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This paper aims to characterize the acoustic field radiated by the piston transducer and measure a few parameters through the data visualization method.

Using the theoretical model of the ultrasonic transducer, the acoustic field data were acquired by scanning the ultrasound field of the piston transducer. And the visualized graphs of the ultrasonic data were displayed through 3D graphs including slice, iso‐surface and volume rendering, respectively. Furthermore, a few parameters of the transducer including beam width and spread angle were measured using the visualized data.

The visualized graphs of the acoustic field radiated by the piston transducer show that the data visualization method can expose obviously the space distribution of the ultrasound field and describe directly the cylindrical shape. And this method provides the basis of reliable measurement and assess for the ultrasonic transducer.

This paper presents a kind of measured method of the acoustic parameters using the visualized data. The measurement range has limitation.

This method is possible used in Medical ultrasonic.

This paper presents the visualized description of the acoustic field of the piston transducer and a measurement of two acoustic parameters using the visualized data.

Objects can be inspected by measuring the way in which they distort acoustic, inductive, capacitive and microwave fields.

A recently developed calculation scheme for the numerical computation of the load‐controlled acoustic noise of power transformers is presented. This modeling scheme allows the precise and efficient computation of the coupled electromagnetic, mechanical and acoustic fields. The equations are solved using the finite element method (FEM) as well as the boundary element method (BEM), resulting in a separation of the acoustic‐magnetomechanical calculation of the winding vibrations resp. the acoustic‐mechanical computation of the tank vibrations (using FEM) and the calculation of the acoustic free‐field radiation (using BEM). The validity of the computer simulations has been verified by means of appropriate measurements. Simulated and measured values for winding and tank surface vibrations as well as the sound power level of the loaded transformer are found to be in good agreement.

This paper aims to Separation and sorting of biological cells is desirable in many applications for analyzing cell properties, such as disease diagnostics, drugs delivery, chemical processing and therapeutics.

Acoustic energy-based bioparticle separation is a simple, viable, bio-compatible and contact-less technique using, which can separate the bioparticles based on their density and size, with-out labeling the sample particles.

Conventionally available bioparticle separation techniques as fluorescence and immunomagnetic may cause a serious threat to the life of the cells due to various compatibility issues. Moreover, they also require an extra pre-processing labeling step. Contrarily, label-free separation can be considered as an alternative solution to the traditional bio-particle separation methods, due to their simpler operating principles and lower cost constraints. Acoustic based particle separation methods have captured a lot of attention among the other reported label-free particle separation techniques because of the numerous advantages it offers.

This study tries to briefly cover the developments of different acoustic-based particle separation techniques over the years. Unlike the conventional surveys on general bioparticles separation, this study is focused particularly on the acoustic-based particle separation. The study would provide a comprehensive guide for the future researchers especially working in the field of the acoustics, in studying and designing the acoustic-based particle separation techniques.

The study insights a brief theory of different types of acoustic waves and their interaction with the bioparticles is considered, followed by acoustic-based particle separation devices reported till the date. The integration of acoustic-based separation techniques with other methods and with each other is also discussed. Finally, all major aspects like the approach, and productivity, etc., of the adopted acoustic particle separation methods are sketched in this article.

The purpose of this paper is to present numerical investigation of the gas/vapor bubble dynamics under the influence of an ultrasonic field to give a more comprehensive understanding of the phenomenon and present new results

In order to formulate the mathematical model, a set of governing equations for the gas inside the bubble and the liquid surrounding it are used. All hydrodynamics forces acting on the bubble are considered in the typical solution. The systems of equations required to be solved consist of ordinary and partial differential equations, which are both nonlinear and time dependent equations. A fourth order Runge-Kutta method is applied to solve the ordinary differential equations. On the other hand, the finite difference method is employed to solve the partial differential equations and a time-marching technique is applied.

The numerical model which is developed in the current study permits a correct prediction of the bubble behavior and its characteristics in an acoustic field generated at this occasion.

Previous studies considering numerical simulations of an acoustic bubble were performed based on the polytropic approximation or pressure uniformity models of the contents inside the bubble. In this study, an enhanced numerical model is developed to study the acoustic cavitation phenomenon and the enhancement concerns taking into account both the pressure and temperature gradients inside the bubble as well as heat transfer through the bubble surface into account which is very important to obtain the temperature of the liquid surrounding the bubble surface.

The purpose of the study is to obtain and analyze vibro-acoustic characteristics.

