Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 12 of 12 for “"Acoustic damping"”.
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Flow induced acoustic resonances in heat exchangers.
This thesis describes an investigation into the acoustic phenomenon in in-line tubular heat exchangers subjected to cross flow. The flow through such a heat exchanger can result in the production of very high noise levels, which occur as a result of the excitation of an acoustic standing wave in …
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Damping acoustic pressure pulsations in pipelines using Helmholtz resonators
… and reciprocating turbomachinery generate acoustic pressure pulsations, which propagate into the pipeline and interact with piping components, potentially causing vibrations, increased fretting wear, and even fatigue failure. In this thesis, an acoustic damping device known as the Helmholtz …
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Exploring the Effect of Irradiation Time on the Damping of Surface Acoustic Waves
… qualities of the signal. In particular, the acoustic damping parameter is scrutinized in relation to the irradiation time of the samples from Byron Nuclear Generating Station. The trend was found to be similar to that of other material properties when compared with irradiation time, denoting …
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Velocity profile in confined elliptic fractures
… to show the frictional effects on acoustic damping. However for flow inside a hydraulic fracture, the 3D velocity profile is highly non-uniform, and the use of Vav creates an error as Vmax >> Vav. The variation in hydraulic diameter associated with an elliptic cross-section of a …
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Damping Parameter Study of a Perforated Plate with Bias Flow
… is the dynamic instability also known as thermo-acoustic instability. Concerns with this ongoing problem have grown with the introduction of Lean Premixed Combustion (LPC) systems developed to address the environmental concerns associated with the conventional combustion systems.</p><p>The most …
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Computational analysis of thermo-acoustic instabilities in combustion chambers and afterburners
A simplified model is introduced to study thermo-acoustic instabilities in asymmetric combustion chambers. Such instabilities can be triggered when correlations between heat-release and pressure oscillations exist, leading to undesirable effects. Gas turbine designs typically consist of a periodic …
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The study of acoustic properties of P205-doped silica fiber
… to numerous fields. The interactions between acoustic phonons and the optical wave are involved in several of these applications. A significant stimulated scattering mechanism observed is stimulated Brillouin scattering (SBS), resulting in strong backward scattering typically within the …
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Acoustic resonators with integrated microfluidic channels for ultra-high Q-factor: a new paradigm for in-liquid gravimetric detection
… Among the various types of biosensors, acoustic biosensors are attractive for their simplicity, robustness, and low cost, particularly in point-of-care (POC) applications. However, the quality factor (Q-factor) of acoustic biosensors is often low, limiting their sensitivity and accuracy …
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The influence of structural-acoustic coupling on the dynamic behaviour of a one-dimensional vibro-acoustic system
… of this thesis is to investigate the structural-acoustic coupling effects on the dynamic behaviour of a vibro-acoustic system under passive/active control. The simplest model of a vibro-acoustic system one can consider is a one-dimensional acoustic cavity driven by a single-degree-of-freedom …
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Investigating Acoustic Properties of Biocomposite from Waste Streams
… curves and polynomials to represent the acoustic absorption coefficients frequency profiles for the studied biocomposites was completed. Also, for each sample set, an approximation to the noise reduction coefficient (NRC) was calculated by averaging the absorption coefficient values from …
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Effect of grazing flow on structural-acoustic response of an elastic plate with sound in a duct
… accurate prediction of the coupled structural-acoustic 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 …
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Parametric investigation of flow-sound interaction mechanism of circular cylinders in cross-flow
Flow-excited acoustic resonance in heat exchangers has been an ongoing issue for the past century. The main challenge in this issue, is in the actual prediction of the resonance occurrence. This is due to the complexity of the flow-sound interaction mechanism that takes place between the packed …