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Showing 1 to 15 of 15 for “"Helmholtz resonator"”.
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Acoustic metamaterials : microperforated shell and Helmholtz resonator
… in designing efficient noise control. Helmholtz has been used to design a high-performance and broadband acoustic silencer. Specifically, five slit-type Helmholtz resonators, which possess a massive viscous area, are packed together to create a single-layer silencer. In turn, two …
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Application of a Helmholtz resonator excited by grazing flow for manipulation of a turbulent boundary layer.
… the oscillatory flow created by a flow-excited Helmholtz resonator for the purpose of minimising the flow instabilities. Attention has been given here to a cylindrical Helmholtz resonator as a possible alternative flow control device. The energy required to activate the Helmholtz resonator comes …
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Modeling and validation of a syntactic foam lining for noise control devices for fluid power systems
… Traditional noise control devices such as Helmholtz resonators, tuning coils, and Herschel-Quincke tubes are generally too large for fluid power systems unless the speed of sound in the device can be reduced. A compliant lining can achieve this effect, but compliance (and lossy compliance) …
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Damping acoustic pressure pulsations in pipelines using Helmholtz resonators
… thesis, an acoustic damping device known as the Helmholtz resonator (HR) is experimentally studied. The effects of HR cavity volume, pipeline diameter, HR location, the use of multiple HRs, and mean flow velocity are investigated to determine their effects on the acoustic attenuation achieved …
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Active, Passive and Active/Passive Control Techniques For Reduction of Vibrational Power Flow in Fluid Filled Pipes
… performance of the quarter wavelength tube and Helmholtz resonator was obtained on implementation of the rubber isolator on the experimental rig. Active control experiments using the side-branch actuator and 1/3 piezoelectric composite yielded significant dB reductions revealing their potential …
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Intake Manifold Design for an Air Restricted Engine
… efficiency per engine rpm. Methods such as Helmholtz Resonator Tuning and Pressure Wave Tuning have been used substantially to determine an engine’s operating conditions. However, these methods are flawed for the restricted engine case due to the assumption that there is an unlimited amount …
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Exploring Novel, Hard, Acoustically Absorbent, Materials
… tiles created utilizing 3D print technology and Helmholtz resonators. Additionally, an empirical study of Helmholtz resonator geometry was performed by analyzing the sound absorption of resonant cavity shape changes. Finally, plots of the absorption coefficients for each material tested were …
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A photophonic instrument concept to measure atmospheric aerosol absorption
… phenomenon discovered by Bell and an acoustic resonator developed by Helmholtz. The design consisted of two chambers: an aerosol chamber and a reference chamber combined into a double Helmholtz resonator configuration. The radiation from the visible light source was amplitude modulated by a …
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Experimental assessment of the internal flow behavior of supercritical carbon dioxide
… to measure the speed of sound through the use of Helmholtz resonators was developed and investigated. Shock tube experiments and static high pressure air tests in the blowdown facility were conducted to determine the viscous damping in the resonators. The results indicate that a Helmholtz …
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A computational and experimental investigation into the aeroacoustics of low speed flows
… The cavity with a lip is shown to behave as a Helmholtz resonator. The plane cavities are characterized by the more familiar Rossiter modes. Both geometries are characterized by intense near field oscillations and strong noise radiation. To quantify the effects of three-dimensional phenomena on …
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Investigating the Feasibility and Stability for Modeling Acoustic Wave Scattering Using a Time-Domain Boundary Integral Equation with Impedance Boundary Condition
… liner models are discussed: the <em>Extended Helmholtz Resonator Model</em>, the <em>Three-Parameter Impedance Model</em>, and the <em>Broadband Impedance Model</em>. In both the <em>Helmholtz</em> and <em>Three-Parameter</em> models, liner impedance is specified at a given frequency, whereas …
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Control of sound transmission into payload fairings using distributed vibration absorbers and Helmholtz resonators
… vibration absorbers (DVA) and optimally damped Helmholtz resonators (HR). A fully coupled structural-acoustic model of a composite cylinder excited by an external plane wave is developed as a first approximation of the system. A modal expansion method is used to describe the behavior of the …
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Acoustic Devices for the Active & Passive Control of Sound in a Payload Compartment
… lightweight designs for acoustic devices such as Helmholtz resonators and loudspeakers used for noise control in rocket payload compartments are developed. Second, active control using a hybrid control system (with structural and acoustic actuators) was tested experimentally. Due to the weight …
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Development of a Model for Predicting the Transmission of Sonic Booms into Buildings at Low Frequency
… rooms. The formulation is based on the Helmholtz resonator approach and is applicable to the very low frequency-range, when the acoustic wavelength is much larger than the opening dimensions. Experimental validation of the numerical model and computer code is presented for three test …
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An Investigation on Acoustic Metamaterial Physics to Inspire the Design of Novel Aircraft Engine Liners
… metamaterials investigated are an array of Helmholtz resonators with and without coupled cavities periodically-spaced along a duct wall. Analytical, numerical, and experimental developments of these acoustic metamaterial systems are used herein to study the effects of this technology on the …