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Showing 1 to 16 of 16 for “"Sound radiated"”.
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Effect of heating on sound radiated from a two-dimensional mixing layer
The effect of heating on sound radiated by instability waves in a two-dimensional mixing layer is studied. A linear stability theory coupled with linearized Euler calculations are used to compute the amplitude of the instability wave and its associated sound field. The linear stability analysis …
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Sound Radiated from Turbulent Flow over Two and Three-Dimensional Surface Discontinuities
… have been performed to understand the sound source mechanism in turbulent boundary layer flow over two and three-dimensional surface discontinuities whose height is smaller than the incoming boundary layer thickness. The work was performed in two different types of boundary layers: a …
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Development & Validation of the Acoustic Analogy Code for Jet Noise Predictions
… the numerical code for predicting the far-field sound radiated from a localized sound source is developed based on Lighthill's acoustic analogy theory. The acoustic analogy equation allows calculating the sound intensity in terms of the integral over the volume with distributed Lighthill tensor …
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An experimental study on the performance of existing and custom quiet propeller designs for unmanned aircraft systems
… the trailing edge has been shown to reduce the sound radiated by the propeller. In total, 37 quiet propeller designs were created and simulated using SolidWorks Flow Simulation. From the simulation results, the three best performing designs were chosen to move on to manufacturing. Bringing these …
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The vibration of rolling discs
… of a rolling disc and an analysis of the sound which is then produced by the disc response. In order to characterise the disc's behaviour the free and forced vibration of a thin disc is analysed with the additional conditions which occur in rolling. These conditions include the geometric …
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The Noise of a Boundary Layer Flowing Over Discrete Roughness Elements
… - 55.2% of the boundary layer thickness. The sound radiated from the various layouts showed that the elements acted as independent sources when separated by three element diameters center-to-center or more. When the elements were placed shoulder to shoulder, interaction between the elements …
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Vertical axis wind turbine acoustics
… in conjunction with analysis of the measured sound spectra in order to locate and identify the noise sources on the VAWT rotors. Initial comparisons of the spectra from the model rotor and a full-scale rotor showed good qualitative agreement, suggesting that the conclusions from the …
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Flow Induced Noise from Turbulent Flow over Steps and Gaps
… pressure fluctuations which can manifest as radiated far field sound and affect the fluctuating near wall pressure field exerted on the flow surface. A significant amount of research has been performed on various step and gap flows; however few have dealt with step heights that are small …
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MODELING AND DESIGN OF A SMART DOUBLE-PANEL SYSTEM FOR THE CONTROL OF SOUND TRANSMISSION INTO AIRCRAFT CABIN
… used in the design of trim panels and additional sound absorption materials are also used in fuselage structures. However, this improvement in interior noise reductions is limited to mid-range and high-range frequencies (above about 1000 Hz). In fact, double-panel sidewall systems currently used …
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Acoustically induced vibration of, and sound radiation from, slender beams
… structures and a surrounding fluid medium. The sound radiated from an unbaffled slender cylindrical beam vibrating transversely at resonance is calculated by solution of the classical wave equation subject to the boundary conditions imposed by the motion of the beam. The relationship between …
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Coupling of Structural Dynamic and Acoustic Analyses Using the FEM and BEM
… from vibrating structures. To calculate the sound radiated from a vibrating structure, both a structural dynamic problem and an acoustic wave problem should be considered. In this study, the finite element method (FEM) is chosen for the structural dynamic analysis in order to calculate the …
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Sound radiation from perforated plates
… means of engineering noise control to reduce the sound radiated by structures. However, there appears to be a lack of representative models to determine the sound radiation from a perforated plate. The aim of this thesis is to develop such a model that can be used to give quantitative guidance …
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The Impact of Three Dimensional Flow Anisotropy and Transients on Turbulence Ingestion Noise in Open Rotors
… separation on the turbulent structure and radiated turbulence ingestion noise of a rotor in two experimental configurations is studied. The first consists of a non-axisymmetric boundary layer wake ingested by a rotor mounted at the aft of a body of revolution inclined at 5 degree angle of …
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Control of Sound Transmission with Active-Passive Tiles
Nowadays, numerous applications of active sound transmission control require lightweight partitions with high transmission loss over a broad frequency range and simple control strategies. In this work an active-passive sound transmission control approach is investigated that potentially addresses …
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Effect of grazing flow on structural-acoustic response of an elastic plate with sound in a duct
… response of thin panels subjected to sound waves are key elements of this design process. Due to the cost of in-flight testing, the experimental assessment of the structural-acoustic response of skin panels is usually conducted in ground-based facilities consisting of a duct in which …
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Laboratory measurements of the sound generated by breaking waves
… to be the dominant source of sea surface sound at frequencies greater than 500 Hz and the presence of breaking waves on the ocean surface has been shown to enhance the scattering of microwave radiation. Previous studies have shown that breaking waves can be detected by measuring the …