中文摘要：

基于能量守恒原理对Rijke管热声效应展开了理论分析,采用内外流场耦合法数值模拟了Rijke管自激励起振和饱和过程的声场特性,并开展了相应的实验研究。推导了Rijke管起振、饱和及高次谐波产生过程中的能量变化,分析了Rijke管非线性效应包括高次谐波和波形畸变的影响因素,提出了改变管口声阻抗可弱化非线性效应的方法。结果表明：在起振阶段热源位置对热声起振的模态有决定作用,传热过程的非线性效应使得管内一阶模态声波逐渐趋于饱和,当速度振幅大于平均流速时,流动反向激发高阶的声学模态,产生高次谐波。在大振幅非线性效应下,声波在管口由于大幅振动形成涡旋而引起声能的附加损耗,进而影响了管内声压波形,使得管内轴向声压分布产生畸变。缩小管末端截面面积改变管口的非线性声阻,可弱化波形的非线性畸变。

英文摘要：

Based on the energy conservation,nonlinear thermoacoustic effects of Rijke tube including excited regime, saturation and higher harmonics were analyzed.The simulation method of the modeling with external flow field,which could couple the inner of a Rijke tube with its outer space was carried out to obtain the acoustic characteristics about the process of self-excited oscillation.The experiment research was also performed to validate the simulation and model result.The nonlinear parameters which influence the acoustic waveform distortion were analyzed.Based on the results, the shrinkage of nozzle for changing the acoustic impedance was applied to reduce nonlinear effects experimentally.The results show that the self-excited mode could be influenced by the position of appearance of higher harmonics.The distortion of pressure wave of Rijke Tube was induced by the acoustic losses of vortices on nozzle for large amplitude oscillation.The method that the shrinkage of nozzle could reduce the waveform distortion was confirmed.