用于分布式光纤声传感的薄壁圆筒声增敏实验研究

Experimental Study on Acoustic Sensitization of Thin-Walled Cylinder for Distributed Optical Fiber Acoustic Sensing

研究了基于光纤缠绕薄壁圆筒的声增敏方法,基于3×3耦合器建立了声压灵敏度标定实验系统,实验探讨了薄壁圆筒的方向特性,实验研究了半径、壁厚尺寸参数对光纤声增敏的影响,实现的声压灵敏度达到1.338 rad/Pa(−117.47 dB re rad/μPa)。光纤缠绕薄壁圆筒接入所搭建的准分布式声传感系统进行实验,在20.06 km传感距离上,恢复的1 kHz正弦波形与施加波形误差不超过4.1%,比未增敏光纤环传感信噪比提高了21.03 dB,显示了薄壁圆筒声增敏的传感效果。该研究结果为高灵敏度的准分布式声传感的进一步发展提供了实验基础。

An acoustic sensitization method based on a fiber-wrapped thin-walled cylinder is studied.The sound pressure sensitivity calibration experiment system is established based on a 3×3 coupler.The directional characteristics of a thinwalled cylinder are experimentally investigated.The influence of the cylinder radius and wall thickness on the acoustic sensitization of fiber is studied experimentally,and the sound pressure sensitivity reaches 1.338 rad/Pa(−117.47 dB re rad/Pa).Then,the fiber-wrapped thin-walled cylinder is applied to a quasi-distributed acoustic sensing system for testing.For a 20.06-km sensing distance,the error between the 1-kHz sinusoidal applied waveform and experimental recovered waveform is below 4.1%.The signal-to-noise ratio(SNR)is 21.03 dB higher than that of unsensitized fiber coil sensing,showing the effect of the acoustic sensitization sensing of the thin-walled cylinder.The results provide an experimental basis for further developing high-sensitivity quasi-distributed acoustic sensing.