【作者】 王超；

【导师】 黄胜；

【作者基本信息】 哈尔滨工程大学 ， 船舶与海洋结构物设计制造， 2010， 博士

【摘要】 随着船舶向大型化和高速化发展,船舶螺旋桨的负荷越来越重,螺旋桨及其后的舵装置都不可避免会发生空泡现象,空泡现象的出现将会降低螺旋桨的性能,产生空化剥蚀,导致船体脉动压力剧增,形成空泡噪声,使螺旋桨噪声成为船舶主要的噪声源。目前舰船声隐身性能成为造船界普遍关注的问题,螺旋桨空泡噪声作为舰船三大噪声源之一已受到越来越多的关注。本论文采用面元法理论结合CFD数值模拟技术系统地对螺旋桨的水动力性能、空泡性能以及噪声性能进行了深入的研究,开展了定常及非定常螺旋桨水动力性能数值计算方法的研究,进行了粘性流场中螺旋桨以及桨-舵之间的性能模拟及流场分析;以面元法和CFD技术为基础分析了螺旋桨的空泡性能,并对螺旋桨的无空泡噪声及空泡噪声进行了探讨。论文首先系统地阐述了船舶螺旋桨理论的发展历程,总结了国内外对螺旋桨的水动力性能、空泡性能及噪声性能等的理论、试验研究现状和发展趋势,并分析了计算流体力学软件在船舶螺旋桨相关性能预报方面的应用及前景。采用理论方法系统地研究了均匀流场和非均匀流场中螺旋桨的水动力性能预报问题,并编制了相应的数值预报程序。其中螺旋桨的定常水动力性能采用基于速度势的低阶面元法预报,非定常水动力性能采用时域方法进行求解。同时,在计算过程中,为了加快计算进度,螺旋桨的数学模型采用主桨叶方法,其他桨叶上的未知量均可由主叶片按一定相位角推算出来,且非定常性能计算时的每一时间步长的计算方法与定常性能计算基本相同。选用整体迭代法结合等压库塔条件预报了螺旋桨在均匀流场和非均匀流场中的空泡性能。计算时用格林公式导出该问题的积分方程,以运动学边界条件、动力学边界条件、无穷远条件、等压库塔条件等作为方程的定解条件。论文中分析了网格划分方式、网格数以及尾涡模型对螺旋桨表面空泡分布预报结果的影响,同时把计算结果与实验结果进行了比较,验证程序的可靠性,在此基础上,计算了非均匀来流中螺旋桨的空泡性能,考察了螺旋桨旋转一周过程中桨叶空泡分布范围的变化。采用雷诺时均(RNS)方程的求解技术对粘性流场中螺旋桨敞水性能进行了计算研究。进行螺旋桨敞水性能计算时,把周期性边界条件引入到模型建立和参数设置中。在模型建立时根据螺旋桨桨叶的不同侧斜程度分别采用直切法、斜切法和样条曲线法;同时对螺旋桨单个桨叶通道内的流场和全桨叶通道的流场进行了数值模拟,得出不同桨叶数、不同侧斜度的螺旋桨水动力系数曲线以及不同剖面处的压力系数分布。通过对采用单通道方法与采用全通道方法所得结果的对比,找出周期性边界条件的优缺点,分析了把周期性边界条件运用于螺旋桨性能计算之中的可行性。同时论文中还对CFD不确定度的验证和确认作了相应阐述,分析了CFD模拟中存在的各种误差及不确定度。选用常规螺旋桨P4381作为研究对象,开展网格收敛研究,分析CFD模拟中网格误差及不确定度占主要成分的数值误差及不确定度,并将部分数值结果与试验数据对比进行有效性确认研究。结果表明:CFD模拟的验证研究工作能够将模拟中的部分误差及不确定度量化,从而为CFD工作者改进模拟结果的工作指明方向;计算结果的有效性确认研究则能够将模拟结果与基准数据作比较研究,增强模拟结果的可信度。采用滑移网格模型结合多块混合网格划分方法对螺旋桨非定常性能以及桨-舵干扰性能进行了模拟计算。在进行非定常计算时采用边界轮廓(Boundary Profiles)来进行伴流场的试验数据的输入,通过数值计算获得了不同时刻螺旋桨桨叶表面上的压力分布云图、某截面处的压力系数分布曲线、旋转一周中试验点的压力系数变化以及螺旋桨主桨叶在旋转一周时的推力系数和转矩系数,由结果分析可知数值计算结果与试验结果以及Hoshino计算结果具有较好的一致性。通过对粘性流场中螺旋桨、舵组合体的水动力性能计算分析,得出舵的存在会使螺旋桨的推力系数和转矩系数均有相应的增加、桨-舵间距的增大使桨-舵相互干扰作用减小、舵的存在使径向与切向速度分布呈现向上下伸展的分布形状而轴向速度恰恰相反等结论。以二维水翼为研究对象,进行翼型定常空泡流的数值模拟,主要分析空泡模型、湍流模型以及壁面函数的选取对计算结果的影响,并对不同空泡数情况下产生的空泡绕流现象与实验值进行了比较分析,通过分析结果获知在进行空泡计算时各种因素参数的合理选择。同时分析了绕三维水翼空泡流动的非定常特性,模拟了空泡的初生、发展、破灭、脱落的过程,获取了空泡发展、演变过程中机翼升力、阻力随时间变化的情况。把基于RANS/LES的混合方法DES (Detached Eddy Simulation)引入到螺旋桨的空泡性能计算中来,进而依据对机翼空泡计算结论选取合适的参数对螺旋桨的空泡现象进行数值模拟计算,分析螺旋桨在均匀和非均匀来流情况下的空泡产生规律。基于CFD软件中的声学模块对螺旋桨的噪声性能进行了数值预报和分析。分别计算了螺旋桨的无空泡噪声和空泡噪声,求解了不同位置处声压谱和声功率谱的特性、噪声随距离变化的衰减特性、不同的计算步长对计算结果的影响、来流速度的变化对频谱的影响以及空泡数变化对螺旋桨相关声谱特性的影响等等。更多还原

【Abstract】 With the development of the large-scale and high speed ship, the load of ship propeller is heavier and heavier. The phenomenon of cavitation inevitably occurs on the surfaces of propeller and rudder, which will reduce the performance of the propeller, result in cavitation and erosion, bring on dramatic increasing in the hull pressure fluctuations and cavitation noise, so that the ship propeller noise becomes a major noise source of the ship. Presently, ship acoustic stealthy technique becomes a popular problem within shipbuilding research. As one of the three major noise sources, the cavitation noise of the ship propeller has become more and more attentive.In this paper, the hydrodynamic performance, cavitation performance and noise performance of propeller were studied systematically by using the method of integrating the theory of panel method with CFD numerical simulation technology. The numerical method research on steady and the unsteady hydrodynamic performance of the propeller was carried out, and the performance of the propeller and propeller - rudder in the viscous flow field was simulated and analyzed. The cavitation performance of propeller was analyzed and the non-cavitation noise and cavitation noise of propeller were discussed based on the panel method and CFD technology.In this paper, the development process of ship propellers was expounded systematically at first, which