scholarly journals Influence of the multi-component electrical feed of air-core industrial reactors on their sound radiation

Acta Acustica ◽  
2020 ◽  
Vol 4 (4) ◽  
pp. 14
Author(s):  
Paul Gning ◽  
Vincent Lanfranchi ◽  
Nicolas Dauchez
Keyword(s):  
Acoustic Pressure ◽  
Acoustic Radiation ◽  
Force Component ◽  
Small Current ◽  
Component Distribution ◽  
Air Core ◽  
Computation Process ◽  
Spectral Components ◽  
Lorentz Forces ◽  
The Magnetic Field

High voltage devices such as dry-type air-core reactors are subjected to environmental noise standards. Their excitation is due to Lorentz forces originated from the magnetic field, created by the coil itself, combined with the feed current. The objective of this paper is to show how spectral components present in the supply current of industrial dry-type air-core reactors is likely to produce a significant acoustic radiation. First, the multi-component distribution of the Lorentz forces is established. Then, the multi-physics computation process allowing to determine the acoustic pressure induced by each force component is presented. Finally, two industrial reactors are studied: a single and a multi-layer coil. It is pointed out that significant acoustic emergence can be induced by the interaction between small current spectral components with the fundamental or with each other.

scholarly journals Acoustophoretic Control of Microparticle Transport Using Dual-Wavelength Surface Acoustic Wave Devices

Micromachines ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 52 ◽  
Author(s):  
Jin-Chen Hsu ◽  
Chih-Hsun Hsu ◽  
Yeo-Wei Huang
Keyword(s):  
Particle Motion ◽  
Acoustic Waves ◽  
Acoustic Pressure ◽  
Acoustic Radiation ◽  
Surface Acoustic Waves ◽  
Microfluidic Channel ◽  
Radiation Force ◽  
Dual Wavelength ◽  
Single Frequency ◽  
Motion Trajectories

We present a numerical and experimental study of acoustophoretic manipulation in a microfluidic channel using dual-wavelength standing surface acoustic waves (SSAWs) to transport microparticles into different outlets. The SSAW fields were excited by interdigital transducers (IDTs) composed of two different pitches connected in parallel and series on a lithium niobate substrate such that it yielded spatially superimposed and separated dual-wavelength SSAWs, respectively. SSAWs of a singltablee target wavelength can be efficiently excited by giving an RF voltage of frequency determined by the ratio of the velocity of the SAW to the target IDT pitch (i.e., f = cSAW/p). However, the two-pitch IDTs with similar pitches excite, less efficiently, non-target SSAWs with the wavelength associated with the non-target pitch in addition to target SSAWs by giving the target single-frequency RF voltage. As a result, dual-wavelength SSAWs can be formed. Simulated results revealed variations of acoustic pressure fields induced by the dual-wavelength SSAWs and corresponding influences on the particle motion. The acoustic radiation force in the acoustic pressure field was calculated to pinpoint zero-force positions and simulate particle motion trajectories. Then, dual-wavelength SSAW acoustofluidic devices were fabricated in accordance with the simulation results to experimentally demonstrate switching of SSAW fields as a means of transporting particles. The effects of non-target SSAWs on pre-actuating particles were predicted and observed. The study provides the design considerations needed for the fabrication of acoustofluidic devices with IDT-excited multi-wavelength SSAWs for acoustophoresis of microparticles.

Experimental Test of the Magnetic Field Active Shimming Method for Air-Core HTS Quadruple Magnet

2020 ◽  
Vol 30 (4) ◽  
pp. 1-5
Author(s):  
Junseong Kim ◽  
Yojong Choi ◽  
Wooseung Lee ◽  
Geonwoo Baek ◽  
Tae Kuk Ko ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Experimental Test ◽  
Air Core ◽  
The Magnetic Field

scholarly journals A hybrid fluxgate and search coil magnetometer concept using a racetrack core

2018 ◽  
Vol 7 (4) ◽  
pp. 265-276 ◽  
Author(s):  
David M. Miles ◽  
B. Barry Narod ◽  
David K. Milling ◽  
Ian R. Mann ◽  
David Barona ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solid Core ◽  
Proof Of Concept ◽  
Noise Performance ◽  
Hardware Complexity ◽  
Search Coil ◽  
Air Core ◽  
Single Sensor ◽  
The Magnetic Field

Abstract. A proof-of-concept hybrid magnetometer is presented, which simultaneously operates as both a fluxgate and a search coil, allowing it to sense the magnetic field from DC to 2 kHz using a single sensor. Historically, such measurements would normally require two dedicated instruments, and each would typically require deployment on its own dedicated boom as the instruments mutually interfere. A racetrack fluxgate core combined with a long solenoidal sense winding is shown to be moderately effective as a search coil magnetometer, and the search coil effect can be captured without introducing significant hardware complexity beyond what is already present in a typical fluxgate instrument. Several methods of optimising the search coil action of the hybrid instrument are compared with the best method providing sensitivity and noise performance between comparably sized traditional air-core and solid-core search coil instruments. This hybrid sensor topology should miniaturise to platforms such as CubeSats for which multiple boom-mounted instruments are generally impractical, so a single hybrid instrument providing modest, but scientifically useful, sensitivity from DC to kHz frequencies would be beneficial.

