechano transduction.

Characteristics of very-low-frequency pulse acoustic fields measured by vector sensor and ocean bottom seismometer in shallow water

In the marine environment, the effects of the seafloor and subbottom elastic media on the propagation of very low frequency (VLF) sound wave should be considered. In order to understand the mechanism of seismoacoustic field propagation, a very-low-frequency sound propagation experiment was conducted in shallow water using seafloor-located acoustic vector sensor and ocean bottom seismometers (OBS) in December 2017. The water depth is about 100 m. Pulse sources detanoted at depths of 7 m and 50 m were employed to emit the VLF signals. Comparing the signals received by OBS with that of the acoustic vector sensor, a narrow-band wave package group at VLF had been observed, which was excited by the interaction of acoustic waves in water with the layered shear seabed. In this paper, the pulse signals are used to analyze the characteristics of sound propagation and spatial correlation, amplitude and phase structure of separated normal modes based on warping transform, horizontal and vertical acoustic energy flow at different ranges. The time arrival structure and time expansion of the elastic-bottom-induced wave package group and its relationship with source distance and depth are also analyzed.

Effect of sea-ice parameters on acoustic propagation in different Arctic scenarios

Depending on the setup and purpose of an acoustic propagation system (communication, navigation, tomography, seismic exploration) in ice covered areas, different parameters of the sea-ice are more significant in the interaction of acoustic waves with the ice. In homogeneous ice, with a source close to the surface, significant energy can be transferred to flexural waves and other ice-coupled modes. The modes in the ice are strongly dependent on the elastic parameters of the ice, as well as the thickness of the ice-plate. Additionally, discontinuities in the ice are very important to their propagation. In the inhomogeneous and fractured pack ice in the Arctic Ocean, where the cold water layer results in an acoustic surface channel, the majority of the acoustic waves will interact with the sea-ice at high incidence angles. Here, the roughness of the underside is more significant. Measurements from seismic experiments in an ice-covered fjord on Svalbard as well as long-range propagation in the ice-covered Fram Strait, together with simulations using OASES, are shown and used to gauge the effect of the different ice parameters. Although there is insufficient foundation for interpolation between the two extremes, the characteristics of the scenarios which determine the dominant ice-parameter are described.

Interaction of acoustic surface waves induced by inter-digital transducer with wall thinning defect in pipe structure

Most structural health monitoring (SHM) systems require transducers permanently attached to or integrated with the monitored structure to form a type of smart structure. It is difficult to permanently attach traditional ultrasonic transducers for non-destructive testing of structures for health monitoring. However, inter-digital transducers (IDTs) can be considered for on-site SHM because of the small size and economic efficiency of the IDT sensor. In this paper, an alternative sensor approach is proposed using IDT rather than conventional transducers to identify the interaction of surface acoustic waves (SAWs) with a wall-thinning defect. The SAWs generated by IDT sensors are modeled using the finite element analysis method. Acoustic wave propagation behavior in plate and pipe structures was reviewed, and the effect of the curvature of curved plate was investigated. From the interaction behavior observed between SAWs and a wallthinning defect in the pipe, which was determined using numerical simulation and tests, a novel concept is proposed for characterizing wall-thinning defects in pipelines.

Acoustic waves effect on the generation of nitrogen oxides by corona discharge in air

We studied the interaction of acoustic waves with negative corona discharge in air at atmospheric pressure. The application of acoustic waves on the discharge causes a mixing of ambient air with the gas between the electrodes, which results in cooling of the gas in the inter-electrode gap. As a rough indirect indicator of the discharge cooling, we used a concentration of nitrogen oxides generated by the discharge. We chose these oxides because they exhibit antibacterial properties. We showed that for a particular discharge power with increasing amplitudes of acoustic displacements, the concentration of generated nitrogen mono/dioxide decreases, and that this decrease could be attributed mainly to the temperature. We also found that application of acoustic waves on the discharge for a particular power substantially decreases transient spark frequency, increases the magnitude of the streamer onset voltage, and increases the difference between the streamer and spark onset voltage.

Acoustic method of atmosphere probing. Modern state and development prospects

Acoustic methods of atmosphere sounding allow us to track the meteorological situation in the atmospheric boundary layer at low costs on-line. The urgency of the these methods development is determined by the need to monitor the environment in conditions of man-caused load increasing. Acoustic waves are much more sensitive to changes in air parameters than electromagnetic waves. However, at present, their effectiveness, compared with laser, thermal and other systems is relatively low. The development of the acoustic sounding method has two directions: the improvement of theoretical descriptions of the interaction of acoustic waves with the atmosphere and the improvement of sounding techniques. Therefore, the evaluation of the most promising paths requires a detailed analysis of the current state, both theoretical foundations and technical implementations of the method. The paper shows that modern acoustic locators are performed at a high technical level and at present the main problem of the method is the lack of an adequate theory of processing the information obtained. The most urgent problems of the method development at the present stage are formulated in the work. They relate to the inverse problems of the fundamental problems of the theory of sound scattering in an inhomogeneous moving medium. Therefore, at present, a number of consecutive progressive steps are required to solve applied problems in the direction of adapting existing achievements to the use in sodar’s systems. Among the urgent tasks that can be developed at the current stage, we can identify the most important. This is a refinement of models of acoustic waves reflection in a stable atmospheric boundary layer in the period of nighttime temperature inversions. Analysis of multi-path probing possibilities for various phase relationships in emitted signals is carried out. Analysis of the prospects for the use of modulated sounding signals is conducted. Naturally, in addition to the above, there are more complex tasks. These include, for example, the reflection analysis in a compressible medium or the optimization of the initial relationships. In practical terms, a clear justification for simplifications in specific tasks is promising.

