Ultrahigh‐Energy Sound Waves Promise New Technologies
Ultrahigh‐Energy Sound Waves Promise New Technologies
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DOI：
10.1063/1.882138
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发表时间：
1998-02
期刊：
影响因子：
3.5
通讯作者：
R. Ladbury
中科院分区：
文献类型：
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作者：
R. Ladbury
也许因为我们不断地受到声音的轰击，所以很容易忘记声波实际上代表着相当小的压力变化。几米外喷气发动机的声音测量值仅为约 20 Pa（约 0.0002 个大气压）。随着进入声波的能量增加，波在其中传播的气体中的非线性过程将越来越多的能量引导到驱动频率的谐波中。谐波使声波失真并最终形成冲击波。正是这些冲击限制了可达到的幅度。声波的低能量水平和压缩比（定义为波形峰值压力和最小压力之比）限制了它们在压缩机和泵等高功率应用中的用途。因此，许多研究人员想知道在某些特殊情况下是否可以避免激波形成所造成的声饱和。
Perhaps because we are constantly bombarded by sound, it is easy to forget that sound waves actually represent quite small pressure variations. The sound of a jet engine a few meters away measures only about 20 Pa (about 0.0002 atmospheres). As one increases the energy going into a sound wave, nonlinear processes in the gas in which the wave propagates direct more and more energy into harmonics of the drive frequency. The harmonics distort the sound wave and ultimately form shock waves. It is these shocks that limit the amplitudes attainable. Soundwaves’ low energy levels and compression ratios (defined as the ratio of the waveform's peak and minimum pressures) have limited their usefulness in high‐power applications such as compressors and pumps. Accordingly, many researchers have wondered whether the acoustic saturation imposed by shock formation can be circumvented in some special circumstances.