summed up the theory, experimental research status and development trends of the propeller hydrodynamic performance, cavitation performance and noise performance at home and abroad. Meanwhile, the applications and future prospects of computational fluid dynamics software in the prediction of ship propellers performance were analyzed.The prediction problem of propeller hydrodynamic performance in the uniform flow field and non-uniform flow field was studied by theory systematically, and the corresponding numerical procedures was composed, which including the steady hydrodynamic performance prediction and unsteady hydrodynamic performance prediction of propeller. The steady hydrodynamic performance of propeller was solved using low-level panel method based on velocity potential, and the unsteady one was solved using time-domain method. Meanwhile, in order to reduce computing time and reduce the computer’s storage capacity, the mathematical model of propeller will be calculated using the method of key propeller blade, the unknown parameter on the other blades can be calculated according to a certain phase angle, and the calculation methods of unsteady performance for each time step are basically the same as the calculation methods of steady performance.In the paper, the method of overall iterative combined with the uniform pressure Kutta condition was used to predict the cavity performance of propellers in uniform flow field and non-uniform flow field. The integral equation of the problem was induced by using Green’s formula, while the kinematics boundary conditions, dynamic boundary conditions, infinite conditions, uniform pressure Kutta condition were used as the determinate solution conditions. The influence of mesh partition method,mesh number and the wake model were took into account to the forecast results of the cavitation distribution in propeller’s blades. Though the comparison of the calculation results and the experimental results, the reliability of the program was validated. By the basis of comparison, cavitation performance of the propeller in non-uniform flow was calculated and the change of distribution scope on the blades was calculated during a period.The open water performance of the propeller in viscous flow field was studied by adopting solve technique of Reynolds average Navier-Stokes(RNS) equations while periodicity boundary conditions were introduced to build the model and set the parameters. Directly Cutting Method, Rake Cutting Method and Spline Curve Method were used respectively in light of different skew angles of the blades. By making numerical simulation on the open water propeller in single blade channel flow field and all blades channel flow field, propulsive performance coefficient curves of different blades and skew angles and the distribution of pressure coefficient in different sections were concluded. The advantages and disadvantages of the periodicity boundary conditions were found out by contrasting the results of single blade channel method and all blades channel method, and the feasibility of applying periodicity boundary conditions to calculate open water performance of the propeller was analyzed. In the paper, validation to the CFD uncertainty was presented and different kinds of error and uncertainty were also analyzed during CFD simulation. General propeller P4381 was chosen to develop grid convergence research and analyze the grid error and numerical error of uncertainty accounting for the bases. At last, some numerical results were compared with experimental results for studying the