介尺度气泡流动结构的声学表征方法研究

The inhomogeneous bubble cluster generated in gas-liquid reactors is a typical mesoscopic structure. The structure of bubble cluster and its acoustic characteristics are quite different from the single bubble or homogeneous gas-liquid flow field. Thus the acoustic features can vividly indicate the evolutionary process of bubble cluster in time-space-frequency domains. In the fields of energy transformation, chemical reactor and petrochemical engineering etc., the quantitative representation of acoustic characteristics for mesoscopic structure can much more efficiently and delicately demonstrate the formation process of the non-uniform bubble cluster in gas-liquid reactor, comparing to using experimental trials and empirical judgments, as well as camera monitoring and other passive measurements. At present, there are many works on the structure and the acoustic properties of the individual bubble and the macroscale gas liquid flow field. But the correlation between the structure of mesoscopic bubble cluster and the acoustic radiating characteristics highly needs further attention. Therefore, this project will study the “aggregative” bubble cluster with multi-granularity by jointly employing the acoustic sensor array measurement, advance signal and image processing techniques (firstly feature extraction of weak acoustic signals from heavy reverberation in closed reactor, then acoustic localization and mapping power distribution, and finally texture model with high resolution based on time-frequency spectrum), bubble-fluid-acoustics simulations and theoretical analysis. The purpose of this research is to evaluate the formation and evolution of bubble clusters, as well as to illuminate the acoustic spectral textures, and to finally establish the acoustic prediction model of mesoscopic bubble cluster. Ultimately, this project aims to provide basis and support for further work of mesoscopic bubble cluster regulation, acoustic diagnosis and data basis on mesoscopic bubble fluid relating to acoustic characterization.

气-液两相反应器中的非均匀气泡群是一种典型的介尺度结构，定量刻画气液反应器非均匀气泡流动结构及其形成过程是装置设计和改进的关键，对研究反应器混合与传递、系统集成放大、实现产品精细化等具有重要意义。本项目以气液两相反应器中形成的多粒度“聚式”气泡团为介尺度研究对象，利用声传感器阵列获得声源定位、声功率空间分布和声频谱纹理特征，从复杂的声传播多径效应中聚焦声源能量的主成分，提取反应器强烈混响干扰下的微弱声源信号，获取介尺度流动结构瞬态演化过程中的声频谱纹理信息，确立典型局部气泡流动结构的辐射声特性，建立流场特性与声特性相对应的数据库。结合典型气泡运动学、气泡流动声源模型和声传播模型等理论方法，研究气液两相反应器中典型介尺度气泡流动结构的声学表征，建立基于声学方法的介尺度气泡流动结构和演化的预测模型，突破“介尺度气泡流动结构的声学表征模型”这一难题。

气-液两相反应器中的非均匀气泡群是一种典型的介尺度结构，定量刻画气液反应器非均匀气泡流动结构及其形成过程是装置设计和改进的关键，对研究反应器混合与传递、系统集成放大、实现产品精细化等具有重要意义。本项目以气液两相反应器中形成的多粒度“聚式”气泡团为介尺度研究对象，利用声传感器阵列获得声源定位、声功率空间分布和声频谱纹理特征，从复杂的声传播多径效应中聚焦声源能量的主成分，提取反应器强烈混响干扰下的微弱声源信号，获取介尺度流动结构瞬态演化过程中的声频谱纹理信息，确立典型局部气泡流动结构的辐射声特性，建立流场特性与声特性相对应的数据库。结合典型气泡运动学、气泡流动声源模型和声传播模型等理论方法，研究气液两相反应器中典型介尺度气泡流动结构的声学表征，建立基于声学方法的介尺度气泡流动结构和演化的预测模型，突破“介尺度气泡流动结构的声学表征模型”这一难题。