A Janus Transducer Radiated In The Radial Direction

The Janus-Helmholtz transducer and Janus-Hammer Bell transducer,which are driven by the Janus transducer,have the characteristics of non-direction in the radial.However,the Janus transducer's radiation modal is a longitudinal quadrupole,which causes its sound energy to concentrate in the axial direction and radially radiates very little.In this paper,a radial radiation Janus transducer is proposed.By using the traditional Janus transducer to drive the bent cover plate,the four radiant surfaces of the transducer cause the difference in source intensity.Sound energy can be concentrated in the radial direction by adjusting the intensity ratio of the source.The low frequency directivity and broadband transmission principle of the transducer are analyzed,and the transmission performance is simulated and optimized.Finally,the experimental prototype was made for testing.Firstly,the directivity of the Janus transducer is derived based on the directivity theory of linear array.At the same time,the directivity of Janus transducer with bent cover plate is calculated,by being regarded as a quaternary array with unequal amplitude and spacing.And the influence of intensity ratio of different sources on directivity is studied.Broadband achieved by three modes coupling,namely first order bending,second order bending and Helmholtz resonance,are proposed.And the reason why the bending mode resonance frequency of the bent Janus transducer is much lower than that of Helmholtz resonance is analyzed theoretically from the perspective of additional radiation mass.Secondly,the equivalent source intensity of each radiant surface of the transducer is extracted by finite element method.By adjusting the structural parameters,the influence of the structural parameters of the transducer on the intensity ratio of the radiant surface source was studied,and the directivity of the transducer is optimized.Then,the transmission performance of the radial radiation Janus-Helmholtz transducer is simulated and optimized by finite element method.Considering the low frequency,wideband and directivity of the transducer,the optimized results are given.Finally,an experimental prototype with a working frequency of 1.4khz-3.4khz was designed and manufactured to test the electro-acoustic performance of the anechoic tank.The Janus-Helmholtz transducer with bent cover plate can realize radial radiation,low frequency,broadband and other excellent performance.The maximum length of the prototype is 330 mm,the weight is 13 kg,and the maximum sound source level can reach 190 dB.Compared with the traditional Janus transducer of the same size,the working frequency is lower.Compared with the Free Flooded Ring transducer of the same frequency,the maximum size is less than half,the weight is less than a quarter,the production cost has a greater advantage.