双声源法主动调制回热器热声效应的机理研究

The hydraulic radius and the acoustic ?eld of a regenerator are the key factors on the thermoacoustic effects. Systemic theoretically and experimentally mechanism studies on this effects under different acoustic fields of regenerator are still lack of. In this proposal, based on the former investigations and thermodynamics theory, taking weak nonlinear effects such as acoustic loss of loudspeaker, cone and nonlinear temperature gradient into account, theoretical model on thermoacoustic effect in a regenerator is developped and set up. Under different acoustic fields, the relations among the driving parameters, configurations of regenerator, the acoustic parameters,temperature gradients and energy flux are determined. The experimental system on a regenerator driving by double loudspeakers method is designed and built up. The dynamic simulation platform is realized. Experimental studies on thermoacoustic effects and entropy generations of regenerator are carried on under different driving voltages, resonant frequencies, phase differences of double loudspeakers and temperature gradients. The ranges of optimal traveling-wave zone and relatively high efficiency zone are acquired. In the microscopic scale,velocity and temperature fields in the channel of regenerator are measured by the combinations of the Patical Image Velocimetry and non-contacting infrared thermometer. The model to actively modulate the acoustic and thermal fields of regenerator is verified and revised based on the experimental results. The investigations are helpful to acquire higher thermoacoustic efficiency of thermoacoustic system.

回热器水力半径和所处声场是影响热声转换效应的两个关键因素，目前尚缺乏系统的理论和实验方法研究可调声场条件下回热器的声场和热场耦合的机理。本申请项目在前期研究基础，从热动力学波动理论出发，考虑声源损失、变径管和非线性温度梯度等弱非线性效应，发展并建立回热器声场和热场耦合的理论模型。揭示声源参数与回热器结构参数、声场（压力、速度和压流相位差）、温度场和能流之间的内在联系。设计并建立双声源法可调声场回热器的实验系统，实现动态实验仿真平台。实验研究不同驱动电压、谐振频率、声源相差和温度梯度下回热器的热声放大机理、熵产。得到回热器的最佳行波区和高效热声转换区。采用粒子成像测速仪和非接触式红外热像仪，获得介观尺度上回热器通道内的速度场和温度场的变化规律。验证并修正回热器热声效应的理论模型。该研究对热声热机获得高效的热声转化效率具有重要实用意义。

回热器水力半径和所处声场是影响热声转换效应的两个关键因素，目前尚缺乏系统的理论和实验方法研究可调声场条件下回热器的声场和热场耦合的机理。本项目考虑声源损失、变径管和非线性温度梯度等弱非线性效应，系统建立和分析了双声源法主动调制回热器热声效应的理论模型，包括多孔型回热器热声转换模型、有限空间辐射声源电声转换模型以及双声源法主动调制系统模型。理论分析了各参数间内在联系分析，包括不同声场条件下，声源参数与回热器结构参数、声场参数（压力、速度和压流相位差）、温度场和能流之间的内在联系。开发完成了可实现宽范围的频率、振幅和相位的自动扫描，宏观声场重构，压力和速度的同步触发测量，动态数据采集存储等多功能的动态实验仿真平台。系统分析了宏观声场重构的测量精度问题，从硬件和软件层面解决压力和速度同步测量问题。设计并搭建完成双声源法主动调制回热器热声效应的实验系统。实验得到了不同声场条件下，回热器结构参数和温度场对声场参数的影响以及回热器进出口交变流动损失。实验观察了粒子成像测速仪(PIV)测量可视化回热器通道内介观尺度上的速度和板叠末端漩涡测量，系统分析了不同声场条件下回热器在声场和热场的耦合特性，从而进一步丰富了回热器热声效应的理论模型。本项目研究结果对热声热机获得高效的热声转化效率具有实用意义。