A unified analysis model for the rotary composite laminated plate and conical–cylindrical double cavities coupled system is established. The related parameters of the unified model are determined by isoparametric transformation. The modified Fourier series are applied to construct the admissible displacement function and the sound pressure tolerance function of the coupled systems. The energy functional of the structure domain and acoustic field domain is established, respectively, and the structure–acoustic coupling potential energy is introduced to obtain the energy functional. Rayleigh–Ritz method was used to solve the energy functional.

The displacement and sound pressure response of the coupled systems are acquired by introducing the internal point sound source excitation, and the influence of relevant parameters of the coupled systems is researched. Through research, it is found that the impedance wall can reduce the amplitude of the sound pressure response and suppress the resonance of the coupled systems. Besides, the composite laminated plate has a good noise reduction effect.

This study can provide the theoretical guidance for vibration and noise reduction.

The modes of fuselage vibration that could be excited by jet‐efflux pressure fields are first discussed, and consideration is given to (he initial acoustic and structural damping of the modes. A simplified theory is presented for the acoustic damping of flat (or nearly flat) panels set in a much larger body, such as a fuselage. Using the results of Part I, an estimate is then made of the effect of Aquaplas damping compound on the vibration stresses, amplitudes and rivet loads of a structure subjected to random jet‐efflux excitation. It is assumed that the structure and the damping compound together constitute a linear system. In the two particular cases considered, the maximum possible reduction of rivet load is found to be about 40 per cent and 70 per cent respectively, and it is concluded that this is insufficient to outweigh the possible adverse effects of certain factors which cannot be introduced into a simplified investigation.

The purpose of this paper is to investigate airfoil self-noise generation and propagation by using a hybrid method based on the large-eddy simulation (LES) approach and Curle’s acoustic analogy as implemented in OpenFOAM.

Large-eddy simulation of near-field flow over a NACA6512-63 airfoil at zero angle of attack with a boundary layer trip at Re_c = 1.9 × 10⁵ has been carried out using the OpenFOAM® computational fluid dynamics (CFD) code. Calculated flow results are compared with published experimental data. The LES includes the wind tunnel installation effects by using appropriate inflow boundary conditions obtained from a RANS κ – ω SST model computation of the whole wind tunnel domain. Far-field noise prediction was achieved by an integral method based on Curle’s acoustic analogy. The predicted sound pressure levels are validated against the experimental data at various frequency ranges.

The numerical results presented in this paper show that the flow features around a NACA6512-63 airfoil have been correctly captured in OpenFOAM LES calculations. The mean surface pressure distributions and the local pressure peaks for the step trip setup agree very well with the experimental measurements. Aeroacoustic prediction using Curle’s analogy shows an overall agreement with the experimental data. The sound pressure level-frequency spectral analysis produces very similar data at low to medium frequency, whereas the experimentally observed levels are slightly over predicted at a higher frequency range.

This study has achieved and evaluated an alternative aeroacoustic simulation method based on the combination of LES with a simple Smagorinsky SGS model and Curle’s analogy, as implemented in the OpenFOAM CFD code. The unsteady velocity/pressure source data produced can be used for any simpler analytically based far-field noise prediction scheme.

A complete integration of the LES and Curle’s acoustic analogy for aeroacoustic simulations has been achieved in OpenFOAM. The capability and accuracy of the hybrid method are fully evaluated for high-camber airfoil self-noise predictions. Wind tunnel installation effects have been incorporated properly into the LES.

In this article, we present an investigation into the sound radiation from a permanent‐magnet DC electric motor using the finite‐element (FE) and boundary‐element (BE) models. A three‐times‐coupled electromagnetic‐mechanical‐acoustic numerical model was set‐up to predict the acoustic field. The first stage was to calculate the magnetic forces that excite the structure of the motor by using the FEM. In the second stage, the exciting magnetic forces were applied to the structural model, where the harmonic analysis was carried out using the FEM. The last stage was to model the acoustics by using the BEM. In order to evaluate the numerical model, the computational results were compared with the vibration and acoustic measurements and a reasonable agreement was found.

The purpose of this paper is to reduce the acoustic noise of helicopter ducted tail rotor.

To predict the noise accurately, a thin-body boundary element method (BEM)/Ffowcs Williams–Hawkings method is developed in this paper. It is a hybrid method combining the BEM with computational aeroacoustics and can be used efficiently to predict the propagation of sound wave in the duct.

Compared with the experimental results, the proposed method of acoustic noise is rather desirable.

Then several geometry parameters are modified to investigate the noise reduction of ducted tail rotor by using the numerical prediction method.

The aerodynamic and acoustic performance of different modification tasks is discussed. These results demonstrate the validity of design parameters modification of ducted tail rotor in acoustic noise reduction.