scholarly journals Active control of a sound field with a state feedback electro-acoustic transducer

2001 ◽  
Vol 22 (2) ◽  
pp. 135-140
Author(s):  
Toshiya Samejima ◽  
Daisuke Yamamoto
Keyword(s):  
Active Control ◽  
State Feedback ◽  
Sound Field ◽  
Acoustic Transducer

Active control of the scattered radiation with a reflecting surface

2019 ◽  
Vol 67 (3) ◽  
pp. 190-196
Author(s):  
Ning Han
Keyword(s):  
Control System ◽  
Active Control ◽  
Scattered Radiation ◽  
Sound Pressure ◽  
Sound Field ◽  
Control Area ◽  
Mirror Image ◽  
Three Dimension ◽  
Control Effect ◽  
Reflecting Surface

Based on a prediction method of the scattered sound pressure, an active control system was proposed in previous work for the three-dimension scattered radiation, where all the relevant simulations and experiments were implemented in three-dimensional free sound field. However, for practical applications, such as the anti-eavesdropping system or the stealth system for submarines, the sound field conditions are usually complex, and the most common case is the one with reflecting surface. It is questionable whether the previous control system is still effective in non-free sound field, or what improvements should be operated to ensure the control effect. In this article, based on the mirror image principle, two methods of calculating the control source strengths are proposed for the scattered radiation control, and numerical simulations with one-channel and multi-channel system are implemented to detect the corresponding control effect. It is seen that the local active control for the scattered radiation is still effective, and the reduction of the sound pressure level as well as the control area is extended with the increasement of the error sensors and control sources.

Active control of fan noise from high-bypass ratio aeroengines: a numerical study

2001 ◽  
Vol 105 (1053) ◽  
pp. 627-631
Author(s):  
P. Traub ◽  
F. Kennepohl ◽  
K. Heinig
Keyword(s):  
Active Control ◽  
Numerical Study ◽  
Active Noise Control ◽  
Sound Field ◽  
Primary Objective ◽  
Scale Model ◽  
Research Centre ◽  
Infinite Length ◽  
Circular Duct ◽  
Bypass Ratio

Abstract Under the national research project, dubbed Turbotech II, in which MTU Aero Engines, DLR Institute of Propulsion Technology and EADS Corporate Research Centre participate, active noise control (ANC) has been tested with a scale model fan of one metre diameter for a high bypass ratio aeroengine. MTU’s task in this project was to develop a computer code to predict the sound field in the intake duct of the fan-rig by the use of active control. The primary objective of the numerical study was to specify numbers of actuators (loudspeakers) and error sensors (microphones) and their positioning to control the harmonic sound power, radiated upstream to the duct intake. The computer model is based on the geometry of an annular or circular duct of rigid walls and infinite length, containing a subsonic axial uniform flow. The modal amplitudes of the primary sound field are input data. The actuators are modelled by acoustic monopoles. Two control algorithms have been used for achieving the control objective. The first consists simply in the reduction of the in-duct mean squared pressures. The second, so called modal control, is designed to cancel dominant modes selectively. Numerical results are presented using a typical configuration of wall mounted actuators and error sensors in the form of a number of rings uniformly distributed along the length of the intake duct. Guidelines have also been derived to design a favourable configuration of actuators and sensors. The findings of the numerical study are compared with the results of the ANC tests.

Active Control of Low-Frequency Sound Radiation From Vibrating Panel Using Planar Sound Sources

2001 ◽  
Vol 124 (1) ◽  
pp. 2-9 ◽  
Author(s):  
Kean Chen ◽  
Gary H. Koopmann
Keyword(s):  
Active Control ◽  
Near Field ◽  
Low Frequency ◽  
Sound Radiation ◽  
Sound Field ◽  
Sound Power ◽  
Frequency Range ◽  
Sound Sources ◽  
Frequency Sound ◽  
Secondary Sources

Active control of low frequency sound radiation using planar secondary sources is theoretically investigated in this paper. The primary sound field originates from a vibrating panel and the planar sources are modeled as simply supported rectangular panels in an infinite baffle. The sound power of the primary and secondary panels are calculated using a near field approach, and then a series of formulas are derived to obtain the optimum reduction in sound power based on minimization of the total radiate sound power. Finally, active reduction for a number of secondary panel arrangements is examined and it is concluded that when the modal distribution of the secondary panel does not coincide with that of the primary panel, one secondary panel is sufficient. Otherwise four secondary panels can guarantee considerable reduction in sound power over entire frequency range of interest.

