动边界下船舶微气泡减阻机理研究

In today's era of global warming and energy crisis, the microbubble drag reduction that can effectively reduce the ship friction, host power consumption and exhaust emissions, is a green energy-saving technologies. Vibrantion under seakeeping is produced in the process of ship navigation, which will change the original motion of microbubble in boundary layer and interfacial kinetics environment of microbubble, meanwhile will influence the coalescent and break up process of micobubble, void friction distribution and drag reduction performance. Therefore, the key problem is recognizing the mechanism of microbubbles field affected by oscillatory ships hull, which is urgently solved in the ship micro-bubble drag reduction technology application. The project combining PIV model test, the theoretical analysis and numerical simulation method, researches the water field with microbubbles interfacial kinetics problem, the composition of diameter density distribution and the law of drag reduction which is affected by the ship hull heave, roll and trim with different cycles and amplitude. Its aim is to set up a mathematic numerical model which can effectively describe the microbubbles coalescent and break up process and consider bubble - water -dynamic boundary interaction by bonding the Euler-Euler two-phase flow, Multiple-size group (MUSIG) based on population balance models and turbulence models. Based on the coupled numerical model to explore the baffle, ventilation layout and type of ship line design and optimization of microbubble drag reduction, the micro-bubble drag reduction research methods will be enriched and improved obviously through abundant research results, and it provide a scientific basis for the real ship applications of micro-bubble drag reduction technology.

当今全球变暖和能源危机，微气泡减阻可有效降低船舶航行阻力，减少主机功耗和尾气排放，是一项绿色环保的节能技术。船舶航行存在耐波运动，将改变原有的边界层微气泡的运动规律和微气泡界面动力学环境，影响微气泡聚合破裂过程、船舶表面含气率分布和微气泡的减阻性能。因此，认识边界运动对微气泡作用机理，是船舶微气泡减阻技术亟需解决的关键问题。本项目拟以采用PIV模型试验、理论分析和数值模拟相结合的方法，研究水与微气泡界面动力学问题，气泡与气泡聚合破裂输运作用机理，边界进行垂荡、横摇和纵倾等不同周期、不同幅值边界条件对气泡运动的影响，及气泡颗粒直径密度分布和减阻规律，并结合欧拉欧拉两相流、气泡群体守恒和湍流模式，建立可考虑气泡聚合破裂的微气泡-水-动边界耦合数值模型。基于该耦合数值模型，探讨挡板、通气布局和型线设计与微气泡减阻优化。成果将丰富和完善微气泡减阻研究方法，为微气泡减阻技术实船应用提供科学依据。

当今全球变暖和能源危机，微气泡减阻可有效降低船舶航行阻力，减少主机功耗和尾气 排放，是一项绿色环保的节能技术。船舶航行存在耐波运动，将改变原有的边界层微气泡的 运动规律和微气泡界面动力学环境，影响微气泡聚合破裂过程、船舶表面含气率分布和微气 泡的减阻性能。因此，认识边界运动对微气泡作用机理，是船舶微气泡减阻技术亟需解决的关键问题。本项目采用PIV模型试验、高速摄像测试技术对气泡聚合破裂源项方程进行了理论分析。基于欧拉-欧拉两相流模型、气泡群体平衡模型和动网格技术建立了动边界下的微气泡减阻数值模拟方法。采用该方法研究了动边界平板模型的减阻规律和气泡减阻性能优化方法。本项目还研究对比了欧拉-欧拉两相流和均质平衡流模型在气泡减阻数值模拟中的优劣。结果表明：本项目所建立的三相耦合数学模型,可有效的模拟动边界下微气泡减阻问题，边界运动对微气泡减阻率具有显著的影响，欧拉-欧拉两相流模型更适用于微气泡减阻研究。