船舶螺旋桨水动力及空泡性能的预测

发布时间：2019-05-21 23:16

【摘要】：螺旋桨因其优良的性能，是目前船舶领域使用最普遍的推进器。海上运输和军用舰船发展日益繁荣的现代社会，各种新型船和高性能船相继出现，船舶发展趋于大型化、高速化。随着船舶主机不断往高转速和大功率发展，空泡引起的桨舵剥蚀、螺旋桨噪声和船舶振动问题变得日益突出。流体的空化是一种复杂的物理现象，涉及到相变、表面张力、湍流、非均匀热力学效应等问题。空化也可认为是在一定温度下由于水动力学压力的减小引起的液体的相变的流体流动现象。空化泡会经历发生、溃灭，其过程是迅速且剧烈的，从而会导致腐蚀、震动、噪声。本文围绕螺旋桨的水动力性能和空化问题展研究，主要的工作有：详细地描述了螺旋桨的几何参数，提出了切面数据的生成方法，利用NURBS曲线拟合桨叶切面，再由拟合的曲线生成蒙皮NURBS曲面，最后总结提出了参数化建模方法及其基本工作流程。采用了单方程Spalart-Allmaras模型和两方程k-ε RNG模型、 k-ω SST三个典型的湍流模型对二维水翼(NACA66mod)的空化进行了计算。结果表明SST湍流模型能模拟出空泡流的更多细节特征，比如可以观察到明显回射流，再对比了Zwart-Gerber-Belamri和Schnerr-Sauer空化模型，发现后者具有更高的精度和适应性。在基于LES方法的二维水翼动态空泡流的模拟中，得到了典型的片状空泡脱落过程，空泡脱落周期为0.29比较接近0.28的试验值，，空泡闭合区的回射流是导致空泡脱落的主要原因，而涡结构则影响脱落空泡的形态。对螺旋桨全湿流和空泡流水动力性能计算中发现两者的结果十分吻合，说明局部空泡不影响桨旋桨的宏观水动力性能。在全流道和单流道模拟中，水动力性能与试验值的误差在8%以内，全流道计算的推力系数和扭矩系数与试验的误差比单流道计算的较小，但是单流道得到空化区大小更接近试验。
[Abstract]:Propeller is the most commonly used thruster in ship field because of its excellent performance. In the modern society with the increasingly prosperous development of maritime transportation and military ships, all kinds of new ships and high-performance ships have emerged one after another, and the development of ships tends to be large-scale and high-speed. With the development of high speed and high power of ship main engine, the problems of propeller rudder denudation, propeller noise and ship vibration caused by cavitation have become more and more prominent. Cavitation of fluid is a complex physical phenomenon, which involves phase transition, surface tension, turbulence, inhomogeneous thermodynamic effect and so on. Cavitation can also be considered to be the fluid flow phenomenon of liquid phase transition caused by the decrease of hydrodynamic pressure at a certain temperature. Cavitation bubbles will experience occurrence and collapse, the process is rapid and violent, which will lead to corrosion, vibration, noise. In this paper, the hydrodynamic performance and cavitation of propellers are studied. The main work is as follows: the geometric parameters of propellers are described in detail, the generation method of section data is put forward, and the blade section is fitted by NURBS curve. Then the skinned NURBS surface is generated from the fitted curve. Finally, the parametric modeling method and its basic work flow are summarized. The cavitation of two-dimensional hydrofoil (NACA66mod) is calculated by using three typical turbulence models: single-equation Spalart-Allmaras model and two-equation k-蔚 RNG model and k-蠅 SST model. The results show that the SST turbulence model can simulate more details of the bubble flow, such as the obvious return jet can be observed, and then the Zwart-Gerber-Belamri and Schnerr-Sauer cavitation models are compared, and it is found that the latter has higher accuracy and adaptability. In the simulation of dynamic cavitation flow of two-dimensional hydrofoil based on LES method, a typical flake cavitation shedding process is obtained. the experimental value of cavitation shedding period of 0.29 is close to 0.28. The backjet in the closed zone of cavitation is the main cause of cavitation shedding, while the vortex structure affects the morphology of falling cavitation. It is found that the results of the total wet flow and the cavitation flow dynamic performance of the propeller are in good agreement with each other, which indicates that the local cavitation does not affect the macroscopic hydrodynamic performance of the propeller. In the simulation of full channel and single channel, the error between hydrodynamic performance and test value is less than 8%, and the error between thrust coefficient and torque coefficient calculated by full channel and test is smaller than that calculated by single channel. However, the size of cavitation zone obtained by single channel is closer to the test.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U664.33;U661.1

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