Translated Abstract
The thermoacoustic engine owns advantages of environmental friendliness, extremely high reliability and effective utilization of waste heat, and in the meantime exists the potential of achieving high efficiency. In recent years, energy situation and environmental problem are becoming serious, so more and more attention from worldwide is paid to thermoacoustic technology, which has been research hotspot around the world. Concentrating on this hotspot, focused on the stack structure and based on the research about the performance of paralleled standing-wave thermoacoustic engine, this study has proposed the non-paralleled stack according to the principle that the spacing between plates is consistent with temperature variation along the axial direction. To suppress the nonlinear Gedeon stream, the Stirling thermoacoustic engine with phase adjuster(PA) has been developed, which can provide theoretical foundation of structural improvement to achieve high efficiency.In this thesis, carried out researches are as follows: 1. The model of standing-wave is developed, and the effects of structure parameters of the resonant cavity and stack on system’s frequency and performance are researched respectively. The results show that the system frequency will drop off with the increase of the length, diameter and cubage of the resonant cavity. Moreover, the influence of the resonant cavity’s diameter is greater than that of length. For the influence of structure parameters of the stack on system, focused research on the influence of plate space, thickness and stack porosity on system performance is carried out. On the basis of oscillation starting, the characteristic of oscillation damping is also studied and the existance of hysteresis loop is verified numerically.2. The non-paralleled standing-wave thermoacoustic engine is proposed and simulated. The effects of taper type stack’s taper angle on oscillation starting character, pressure ratio and sound power are researched when the number of plates is less. Results show that the best taper angle will exist to make the system performance optimal. What’s more, compared with paralleled and taper type thermoacoustic engine, we find that it’s easier for taper type system to start oscillation and its performance is better.3. To make a comparation of influence mechanism of non-paralleled stack on thermoacoustic system performance, the stacks with more plates, including taper type, divergent type and paralleled type have been developed. Results show that the increase of plate number can improve the performance of thermoacoustic engine greatly, especially for divergent and paralleled type stacks. What’s more, performance of divergent type stack improves more remarkably and is even better than that of taper type.4. Systematical study focusing on phase adjuster (PA) in Stirling thermoacoustic engine has been carried out, and the effects of PA’s diameter and position on system performance, including pressure amplitude, volume flow rate, phase difference and sound power have been obtained. Above all, the existence of Gedeon stream and influence of PA on it are verified numerically. Results show that except Gedeon stream, performance parameters such as the pressure ratio, sound power and so on can reach the best when the distance between PA and regenerator is less than 0.43m, and the diameter of PA is about 50~60mm. To make the Gedeon stream least, the distance between PA and regenerator should be larger than 0.62m, and the diameter of PA is about 20mm. Therefore, when we determine the position and diameter of PA, all factors should be taken into consideration.KEY WORDS: Thermoacoustic engine Numerical simulation Non-paralleled stack Phase adjuster Self-excited oscillationTYPE OF THESIS: Applied Fundamentals
Translated Keyword
[thermoacoustic engine numerical simulation non-paralleled stack phase adjuster self-excited oscillation]
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