定加热温度下热声发动机声功输出特性研究

Acoustical power output characteristics of traveling-wave thermoacoustic engines operating with fixed heating temperature

对定加热温度下行波热声发动机驱动阻容负载进行了数值模拟,分析讨论了声阻和容抗对声功输出的影响。以氦气为工质,在充气压力为3 MPa、加热温度为923 K的条件下,对不同气库体积的热声系统进行了模拟;此外,还采用负体积气库模拟了阻抗虚部为正值的情况。计算结果表明,容抗值较大时,在负载相位角约为-45°(或45°)时,声功率存在一个极大值;当容抗值较小时,声功率会出现两个极大值和一个极小值,且在负载阻抗相位角约为-45°(或45°)时为极小值;此外,声功输出最大值与效率最大值对应的阻抗并不相同。

Numerical simulation of RC-type （resistance and capacitance） acoustical load driven by a traveling-wave thermoacoustic engine with fixed heating temperature was carried out. The influence of acous- tic resistance and acoustic capacitance impedance on the net acoustical power output was analyzied. The simulation of the thermoacoustic system for different capacitance volume was carried out under fixed heating temperature of 923 K, a mean pressure of 3 MPa. Furthermore, negative capacitance volume was used to simulate the acoustical impedance with positive imaginary parL The computation result shows that the net a- coustical power output can reach maximum at the phase angle of -45° or 45°. There are two maximum val- ues of acoustical power output when the acoustical capacitance is small enough, with the minimum values of acoustic power at the phase angle of -45° or 45°. In addition, the optimum acoustic impedance for maxi- mum output acoustical power is not the same as the value for maximum thermal efficiency.