摘要研究水下航行体的通气空化流场特性及空泡脱落泄气机理具有十分重要的理论意义及工程应用价值。本文以带空化器的回转体为研究对象，采用数值计算的方法，分别研究不同工况下的空泡形态、流场特点及泄气机理。结果表明：相比于k-ɛ模型，PANS湍流模型能够更好地模拟出较大尺度的脉动现象，捕捉到更明显的非定常涡团结构，这与相应的实验结果更为接近；保持通气率不变，随着空化数的降低，自然空化产生的低压区能够诱导通气超空化的发展，导致绕回转体气液两相流动与气汽液三相流动空泡形态明显不同；不同Fr时，空泡的脱落特性有着明显的不同，随着Fr的增大，空泡尺度减小，脉动特性增强，且空泡脱落周期变小。83252

毕业论文关键词  回转体  通气空化  湍流模型  流场特性  脱落特性

毕业设计说明书外文摘要

Title  Numerical investigations of complex multiphase cavitating flow structures 

Abstract The investigation of the flow field characteristics about ventilated cavitation and the mechanisms of gas leakage of underwater vehicle is theoretically significant and important in engineering field。 As to an axisymmetric body with a cavitator, the numerical method is used to study the cavity shape, flow field characteristics and the mechanisms of gas leakage under different conditions, and the numerical results are compared with the experimental results。 The results show that PANS model can better simulate large scale of pulsation phenomenon than k-ɛ model, it was able to capture more obvious unsteady eddy structure, which is more close to the experiment; At a constant ventilation rate, with the decrease of cavitation number, natural cavitation appears with low pressure region, which can induce the occurrence of the ventilated supercavitation。 Consequently,the cavity shape of two-phase flow and three-phase flow around axisymmetric body are obviously different; Different Fr values can induce different cavity shedding patterns。 With the increase of Fr, the size of cavity increases, the characteristics of pulsation are enhanced, and the period of the cavity shedding becomes small。

Keywords   axisymmetric body  ventilated cavitation  Turbulence model flow field characteristics  shedding characteristics

目   次

1  绪论 1

1。1 研究背景及意义 1

1。2 国内外研究现状及发展状况 2

1。2。1 自然空化 2

1。2。2 通气空化 3

1。2。3 国内外研究现状 5

1。3 本文主要研究内容 7

2  通气空化流动的数值计算方法研究 8

2。1 控制方程与数学模型 8

2。1。1 多相流模型 8

2。1。2 基本控制方程 9

2。1。3 湍流模型 9

2。1。4  Kubota空化模型 10

2。2 湍流模型的应用及评价 12

2。2。1 几何建模及网格划分 12

2。2。2 网格无关性验证 14

2。2。3 计算域及边界条件的设置 15

2。2。4 PANS模型与k-ɛ模型的计算结果对比分析 17