R.Christensen, and U. Skov
A compression driver is a certain type of electrodynamic loudspeaker which has a phase plug with slits in front of the diaphragm. The slits are narrow enough that the so-called viscothermal effects are of significant importance. In this paper a 2D axisymmetric finite element model of a commercial compression driver is established where the vibroacoustic behavior can be evaluated. The ...
Application of a Weakly Non-Linear Analysis to the Analysis of Thermoacoustic Combustion Instabilities - new
D. Laera, S. M. Camporeale, G. Campa
Politecnico di Bari, Bari, Italy
Ansaldo Energia, Genoa, Italy
The thermoacoustic combustion instabilities are complex phenomena that may occur in steady flow combustion systems that are aboard of, e.g., rocket engines or gas turbines. The phenomena involve the interaction of chemical reactions with fluid-dynamic and propagation of pressure waves in the combustion chamber. Combustion instabilities may lead to a stable condition (known as “limit-cycle”) ...
S. H. Abadi , A. T. Lim ,
 University of Washington, Bothell, WA, USA
Underwater acoustics is an area that studies the sound propagation in water and the interactions with other objects and water boundaries. There are many technologies available for acoustic exploration of the ocean. Underwater vehicles are robots used in ocean sciences that travel underwater autonomously and can tow a hydrophone as a mobile sensor to record sound. The turbulent flow induced by ...
ÅF, Stockholm, Sweden
In this paper a pre-study on using COMSOL Multiphysics for rotordynamic analysis is presented. It is concluded that it is possible to use COMSOL Multiphysics to perform rotordynamical analysis. However, there are no standard environment for rotordynamics, hence the user has to extend the structural model with the rotordynamics effect such as gyroscopic effect and rotordynamical coefficients. By ...
Seagate Technology, Bloomington, MN, USA
Ultrasonic based cleaning process, widely used in various industries, mainly utilizes the cavitation effect to achieve contamination removal. For a given set of ultrasonic tank parameters, such as cleaning fluid, temperature, frequency etc, the cavitation effect is largely impacted by the amount of ultrasonic energy. Determining optimal ultrasonic energy level often becomes the key to the ...
屈治国 , 张秀海 ,
引言 超材料是一类具有天然材料所不具备的特殊性质的材料[1-3]。近年来，有学者开始研究超材料对波的旋转效应，这一研究有着工程应用价值。江雪等设计并实验验证了一种声场旋转器。江雪等进一步研究了声场旋转器整体尺寸大小对其工作带宽的影响及声场旋转器中心处的旋转角度与其结构单元长度的关系。但未见声场旋转器结构单元尺寸对其工作带宽影响的研究。 COMSOL Multiphysics® 的使用 采用 COMSOL Multiphysics® 的声学模块和结构力学模块模拟图1的俯视二维结构，采用完美匹配层以获得更好的模拟结果。 结果 本文模拟了5个声场旋转器在不同频率下的声场，发现随着长方体结构单元长宽比的增加，尽管声场旋转器在低频仍能工作，但可以工作的高频频率是下降的，即声场旋转器的工作带宽是变窄的。为了确定声场旋转器的高频工作截止频率，本文采用二分法确定声场旋转器 ...
S. Floody, R. Venegas, and F. Leighton
Universidad de Chile, Facultad de Artes, Departamento de Música y Sonología, Licenciatura en Sonido, Santiago, Chile
University of Salford, Acoustics Research Centre, Salford, UK
Universidad Tecnológica de Chile Inacap, Sede Pérez Rosales, Santiago, Chile
The present article presents a method to redistribute the acoustic modes of a rectangular enclosure in the low frequency range using slit resonators. The objective of the present work is to compare different strategies of optimal design in order to determine the dimensions of the resonators. The method of the finite elements will be used to model the acoustic physical behavior of the room. In ...
N. Alcheikh, C. Ayela, I. Dufour
Univ. Bordeaux, IMS Lab, Pessac, France.
Electrostrictive polymers have been of significant interest over the last years for energy harvesting. Principle is based on the conversion of a mechanical deformation into electricity. The stored energy basically depends on the mechanical strain induced into an electrostrictive polymer by the mechanical resonant vibration of a microcantilever supporting the electrostrictive layer. In this work, ...
Poznan University of Technology, Poland
This paper examines a sound propagation without airflow through circular ducts with spiral element inside. Models are numerically computed in three-dimensions. The spiral element in the duct is a newly analyzed acoustical element, geometrically similar to the well-known Archimedes screw. It can be applied significantly in ducted systems, such as ventilation, air-conditioning and heat ...
Effect of Manufacturing Defects in the Form of Internal Leakages on the Acoustic Performance of Mufflers
D. Neihguk, A. Prasad 
 Mahindra & Mahindra Ltd, Chengalpattu, Tamil Nadu, India
The presence of manufacturing defects in the form of incomplete welding and missing perforated holes leads to internal leakages in mufflers. This results into unintended acoustic impedance modifications as well as the Herschel-Quincke effect. The narrow region acoustics model of COMSOL Multiphysics® software is used to simulate the thermoviscous losses associated with the leakages. The ...