水与流体饱和孔隙介质界面上非镜面反射声场的实验研究

用光学法和发射-接收法研究了水与流体饱和孔隙介质界面上声波的非镜面反射声场．测量了入射角θi为16°－80°范围内的反射系数R，记录了θi在Rayleigh波临界角θc附近±4°范围内两束反射波的反射角、波束位移△、波形和频谱．实验发现：(1)在θc附近±4°范围内，观察到θi两束反射波A和B，其中波束B沿界面有波束位移△，实验测出△随θi增大而减小，并非在θi=θc时最大．(2)反射角等于θi的波束的频谱很接近于入射波的频谱，反射角等于θc的波束的频谱相对于入射波有频谱的负偏移．(3)波束A的相位与发射换能器直达波的相位一致，波束B的相位与波束A相反

EXPERIMENTAL STUDY OF NON-SPECULAR REFLECTED ACOUSTIC FIELD ON A WATER-FSPM INTERFACE

In this paper,the non specular acoustic reflected field on a Water FSPM (fluid saturated porous media interface by the optical method and the transmitter receiver method. The reflection coefficient R was measured for incident angle of 16°～80°. The reflection angles of two beams, their beam displacements, wave forms and spectra were recorded in the range of the incident angle ±4° near the Rayleigh critical angle θ c. The experiment was found （1） that for the range θ i of ±4° near θ i two reflected beams A and B were observed. The measured displacement Δ of the beam B decreases as the incident angle θ i increases and is not a maximum at θ c= θ i, （2） that spectrum of the beam with the reflection angle equal to θ i is much closed to that of the incident beam, and the spectrum of the other beam with the reflected angle equal to θ c has a negative shift to that of the incident beam, （3） that the phase of beam A is the same as that of directly received from transmitter, and the phase of the beam B is inverse to that of beam A .