Sound Field Simulation Research Articles

Design and optimization of acoustic reflector for uniform diffusion

Sound diffusion performance is considered as an important issue in building acoustics. A well-diffused sound field can effectively enhance the human listening experience. To this end, we have investigated several optimization strategies to design a sub-wavelength acoustic metasurface that can achieve broadband uniform diffuse reflections. These designs are based on Fresnel lens surface, groove-like structure, level-set method, topology optimization approach, respectively. Meanwhile, a strategy combining Monte-Carlo searches and other derivative-free algorithms has been analyzed and used to ensure, as far as possible, a global optimum for the objective function when dealing with the multi-peak problem encountered in complex sound fields. Numerical simulations show that the resulting metasurfaces with the best diffusion performance have similar configurations between different design methods. The simulated sound pressure field was also verified by experimental measurements. From a general perspective, the proposed optimization strategy and simulation framework can provide a greater degree of freedom for geometric configuration and benefit the design of interior components in building acoustics.

Research on heat exchanger tube sheet to shell fillet weld testing and engineering application using total focusing phased array technique

Abstract According to structure of the heat exchanger tube sheet to shell fillet weld, the total focusing phased array technique was adopted to settle down this testing difficulty. Firstly, the inspection background and detection difficulties of the fillet weld was introduced in this paper. Secondly, the sound field simulation and typical flaw response simulation was carried out using CIVA software, and the special blocks were manufactured on the base of the simulation result. Thirdly, the total focusing phased array testing study was carried out in laboratory, and the drilled holes, grooves, as well as the typical flaws of incomplete fusion, incomplete penetration and crack in blocks were successfully detected. Finally, the total focusing technique engineering application of one heat exchanger in chemical device was put into effect, the incomplete fusion and incomplete penetration flaws were successfully detected. The total focusing phased array technique was successfully applied to the heat exchanger inspection project, the research result of this paper have high practical value for ensuring the safe and reliable operation of heat exchanger, and can be popularized and applied in the engineering project.

Two-dimensional distribution experiment of ‘lattice diffraction’ using ultrasound in an educational laboratory

Abstract A device that can study the two-dimensional distribution of ultrasonic diffraction on lattice structures was developed for educational laboratories, enabling students to design the size, shape and dimension of diffraction obstacles independently. In this experiment, metal balls were used to simulate atomic lattice structures, and the two-dimensional diffraction distribution data of simple cubic, body-centered cubic, and hexagonal close-packed structure were collected. The results were compared with the sound field simulation of COMSOL, and a good consistency was found. By observing the diffraction results of complex structures, students can gain a better understanding of the concept of diffraction.

Certification considerations and sound field simulation of civil aircraft cabin passenger address

Abstract In the design of a civil aircraft cabin passenger address system, it is quite necessary and very important to sufficient consider and demonstrate the system design architecture, equipment selection and arrangement to ensure that the system sound quality complies with the requirements of CCAR25.1423(c). In the design phase, the certification considerations of the passenger address system should be researched in advance to comply with CCAR25.1423(c). The cabin sound field distribution and STI of the civil aircraft cabin passenger address system should be simulated through professional tools to predict, demonstrate and judge the sound quality before the system preliminary design review (PDR). In this paper, the certification considerations of passenger address are developed and elaborated from the system equipment arrangement, automatic gain design, and inhibit method of the Larsen effect. Based on two loudspeaker arrangement options, the cabin sound field distribution and STI of the passenger address are simulated to indicate its compliance with CCAR 25.1423(c) from the proposal design level theoretically.

Research on engineering technology of compact thermoacoustic air conditioner for vehicles

