通气空泡非定常流动特性及机理研究

High-speed underwater vehicle is closely related to high-speed hydrodynamics. Ventilated supercavitation is an efficient technology to reduce drag and makes the underwater vehicle realize high-speed. The formation and development of supercavitation in the underwater high-speed vehicle is closely related to the multi-scale flow characteristics and turbulent flow structures in the cavity. This project aims to develop a synchronous multi-physical field measurement to obtain the cavity shape and velocity field and so on. In order to obtain accurate turbulent flow field, a particle image processing based on adaptive correlation method is applied. An integrative image measurement technique is proposed to effectively identify multi-scale bubbles and obtain the quantitative data (bubble distribution and bubble size) in the cavity. The characterization method of turbulent vortex structures is developed to extract the different scale of vortices in the flow field. The flow pattern characteristics and evolution of ventilated cavitation, and the characteristics of multi-scale bubbles and turbulent vortices in the cavity are investigated to systematically reveal the characteristics and mechanism of unsteady ventilated cavitating flow.

水下航行体的高速化与高速水动力学密切相关，超空泡减阻是一种实现水下航形体高速航行的重要技术。水下高速航行体超空泡生成与发展过程与空泡内部多尺度空泡的流动特性及湍流流动结构密切相关。本项目拟发展空泡内部流动特性及湍流流动结构的测量技术，实现空泡形态、速度场等多相流场结构特征信息的同步精细化测量；建立超空泡流场的PIV精细测量技术，基于自适应相关法实现对PIV粒子图像处理，获得精确的湍流流场信息；提出一种综合空泡图像处理技术，有效识别流场中多尺度空泡，获得空泡分布等定量分析；发展湍流旋涡结构的表征方法，提取流场中不同能级的旋涡结构；研究通气空泡的流型特征及发展演化规律, 获得通气空泡流型图谱，分析空泡内部多尺度流动特性以及内部湍流旋涡结构的生成与时空演化规律，从而系统地揭示通气空泡非定常流动特性及机理。

超空泡减阻是一种实现水下航形体高速航行的重要技术。超空泡生成与发展过程与空泡内部多尺度空泡的流动特性及湍流流动结构密切相关。本项目获得了不同来流条件和通气参数下通气空泡流型特征及其转变规律，建立了通气空泡流动流型图谱。发展了通气空泡内部流场结构精细化测量和后处理分析技术，定量地获得了空泡内部流场结构分布特征，分析了空泡发展演变过程与湍流流场的相关特性以及不同空泡流型下湍流旋涡结构的时空演化规律。提出了空泡识别方法对空泡尺寸、大小和位置进行统计分析，获得了空泡尾迹区小尺度空泡无量纲泡径分布规律。基于本征正交分解法提取了空泡流场中大尺度湍流相干结构，获得通气空泡流型转变与内部流动结构之间的相互作用机制，揭示了通气空泡非定常流动特性及机理。