Numerical and experimental studies of a flat acoustic source that is actuated by an integrated flexure-based piezoelectric mechanism

This paper focuses on extensive numerical and experimental investigations of a thin sandwich acoustic source. Due to an energy inefficient actuation design, a thin sandwich acoustic source that was proposed in an early study is redesigned and reconstructed in the current research. The thin acoustic source in the present paper is actuated by long...

The influence of energy recovery on the overall efficiency of acoustic sources at low frequencies

Numerical modeling of a flexural displacement-converter mechanism to excite a flat acoustic source driven by piezoelectric stack actuators

This paper studies an acoustic source with a relatively small thickness and a high bending stiffness. The acoustic source operates in the low frequency, quasi-static regime. The focus of the current study is on the actuation part in order to design an appropriate excitation mechanism. A flexural mechanism is modeled in combination with a...

Numerical modeling of alumpedacoustic source actuated by a piezoelectric stack device that is driven by a switching amplifier

This paper studies an acoustic source with a relatively small thickness and high bending stiffness. Piezoelectric actuators are used to drive the moving component of the acoustic source. In the current study, a lumped model is used to represent the acoustic source that is excited by a piezoelectric stacked actuator. The equivalent electrical...

Modelling propagation of sound emitted by mini-airguns

A modelling approach is described in which time-domain underwater-acoustic source functions are generated using a model that predicts the motion of air-bubbles generated by mini-airguns operated at various pressures. These time-series are Fourier-transformed to produce frequency-domain descriptions of the source. These are combined with complex...

Active control of a lumped acoustic source driven by various actuators

This paper studies a lumped model of an acoustic source with a relatively small thickness and high bending stiffness. Voice coil and piezoelectric actuators are used to drive moving components of the acoustic source. Feedback and feedforward damping control techniques are used to actively obtain a smooth frequency response, especially at low...

An acoustic radiator with integrated cavity and active control of surface vibration

This paper presents a method to realize an acoustic source for low frequencies with relatively small thickness. A honeycomb plate structure which is open on one side combines the radiating surface and the major part of the air cavity. The vibration of the plate is controlled with a decentralized feedback controller. The fundamental resonance...

Numerical modeling of electrical-mechanical-acoustical behavior of a lumped acoustic source driven by a piezoelectric stack actuator

The present work describes the electrical, mechanical and acoustical behavior of a thin honey-comb structure as an acoustic source. The acoustic source has to operate in the low frequency, quasi-static regime and is driven by a piezoelectric stack actuator. In addition, a two-way energy flow between the actuator and a connected amplifier is...

Direct measurements of acoustic damping and sound amplification in corrugated pipes with flow

The flow-induced pulsations in corrugated pipes result from a feedback loop between an acoustic resonator and the noise amplification at each shear layer in the axisymmetric cavities forming the corrugations. The quality factor of the resonator is determined by the reflection coefficients at the ends of the corrugated pipe and by the damping in...

Monitoring Programme for the Maasvlakte 2, Part III - The Effects of Underwater Sound

The Port of Rotterdam is expanding to meet the growing demand to accommodate large cargo vessels. The construction of Maasvlakte 2 (MV2) started in September 2008. One of the licensing conditions is the monitoring of the underwater sound produced during its construction, with an emphasis on the establishment of acoustic source levels of the...

The acoustic source strength of high-energy blast waves: combining measurements and a non-linear model

In the densely populated area of the Netherlands, the objective of the Netherlands Ministry of Defence is to find an optimal balance between military training and the impact on the surrounding civilian community. A special case concerns large weapons, such as artillery or demolitions, which create high-energy blast waves. These waves have a low...

A model for flow-induced noise of Helmholtz resonator-like cavities

This paper presents a single prediction model for the noise generated by a turbulent boundry layer flow grazing on the opening of a Helmholtz-resonator like cavity. The prediction model is validated by comparison with an experimental study. The measured spectra inside the cavity are correctly predicted by the model.

Measuring TGV source strength with Syntacan

A 10 m high, vertical, synthetic acoustic antenna (Syntacan) has been used to measure the acoustic source strength and the vertical source distribution of a French TGV, as a function of the speed of the train, the frequency of the sound and the coach type (passenger coach, power car). The results are intended as input for calculation schemes and...