本文基于均質(zhì)混合流假設(shè),通過(guò)考慮空穴潰滅過(guò)程釋放的能量,提出了一種新的空蝕模型,為水力機(jī)械安全、穩(wěn)定運(yùn)行提供了重要的理論支撐。人們以往采用商用軟件與實(shí)驗(yàn)結(jié)合的方法研究空化與空蝕機(jī)理。已有的數(shù)值模擬結(jié)果表明,雖然非定�？栈F(xiàn)象可以較好地再現(xiàn),但對(duì)空蝕只能作定性預(yù)測(cè),且計(jì)算的空蝕區(qū)域與實(shí)際存在偏差,其原因是沒(méi)有考慮含氣率對(duì)空蝕的影響。在均質(zhì)混合流假設(shè)的基礎(chǔ)上考慮含氣率時(shí),首先是要優(yōu)化非定常片空化的數(shù)值模擬方法。凝結(jié)和蒸發(fā)過(guò)程的非對(duì)稱(chēng)性是空化-空蝕的一個(gè)重要因素。因此,本文提出了改進(jìn)的Zwart-Gerber-Belamri（Z-G-B）模型,并將C++語(yǔ)言嵌入到OpenFOAM作為新求解器。其次,為了避免質(zhì)量傳輸和亞格子應(yīng)力模型之間的顯式耦合,采用了隱式大渦模擬來(lái)計(jì)算強(qiáng)湍流。通過(guò)對(duì)繞NACA0015、NACA66以及凸平面水翼的空化湍流進(jìn)行模擬分析,再現(xiàn)了前緣附著空泡、回射流、空化脫落、空泡分離和空泡潰滅,預(yù)測(cè)的斯特勞哈爾數(shù)接近0.2,與實(shí)驗(yàn)結(jié)果吻合良好,證實(shí)本文提出的方法可以較好地預(yù)測(cè)空化現(xiàn)象。此外,用CFL條件數(shù)控制時(shí)間步長(zhǎng),避免了因網(wǎng)格尺度和信息傳輸與預(yù)測(cè)速度之間的差異而造成的浮點(diǎn)異... 

【文章來(lái)源】：清華大學(xué)北京市 211工程院校 985工程院校 教育部直屬院校

【文章頁(yè)數(shù)】：151 頁(yè)

【學(xué)位級(jí)別】：博士

【文章目錄】：
摘要
Abstract
Nomenclature
Chapter 1 Introduction
    1.1 Background
    1.2 Literature review
        1.2.1 Cavitation erosion prediction using CFD
        1.2.2 Free software
    1.3 Objectives
    1.4 Main contents of the dissertation
Chapter 2 Numerical modeling methods used for cavitating turbulent flow simula-tions
    2.1 Homogeneous mixture flow assumption
    2.2 Cavitation models
        2.2.1 Kunz model
        2.2.2 Schnerr-Sauer model
        2.2.3 Zwart-Gerber-Belamri model
    2.3 Turbulence modeling methods
    2.4 OpenFOAM
        2.4.1 OpenFOAM set up
        2.4.2 Volume-of-Fluid
        2.4.3 Grid mesh
    2.5 Summary
Chapter 3 Numerical analyses for cavitating turbulent flows around hydrofoils
    3.1 Partial cavitation over NACA0015 hydrofoil
        3.1.1 Hydrofoil geometry
        3.1.2 Mesh generation
        3.1.3 Computation setup
        3.1.4 Python image processing
        3.1.5 Results and discussions
    3.2 Unsteady partial cavitation around a plane-convex hydrofoil
        3.2.1 Hydrofoil geometry and computational domain
        3.2.2 Mesh generation
        3.2.3 Boundary conditions
        3.2.4 Results and discussions
        3.2.5 Comparison for ILES and ELES
    3.3 Unsteady cavitation around a NACA66 hydrofoil using dynamic time step
        3.3.1 Variable time step
        3.3.2 The total vapor volume
        3.3.3 Hydrofoil geometry, mesh generation and boundary conditions
        3.3.4 Results and discussions
    3.4 Summary
Chapter 4 Cavitation erosion prediction using CFD
    4.1 Erosion model
        4.1.1 Microjet assumption
        4.1.2 Flow aggressiveness and material damage
    4.2 Numerical prediction of cavitation-erosion on a NACA66 hydrofoil and aplane-convex hydrofoil with a semi-circular obstacle
        4.2.1 Computational domains
        4.2.2 Mesh generation
        4.2.3 Boundary conditions
        4.2.4 Results and Discussions
    4.3 Numerical prediction of cavitation-erosion on axisymmetric nozzle
        4.3.1 Computational domain
        4.3.2 Mesh generation
        4.3.3 Results and discussions
    4.4 Numerical prediction of the affected region by unsteady cavitating flow fora NACA0015
        4.4.1 Mesh generation and boundary conditions
        4.4.2 Results and discussions
    4.5 Summary
Chapter 5 Conclusions and future work
    5.1 Main concluding remarks
    5.2 Innovation points
    5.3 Future work
References
致謝
Appendix A Mesh analysis for NACA0015
    A.1 Cavitating Flow Simulation with Mesh Development using Salome OpenSource Software
Appendix B Developed software for the study case of NACA0015
    B.1 Python processing image algorithm
    B.2 Code of the pressure fluctuation plot at x/c = 0.2
Appendix C Developed software for the study case of a plane-convex hydrofoil
    C.1 Zwart-Gerber-Belamri cavitation model
    C.2 Code for plotting Cpand α
Appendix D Developed software for the study case of a NACA66 hydrofoil usingvariable time step
    D.1 NACA66 hydrofoil
    D.2 FFT program
Appendix E Cavitation erosion model: mesh and programs
    E.1 The mesh of the plane-convex hydrofoil with semicircular obstacle
    E.2 Program for the total vapor volume
    E.3 Developed software for the implementation of the cavitation-erosion model
    E.4 Gnuplot code for residuals
Resume and published papers


【參考文獻(xiàn)】：
期刊論文
[1]Implicit large eddy simulation of unsteady cloud cavitation around a plane-convex hydrofoil[J]. HIDALGO Victor,羅先武,ESCALER Xavier,季斌,AGUINAGA Alvaro.  Journal of Hydrodynamics. 2015(06)
[2]A cavitation aggressiveness index within the Reynolds averaged Navier Stokes methodology for cavitating flows[J]. KOUKOUVINIS P.,BERGELES G.,GAVAISES M..  Journal of Hydrodynamics. 2015(04)
[3]Numerical study of unsteady cavitation on 2D NACA0015 hydrofoil using free/open source software[J]. Victor Hidalgo,Xianwu Luo,Bin Ji,Alvaro Aguinaga.  Chinese Science Bulletin. 2014(26)
[4]PARTIALLY AVERAGED NAVIER-STOKES METHOD FOR TIME-DEPENDENT TURBULENT CAVITATING FLOWS[J]. HUANG Biao,WANG Guo-yu School of Vehicle and Transportation Engineering,Beijing Institute of Technology,Beijing 100081,China.  Journal of Hydrodynamics. 2011(01)



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