Thermoacoustic Theory Essay

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midpoint and maximum at both ends. There is also a velocity jump right at the heater, which is due to the local coupling between velocity and the heat released at the source. These results are consistent with the thermoacoustic theory. Conditions at the two sides of heat source: According to the diagram of temperature distribution along the tube, at the first T 5 1 time step, the temperature remains constant up until the heater, and there is a temperature jump at the heater. Then, temperature is reduced exponentially after the heater. Effect of heat source location: Figures 16~19 show the variations in pressure, density, velocity and heat transfer from the source to the air at a point after the source after the start of disturbances until regular…show more content…
According to previous studies, thermoacoustic instabilities are apparently a result of the presence of unstable heat release components of Q   when it in phase with pressure disturbances p . In this case, based on the Rayleigh criteria, there is a positive energy conversion from heat to sound. The general Rijke tube model was first studied analytically, and various mathematical models such as simplified, linear, and numerical (CFD) were explained. Fluent and finite volumes method were then used to solve the conservation equation of mass, Navier-Stokes and energy, and equation of state of perfect gas in steady and unsteady states. Finally, for validation, Fluent’s output diagrams were compared against general behavior of thermoacoustic oscillations in Rijke tube. Diagrams of variations in pressure, density, velocity and heat transfer from the source to the air at a point are drawn after the source from the start of disturbances until regular fluctuations for a number of heater positions. Heater position is a key factor in the generation of fluctuations inside the Rijke tube. When the heater is located at

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