The effect of waveguide open end modification on acoustic wave attenuation

The work presents experimental research on the possibility of attenuation acoustic wave radiation through the waveguide open end without flow, depending on its modification. One of the methods of noise protection is a modification consisting in changing the outlet impedance by applying a various types of acoustic systems. The work focused on determining the outlet impedance of a waveguide outlet with a modified geometry in the plane wave range using the transfer function method. A measurement setup was constructed on which measurements were performed analogously to those in an impedance tube. The measurement setup was verified based on the measurements of the reference sample as well as theoretical and numerical calculations. The results of experimental studies of parameters related to acoustic wave attenuation for different variants of open-end waveguide modifications are presented.