S. R. Fischbach ,
 Jacobs ESSSA Group, NASA Marshall Space Flight Center, Huntsville, AL, USA
 Qualis Corporation, Huntsville, AL, USA
Combustion instability modeling of Solid Rocket Motors (SRM) remains a topic of active research. Many rockets display violent fluctuations in pressure, velocity, and temperature originating from the complex interactions between the combustion process, acoustics, and steady-state gas dynamics. Recent advances in defining the energy transport of disturbances within steady flow-fields have been ...
M. Cobianchi, M. Rousseau
 B&W Group Ltd, Steyning, UK
While musical instruments often rely on a body which resonates on purposefully to amplify the vibration produced by a string or a membrane, such as in a violin or a guitar, loudspeaker cabinets should not contribute at all to the total sound radiation, but aim instead to be a perfectly rigid box which encloses the drive units in charge to transform the electrical signal at their terminal into ...
M. K. Nguyen, R. Haettel, A. Daneryd
KTH, Stockholm, Sweden
ABB Corporate Research,Västerås, Sweden
Induction motors, as any other industrial products, have to comply with various requirements on noise levels. Therefore, it is essential to use an appropriate prediction tool to verify and optimize the design of an induction motor with respect to the acoustic performances. The paper will focus on the prediction of the magnetic noise generated and radiated by a specific motor. The challenge is ...
J. H. Lee , S. M. Al-Said ,
 American University of Sharjah, Sharjah, United Arab Emirates
 Jordan University of Science and Technology, Irbid, Jordan
In this paper, the effect of a crack to the flow-induced vibration characteristics of supported pipes is investigated based on vibration method. In order to estimate the crack location and depth in the pipe, we need to utilize the variation of the difference between the natural frequencies of the pipe conveying fluid with and without crack. The pipe is fluid loaded via interaction with the ...
T. Graf, T. Gisler, P. Sollberger, O. Schaelli
School of Engineering and Architecture, Lucerne University, Horw, Switzerland
Axisymmetric acoustic waves propagating along buried water pipes have been investigated by FEM and experimentally. Universal dispersion relations of the fundamental mode were obtained as a function of the standard dimension ratio SDR and of the material surrounding the pipe (soil, air). At low frequency there exists little dispersion and the “dc” phase velocity of the leak noise is independent ...
Anumeha Dwivedi, Dr. R. Dey
BITS Pilani K.K. Birla Goa Campus, Goa, India
Associate Professor, BITS Pilani K.K. Birla Goa Campus, Goa, India
Adulteration of automobile fuels, especially petrol and diesel is a rampant malpractice in India. With the rising prices of fuel and the subsidy on kerosene, getting away with even 10-15% adulteration is immensely profitable.To check adulteration effectively, it is necessary to monitor the fuel quality at the distribution point itself. The equipment for this purpose should be handy and the ...
Mitsubishi Turbocharger & Engine Europe, Almere, The Netherlands
This study presents a rotordynamic analysis of a rotor on hydrodynamic bearings using COMSOL Multiphysics®. In this paper, the complexity of the model is gradually increased. Starting point of the analysis is the modal analysis of the rotor in free-free conditions. A Reynolds model is set up to predict the film pressure distribution under shaft loading. Due to the cross coupling terms of the ...
Rakesh Kumar Pati , SK Mohammed ali, Sakuntala Mahapatra, Millee Panigrahi
MEMS Design Centre, Dept. of ETC, Trident Academy of Technology, Bhubaneswar, Odisha, India
Despite of the existing successful clinical applications, however, the interaction, i.e. artificial sensing, between the robot and the patient is still very limited. With the help of various cameras, vision is almost the only feeling that a robot can have. In order to imitate the human skin, various signals e.g., the strength of pressure, change of strength, speed and acceleration should be ...
B. Behera , H. B. Nemade , S. Trivedi ,
 Indian Institute of Technology Guwahati, Guwahati, Assam, India
The paper presents finite element simulation of a surface acoustic wave (SAW) linear motor. The function of SAW linear motor depends on the principle of friction drive provided by SAW propagating on a piezoelectric substrate. The SAW motor comprises of a slider driven by Rayleigh wave generated on a piezoelectric stator using an interdigital transducer (IDT) fabricated on surface of the stator. ...
Zhejiang Electro-Acoustic R&D Center, CAS, Zhejiang, China
扬声器的失真问题一直受电声业界的关注，尤其是谐波失真，它是影响扬声器重放声音音质的主要因素之一。 本文提出了一种基于 COMSOL Multiphysics® 软件预测扬声器谐波失真的仿真分析方法。该方法需建立包括磁场、振动系统和声场等多个物理场的扬声器的全模型，给扬声器加载一单频电压信号，用瞬态分析的方法可求解得到该频率激励下的扬声器的多个重要物理量随时间的变化函数，如流经音圈的电流I(t)、音圈的受力F(t)、振动系统表面上任意点的位移x(t)，以及声场中任意点的声压P(t)等。给扬声器加载一个时间长度为0.1s的单频电压信号，仿真分析所得的防尘帽顶点的位移曲线 x(t) 如图1所示，图2则是对应的在扬声器正前方0.1m处的声压曲线 P(t)。 再对所得的声压信号的稳态部分做FFT频谱分析，便可获得输入信号的各阶次谐波分量 ...