A Method for Enhancing the Acoustic Scattering Characteristics of Underwater Acoustic Corner Reflectors in Vacuum Cavities

To alleviate the problem of unsatisfactory target strength and scattering stability of an underwater corner reflector, a method to enhance the acoustic scattering characteristics using a vacuum cavity as an acoustic reflecting layer is proposed. According to the principle of acoustic impedance mismatch of a water-reflecting layer, a vacuum cavity corner reflector is designed to take advantage of the property that sound waves cannot propagate under vacuum conditions. The acoustic vacuum reflecting layer has a theoretical acoustic reflecting coefficient of one. Comparative analyses are carried out with the single-layer metal corner reflector in terms of frequency and angle of incidence. For the concave structure of the underwater corner reflector, the structural finite element software ANSYS combined with the acoustic analysis software SYSNOISE is used to simulate and analyse the acoustic scattering characteristics, and the consistency of the simulation calculations and experimental data is verified through the pool experiments for typical cases. The results show that under the same reflection area, the vacuum cavity underwater corner reflector has large scattering intensity, good antiacoustic performance, no obvious frequency characteristics, and good decoupling effects. The target echo intensity value can be increased by 2 dB for better scattering stability. The overall weight is reduced by about 20 kg, with considerable engineering practicality, proving that the true cavity corner reflector is an ideal underwater acoustic counter-acoustic device.