驻波热声系统的振荡机理和热力学优化

发布时间：2018-02-19 17:32

本文关键词： 热声热机自激振荡网络稳定性混沌辛热力学循环优化　出处：《武汉工程大学》2014年硕士论文　论文类型：学位论文

【摘要】：热声热机是能实现热能与声能相互转换的一种新型能量装置，热能转化为声能是热声发动机，声能驱动热能泵送是热声制冷机，热声发动机与热声制冷机的耦合成为完全无运动部件的制冷机，因此研究热声发动机的热功转换机理具有重要意义。热声发动机从初始状态到正常运行的过程是起振过程，也是一个建立自激振荡的过程，对热声自激振荡机理的研究有助于进一步了解热声转换实质。本文在全面了解和总结热声理论的基础上，分别从网络理论、动力学和热力学几个角度分析了驻波热声发动机的自激振荡机理，在实验的基础上分析了充气压力对维持自激振荡的阀值温度的影响。本文的工作主要由以下几个部分组成：根据热声分布参数网络模型，推导了各热声组件的网络导纳矩阵，建立了各热声组件的网络拓扑结构以及整机的网络拓扑。将整机网络比拟成电网络，利用哈密特式计算了输入整机网络的功流，网络功流平衡对应自激振荡，根据这一判据利用闭环网络拆环原理将整机网络拆成二端口开环网络，在角频率虚部为零的情况下计算了驻波热声发动机的阀值温度和工作频率，计算值与实验值吻合良好。从动力学的角度考查了热声自激振荡系统的稳定性。根据热声系统的基本方程组推导了一阶波动量下的热声自激振荡系统的时域自治方程组，计算了热声发动机在建立自激振荡过程中的定态点，，利用Lyapunov稳定性理论考查了定态的稳定性，利用混沌动力学的相关概念描述了建立自激振荡的过程中热声系统的稳定性随时间演变的动态行为。降低热声发动机系统的能量损耗有利于降低维持自激振荡的阀值温度，提高对低品位能量的利用能力。对各热声组件的分布参数网络传输矩阵进行了辛对称分析，在网络传输矩阵辛对称的基础上，利用瑞利商式计算了各热声组件的最小本征阻抗，最小本征阻抗对应最小网络损耗，即最小能量损耗，给出了在热声系统的优化设计中降低能量损耗能达到的最低限度，并考查了运行工况对最小网络损耗的影响。从热力学的角度考查了热声自激振荡在热力学空间中的体现。热力学循环是一种自激振荡，根据流相工质的振荡特性，建立了不可逆驻波热声发动机微热力学循环以及不可逆驻波热声制冷机微热力学循环的理论模型，该模型在p-V相图上是一个椭圆，推导了循环声功率和热效率以及循环制冷率和制冷系数，并利用有限时间热力学的方法以热力学第一性能、热力学第二定律性能、生态学性能为优化目标考查了不可逆热声发动机微热力学循环以及不可逆热声制冷机微热力学循环的性能。最后，在实验室现有实验装置的基础上进行了实验，观察了驻波热声发动机建立自激振荡的过程，考查了充气压力对阀值温度的影响，并与计算值进行了对比。
[Abstract]:Thermoacoustic heat engine is a new type of energy device which can realize the conversion between heat energy and sound energy. The conversion of heat energy to sound energy is a thermoacoustic engine, and sound energy driving heat pump is a thermoacoustic refrigerator. The coupling of thermoacoustic engine and thermoacoustic refrigerator becomes a completely motionless refrigerator, so it is of great significance to study the thermo-power conversion mechanism of thermoacoustic engine. The process of thermoacoustic engine from initial state to normal operation is the process of starting vibration. It is also a process of establishing self-excited oscillation. The study of the mechanism of thermoacoustic self-excited oscillation is helpful to further understand the essence of thermoacoustic conversion. The self-excited oscillation mechanism of standing wave thermoacoustic engine is analyzed from several angles of dynamics and thermodynamics, and the effect of inflatable pressure on the threshold temperature for maintaining self-excited oscillation is analyzed on the basis of experiments. The work of this paper consists of the following parts:. According to the network model of thermoacoustic distribution parameters, the network admittance matrix of each thermoacoustic component is derived, the network topology of each thermoacoustic component and the network topology of the whole machine are established. The power flow of the input whole machine network is calculated by using the Hamilton formula, and the power flow balance of the network corresponds to the self-excited oscillation. According to this criterion, the whole machine network is divided into a two-port open-loop network by using the closed-loop network detaching principle. The threshold temperature and operating frequency of the standing wave thermoacoustic engine are calculated when the imaginary part of the angular frequency is zero, and the calculated values are in good agreement with the experimental values. The stability of thermoacoustic self-excited oscillation system is investigated from the point of view of dynamics. According to the basic equations of thermoacoustic system, the time-domain autonomous equations of thermoacoustic self-excited oscillation system under first-order fluctuation are derived. The steady-state points of thermoacoustic engine in the process of self-excited oscillation are calculated, and the stability of steady state is investigated by using Lyapunov stability theory. The dynamic behavior of the stability of thermoacoustic system during the process of establishing self-excited oscillation is described by using the related concepts of chaotic dynamics. Reducing the energy loss of thermoacoustic engine system is beneficial to reduce the threshold temperature of maintaining self-excited oscillation and improve the utilization ability of low-grade energy. The symplectic symmetry analysis of the distribution parameter network transmission matrix of each thermoacoustic module is carried out. On the basis of symplectic symmetry of network transmission matrix, the minimum eigenimpedance of each thermoacoustic module is calculated by Rayleigh quotient, and the minimum eigenimpedance corresponds to the minimum network loss, that is, the minimum energy loss. The minimum energy loss can be reduced in the optimal design of thermoacoustic system, and the influence of operation condition on the minimum network loss is investigated. The thermoacoustic self-excited oscillation in thermodynamic space is investigated from the point of view of thermodynamics. The thermodynamic cycle is a kind of self-excited oscillation. The theoretical models of the microthermodynamic cycle of an irreversible standing wave thermoacoustic engine and the microthermodynamic cycle of an irreversible standing wave thermoacoustic refrigerator are established. The model is an ellipse on the p-V phase diagram. The cyclic sound power and thermal efficiency, the cycle refrigeration rate and the refrigeration coefficient are derived. The first performance of thermodynamics and the second law of thermodynamics are obtained by using the method of finite time thermodynamics. The performance of microthermodynamics cycle of irreversible thermoacoustic engine and microthermodynamics cycle of irreversible thermoacoustic refrigerator were investigated for the optimization of ecological performance. Finally, on the basis of the existing experimental equipment in the laboratory, the process of establishing self-excited oscillation of standing wave thermoacoustic engine is observed, and the effect of inflatable pressure on the threshold temperature is examined and compared with the calculated value.
【学位授予单位】：武汉工程大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TK05;TK123;TB651

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