Acoustic and Vibration Characteristics of Stiffened Finite Cylindrical Shells in Water under Multiple Axial-Excitations

2013 ◽  
Vol 662 ◽  
pp. 721-725
Author(s):  
Qi Zheng Zhou ◽  
De Shi Wang ◽  
Sheng Yao Gao
Keyword(s):  
Analytical Solution ◽  
Shell Theory ◽  
Acoustic Pressure ◽  
Acoustic Radiation ◽  
Cylindrical Shells ◽  
High Frequencies ◽  
Acoustic Coupling ◽  
Coupling Equations ◽  
Vibration And Sound Radiation ◽  
Thin Shell Theory

A research on the vibration and acoustic radiation of stiffened finite cylindrical shells in water under a multiple axial-excitations driven was presented. The vibro-acoustic coupling equations of shell under multiple axial-excitations based on Flügge thin shell theory were established. The displacements, surface acoustic pressure and stiffener impedances were expressed in terms of the numbers of normal modals and modes, and considering multiple excitations, the forces were expressed in terms of the numbers of normal modals and modes. Then analytical solution was derived for the vibration and sound radiation from the stiffened shell under multiple excitations. Based on the analytical solution, the influences of excitations’ positions to the vibration and acoustic radiation were investigated. The results show that for double excitations, at high frequencies, the distance between excitations was more large, the average velocity was more low. The results could be used to control the underwater vehicle’s vibration and acoustic radiation.

scholarly journals A Hybrid Fluxgate and Search Coil Magnetometer Concept Using a Racetrack Core

2018 ◽  
Author(s):  
David M. Miles ◽  
B. Barry Narod ◽  
David K. Milling ◽  
Ian R. Mann ◽  
David Barona ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solid Core ◽  
Proof Of Concept ◽  
Noise Performance ◽  
Hardware Complexity ◽  
Search Coil ◽  
Air Core ◽  
Single Sensor ◽  
The Magnetic Field

Abstract. A proof-of-concept hybrid magnetometer is presented which simultaneously operates as both a fluxgate and a search coil allowing it to sense the magnetic field from DC to two kHz using a single sensor. Historically, such measurements would normally require two dedicated instruments and each would typically require deployment on its own dedicated boom as the instruments mutually interfere. A racetrack fluxgate core combined with a long solenoidal sense winding is shown to be moderately effective as a search coil magnetometer and the search coil effect can be captured without introducing significant hardware complexity beyond what is already present in a typical fluxgate instrument. Several methods of optimizing the search coil action of the hybrid instrument are compared with the best providing sensitivity and noise performance between comparably sized traditional air core and solid core search coil instruments. This hybrid sensor topology should miniaturize to platforms such a CubeSats where multiple boom-mounted instruments are generally impractical so a single hybrid instrument providing modest, but scientifically useful, sensitivity from DC to kHz frequencies would be beneficial.

Identification of the Types of Measured Acoustic Modes Inside the Operator's Cab in a Bulldozer

2015 ◽  
Vol 39 (4) ◽  
pp. 653-663
Author(s):  
Zygmunt Dziechciowski ◽  
Marek S. Kozień
Keyword(s):  
Rotational Speed ◽  
Acoustic Pressure ◽  
Natural Frequencies ◽  
Underground Mine ◽  
Reverberation Time ◽  
Structural Vibrations ◽  
Acoustic Modes ◽  
Spectral Components ◽  
Pulse Type ◽  
Caterpillar Track

Abstract The aim of the study was to identify acoustic and structural modes in the spectrum obtained exper-imentally inside an operator's cab in a bulldozer. Measurements were taken inside the operator's cab in a caterpillar-track bulldozer Polremaco TD12NPH2E-2000, designed for work in underground mine enclosures. The acoustic pressure spectrum was obtained for varied rotational speeds of the engine during the free run of the machine. The reverberation time of the cab was determined basing on the pulse-type excited pressure response, followed by identification of the spectral components registered by measurements. Thus, identified frequencies were compared with natural acoustic frequencies registered inside the operator's cab and with frequencies associated with the valves and ignition frequencies due to rotational speed and natural frequencies of structural vibrations of the cab's walls. This study was conducted in an attempt to reduce the noise inside the operator's cab using passive methods

ALTERNATE INTEGRAL-FORMULATION METHOD FOR PREDICTING ACOUSTIC RADIATION

2007 ◽  
Vol 15 (01) ◽  
pp. 81-93 ◽  
Author(s):  
ZHI NI ◽  
SEAN WU
Keyword(s):  
Acoustic Pressure ◽  
Acoustic Radiation ◽  
Free Field ◽  
Integral Formulation ◽  
Numerical Computations ◽  
Line Integral ◽  
Speed Up ◽  
Exterior Regions ◽  
Particle Velocities ◽  
Very High