Combining Mass Spectrometry, Surface Acoustic Wave Interaction Analysis, and Cell Viability Assays for Characterization of Shiga Toxin Subtypes of Pathogenic Escherichia coli Bacteria.

Shiga toxin (Stx)-producing Escherichia coli (STEC) and enterohemorrhagic E.coli (EHEC) as a human pathogenic subgroup of STEC are characterized by releasing Stx AB5-toxin as the major virulence factor. Worldwide disseminated EHEC strains cause sporadic infections and outbreaks in the human population and swine pathogenic STEC strains represent greatly feared pathogens in pig breeding and fattening plants. Among the various Stx subtypes, Stx1a and Stx2a are of eminent clinical importance in human infections being associated with life-threatening hemorrhagic colitis and hemolytic uremic syndrome, whereas Stx2e subtype is associated with porcine edema disease with a generalized fatal outcome for the animals. Binding toward the glycosphingolipid globotriaosylceramide (Gb3Cer) is a common feature of all Stx subtypes analyzed so far. Here, we report on the development of a matched strategy combining (i) miniaturized one-step affinity purification of native Stx subtypes from culture supernatant of bacterial wild-type strains using Gb3-functionalized magnetic beads, (ii) structural analysis and identification of Stx holotoxins by electrospray ionization ion mobility mass spectrometry (ESI MS), (iii) functional Stx-receptor real-time interaction analysis employing the surface acoustic wave (SAW) technology, and (iv) Vero cell culture assays for determining Stx-caused cytotoxic effects. Structural investigations revealed diagnostic tryptic peptide ions for purified Stx1a, Stx2a, and Stx2e, respectively, and functional analysis resulted in characteristic binding kinetics of each Stx subtype. Cytotoxicity studies revealed differing toxin-mediated cell damage ranked with Stx1a > Stx2a > Stx2e. Collectively, this matched procedure represents a promising clinical application for the characterization of life-endangering Stx subtypes at the protein level.

Quantitative evaluation of surface crack depth with a scanning laser source based on particle swarm optimization-neural network

In this study, laser-generated surface acoustic wave (SAW) interaction with surface-breaking cracks is numerically investigated to identify the relationship between crack depth and features of SAWs. The Scanning Laser Source (SLS) technique is utilized to detect and quantify cracks by monitoring the changes of the SAWs as a laser source scans over the uniform and detective area. The simulation results show that crack depth can be described by several important features of the transmitted waves and reflected waves. These features are used as inputs to a quantitative machine learning approach for crack-depth evaluation based on a Neural Network (NN) optimized with Particle Swarm Optimization (PSO) algorithm. The results show the feasibility of the proposed machine learning method to estimate the crack depth rapidly and accurately using SLS data.

Highly localized distributed Brillouin scattering response in a photonic integrated circuit

The interaction of optical and acoustic waves via stimulated Brillouin scattering (SBS) has recently reached on-chip platforms, which has opened new fields of applications ranging from integrated microwave photonics and on-chip narrow-linewidth lasers, to phonon-based optical delay and signal processing schemes. Since SBS is an effect that scales exponentially with interaction length, on-chip implementation on a short length scale is challenging, requiring carefully designed waveguides with optimized opto-acoustic overlap. In this work, we use the principle of Brillouin optical correlation domain analysis to locally measure the SBS spectrum with high spatial resolution of 800 μm and perform a distributed measurement of the Brillouin spectrum along a spiral waveguide in a photonic integrated circuit. This approach gives access to local opto-acoustic properties of the waveguides, including the Brillouin frequency shift and linewidth, essential information for the further development of high quality photonic-phononic waveguides for SBS applications.

Investigation of shock–acoustic-wave interaction in transonic flow

The buffet flow field around supercritical airfoils is dominated by self-sustained shock wave oscillations on the suction side of the wing. Theories assume that this unsteadiness is driven by an acoustic feedback loop of disturbances in the flow field downstream of the shock wave whose upstream propagating part is generated by acoustic waves. Therefore, in this study, first variations in the sound pressure level of the airfoil’s trailing-edge noise during a buffet cycle, which force the shock wave to move upstream and downstream, are detected, and then, the sensitivity of the shock wave oscillation during buffet to external acoustic forcing is analyzed. Time-resolved standard and tomographic particle-image velocimetry (PIV) measurements are applied to investigate the transonic buffet flow field over a supercritical DRA 2303 airfoil. The freestream Mach number is $$M_{\infty } = 0.73$$ , the angle of attack is $$\alpha = {3.5}^{\circ }$$ , and the chord-based Reynolds number is $$Re_c = 1.9\times 10^6$$ . The perturbed Lamb vector field, which describes the major acoustic source term of trailing-edge noise, is determined from the tomographic PIV data. Subsequently, the buffet flow field is disturbed by an artificially generated acoustic field, the acoustic intensity of which is comparable to the Lamb vector that is determined from the PIV data. The results confirm the hypothesis that buffet is driven by an acoustic feedback loop and show the shock wave oscillation to directly respond to external acoustic forcing. That is, the amplitude modulation frequency of the artificial acoustic perturbation determines the shock oscillation.

