气泡卷吸和溶解过程的机理及LBM模型研究

Abstract: The aeration flow and supersaturation of dissolved gas in hydraulic engineering have attracted much attention. However, it is lack of mesoscale basic theory and fine numerical model on flow aeration and gas dissolution. Without doubt, the lack has seriously restricted the overall prediction of aerated flow and its supersaturation. In this project, the integrated method of model experiment, theoretical analysis and numerical simulation will be adopted to study mesoscopic process and mechanism with whole cycle from bubble entrainment, dissolution, mass transfer, to release in flood discharge. System platform of synchronous multi-field measurement with trinity will be constructed. This platform can be used to synchronously observe hydrodynamic parameters of flow field, aeration concentration field, dissolved gas content, boundary pressure and water temperature as well as "micro" process and rules on real-time change of water quality. Moreover, mesoscopic evolution from bubble entrainment process, dissolution and mass transfer, to dissolution precipitation and release process can be obtained. Besides, the law of full cycle change from bubble entrainment to release of supersaturated gas can be explored. Based on kinetic mesoscopic model of lattice Boltzmann method, by constructing the external force term representing gas dissolving in thermodynamic equation of state, the multiphase lattice Boltzmann model of simulating supersaturated gas will be established. Then, the mechanism of bubble entrainment, dissolution and precipitation can be revealed fully. So, a numerical model of predicting actual aerated flow and concentration distribution of supersaturated gas will be developed. Therefore, this project has important theoretical significance and practical value.

水利工程泄洪产生的掺气水流及其溶解气体过饱和问题备受关注。但缺乏细观尺度水流掺气及气体溶解全过程的基础理论及其精细数值模型，已严重制约掺气水流及其过饱和预测的整体水平。本项目拟采用模型试验、理论分析和数值模拟的综合方法，研究泄洪水流气泡卷吸、溶解传质、析出释放全周期细观过程与机理。搭建三位一体的多场同步测量系统平台，同步观测流场、掺气浓度场、溶解气体含量、边界压力、水温等水动力参数与实时水质变化“显微”过程及规律；获取气泡卷吸过程、溶解传质规律、析出释放过程等细观演变规律；探寻从气泡卷吸掺入到过饱和气体释放的全周期变化规律；基于动理学玻尔兹曼方程的介观LBM数值模型，构建植入气体溶解热力学状态方程的外力项，建立用于模拟计算过饱和气体的LBM多相流模型；全面揭示气泡卷吸、溶解与析出机理；开发一套用于实际的预测掺气水流过饱和气体浓度分布的数值计算方法。因此，本研究具有重要的理论意义和实际价值。

水利工程泄洪产生的掺气水流及其溶解气体过饱和问题备受关注。但缺乏细观尺度水流掺气及气体溶解全过程的基础理论及其精细数值模型，已严重制约掺气水流及其过饱和预测的整体水平。本项目针对上述科学问题，研究揭示了不同温度，压力，紊动强度对TDG吸入和析出的规律，获得了温度、压力、紊动强度与掺气浓度以及溶解气体浓度的相关关系，完善了现有的过饱和气体卷吸—溶解传质—析出过程理论；建立了可用于计算大密度比大粘滞系数比二相流中气体溶解的LBM多相流模型，精确模拟了气体卷吸—溶解传质—析出释放全周期过程，减少和简化了传统TDG模型源项中所需要涉及到的气体浓度，流量，紊动强度，水深，气泡分布等诸多参数的率定；基于准确地揭示气体卷吸—溶解传质—析出释放细观机理基础上，开发出一套能够准确预测不同水利工程消能工对下游影响的数值预测方法，为工程应用提供了一种新的数学模型支撑。.本项目完成学术论文8篇，其中SCI收录论文7篇，中文核心期刊论文1篇。申请公开国家发明专利4项，其中授权国家发明专利3项，1项专利技术已在实际工程中得到成功应用，取得了显著的社会和经济效益。在本项目的资助下，培养博士研究生4人，其中2人圆满完成学业取得工学博士学位；培养硕士研究生4人，均圆满完成学业取得硕士学位。