Algorithms for an alternative integral-formulation method (AIM) are developed for predicting acoustic radiation from an arbitrary source in a free field. The main advantages of these algorithms are that the solution is always unique and the efficiency in numerical computations is very high. The input data to these algorithms consist of the normal and tangential components of the particle velocities that are specified on a hypothetical surface enclosing the source, and output data are the acoustic quantities that include the acoustic pressure, particle velocity, and acoustic intensity on and beyond the enclosure. To speed up the numerical computations, the Dijistra algorithm is adopted that searches automatically the shortest path between two neighboring nodes in carrying out line integral. Experiments in both interior and exterior regions are conducted, and the predicted acoustic pressure is checked against the benchmark value measured at the same location. The efficiency of AIM is examined and compared with that of conventional boundary element method (BEM) based Helmholtz integral formulations.

An Element-Free Galerkin Coupled with Improved Infinite Element Method for Exterior Acoustic Problem

2019 ◽  
Vol 27 (02) ◽  
pp. 1850021 ◽  
Author(s):  
Shaowei Wu ◽  
Yang Xiang ◽  
Jiachi Yao ◽  
Shuai Wang
Keyword(s):  
Acoustic Pressure ◽  
Shape Function ◽  
Acoustic Radiation ◽  
Variable Order ◽  
Infinite Domain ◽  
Element Free Galerkin ◽  
Infinite Element Method ◽  
Element Free ◽  
Function Construction ◽  
Element Method

It is known that the variable-order infinite acoustic wave envelope element (WEE) must be coupled with finite element method (FEM) by element matching for computing acoustic field radiated from radiators with complex geometric shapes. Therefore, the WEEs have to be reconstructed when the finite elements are refined or changed. To overcome the shortcoming, the element-free Galerkin (EFG) coupled with improved WEE (IWEE) method is presented to compute acoustic problems in the infinite domain. The continuity and compatibility of the acoustic pressure are maintained by IWEE that is composed of a standard WEE and a fictitious finite mesh. A key feature of the method is the introduction of the EFG method which is employed to eliminate the element matching and improve the accuracy of predicted acoustic pressure. The factors that affect the performance of the method are investigated by numerical examples, which include shape function construction, the weight function and the size of the influence domain. The numerical results show that the present method provides more accurate results compared to the coupled FEM-WEE method. The experimental results show that the method is very flexible for acoustic radiation prediction in the infinite domain.

Broad-Band Noise Mitigation in Vibrating Annular Plates by Dynamic Absorbers

2016 ◽  
Vol 16 (06) ◽  
pp. 1550014 ◽  
Author(s):  
Rezgar Shakeri ◽  
Davood Younesian
Keyword(s):  
Acoustic Pressure ◽  
Acoustic Radiation ◽  
Response Spectrum ◽  
Broad Band ◽  
Integral Approach ◽  
Noise Mitigation ◽  
Annular Disk ◽  
Annular Plates ◽  
New Formulation ◽  
Laplace Transform Inversion

Steady-state and transient acoustic radiation characteristics of clamped-free annular plate with tuned mass damper (TMD) device is studied. Galerkin’s procedure is employed to obtain the transverse vibration of the annular disk. Based on the Rayleigh integral approach, acoustic pressure radiation is obtained and subsequently the modal sound power and modal radiation efficiency are obtained. A new formulation for the transient acoustic pressure in Laplace domain is presented for the first time in this paper. Durbin’s numerical Laplace transform inversion scheme is employed to obtain the response spectrum. The optimum parameters of vibration absorbers are proposed for suppressing the dynamic vibration and acoustic pressure. A parametric study is carried out and the effects of vibration absorber characteristics are investigated using the analytical procedure. Limiting cases are considered and good agreements with the finite element solution, as well as with those available in the literature, are achieved.

scholarly journals MOEMS Based Single Chip Lorentz Force Magnetic Gradiometer

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 724
Author(s):  
Matthias Kahr ◽  
Michael Stifter ◽  
Harald Steiner ◽  
Wilfried Hortschitz ◽  
Gabor Kovacs ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Single Chip ◽  
Gradient Magnetic Field ◽  
Magnetic Gradient ◽  
Fixed Frame ◽  
Lorentz Forces ◽  
Gradient Fields ◽  
Field Sensor ◽  
The Masses ◽  
The Magnetic Field

The functional principle of an optical gradient magnetic field sensor consisting of two independent laterally oscillating masses on a single chip is reported. These oscillations are caused by the Lorentz forces resulting from an alternating current through the masses interacting with a static magnetic field. Light is modulated by relative in-plane movement of the masses and a fixed frame and subsequently detected by two photodiodes. Evaluation of magnitude and phase of the output signal reveals information about the uniformity of the magnetic field. The sensor is capable of detecting uniaxially strength and direction of magnetic gradient fields, offset gradient fields and homogeneous fields.

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