Study on vibrating velocity in high-intensity standing wave field

The vibrating velocity in a high-intensity standing wave tube was measured by laser Doppier anemometry. The results show that the flow field is strongly modulated by intense acoustic field which makes the flow field vacillate with the sound wave synchronously. Moreover, the amplitude of vibrating velocity increases with increasing sound intensity. When sound intensity is not very high, the experimental results are consistent with the theoretical values. However, there is a distinct deviation between measured results and theoretical values when sound pressure level is higher than 160 dB, which indicates that the acoustically induced turbulence appears. When sound pressure level at the sound pressure loop reaches 164 dB, the rms turbulent velocity at the measuring position (sinkx = 0.67), 130 mm from the reflecting plate, is 3.50 m/s, which is about 45% of the amplitude of vibrating velocity at the location. It is indicated that the acoustically induced turbulence in a high-intensity standing wave field is drastic.