Thermoacoustic refrigeration technology presents a promising solution for sustainable and efficient air conditioning in vehicles. However, traditional thermoacoustic systems typically employ rigid resonant tubes, which pose challenges in terms of assembly and spatial layout during experimentation. Additionally, electric heating is predominantly utilized as the heat source in most experimental setups.To address the need for compact thermoacoustic air conditioning systems suitable for vehicle applications, this paper introduces the concept of employing flexible resonant tubes in heat-driven thermoacoustic refrigeration systems. Our study begins by constructing a heat-driven thermoacoustic refrigeration platform designed to simulate real automotive exhaust conditions. The DeltaEC software is employed to optimize the design of each component within the system.Both flexible and rigid resonant tubes are used in experimental research. Our findings reveal that the pressure amplitudes measured from experiments using both types of tubes closely match the simulated sound field. Operating at 8.7 MPa, the cooling capacity of the thermoacoustic system with flexible tube is 3.4 kW at 10 ℃. Using more gentle bending of flexible resonant tubes can reduce small losses caused by bending in rigid resonant tubes. Consequently, under similar working conditions, the cooling capacity generated by the system employing flexible resonant tubes slightly exceeds that of systems employing rigid resonant tubes. Furthermore, our study demonstrates a thermoacoustic conversion efficiency of 20.8 % and a refrigerator refrigeration efficiency of 2.34.These findings provide empirical validation for the use of flexible resonant tubes within vehicle exhaust heat-driven thermoacoustic refrigeration systems. The experimental results clearly demonstrate the ability of vehicle exhaust as a heat source to provide heat for thermoacoustic systems, and the ability of flexible thermoacoustic systems to generate sufficient cooling capacity. Ultimately, this research contributes to the advancement and practical implementation of thermoacoustic air conditioning within vehicles.

Directional wave spectrum evolution modelling of ship noise

A new underwater acoustic propagation model that is well suited to modelling ship noise is described. The model describes the spatio-temporal evolution of the directional energy spectrum of a sound field. The governing equation can be thought of as an advection-diffusion equation for spectral energy in phase space (position, angle). Numerical simulations of sound fields excited by both isotropic compact sources and by highly anisotropic ship noise provide confidence that the model works well, with caveats that will be discussed. [Work supported by ONR.]

The influence of blade curvature radius on the internal unsteady characteristics of a centrifugal pump

AbstractTo study the influence of the blade curvature radius on the flow‐induced vibration and noise of the centrifugal pump, the internal sound field of the IS 80‐65‐160 centrifugal pump was numerically calculated by adjusting the blade wrap angles to change the blade curvature radius. The RNG (Reynolds Time Average Simulation) turbulence model was selected for the numerical calculation of the centrifugal pump. The numerical simulation of the whole flow channel of the centrifugal pump was carried out using Ansys Fluent software, and the external characteristic curve of the centrifugal pump was obtained. The influence of different blade wrap angles on the internal pressure, velocity and Turbulent Kinetic Energy of the centrifugal pump was obtained. On the basis of the sound–structure coupling equation, the unsteady sound field of the centrifugal pump was calculated, and the time domain and frequency domain characteristics of the pressure pulsation at each monitoring point were obtained. The calculation results showed that the dynamic and static interference between the impeller and the volute tongue mainly caused the vibration of the centrifugal pump. By appropriately increasing the blade wrap angles, the pressure pulsation in the volute fluid domain could be effectively reduced. The vibration and noise test bench of the centrifugal pump was set up to verify the test. The experimental results showed that at the double‐blade frequency, the variation trend of the experimental value and the simulated value of the outflow flow‐induced noise of the centrifugal pump were consistent, which verified the accuracy of the sound field simulation calculation. When the blade wrap angle , it could effectively reduce the internal sound pressure level and the flow‐induced vibration and noise of the centrifugal pump. By adopting measures such as grid encryption at the position of the tongue, nonstationary calculation and comparison of different turbulence models, the accuracy of the calculation results of the internal flow field and sound field of the centrifugal pump is effectively improved, and the accuracy and reliability of the experimental results are ensured. The above research results had certain reference significance and application value for improving the working efficiency of centrifugal pumps and reducing flow‐induced vibration and noise.

Study of GSO-GL based secondary source configuration optimization method for broadband sound field reproduction

Sound field reproduction is a method that uses multiple secondary sound sources to reproduce a predefined desired sound field in a listening area. The configuration of the secondary sound sources is a key factor affecting the reproduction performances. To optimize the secondary source configuration, this study proposes a new method that combines the Gram-Schmidt orthogonalization method with the group Lasso method, which is called GSO-GL method. Firstly, it selects a certain number of the secondary sources from all the alternative secondary sources using the Gram-Schmidt orthogonalization method. The excitation sources are then further selected from the secondary sources selected in the previous step using the group Lasso method. The sound field simulation from the 2D room model show that the GSO-GL method outperforms the Gram-Schmidt orthogonalization method or the group Lasso method alone, combining the high system stability of the Gram-Schmidt orthogonalization method with the high reproduction accuracy of the group Lasso method.

