Articles techniques et présentations

Ici vous trouverez les présentations issues des Conférences COMSOL à travers le monde. Réalisées par des utilisateurs de COMSOL Multiphysics, ces présentations explorent tous les domaines actuels d'innovation. Les applications couvrent pratiquement tous les secteurs industriels et impliquent des phénomènes électriques, mécaniques, fluidiques et chimiques. Utilisez la recherche rapide pour trouver les présentations les plus intéressantes dans votre domaine d'intérêt.

Computational Acoustic Attenuation Performance of Helicoidal Resonators

W. Lapka
Poznan University of Technology
Poznan, Poland

This paper concerns the problem of obtaining proper acoustic attenuation performance through computations. COMSOL was used to solve acoustics systems with helicoidal resonators in the frequency domain. Based on the studies of insertion and transmission loss of helicoidal resonators, a high consistency between the results obtained by numerical calculations with experimental measurements was ...

Optimal Placement of Piezoelectric Plates to Control Multimode Vibrations of Rotating Beam

F. Botta[1], D. Dini[2], S. Gentili[1], G. Cerri[1]
[1]Dipartimento di Ingegneria Meccanica e Industriale, Università degli Studi di Roma Tre, Roma, Italy
[2]Department of Mechanical Engineering, Imperial College London, London, United Kingdom

Turbomachines blades are forced by a load resulting from the interaction with the fluid. The consequent vibrations, and the associated fatigue phenomena, can give catastrophic failures and the reduction of the blades life. It could be increased if damping system are used. The piezoelectric materials has received considerable attention by many researcher for their potential application in the ...

Modeling Low Frequency Axial Fluid Acoustic Modes in Continuous Loop Piping Systems

E. Gutierrez-Miravete[1], E.R. Marderness[2]
[1]Rensselaer Polytechnic Institute, Hartford, CT, USA
[2]General Dynamics-Electric Boat, Groton, CT, USA

Industrial fluid systems often involve continuous piping loops. These systems consist of varying lengths of pipes and hoses connecting multiple components together. Fluid resonances can detrimentally affect the operation of fluid systems and components. This work used COMSOL to investigate the frequency and mode shapes of axial fluid resonances within a system of piping and components that form ...

Design Of Acoustic Metamaterials Based On The Concept Of Dual Transmission Line

A-S.Moreau[1], H.Lissek[1], and F. Bongard[2]
[1]Ecole Polytechnique Fédérale de Lausanne, Switzerland
[2]JAST SA, Antenna Systems, Lausanne, Switzerland

In this context, a one-dimensional acoustic transmission line, exhibiting metamaterial properties, is presented. It is composed of an acoustic waveguide, periodically loaded with membranes having the function of series capacitances, as well as transversally connected open channels (denoted stubs) having the function of shunt inductances. A validation of the transmission line design is made with ...

Numerical Simulations of Ultrasonic Non Destructive Techniques of Masonry Buildings

S. Carcangiu[1], B. Cannas[1], M. Usai[1], and G. Concu[2]
[1]Department of Electric and Electronic Engineering, Cagliari, Italy
[2]Department of Structural and Infrastructural Engineering and Geomatics, Cagliari, Italy

An experimental program has been developed, with the purpose of evaluating the reliability in building diagnosis and characterization of an integrated analysis of several parameters, associated with acoustic waves propagating through the material. The Direct Transmission Technique has been applied. In this paper we developed a numerical model using the Transient Acoustics-Piezoelectric ...

Thermo-Acoustic Analysis of an Advanced Lean Injection System in a Tubular Combustor Configuration

A. Giusti[1], A. Andreini[1], B. Facchini[1], F. Turrini[2], Ignazio Vitale[2]
[1]Department of Energy Engineering, University of Florence, Florence, Italy
[2]Avio, Turin, Italy

In this work a thermoacoustic analysis of a tubular combustor with an advanced lean injection system is presented. The performed analysis is based on the resolution of the eigenvalue problem related to an inhomogeneous wave equation which includes a source term representing heat release fluctuations (the so called Flame-Transfer-Function, FTF) in the flame region. The effect of the mean flow is ...

Design of a MEMS Resonator for a Centre Frequency Greater than 26.35 MHz and Temperature Coefficient Frequency Less than 0.5 ppm

S.Manikandan[1], R.Radeep krishna[1]
[1]Kalasalingam University, Department of ECE, Srivilliputtur ,Krishnan koil, Tamil Nadu, India

The variability of the design parameters caused by material properties like thermal conductivity is the major challenge in Micro Electromechanical System (MEMS). In resonator design the basic problem is that the frequency changes with temperature variation and quantitative explanation with respect to this varies. The change can be attributed to the stability in terms of frequency drift in parts ...

Accuracy of Fully Coupled Loudspeaker Simulation Using COMSOL

M. Hedges[1][2] and Y.W. Lam[1]
[1]Acoustics Research Centre, School of Computing, Science & Engineering, University of Salford, Salford, United Kingdom
[2]Monitor Audio Ltd., Rayleigh, Essex, United Kingdom

Loudspeaker simulation is used to inform the designer as to the performance of a design. In recent years the Finite Element Method (FEM) has been used to model the mechanical and acoustical attributes of a loudspeaker with varying success. This paper shows how a model that incorporates the magnetic, electromagnetic, mechanical and acoustical domains performs. These domains will be coupled where ...

Can the Drumhead be Decomposed from Spectra? - An Application for the Chesapeake Bay

K. McIlhany[1], and R. Malek-Madani[2]
[1]Physics Department, United States Naval Academy, Annapolis, MD, USA
[2]Mathematics Department, United States Naval Academy, Annapolis, MD, USA

In 1966, mathematician Mark Kac proposed the question "Can One Hear the Shape of a Drum?" in an article for American Mathematical Monthly. In attempting to resolve the Chesapeake Bay from an eigenfunctional approach, a one-to-one mapping of this famous problem has been identified. The quote above will re-write to "Can One Hear the Shape of a Drum from Multiple Point-Sampled Spectra?". This ...

Numerical Modelling Of Sound Absorptive Properties Of Double-Porosity Granular Materials

R. Venegas, and O. Umnova
Acoustics Research Centre, University of Salford, Salford, United Kingdom

Granular materials have been conventionally used for acoustic treatment due to their sound absorptive and sound insulating characteristics. An emerging field is the study of acoustical properties of multi-scale porous materials. An example of these is a double-porosity granular material in which the grains are porous themselves. In this work, a computational methodology for modelling this type ...

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