【作者】 肖勇；

【导师】 邱利民；

【作者基本信息】 浙江大学 ， 制冷及低温工程， 2007， 硕士

【摘要】 热声发动机是利用热声效应，将热能转化为声能进而实现声功输出的声波发生器。热声发动机以其潜在高效率、结构简单、运行可靠和工质环境友好等优点引起了广泛关注。本文首先介绍了热声发动机的发展历程和研究现状，概述了热声理论，并重点对声压放大器和双路声功输出特性进行了深入研究。声压放大器是一种可显著提高热声发动机输出压力振幅和压比的装置，然而它的主要问题是声功损失过大。本文提出采用较大管径的改进型声压放大器进一步提高其性能的方法。改进的单级声压放大器在大幅度提升输出压比的同时，没有明显降低发动机内的压比和破坏发动机内部声场，能使发动机工作在较高的品质状态。采用变负载法测量声功的实验结果也表明，改进型的单级声压放大器有效地解决了声功损失过大的问题。在此基础上，本文提出了两级声压放大器的概念。实验中以氮气为工质、工作压力为2.2MPa时，两级声压放大器将压比从1.177放大到1.619，这是目前国内外公开报道的最大压比。采用变负载法的研究表明：只有保证负载的阻抗和两级声压放大器的良好匹配，才能充分发挥两级声压放大器驱动负载的良好性能。为进一步提高热声发动机的声功输出能力，实现能量的梯级利用，本文对本课题组提出的双路声功输出方案进行了实验研究。以氮气为工质，工作压力为2.4MPa，在热声发动机环路压比稳定在1.20的情况下，从环路声容和谐振管处同时引出声功，获得了364.25W的最大声功，11.2％的最大声功输出效率以及16.02％的最大声功输出(火用)效率，这比单独从环路引出时分别提高了52.2％，33.3％和22.57％。以He为工质，工作压力为2.2MPa，在热声发动机系统加热温度稳定在660℃的情况下，双路同时引出声功的效率最大为11.14％，这比单独从环路引出的最大效率提高了38.56％。更多还原

【Abstract】 A thermoacoustic engine(TE) converts thermal energy into acoustic power by thermoacoustic effect. Wide attention has been focused on thermoacoustic engine for its potentially high efficiency, simple configuration, reliability and environmentally friendly working gas.The history and development of TE are reviewed, followed by a brief introduction of thermoaoustic theory. Further study is made about the acoustic amplifier and the output characteristic of TE with double loads.Acoustic amplifier is a simple device which can significantly improve output pressure amplitude and pressure ratio of TE. However, the main problem of acoustic amplifier is the large acoustic power loss. Based on theoretical study, we propose a modified acoustic amplifier with larger diameter capable of further improving the performance of TE. It is shown that the modified amplifier can increase the output pressure ratio, and not significantly decrease the pressure ratio in the engine. Based on the acoustic power measurement with variable-load method, the experiments verified that the modified acoustic amplifier can decrease acoustic power loss effectively. The concept of two-stage acoustic amplifier is also proposed. In experiments, a two-stage acoustic amplifier amplifies the pressure ratio from 1.177 to 1.619 with nitrogen of 2.20 MPa as working gas, which is the highest pressure ratio obtained to date. The performance of two-stage acoustic amplifier depends on good match between the load impedance and the two-stage acoustic amplifier.In order to further improve the performance of acoustic power output and make full use of acoustic energy of TE, experiment study on double-output method is made. With working pressure and maximum pressure ratio in the torus of 2.4MPa and 1.20 respectively, investigation on acoustic power output from the torus and resonator simultaneously is carried out when nitrogen gas is used. The maximum output power, thermal efficiency and exergy efficiency reach 364.25W, 11.2% and 16.02%, which increase by 52.2%, 33.3% and 22.57% respectively than those using only one R-C load in the torus. With helium of 2.2MPa as working gas and heating temperature of 660℃, the maximum thermal efficiency reaches 11.14% with double-output method, which increases by 38.56% than that with single-output method.更多还原