A Forward−Backward Splitting Equivalent Source Method Based on S−Difference

The regularization method has a direct impact on the accuracy of the reconstructed sound field in the process of inverse calculation of near−field acoustic holography using the equivalent source method. To expand the frequency range of sound field reconstruction and improve computational accuracy, a forward-backward splitting equivalent source method based on s−difference was proposed, which uses the ratio of the output results of the broadband acoustic holography algorithm as the regularization parameter. Numerical simulations of single source and coherent source sound fields were conducted under different frequency conditions to analyze the performance of the forward-backward splitting regularization algorithm based on s−difference, and experimental verification was performed. The simulation results show that the proposed method can accurately reconstruct the sound field in a wider frequency range, and has high accuracy in reconstructing the sound field of low−frequency coherent sources. The experimental results demonstrate the accuracy and effectiveness of this method in reconstructing mid−to−low−frequency sound fields.

Development of sound field simulation and optimization over large acoustic space by use of novel SEA method

Panasonic is committed to providing customers with optimal PA system. The ability to predict PA system performance from digital mock-up is key to help designing optimal system under various conditions. Sound predictions over large spaces are challenging with FEM/BEM methods due to high computational cost and response sensitivity. Additionally, adding detail in source or boundary is difficult with Ray-tracing methods. Finally, traditional SEA methods don't provide sufficient resolution of response. We have investigated a novel SEA method with ability to predict spatial variations in acoustic response. Sound propagation in large public spaces over the full audio range was predicted, accounting for detailed loudspeaker source characteristics, room geometry and boundaries absorption. Predictions were validated against test in a Panasonic auditorium. Method was then used to predict PA system performance in public space under realistic noise conditions. Inverse method was used to synthesize background noise source from limited test data. STI predictions were then performed and optimization carried out to identify PA system loudness requirements in order to achieve best STI performance over wide area while minimizing signal loudness at any position for various background noise conditions.

Data-driven simulation for two-dimentional sound field considering room shape

Estimating the sound fields in a room using numerical simulations based on the wave equation typically requires extensive computation time. Consequently, several recent studies have explored the use of deep learning to reduce computation time. However, these studies have not adequately accounted for differences in room shapes, which significantly affect reverberation. In this study, we propose a novel approach that utilizes sound field simulation results for deep learning training data to estimate the sound field in rooms of various shapes. Our target data were obtained using the boundary element method, and we employed full-resolution residual networks as our deep learning models. Through our experiments, we evaluated the accuracy of our proposed method for sound field estimation as well as the computational time required.

Comparison and simulation-based analysis of the sound field of Dong drum tower buildings

Drum towers are the most prominent cultural markers and the major site for cultural ceremonies in Dong villages. The visibility and audibility of drum towers are important factors influencing the location and construction of buildings in Dong villages. In this paper, the authors map and classify 21 drum tower buildings according to three characteristics: shape of the plan, elevation of the enclosure, and aspect ratio of the longitudinal section. Having used the sound field simulation software Odeon to filter two of the three characteristics that were identical, the authors simulated drum towers with different values of the third characteristic to study the factors influencing their sound field. The correlation between the construction of the drum tower and its characteristics of sound was established, and the characteristics of the sound field as well as their adaptability were assessed by comparing different forms of drum towers. This can provide technical support for the protection and repair of drum towers, their renovation and upgrade, and the construction of new drum towers in the Dong region.