validity confirmation. Results indicated that the study on validation of CFD simulation could make some errors and uncertainty quantitatively described and show the way clearly for the CFD workers to improve the simulation results. On the other hand, the study of validity confirmation could be used to improve the reliability of the simulation results by comparing them with normal data.By slipping grid model combined many blocks of mixing mesh method, some numerical simulation was made on the unsteady performance of propeller and the interaction performance of propeller-rudder. In the course of unsteady calculation, Boundary Profiles were used to input the experimental data. The pressure distribution nephogram of the propeller blades at different time, the pressure coefficient distribution curve at a cross-section, the pressure coefficient change of the test point in one period as well as the thrust and torque coefficients of one blade were obtained by numerical calculation. It shows that simulation results and experimental results and Hoshino calculated results have good consistency from the results analysis. Through the hydrodynamic performance calculation and analysis of the propeller and rudder combination in the viscous flow, it can be seen that the presence of the rudder will come to a corresponding increase in both the propeller thrust coefficient and torque coefficient and the increasing of distance between the propeller and rudder will decrease the interaction and the presence of the rudder will make the radial and tangential velocity distributions take on extending up and down while the axial velocity distribution has the opposite conclusion and so on.The numerical simulation of the Two-dimensional hydrofoil in steady cavitation flow was made. The impact of cavitation model, turbulence model and wall function selection on the calculation results was analyzed. The comparison between the calculative results in different cavitation number and experimental data was also analyzed. Various factors and parameters selection during cavitation calculation could be obtained though analyzing the results. At the same time, unsteady characteristics of cavitation flow around the three-dimensional hydrofoils were analyzed。The inception, development, burst, shedding process of the cavitation around the three-dimensional hydrofoils was simulated, and the change of wing lift and resistance with time in the course of cavitation development and evolvement was numerical calculated. DES (Detached Eddy Simulation) was introduced into the cavitation performance calculation of the propeller, which is the mixing method based on RANS/LES. The appropriate parameters to made numerical simulation calculation of the propeller cavitation phenomenon was selected in light of the results of aerofoil cavitation calculation. Lastly, the cavitation performance of propeller in uniform and non-uniform flow was analyzed. Based on the acoustics module of CFD software, numerical prediction and analyses were made on the noise performance of the propeller. The noise of propeller with and without cavitaion was calculated respectively. The sound pressure level and sound power spectral density in different positions, the noise attenuation characteristics with distance changing, the impact of the different calculation steps on the calculation results, the impact of velocity changes in flow on frequency spectrum as well as the impact of change of the cavitation number on the acoustic spectral characteristics related to the propeller and so on were solved in the paper.更多还原