Sound insulation properties in low-density, mechanically strong and ductile nanoporous polyurea aerogels

Aerogels are quasi-stable, nanoporous, low-density, three-dimensional assemblies of nanoparticles. In this paper, an extremely high sound transmission loss for a family of ductile polyurea aerogels (e.g., over 30dB within 1 to 4kHz at bulk density 0.25g/cm3 and 5mm thickness) is reported. The fundamental mechanisms behind the aerogel acoustic attenuations are investigated. Sharing striking similarities with acoustic metamaterials, initially, aerogels are studied via a one-dimensional multi degree-of-freedom mass-spring system. Different effects such as spring constant disparity are investigated in regards to the structural vibration wave transmission loss. Results are given for different configurations consistent with the aerogel nano/microstructures. A significant wave attenuation is observed by considering a random spring distribution. In the next step towards modeling such a complex hierarchical and random structural material, the continuum Biot's dynamic theory of poroelasticity is implemented to analyze the experimental sound transmission loss results. In this framework, a two-dimensional plane strain analysis is considered for the interaction of a steady state time-harmonic plane acoustic wave with an infinite aerogel layer immersed in and saturated with air. The effects of bulk density and thickness on the aerogel sound transmission loss are elucidated. By comparing the theoretical results with the experimental observations, this study develops a qualitative/quantitative basis for the dynamics of the aerogel nanoparticle network as well as the air flow and solid vibroacoustic interactions. This basis provides a better understanding on the overall acoustic properties of the aerogels that might also be helpful in the design of the future hierarchical materials.

Analysis of nonlinear acoustic wave propagation in HIFU treatment using Westervelt equation

Currently, the HIFU (High Intensity Focused Ultrasound) therapy method is known as one of the most advanced surgical techniques in tumor ablation therapy. Simulation of the non-linear acoustic wave and tissue interaction is essential in HIFU planning to improve the usefulness and efficiency of treatment. In this paper, linear, thermoviscous and nonlinear equations are applied using two different media, namely liver and water. Transducer power of 8.3-134 Watts with the frequency of 1.1 MHz is considered as the range of study to analyze the wave and tissue interaction. Results indicate that the maximum focal pressure of about 0.5-4.3 MPa can be achieved for transducer power of 8.3 to 134 W. Simultaneous solving of the acoustic pressure equation and Pennes’s bio-heat equation are used to determine the temperature rise at focal point and the ablated area. Finally, the linear and nonlinear simulations are compared, and the turning point of transition from linearity to nonlinearity is determined. The simulated results provide information about the behavior of the focalized ultrasound in interaction with liver tissue. The performance of phased array HIFU transducer can be improved for treatment considering the lesion size, temperature rise in tissue and choosing best range of operational power.

Interaction of surface plasmon polaritons and acoustic waves inside an acoustic cavity.

In this Letter, we introduce an approach for manipulation of active plasmon polaritons via acoustic waves at sub-terahertz frequency range. The acoustic structures considered are designed as phononic Fabry-Perot microresonators where mirrors are presented with an acoustic superlattice and the structure's surface, and a plasmonic grating is placed on top of the acoustic cavity so formed. It provides phonon localization in the vicinity of the plasmonic grating at frequencies within the phononic stop band enhancing phonon-light interaction. We consider phonon excitation by shining a femtosecond laser pulse on the plasmonic grating. Appropriate theoretical model was used to describe the acoustic process caused by the pump laser pulse in the GaAs/AlAs-based acoustic cavity with a gold grating on top. Strongest modulation is achieved upon excitation of propagating surface plasmon polaritons and hybridization of propagating and localized plasmons. The relative changes in the optical reflectivity of the structure are more than an order of magnitude higher than for the structure without the plasmonic film.

Investigation of interaction of shear horizontal surface acoustic wave with controlled electroinduced domain structure

In recent years, there has been great interest in developing different kinds of phononic crystals (PCs) with advanced ultrasound properties. In this study, we examined the possibility of creating a periodic domain structure controlled by an external electric field. The electric field was induced using crossed electrodes on the surface of a LiTaO3 single crystal. We investigated the domain formation process, in which the external electric field was smaller than the coercive electric field, and spontaneous polarization is not inverted. We proposed a new type of surface acoustic wave device and studied the parameters of interaction of a low-velocity shear horizontal acoustic wave with an electroinduced domain structure. This new kind of acoustic device allows the study of various ultrasound effects and the development of advanced controllable acoustoelectronic devices.