Development and testing of coarse-grained models for ultrasonic simulations of cast austenitic stainless steel

Ultrasonic inspection of cast austenitic stainless steel (CASS) in the nuclear industry is particularly challenging because of sound field scatter and attenuation caused by the coarse-grained microstructure. Modeling and simulation are important tools in ultrasonic testing, as they can be used to help address key aspects of inspections, such as developing new probe designs, predicting inspection reliability, and testing phased-array focal laws. However, developing a useful and reliable CASS model is challenging due to the many grain interfaces and crystalline orientations that must be captured. We demonstrate a method of creating a realistic CASS model that is usable in CIVA, a commercially available modeling and simulation software platform. Using polished and chemically etched sections to highlight the grain structure and orientation, we generate models of a coarse-grained equiaxed specimen and a columnar specimen. We also test an alternative method of generating a coarse-grained model using Voronoi regions. We qualitatively compare sound field scatter and quantitatively compare sound field attenuation and beam partitioning in simulated sound fields to those of laboratory-measured sound fields. Results show that the Voronoi models perform as well as or better than the models based on actual grain morphology. We also show that model-to-model randomness in Voronoi grain structure can impact the magnitude of a simulated echo response by a factor of two or more. Although CASS models are potentially a good depiction of reality for a given scenario, they should not be considered representative since CASS morphology can change significantly from specimen to specimen or within the same specimen.

Vectorized Matrix Formulation for Sound Power Determination Through Inverse Problems and Regularization Techniques

Sound power estimation is a widely investigated research topic. Some of its state-of-the-art measurement solutions include taking velocity values on the source boundary, discrete pressure assessment on a virtual outer surface or evaluations with a sound intensity probe. The increased availability of microphone arrays proposes a new tool to obtain these results. The inverse boundary element method, the equivalent source method, the Helmholtz equation least-squares, and an approach based on the radiation resistance matrix provide vectorized formulations for estimating sound power. In this study, the results for different regularization techniques on the sound power deviation from a discrete line source are presented based on a backward reconstruction scheme from simulated sound pressure field points on four microphone arrays. Additionally, in this study, time improvement between single-frequency calculations and multi-frequency execution on multiple graphics processing units is presented. The outcome shows good accuracy and reduced computation time in graphics card implementations.

Formation of Scattering Characteristics for Acoustical Ray Tracing Simulation

Ray tracing simulation of sound field in rooms is a common tool in room acoustic design for predicting impulse response. There are numerous commercial engineering tools utilising ray tracing simulation. A specific problem in the simulation is the modelling of diffuse reflections when contribution of individual surface is prevailing. The paper introduces modelling of scattering which is interesting when the whole impulse response of a room is not a goal but contribution of certain surface. The main goal of the project is to shape directivity characteristics of scattered reflection. Also, an innovative approach is suggested for converting the energy histogram information obtained by ray tracing into an “equivalent impulse response”. The proposed algorithm is tested by comparing the results with measurements in a real sound field, realised in a scaled model where a diffusing surface is hardware-implemented.

An Inversion Method for Geoacoustic Parameters in Shallow Water Based on Bottom Reflection Signals

The inversion method based on the reflection loss-grazing angle curve is an effective tool to obtain local underwater acoustic parameters. Because geoacoustic parameters vary in sensitivity to grazing angle, it is difficult to get accurate results in geoacoustic parameter inversion based on small-grazing-angle data in shallow water. In addition, the normal-mode model commonly used in geoacoustic parameter inversion fails to meet the needs of accurate local sound field simulation as the influence of the secant integral is ignored. To solve these problems, an acoustic data acquisition scheme was rationally designed based on a sparker source, a fixed vertical array, and ship drifting with the swell, which could balance the trade-off among signal transmission efficiency and signal stability, and the actual local acoustic data at low-to-mid frequencies were acquired at wide grazing angles in the South Yellow Sea area. Furthermore, the bottom reflection coefficients (bottom reflection losses) corresponding to different grazing angles were calculated based on the wavenumber integration method. The local seafloor sediment parameters were then estimated using the genetic algorithm and the bottom reflection loss curve with wide grazing angles, obtaining more accurate local acoustic information. The seafloor acoustic velocity inverted is cp=1659 m/s and the sound attenuation is αp=0.656 dB/λ in the South Yellow Sea. Relevant experimental results indicate that the method described in this study is feasible for local inversion of geoacoustic parameters for seafloor sediments. Compared with conventional large-scale inversion methods, in areas where there are significant changes in the seabed sediment level, this method can obtain more accurate local acoustic features within small-scale areas.

