【作者】 邱磊；

【导师】 邹早建；

【作者基本信息】 武汉理工大学 ， 流体力学， 2003， 博士

【摘要】 采用计算流体动力学(CFD)技术实现在船舶设计阶段对船舶水动力性能的精确预报，是船舶水动力学学科中一个具有重大理论和实用意义的、富有挑战性的课题。近十年来，随着船舶CFD计算方法和计算能力的发展，数值预报精度不断提高，其对船舶优化设计的指导作用也日益突出，并有与船模试验并驾齐驱、取代部分船模试验的趋势。三维船舶粘性流计算方法，具有准确捕捉船体周围粘性流动细节包括船模试验难以测量的流动形态的能力，已成功地应用于船舶快速性方面的阻力预报；在船舶操纵性方面，这类方法虽处于初始发展阶段，但也已获得重大进展，具有精确预报船舶操纵水动力的潜力。本文即在这种背景下，瞄准船舶操纵水动力预报方面的国际前沿和热点课题，通过对现代船舶粘性流计算方法的研究，自主开发了一个船舶操纵粘性流求解器，并将所开发的求解器成功地应用于一系列和船舶操纵问题相关的粘性流动与水动力计算，得到了令人满意的结果。 本文选取RANS方程作为控制方程，并用标准κ-ε湍流模式结合壁函数封闭方程；分析了常用的边界条件，特别是入流边界条件、壁面边界条件和轴边界条件，提出了处理这些边界条件的方法；在分区结构网格上，运用有限体积法(FVM)对RANS方程进行离散，其中，对流项采用混合迎风、中心差分格式，扩散项采用中心差分格式，源项采用中心差分格式并进行部分隐式化以增强离散方程系数矩阵主对角占优；压力、速度等采用非交错配置，并用SIMPLE法耦合求解；对离散后得到的代数方程组选用稳定和收敛性能佳的强隐式法(SIP)迭代求解，并在每步迭代之前对线性方程的矩阵系数进行亚松弛预处理以增强求解的稳定性；为提高数值解的稳定性和收敛性，采用了多重网格法。基于上述方法，采用C++程序设计语言，研究和开发了一个船舶操纵粘性流求解器(VSMAN)。 应用所开发的求解器，以NACA0015翼型舵为算例计算了船舵在不同雷诺武汉理三「;大学博士学位论文数下大舵角范围内的三维粘性流场及水动力，成功地预报了舵的失速角和最大升力，并初步探讨了雷诺数对舵水动力的影响;计算结果与现有试验和计算数据比较，吻合程度相当好，初步检验和验证了该求解器精确模拟粘性流动和计算水动力的能力。 应用所开发的求解器，以6:1长椭球体为算例计算了回转体在大攻角下定常斜航运动时的三维粘性流场及水动力，对层流流动和湍流流动分别进行了计算，分析了层流与湍流分离流动和涡旋产生的特点及其对水动力的影响;计算结果与他人的试验和计算数据比较，吻合程度良好，表明应用本求解器能够正确模拟这种以层流/湍流分离流为主的复杂粘性流动，得到相当精确的水动力，检验和验证了该求解器精确模拟回转体在大攻角下的粘性分离流动和计算水动力的能力。 应用所开发的求解器，以wigley船型为算例计算了大角度斜航船体粘性流场和水动力，分析了漂角的变化对船体所受到的粘性水动力的影响，相当精确地预报了以横流分离和般涡生成与泄出为特征的操纵运动船体特有流动形态及横向水动力和转脂力矩，经与现有试验和计算数据比较，检验和验证了该求解器精确模拟绕斜航运动船体的大尺度分离流动和计算非线性水动力的能力。 利用两个开放源代码的软件库FOX和VTK，设计开发了一个高效、友好的船舶CFD可视化系统(SCFDVS)，实现了以多种方式绘制ZD/3D几何体和计算网格、ZD/3D标量场和矢量场的功能，并在本文计算的前、后处理过程中得到了成功的应用。 本文完成的工作缩短了我国在船舶操纵水动力预报方面与国际先进水平的差距。由于操纵运动粘性流动的复杂性，粘性流方法目前在船舶操纵水动力计算领域的开发与应用尚处于初始发展阶段，其应用能力和计算精度还不能满足工程实用的要求。本文在研究基础薄弱、研究条件差的情况下对船舶操纵粘性流动及水动力计算进行了有益的探索，取得了一定的成功，但仍有许多问题值得进一步探讨和研究。更多还原

【Abstract】 Numerical prediction of ship hydrodynamic performance at design stage using computational fluid dynamics (CFD) technique is a most important and challenging subject in the field of ship hydrodynamics. With the rapid development of computational methods and computer technology, CFD is becoming a practical tool in ship design. In this respect, it tends to be an alternative of towing tank tests. The solution of 3D viscous flows around a ship in steady straightforward courses is capable of capturing more nearfield flow features than model tests and predicting viscous resistance with high accuracy, whilst for viscous flows around a ship in maneuvering motions such predictions are only in general good.A multi-block incompressible viscous flow solver has been developed that can be applied to simulation of a variety of ship maneuvering related flows and calculation of hydrodynamic forces. Validation and verification of the solution procedure are carried out on several model problems with good agreement to experimental and numerical results.The present block-structured viscous flow solver is based on solving the Reynolds-averaged Navier-Stokes (RANS) equations with a second-order cell-centered finite volume method (FVM) on non-staggered grids. The standard k-ε turbulence model with wall function is incorporated into the RANS solver for turbulent flow modeling. Several procedures are proposed for satisfying boundary conditions. The convection term is approximated by hybrid upwind/central differencing scheme, the diffusion and source terms are approximated using central differencing scheme with locally approximated implicit terms taken to strengthen the main-diagonal of the final coefficient matrix. The SIMPLE method is used for the pressure coupling, and the Strong Implicit Procedure (SIP) is adopted for solution of the discretized equations. The solution algorithm employs under-relaxation in eachiterative step for numerical stability and the multigrid method for better convergence rate. The solver is coded using the C++ programming language and named VSMAN.The present flow solver is demonstrated for block-structured meshes with calculations of the viscous flows around a rudder with NACA0015 foil profile at a range of attack angles. The effect of Reynolds number on rudder hydrodynamic performance is also analyzed. Up to the stall angle the computed lift and drag agree well with measurements and other author’s calculations, whereas stall angle, lift and drag beyond the stall angle are slightly under-predicted.The solver is used to investigate laminar and turbulent separated flows around a 6:1 prolate spheroid at high incidence angles and their effects on hydrodynamic forces. The second separation flows are successfully identified in both laminar and turbulent flow simulations. The computations are shown to agree well with available experimental and numerical data and the physics of 3D large-scale flow separations and vortex shedding are confirmed.The simulation of the flow around a maneuvering Wigley hull is a demonstration of capability for calculations of sway forces and yaw moments acting on a hull moving obliquely at a large range of yaw angles. The focus of study is large-scale cross-section separation flows, bilge-vortex development along the hull in the longitudinal direction and their effects on hydrodynamic forces. The results are compared with the available experimental and numerical data which has shown good agreement.A visualization program named SCFDVS is developed specifically for plotting 2D/3D geometries and numerical grids, 2D/3D scalar and vector fields in ship CFD simulations. The visualization system is quite efficient and user-friendly, and is already used for better presentation of numerical results.The work covered in this thesis is hoped to shorten the gaps to the world advanced level in prediction of hydrodynamic forces on maneuvering ships. Due to the complexity of ship maneuvering viscous flows, the computational methods for such flows are nevertheless in its infant, t更多还原