高速水下航行体空泡流中动量、质量和能量传递机理的研究

In this project, in order to get more detailed informations about field structures, cavitation character and stability, we will combine of those methods of water-tunnel experiment, numerical simulation and theory to analyze, and try to build up validated cavitation model. Furthermore, those informations will also give solid base on deeply reseaches of the drag decrease of ventilated cavitation. On the one hand, from the aspect of theory reseaches, we will design the two-fluid model, and base on the large eddy simulation to finally explore the unstable code for the numerical simulation of cavitating flows; in addition, in order to enhance the precise of simulation, robustness and save the CPU time, we will substitute symmetric singular schemes designed by myself for the centre scheme in the model of large eddy simulation. On the other hand, from the aspect of experimental reseaches, we will execute the experiment of turbulence and caviting flows, and further accomplish the experiments of ventilated cavitation considered by thermaldynamical effects, so that we can compare of their shapes of ventilated cavitation, the surface waves and oscillation et al in defferent ventilated gases or liquids with different ventilated values and thermalphysical states even at the same inlet velocities, pressures, inlet angles and cavitator shapes. In a word, we will study the mechanism of momentum, heat and mass transfer during the evolution of cavitation, and further try to find out the main effect factors to control the development of the ventilated cavitation.

本课题拟采用水洞试验、数值模拟和理论分析相结合的方法，不仅对动力学特性进行分析，同时也从热量和质量传递的本质出发，全面研究空泡流动的数学模型、流场结构、空泡形态和稳定性，为通气空泡减阻机理的深入研究奠定基础。 理论研究方面，本课题拟开发基于LES大涡模拟技术、考虑热力学效应的非定常空泡流数值计算程序；用自己开发的"对称奇阶"对流项高精度差分格式替代中心差分格式以提高LES方法的计算精度、健壮性和节省CPU时间；实验研究方面，本课题将进行考虑热力学效应的通气以及"相变式"通气空泡实验，对比研究当通入不同热力学状态及物性参数的气体或液体，改变不同的通气量时，在相同的流速、压力、攻角以及空化器外形等参数下，通气空泡外形、表面波动和振荡等特性。最终目标：在认识空泡演变的动量、热量和质量传递机理的基础上，进一步深入发掘影响和控制通气超空泡演化的主要因素和参数，为超空泡减阻技术在实践中的应用打下基础。

本课题采用数值模拟和理论分析相结合的方法，不仅对动力学特性进行分析，同时也从能量守恒的本质出发，全面研究空泡流动的数学模型、流场结构、空泡形态和稳定性，为空泡减阻机理的深入研究奠定基础。本课题利用OpenFOAM开源软件并修正了interPhaseChange源代码求解器用于空泡流数值计算，并用OpenFOAM前处理网格生成 code SnappyHexMesh 生成了三维几何结构的结构化网格；在空泡流计算中，我们分别利用了雷诺时均（RANS）、分离涡模拟（DES）和大涡模拟（LES）方法并混合 Mixture 空泡流模型较全面研究了二维、三维不同头型下不同来流条件、不同攻角下空泡流发生以及发展演化特性，并在研究中发现了新的空化初生及演化机理，提出了新的用于计算“空泡流”、“多相流”问题的公式，这些新机理和公式为后续更深入的进行空泡流特性研究奠定了重要的理论基础；在本项目的支持下，本课题还初步研究了带自由液面以及可压缩特性影响下的空泡流问题，为后续项目申请打下铺垫。