基于边界元法的带空泡航行体的附加质量研究

发布时间：2018-03-23 00:17

本文选题：高阶边界元法　切入点：空泡　出处：《中国舰船研究院》2016年硕士论文　论文类型：学位论文

【摘要】：附加质量是研究水下航行体操纵性、水下振动特性等的重要参数。当有空泡时,附着空泡改变了航行体的湿表面积,同时空泡面的变形也会对流场产生影响。因此,带空泡航行体的附加质量与全湿流中有很大不同,它不仅与航行体的外形有关,还受到其运动过程的影响。考虑到实验测量的困难,对该问题开展数值计算方法研究具有重要意义。本文编写了三维高阶边界元法程序,研究了带空泡航行体刚体运动和弯曲振动的附加质量。主要包括以下内容:1)采用非均匀有理B样条(NURBS)表达边界曲面,用B样条表达源(汇)强、偶极强等未知量,用三次多项式变换方法处理面元奇异积分,通过配置点法形成最终的代数方程组,建立了基于NURBS的高阶边界元法。通过计算全湿流中的附加质量验证了方法和程序的可靠性。2)基于高阶边界元法计算了水下航行体的轴对称定常空泡形态及流场。根据空泡独立膨胀原理计算初始空泡外形,大幅减少了迭代步数。所得空泡形态与现有的实验和数值计算结果吻合较好。在此基础上,研究了航行体头型锥角、空化数对定常空泡形态的影响。3)把Uhlman所建立的方法应用到带局部空泡的航行体,在频域中计算了其轴向平移、横向平移和转动的附加质量。研究了附加质量与振荡频率、空化数、航行体头型锥角等的关系。从空泡自由面变形对流场的影响出发,对附加质量与频率的关系重新进行了解释。4)将计算方法从刚体推广到弹性体。采用有限元法计算航行体简化模型的弯曲振动模态。利用推广的边界条件和表达式,研究了带空泡航行体的各阶弯曲振动模态、弯曲振动模态间耦合以及弯曲振动模态与刚体模态耦合的附加质量,为采用干模态法解决带空泡航行体的流固耦合响应问题奠定了基础。
[Abstract]:The additional mass is an important parameter to study the maneuverability and vibration characteristics of underwater vehicle. When there is a cavitation, the attached cavitation changes the wet surface area of the vehicle, and the deformation of the cavitation surface also affects the flow field. The additional mass of a vehicle with a cavitation is quite different from that in a full wet flow. It is not only related to the shape of the vehicle, but also affected by its motion. It is of great significance to study the numerical method for this problem. In this paper, the program of three dimensional high order boundary element method is written. The additional mass of rigid body motion and bending vibration of a sailing body with cavitation is studied. The main contents are as follows: 1) the boundary surface is expressed by using non-uniform rational B-spline (Nurbs), and the unknown quantities such as strong source (sink) and dipole strong are represented by B-spline. The cubic polynomial transformation method is used to deal with the singular integral of plane elements, and the final algebraic equations are formed by collocation point method. The high order boundary element method based on NURBS is established. The reliability of the method and program is verified by calculating the additional mass in the total wet flow. (2) based on the high order boundary element method, the axisymmetric steady cavitation and flow field of underwater vehicle are calculated. According to the principle of independent expansion of cavitation, the shape of initial cavitation is calculated. The number of iterative steps is greatly reduced. The resulting cavitation morphology is in good agreement with the existing experimental and numerical results. On this basis, the head cone angle of the vehicle is studied. The effect of cavitation number on the shape of steady cavitation. 3) the method established by Uhlman is applied to the navigation body with local cavitation. The additional mass of axial translation, lateral translation and rotation are calculated in the frequency domain, and the additional mass and oscillatory frequency are studied. The relationship between cavitation number, head cone angle, etc., based on the effect of the deformation flow field on the free surface of cavitation, The relation between additional mass and frequency is reinterpreted. (4) the calculation method is extended from rigid body to elastic body. Finite element method is used to calculate the bending vibration mode of simplified model of navigational body. The generalized boundary conditions and expressions are used. In this paper, the bending vibration modes, the coupling between the bending vibration modes and the coupling between the bending vibration modes and the rigid body modes of a vehicle with cavitation are studied, and the additional mass of the coupling between the bending vibration modes and rigid body modes is studied. It lays a foundation for solving the fluid-solid coupling response problem of the vehicle with cavitation by dry mode method.
【学位授予单位】：中国舰船研究院
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TJ6;U661.1

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