Active Control of Structural Sound Radiation in an Acoustic Enclosure Using Distributed Point Force Actuators

2014 ◽  
Vol 1082 ◽  
pp. 517-520
Author(s):  
Da Lin Chen ◽  
Nan Chen
Keyword(s):  
Active Control ◽  
Sound Pressure Level ◽  
Cooperative Control ◽  
Sound Pressure ◽  
Control Method ◽  
Sound Radiation ◽  
Sound Field ◽  
Pressure Level ◽  
Point Force ◽  
Flexible Plates

This paper demonstrates an investigation about the active control of sound radiation in the enclosure cavity consists of two flexible plates. One of the flexible plates is driven by a point force to generate the primary sound field in the cavity, and using some point forces which are located at different locations on the receiving plate to suppressing the panel vibration and then to minimum the cavity sound pressure level (SPL); meanwhile some actuators are located on the other panel surfaces to reduce the sound pressure level at some frequencies that can’t be well reduced by only effect on one panel. The better result shows the possibility of applying distributed cooperative control method to the structural-acoustic coupled system.

Numerical Study of Active Control of Interior Noise in a Structural-Acoustic Enclosure

2011 ◽  
Vol 486 ◽  
pp. 103-106
Author(s):  
Ming Gang Zhu ◽  
Guo Yong Jin ◽  
Na Feng
Keyword(s):  
Control System ◽  
Active Control ◽  
Lead Zirconate Titanate ◽  
Numerical Study ◽  
Sound Field ◽  
Lead Zirconate ◽  
Interior Noise ◽  
Placement Problem ◽  
Total Potential ◽  
Flexible Plates

This paper is concerned with the numerical study of active control of interior noise induced by the flexible plates in a coupled enclosure. A cabin-like enclosure with four acoustically rigid walls and two flexible plates is considered. Two types of actuators are used, i.e. acoustic actuators and distributed lead zirconate titanate piezoelectric (PZT) actuators instead of point force actuators. With the control system designed to globally reduce the sound field, different control configurations are considered, including the structural actuator on the incident panel, actuator on the receiving panel, acoustic actuator on the cavity, and their combinations. The effectiveness and performance of the control system corresponding to each configuration are studied numerically, and desirable placement problem of structural actuators in terms of total potential energy reduction are of particular interest.

Fuzzy Modal Active Control of Flexible Structures

2005 ◽  
Vol 11 (1) ◽  
pp. 67-88 ◽  
Author(s):  
M. Malhis ◽  
L. Gaudiller ◽  
J. Der Hagopian
Keyword(s):  
Active Control ◽  
State Feedback ◽  
Flexible Structures ◽  
Element Model ◽  
Transverse Plane ◽  
Digital Controller ◽  
Flexible Beam ◽  
Modal Control ◽  
Modal Reduction ◽  
Active Control Strategy

In this paper we propose a new active control strategy to control the dynamic behavior of flexible structures: fuzzy modal control (FMC). This strategy, based on the modal state feedback of the structure, uses independent fuzzy controllers for each mode to be controlled. This method is applied to a flexible beam controlled by a transverse plane of action using piezoelectric actuators. First of all, a model of a piezoelectric actuator is proposed, followed by the formulation of a finite-element model of the mechanical structure/actuator. The model is then fitted using an identification of the characteristics. After modal reduction, the FMC is carried out in two steps: the control of the beam in only one transverse direction by a piezoelectric pusher, then in two transverse directions by two orthogonal piezoelectric pushers located on the same plane. A digital controller was built in the Matlab®-Simulink® environment, and implemented on specialized cards in order to perform the corresponding experiment. The method is validated by comparing the results between the simulation and the experiment.

Global Active Control of Transmitted Sound Into Acoustic Cavity With Speakers and Piezoelectric Patch Actuators

2009 ◽  
Author(s):  
Masih Hanifzadegan ◽  
Abdolreza Ohadi
Keyword(s):  
Active Control ◽  
Plane Waves ◽  
Sound Field ◽  
Coupled System ◽  
Mode Shapes ◽  
Flexible Plate ◽  
Acoustic System ◽  
Acoustic Cavity ◽  
Piezoelectric Patch ◽  
Rigid Walls

In this work modeling of a vibro-acoustic system and global sound field control with both acoustic and structural actuators have been studied. The model of the system consists of a 3D rectangular cavity with five acoustically rigid walls and a flexible plate on the top of cavity. First, modeling of the vibro-acoustic system has been acquired and subsequently the mode shapes and natural frequencies of the coupled system have been calculated. Plane waves on the plate surface are the main sources of disturbances in this system. Undesired sound (noise) which is propagated into the enclosure is controlled by mounted piezoelectric patch actuators on the plate and acoustic piston sources (speakers) inside cavity. The global active control is designed to minimize the acoustic potential energy inside the cavity. The control performance has been investigated by acoustic and structural actuators separately and simultaneously.

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