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Showing 1 to 20 of 22 for “"Rijke"”.
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A Thermoacoustic Characterization of a Rijke-type Tube Combustor
… phenomena related to thermoacoustics, a simple Rijke-type tube combustor was built and studied. Extensive experimental results, as well as theoretical analyses related to the Rijke tube are presented in this thesis. The results, attributable to both the analyses and the experiments, help explain …
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Linear Stability Analysis of a Rijke Tube and Modeling of Turbulent Combustion Using Dynamic Well-Stirred Reactors
… work, instability is correctly predicted for a Rijke tube with a new two-term acoustic forcing term derived from a one-dimensional flame dynamics model. The new two-term acoustic forcing term, which is comprised of the summation of chemical heat release rate and heat transfer due to convection, …
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Experimental Sensitivity Analysis and Control of Thermoacoustic Systems in the Linear Regime
… performed on (i) a vertical electrically-driven Rijke tube, and (ii) a vertical flame-driven Rijke tube. On the electrically-driven Rijke tube, the feedback sensitivity is studied by investigating the shift in linear growth and decay rates and oscillation frequency observed during periods of …
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Implementation of Adaptive Filter Algorithms for the Suppression of Thermoacoustic Instabilities
… The second was a flat flame, methane-air Rijke tube. The third can be considered a quasi-LDI liquid fuel combustor with a thermal output of approximately 30 kW. Actuation included the use of an acoustic actuator for the Rijke tube and a proportional throttling valve for the liquid fuel …
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Nonlinear Control of a Thermoacoustic System with Multiple Heat Sources and Actuators
… such as Nitrous Oxide (NOX).</p> <p>A Rijke tube, representing a resonator with a mean flow and a concentrated heat source, is a convenient system to study the thermoacoustic phenomena. Under certain conditions of the main system, a loud sound is generated through a process similar to …
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Methods for Analysis of Nonlinear Thermoacoustic Systems
… is examined in a simple model of a horizontal Rijke tube. A triggering mechanism is presented whereby the system transitions from a stable fixed point to a stable limit cycle, via an unstable limit cycle. The practical stability of the Rijke tube was investigated when the system is forced by …
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Sensitivity analysis and optimization in low order thermoacoustic models
… modes of five different configurations: a Rijke tube, a choked combustor, a longitudinal combustor, a generic lean premix prevaporized annular combustor and the laboratory scale annular combustor built in Cambridge University Engineering Department. The continuous and discrete adjoint …
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Computational Investigations of Boundary Condition Effects on Simulations of Thermoacoustic Instabilities
… Thermoacoustic instabilities in a self-excited Rijke tube are investigated following the relatively simple thermoacoustic convection problem. The complexity of simulating the Rijke tube increases in both dimensions and mechanisms which incorporate the species transport process and chemical …
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Adjoint-accelerated Bayesian inference in thermoacoustics
… thermoacoustic systems: an electrically heated Rijke tube, a ducted laminar conical flame, and a ducted turbulent conical flame. With the electrically heated Rijke tube, we demonstrate the full set of tools in the Bayesian framework. Using these tools, we create a thermoacoustic model that (i) …
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Shape Optimization of Annular Combustors with an Open Source Parallelized Thermoacoustic Helmholtz Solver
… instability, from the one-dimensional Rijke tube to the three-dimensional MICCA combustor. The implementation of Bloch-type boundary conditions is explained and tested. We use helmholtz-x to perform shape optimization of thermoacoustic systems. We first propose a surface parametrization …
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Development of Reduced-Order Flame Models for Prediction of Combustion Instability
… model was developed and identified for the Rijke tube experiment. Closed-loop thermoacoustic modeling using the first principles flame model coupled to the linear acoustics successfully reproduced the linear instability and predicted the thermoacoustic limit cycle amplitude. With the …
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Phase Shift Control: Application and Performance Limitations With Respect to Thermoacoustic Instabilities
… bandwidth bandpass filter, is developed for a Rijke tube combustor and shown to closely match the response of an LQG controller designed only for system stabilization. Both the optimal phase shifter and the LQG controller are developed based on a modified model of the thermoacoustic loop which …
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Probabilistic machine learning for the elimination of thermoacoustic instabilities
… First, we demonstrate on a laboratory-scale Rijke tube driven by a turbulent flame that it is possible to predict decay rates of acoustic pulses from the spectrum of 100 millisecond combustion noise samples, thus enabling us to monitor the combustor's thermoacoustic stability in real time. We …
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Feedback control of oscillations in combustion and cavity flows
… experimentally to combustion oscillations in a Rijke tube. Another type of fluid-acoustic resonance is then considered: the compressible flow past a shallow cavity. We start by finding a linear model of the cavity flow's dynamics, or its `transfer function', which we identify from direct …
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Adaptive Control Methods for Non-Linear Self-Excited Systems
… is shown to effectively stabilize an unstable Rijke tube combustor while preventing the creation of additional controller induced instabilities. The loopshaping design method is then used in conjunction with a trained artificial neural network to demonstrate stabilizing control in the presence …
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Characterization of leukemia - associated minor histocompatibility antigens as targets in anti-leukemic immunotherapy.
Contains fulltext : 30117_charoflea.pdf (Publisher’s version ) (Open Access)
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Physics-Based Statistical Learning in Thermoacoustics
… experiments on an electrically-heated vertical Rijke tube. We use the ensemble Kalman filter to infer the parameters of a conjugate heat transfer model driven by natural convection. Then we use the Markov Chain Monte Carlo (MCMC) method to infer the parameters of a linear acoustic model that is …
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Modelling and analysis of nonlinear thermoacoustic systems using frequency and time domain methods
… of the thermoacoustic equations in the Rijke tube, in which the acoustic response is not limited to a single-Galerkin mode, and is embedded in a state-space model. The weakly nonlinear analysis is strictly valid only close to the expansion point, but is much cheaper than any other …
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Shape optimization for thermoacoustic instability with an adjoint Helmholtz solver
… model and analysis to an electrically heated Rijke tube and a turbulent swirl combustor in 2D. Both systems exhibit an unstable longitudinal mode. We parametrize the shapes using B-splines, calculate the shape derivatives and apply the most stabilizing changes until we make the systems stable. …
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