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 20 of 89 for “"Thermoacoustic"”.
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Investigation of thermoacoustic muffler
The design, construction and testing of a thermoacoustic muffler is discussed. The performance of the muffler is characterized by its ability to reduce the quality factor Q of an acoustic resonator. Measurement of the Q of a helium filler muffler were made for temperature differences ranging from 0 …
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Active Stabilization of Thermoacoustic Oscillation
… addresses the problem of actively controlling thermoacoustic instabilities in a laboratory test com- bustion chamber. Different strategies for actuation are discussed and evaluated experimentally. Relations to industrial relevance are taken into consideration, and a fuel actuator is developed …
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Dual-modality thermoacoustic and photoacoustic imaging
… the key to survival. The combined contrasts from thermoacoustic and photoacoustic tomography: TAT and PAT) can potentially predict early stage breast cancer. We have designed and engineered a breast imaging system integrating both thermoacoustic and photoacoustic imaging techniques to achieve …
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Thermoacoustic Oscillations in Supercritical Fluid Flows
Pressure oscillations in supercritical Jet-A fuel flowing through four parallel, heated tubes connected to common manifolds have been observed in this study. Tests were performed with fuel inlet temperatures ranging from 70F to 700F, and fuel pressures ranging from 360-700 psi. Total fuel flow rate …
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Prototype Design for Thermoacoustic Flashover Detector
The thermoacoustic flashover detector integrates the phenomenon of thermoacoustics into a fire fighting application. This report presents the prototype design for the thermoacoustic flashover detector to ultimately be implemented in a firefighter's gear. Upon increases in compartment fire heat flux …
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Methods for Analysis of Nonlinear Thermoacoustic Systems
This thesis examines the nonlinear behaviour of thermoacoustic systems by using approaches from the field of nonlinear dynamics. The underlying behaviour of a nonlinear system is determined by two things: first, by the type and form of the attractors in phase space, and second, by the mechanism …
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Numerical modelling of thermoacoustic engines and coolers
Thermoacoustic systems offer a promising alternative for sustainable energy conversion, leveraging the interaction between temperature gradients and acoustic waves to facilitate both power generation and cooling applications. These devices operate without moving parts, enhancing reliability and …
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Modeling and Control of Gas Turbine Thermoacoustic Pulsations
Diese Arbeit befasst sich mit der Analyse thermoakustischer Instabilitäten in Gasturbinen-Brennkammern. Passive Methoden wurden entwickelt, um die durch die Instabilitäten entstehenden Druckschwankungen zu unterdrücken. Zunächst wurden unter der Annahme kleiner Mach-Zahlen die thermoakustischen …
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Investigation of edge effects in thermoacoustic couple measurements
Previous measurements of thermoacoustic heat transport across stacks of short plates, called thermoacoustic couples or TACs, revealed serious discrepancies between theory and experiment. The discrepancies are worst at higher drive ratios (the ratio of the peak acoustic pressure amplitude at a …
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Theoretical and experimental analysis of the thermoacoustic refrigeration
The thermoacoustic theory is studied in detail and its application to refrigeration is analyzed. This new refrigerator which uses resonant high amplitude sound in inert gases to pump heat will be described. It will be seen that without any moving parts, except the driver (speaker diaphragm), this …
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Thermoacoustic Imaging and Spectroscopy for Enhanced Cancer Diagnostics
… detection utilizing light and microwave induced thermoacoustic imaging. In the second chapter, the well-established pre-clinical mouse window chamber model is interfaced with simultaneously acquired high-resolution pulse echo (PE) ultrasound and photoacoustic (PA) imaging. Co-registered PE and PA …
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Linearly-acting variable-reluctance generator for thermoacoustic applications
… solution lies in portable, high-frequency thermoacoustic engines, which can provide a battery recharge station or direct power supply for soldiers in-field, with the flexibility of operating on any quality heat source such as a butane heater. In this work, a linearly-acting …
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A study of a class of thermoacoustic oscillations
Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering, 1954.
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Identification of Thermoacoustic Dynamics Exhibiting Limit Cycle Behavior
Identification of thermoacoustic dynamics that exhibit limit cycle behavior is needed to gain a better intuitive feel of the system, to design complex control strategies, and to validate modeling efforts. Limit cycle oscillations arise in thermoacoustic systems due to the coupling between a …
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Sensitivity analysis and optimization in low order thermoacoustic models
… of NOx but increase the susceptibility to thermoacoustic oscillations. These oscillations can produce structural damage and need to be eliminated. The stability of a given configuration can be examined with a thermoacoustic model. In this thesis a wave-based network model is used. Using …
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Probabilistic machine learning for the elimination of thermoacoustic instabilities
Thermoacoustic instabilities have hindered the development of high energy density combustors, such as those in jet engines, gas turbines or rockets, for decades. They are notoriously difficult to model and despite efforts to eliminate them, can show up unexpectedly. The current thesis demonstrates …
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Nonlinear thermoacoustic oscillations of a ducted laminar premixed flame
… is one of the central problems of nonlinear thermoacoustics. However, a limit cycle is not the only type of self-excited oscillation in a nonlinear system. Nonlinear systems can have quasi-periodic and chaotic oscillations. This thesis examines the different types of oscillation in a …
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Physics-based flame dynamics modeling and thermoacoustic instability mitigation
… unsteady heat release mechanisms responsible for thermoacoustic instabilities under different flame anchoring configurations, (ii) to develop reduced-order models to predict the dynamic flame response, and (iii) to develop passive instability mitigation strategies by modifying the dynamics of the …
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