Investigation On Radiated Impedance Characteristics Of Sound Sources In Enclosed Space

The radiated impedance of sound source is an important factor affecting the radiated sound power.Studying the radiated impedance characteristics of the sound source in a closed space is practical for measuring the low-frequency radiated sound power of underwater sound sources and expanding the low-frequency application of non-anechoic pools.In this paper,we study the influence mechanism of the sound field boundary on the radiated impedance characteristics of the sound source in a closed space,and grasp the internal relationship between the radiated impedance and the free field radiated sound power in order to explore the relationship between the variations of sound source radiated impedance and radiated sound power.In this paper,the numerical calculation model of underwater acoustic source radiation impedance in a closed space is established.In view of the simulation analysis,the influence of several elements of closed-space acoustic environment on the radiation impedance of sound source is studied,and the effect of the radiated impedance variation of sound source on the sound power is analyzed.Finally,the reverberation tank measurement experiment of underwater sound source radiation impedance was carried out,and some simulation results were verified.The research shows that the results of pulsating ball source closed space Actran simulation method and the cylindrical shell sound source closed space Comsol modeling method are the same as the analytical solution.Therefore the numerical method is correct and feasible.When the acoustic environment of the a closed space is changed,the value of the radiated impedance of the pulsating ball source changes significantly at the acoustic mode frequency,and the change of the radiation resistance leads to the change of the radiated sound power of the pulsating ball source in the closed space.The radiation resistance of the cylindrical shell sound source in the closed space is not one-to-one correspondence with the peak value of the sound field mean square pressure level,which is related to the average surface velocity.In the soft boundary enclosed space case,except for the individual frequencies,the radiation resistance ratio of the cylindrical shell sound source at the center of two different scale closed spaces in the low frequency band or at two symmetric positions in the closed space is approximately one,and sound source radiated power ratio of the cylindrical shell in the closed space is equal to the ratio of the square mean velocity.Particularly,in the same frequency range of the plane average velocity,the sound energy of the cylindrical shell sound source of the two symmetric spaces in two closed spaces or closed spaces is the same.The experimental measurements of the radiation resistance of the cylindrical shell sound source were carried out in the muffler pool and different reverberation tanks,respectively.The boundary characteristics of the reverberation tank and the influence of different emission positions on the radiation resistance of the cylindrical shell source were compared,the applicable conditions for measuring low-frequency radiated sound power of the cylindrical shell sound source in the reverberation tank are given.