Anechoic cell for constituting anechoic surface covering of large immersed/submersible surface, has front diaphragm deformed by pressure of acoustic wave traversing water to drive viscous fluid via perforations of resistor plate

摘要

The cell has a front diaphragm (28) that is initially deformed by pressure of an acoustic wave (46) traversing the water (48), in a direction of a surface (2) to drive back a part of viscous fluids through circular perforations (36) of a resistor plate (34). The driving of the part of the fluids permits to absorb a large part of the kinetic energy by reducing produced high shearing constraints and by pushing a rear diaphragm (30). The front diaphragm is flat or offers a convex surface to the acoustic waves. The plate has a density of 1045 equidistant holes of 1 millimeter diameter in a surface of 13 square centimeter and uses viscous fluid such as silica oil of 2000 centistokes, so that characteristic acoustic impedance of the cell ranges between one time and 0.1 times that of the water.