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Janus-Helmholtz换能器利用驱动振子纵向谐振与Helmholtz谐振腔的液腔谐振耦合, 具有大功率、宽带声发射特性. 传统观点认为导纳曲线中低频谐振峰对应液腔谐振频率, 而高频谐振峰对应纵振动谐振频率, 然而大量的实验研究发现该结论存疑. 本文结合一只Janus-Helmholtz换能器实验样机的实验结果, 运用等效电路法结合有限元法分析并求解了驱动振子纵向模态的谐振频率, 使用有限元法分析并求解了Helmholtz谐振腔的液腔谐振频率. 研究结果表明, 与传统观点相反, 导纳曲线中第1个谐振峰为驱动振子的纵向谐振, 第2个谐振峰为Helmholtz谐振腔的液腔谐振; Janus换能器4个大尺寸辐射面带来的可观辐射质量是造成纵向振动谐振频率在水中大幅度下降的原因; Janus-Helmholtz换能器中存在两个等体积的Helmholtz共振腔而非传统认为的仅存在一个共振腔. 这些结论对于正确认识Janus-Helmholtz换能器的结构及性能特性起到了正本清源的作用, 也为优化创新该换能器的结构、改善换能器的声发射特性提供了技术支撑.
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关键词:
- Janus-Helmholtz换能器/
- 谐振频率/
- 等效电路法/
- 辐射质量
Janus-Helmholtz transducer has the characteristics of high-power and broadband transmission due to the coupling between the longitudinal resonance of the driver and the liquid cavity resonance of Helmholtz resonator. Traditional view holds that the low frequency resonance peak in the transmitting voltage response curve in water is fluid cavity mode of Helmholtz resonator while the high frequency resonance is the longitudinal mode of Janus transducer. However, in the past few decades, a large number of experimental studies have found that this conclusion is questionable. This work is to distinguish the two resonances in the response curve and the two vibration modes of Janus-Helmholtz transducer. Based on the Janus-Helmholtz transducer prototype reported in the literature, the resonance frequencies of the vibration modes of Janus-Helmholtz transducer are studied theoretically. The structure dimensions and material parameters of the prototype are listed in detail. The test results and simulation results of conductivity are also presented. The longitudinal resonance of the driver is determined by using the equivalent circuit method and finite element analysis. Radiation masses of both Janus transducer and typical longitudinal vibration transducer are also calculated to analyze the phenomenon of the sharp decrease of longitudinal resonance frequency in water. Acoustic modal analysis by using ANSYS software is performed to investigate the resonance frequency of complex Helmholtz resonator in Janus-Helmholtz transducer. Correction length on the vent introduced by external fluid sound radiation is used to obtain the accurate Helmholtz resonance frequency. The sound pressure distribution of Helmholtz resonator obtained through finite element method is investigated, and the correct equivalent formula for solving the Helmholtz resonance frequency is obtained. The results reveal that the first resonance in the response curve is driver resonance while the second one is Helmholtz resonance, which is contrary to the traditional view. The considerable reduction of driver resonance frequency in water is mainly due to the large radiation mass on the four large radiation surfaces of the Janus transducer, which also causes the sharp response of driver resonance. In Janus-Helmholtz transducer, there are two Helmholtz resonators with the same size, instead of only one resonator in the traditional view. The two resonance frequencies solved by the method proposed in this work are in good agreement with the test and simulation results. These conclusions play an important role in correctly understanding the structure and characteristics of Janus-Helmholtz transducer at source, as well as provide technical support for structural optimization and innovation, thus improving the acoustic emission properties of the transducer.-
Keywords:
- Janus-Helmholtz transducer/
- resonance frequency/
- equivalent circuit method/
- radiation mass
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$ {r_1} $ $ {r_2} $ $ {r_3} $ $ {r_4} $ $ {r_5} $ $ {t_1} $ $ {t_2} $ $ {t_3} $ $ {t_4} $ $ {t_5} $ $ {l_1} $ $ {l_2} $ 0.05 0.035 0.145 0.148 0.158 0.025 0.11 0.008 0.065 0.01 0.08 0.138 
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$ c_{{11}}^{\text{E}}/{\text{GPa}} $ $ c_{12}^{\text{E}}/{\text{GPa}} $ $ c_{13}^{\text{E}}/{\text{GPa}} $ $ c_{33}^{\text{E}}/{\text{GPa}} $ $ c_{{44}}^{\text{E}}/{\text{GPa}} $ $ {e_{31}}/({\text{C}}{\cdot}{{\text{m}}^{{{ - 2}}}}) $ $ {e_{33}}/({\text{C}}{\cdot}{{\text{m}}^{{{ - 2}}}}) $ $ {e_{15}}/({\text{C}} {\cdot} {{\text{m}}^{{{ - 2}}}}) $ $ {\varepsilon _{33}} $ $ {\varepsilon _{11}} $ 139 77.8 74.3 115 25.6 –5.2 15.1 12.7 35 30 下载:
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换能器部件 材质 $ Y/{\text{GPa}} $ $ \rho /({\text{kg}}{\cdot}{{\text{m}}^{{{ - 3}}}}) $ $ c/({\text{m}}{\cdot}{{\mathrm{s}}^{{{ - 1}}}}) $ 中间质量块 不锈钢 193 7900 4940 辐射盖板、腔体 硬铝 71 2700 5150 下载:
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