双重耦合机制下声-电换能器低频灵敏度建模与参数辨识

Accurate modeling and parameters identification of the low-frequency sensitivity of acoustic-electric transducers are the promise of quantitative study on low-frequency sound and the key of breaking through the bottleneck of air pressure reference. However, the dual effect of leakage and heat conduction coupling attenuation of pressures in the transducer and calibration device, and the pressure coupling on transducer's sensitive cell causes unquantifiable errors in the theoretical model and calibration results. In this project, we study the pressure attenuation mechanism from the leakage and heat conduction coupling effect. Equivalent models of the leakage and heat conduction boundaries are presented and the coupling model is improved. Secondly, the pressure coupling mechanism of the sensitive cell is revealed. Deformation functions are derived both in pressure field and free field on basis of force equilibrium. Low-frequency sensitivity models are derived correspondingly. Finally, considering the uncharted model accuracy and the difficulty in measuring parameters. An identification method is proposed based on pressure field and free field contrastive calibration and is verified on the established platform. This project reveals the dual coupling mechanism in low-frequency primary calibration of acoustic-electric transducers, and theoretically supports its principle error quantification. The idea can be extended to the design of acoustic-electric transducer's calibration apparatus, pressure vessels, etc. So the project has important theoretical value and application prospect.

通过原级校准确定的声-电换能器低频灵敏度，受换能器与校准装置各自腔内声压的泄漏和热传导耦合衰减，以及换能器敏感极两侧声压耦合激励的双重作用，理论模型与校准结果中存在难以定量的原理性误差，其准确建模与参数辨识是低频声波定量研究的前提和突破空气声声压基准下限瓶颈的关键。本项目研究声压的泄漏和热传导耦合衰减机制，重点研究泄漏和热传导复杂物理边界的模型等效问题，完善泄漏和热传导耦合衰减模型；揭示换能器敏感极两侧声压的耦合机制，重点基于压力场和自由场下敏感极的力平衡特征构建其形变函数，建立相应声场下声-电换能器的低频灵敏度参数化模型；针对模型精度未知和参数测量困难问题，探究基于压力场和自由场对比校准的参数辨识方法，并搭建平台进行验证。本项目揭示声-电换能器低频原级校准的双重耦合机制，为量化原理性误差提供理论支撑，其思路可扩展到声-电换能器校准装置和压力容器等的设计领域，具有重要的理论价值和应用前景。

低频声波和次声波的定量研究依托传声器、次声传感器等声-电换能器的精确测量实现。由于声-电换能器受泄漏和热传导因素影响，具有明显的低频非线性衰减特征，因此揭示低频校准过程中多物理因素综合作用下声-电换能器的灵敏度波动机制、建立特定原级校准方案和内外均压校准模式下的灵敏度模型，并对其进行有效的参数识别是保证声-电换能器精确测量，也是声压量值溯源的根基。.理论方面，本项目深入研究了声-电换能器的原级校准原理，分别构建了校准腔和传声器背腔内声压的泄漏和热传导耦合衰减模型，完整揭示了声压的幅频和相频波动机理。然后，创新性地基于传声器振膜力平衡构建了内外均压校准模式下的低频灵敏度参数化模型。该模型首次实现了对声-电换能器低频灵敏度的显式表征，能够直接揭示低频灵敏度的波动机制，相较于传统模型具有突出优势。.进一步的，基于COMSOL多物理场仿真软件进行对比验证，分别在时域与频域模块下对校准腔和传声器背腔内的声场特征进行了数值仿真，完美验证了声压幅频和相频波动机理。然后，创新性地提出了模型比较法，准确量化低频校准核心的泄漏、热传导独立与耦合修正量。最后，对声-电换能器低频校准过程进行了联合数值模拟，揭示了泄漏、热传导、内外均压等因素对灵敏度的影响规律。.最后，发明了基于低速伺服电机的活塞发声器原级校准平台。建立了驱动系统动力学模型并与多体动力学仿真相验证，进行了电机选型。对校准装置的关键参数，即泄漏时间常数、温度传递函数等进行了实验辨识。最后，对不同声-电换能器进行了原级校准实验，首次且初步通过实验手段发现了内外均压校准模式下声-电换能器低频灵敏度的明显不同。.本项目对于低频声波和次声波的声压量值溯源具有重要意义，相关研究取得了超出预期的研究成果，构建的理论模型、仿真分析方案可直接支撑声压校准装置和声-电换能器的设计开发，发明的活塞发声器原级校准平台性价比高、通用性和灵活性强、维护保养简单，可直接在声学领域推广。