Coupled simulation of vibration and sound field of Stradivari violin

The aim of this study is to clarify the relationship between the vibration of violins made by Antonio Stradivari and the acoustic radiation around it. The highly precise geometry of the violin was determined with a micro-computed tomography scanner, and the material properties of the violin body (spruce and maple) were set as the orthotropic properties in the numerical simulation. Then, the numerical simulations coupling the vibrations by a forced oscillation on a bridge with the acoustic field pressure around the violin were performed. Furthermore, the sound pressure emanating in a huge rectangular box was successfully calculated by large scale computing and the open-source parallel acoustic analysis software.

Research on Dynamic Visual Simulation of Hydropower Project Construction Based on Virtual Reality

In this paper, the basic theories and algorithms of virtual reality technology are studied, and the key technologies for drawing outdoor large-scale virtual scenes, realistic terrain simulation, virtual sound field simulation, and traffic layout in the construction site, three-dimensional road design, and dam construction simulation Visualization has been studied, and the system simulation information and graphics are closely combined to provide a new environment for the design and management of water conservancy and hydropower projects, and to provide decision-makers with a more scientific and intuitive basis.

Parallel numerical simulation of weakly range-dependent ocean acoustic waveguides by adiabatic modes based on a spectral method

With the increasing demand for underwater detection, interest in the acoustic field of range-dependent ocean waveguides is also growing. For weakly range-dependent ocean waveguides, adiabatic modes represent a compromise between accuracy and computational cost and occupy an important place in the simulation of numerical sound fields. However, either existing adiabatic-mode programs consider too few layers of media or the root-finder tends to miss roots. In addition, none of the programs can solve the acoustic field excited by a line sound source located anywhere in the plane. In this paper, we first derive an expression for the acoustic field excited by a line source by adiabatic modes and then introduce a high-precision spectral method to solve the local eigenmodes. For the lower boundary condition of the acoustic half-space, we use the eigenvalue transformation technique to transform the transcendental algebra system formed by spectral discretization into a generalized eigenvalue problem. Several representative numerical experiments are designed to verify the accuracy of the algorithm. After analyzing the parallelism, the multiprocess and multithread hybrid strategy is adopted to further accelerate the algorithm in parallel, and parallel numerical simulation is carried out on the Tianhe–2 multicore supercomputer; favorable acceleration is achieved.

Numerical simulation method of nonlinear contrast-enhanced ultrasound imaging

<sec>Contrast-enhanced ultrasound imaging (CEUS) based on the acoustic nonlinearity of ultrasonic microbubble has received great attention in recent years. Compared with conventional linear ultrasound imaging, nonlinear CEUS can further improve the imaging resolution while overcoming the challenge of clutter filtering. Simulation, acting as an effective tool for research on new mechanisms and technologies of ultrasound imaging, has been a long-term focus of computational acoustics. In the community of biomedical ultrasound, common sound field simulation tools are mainly based on finite element method (FEM), analytical method, <i>k</i>-space pseudospectral method and finite-difference time-domain method (FDTD), which are relatively mature solutions for simulating the nonlinear characteristics of tissue. However, it is still not trivial to simulate nonlinear CEUS by using the prevailing methods, as the nonlinearity of microbubble is often not considered.</sec><sec>In this paper, we propose a simulation method of nonlinear CEUS imaging that successfully combines the microbubble nonlinearity and classic <i>k</i>-space pseudospectral method. Specifically, forced oscillation response of the microbubble is computed based on the modified Rayleigh-Plesset equation and such a nonlinear response is further dealt as an additional source for analyzing the nonlinear component propagation and CEUS imaging. To investigate the performance of the proposed method, B-mode images of single microbubble and clustered microbubbles are simulated based on plane wave imaging. The plane wave based CEUS imaging can thus be carried out with different compounding angles and different contrast pulse sequencing (CPS) strategies (pulse inversion, amplitude modulation, pulse inversion & amplitude modulation, and probe element alternation). Different soft-tissue and mechanical parameters of the microbubble can be adjusted by using the proposed nonlinear simulation strategy, thus providing efficient solution for CEUS simulation. Such a method can evaluate the performances of different CPS strategies, and further contribute to the CEUS development.</sec>