突变截面驻波管和极高纯净驻波场的实验研究

突变截面驻波管属于失谐驻波管,即其高阶共振频率不是一阶共振频率的整数倍。通过对STAS的优化设计,利用STAS的失谐性质在一阶和二阶共振频率下激励分别获得了180 dB和177 dB的极高纯净驻波声场。尽管声压级已经很高,但在接下来的对一阶和二阶共振频率激励下的声波波形畸变和谐波饱和情况进行的实验研究中仍然没有观察到谐波饱和现象。与此同时,对三阶共振频率激励下的声场进行了实验研究,由于三阶共振频率激励下的大振幅非线性声场的二次谐波频率接近六阶共振频率,在声压级达到170 dB时观测到了三阶共振频率激励下的声波波形畸变和谐波饱和现象。

Experimental investigation on the standing-wave tube with abrupt section and the extremely nonlinear pure standing wave field

Standing-wave tube with abrupt section (STAS) is a dissonant standing-wave tube whose higher resonance frequencies are not the integral multiplies of the first one. Through the optimization and the dissonant property of STAS,the 180 dB extremely nonlinear pure standing wave field is obtained at the first resonance frequency and 177 dB at the second resonance frequency. At the two resonance frequencies, the distortion of waveform and the saturation of harmonics are studied experimentally,and yet the saturations are not found even though the pressures are so high. Meanwhile,the nonlinear sound field is experimentally studied at the third resonance frequency, and the distortion of waveform and the saturation of harmonics are observed as the pressure approaches 170 dB because the frequency of the second harmonic at the third resonance frequency is close to the sixth resonance frequency of the STAS.