三维滑行艇模型流体动力.doc

摘要

随着对于高速海上交通工具的需求的增长，出现了很多先进的船体型式的设计。滑行艇滑行过程中能够产生动升力，而且能有效减小兴波阻力,在同样的主机功率下能够得到很高的速度。相比于普通船型，具有显著优势。滑行艇的水动力性能与安全性紧密相关，由于滑行艇在航行时常处于不同的滑行状态,阻力成分及各成分的比例变化复杂，使滑行艇水动力性能的研究远较常规排水船困难,目前尚有大量未解决的问题。
应用计算流体力学软件Fluent探讨不同攻角、不同体积傅汝得数下的三维滑行艇静水直航水动力特性及流场分布，并与经验公式估算值相比较，分析滑行艇的水动力性能变化情况。通过简化的数值模型与计算控制程序相结合，数值模拟滑行艇的升沉纵摇耦合运动，进行不同航行阶段：排水航行阶段、过渡阶段和滑行阶段下的滑行艇运动响应比较分析，探讨滑行艇从初始状态开始航行过程中的姿态调整，包括艇体重心位置的变化及航行中纵摇角的变化量，并将计算结果与固定姿态计算结果进行比较分析。以斜航试验为基础，建立不同漂角下计算模型并运用流体力学软件Fluent展开了滑行艇在滑行状态下的数值模拟，包括计入风载荷作用工况，对不同漂角三维滑行艇模型在滑行状态下的阻力性能进行比较分析。对数值结果进行计算处理，得到水动力系数测定曲线，为滑行艇水动力系数的数值测定提供了一种摆脱实验条件限制的参考方法。对滑行艇水动力性能研究由一定的实际意义和参考价值。
目前，对于滑行艇的水动力性能研究还是个较困难的问题，通常都是船模试验来解决。但是滑行艇的操纵性试验由于模型小、航速高，试验条件较为苛刻，这部分研究并不够充分。通过CFD方法研究，能科学的模拟计算其航行情况，克服了试验的局限性，而且，在研究中将空气和水结合起来考虑，更符合实际情况，对进一步深入研究滑行艇水动力性能有重要意义。随着数值模拟技术的发展，用数值方法模拟滑行艇的运动状况来研究其运动性能，将成为具有重要意义的解决方案。本文的研究内容和方法为滑行艇水动力性能研究提供了可靠的数值计算模型，提出了一些经验及建议，为今后的研究起到铺垫作用。

关键词：三维滑行艇；水动力特性；运动响应；不同攻角；不同漂角；数值模拟



Abstract

Lots of advanced designs of hull form appear as the demand for high-speed marine vehicles increases. The planning ship can produce dynamic lift force during the planning process which can effectively reduce the wave making resistance and get higher speed under the same power of main motor. The planning ship has remarkable advantage in comparison with other hull forms. Hydrodynamic performance are closely interconnected with the safety of planning ship. The change of components of resistance force and the relative size of each item included in total is complex because of the planning ship is always in different movement state, so the research of hydrodynamic characteristics is much more difficult than other regular displacement type vessel, and there are still lots of problems unsolved.
This research focuses on the application of numerical simulation method which is used to study the changes of hydrodynamic force of 3D planning ship. Hydrodynamic performance of 3D planing ship was numerically simulated using computational fluid dynamics software FLUENT. Hydrodynamic characteristics of 3D planing ship model at two different attack angles and different Froude numbers were calculated. Results were compared with theoretical eva luation results and show good agreement. The surrounding flow field of planing ship during the motions was numerically simulated. By combining the simplified numerical model and computational control program, the heave-pitch coupled motion of planing ship was numerically simulated. Motion response of planing ship under different movement states was compared and analyzed. Curves of centre-of-gravity position and pitch angle were given in the paper and numerical results were compared with results of planing ship moving with fixed attitude. Based on loxodromic towing test, computational models of different drift angles were established and numerical simulation was carried out using Fluent. Resistance performance of planing ship under different drift angles were compared and analyzed. Curves about testing the hydrodynamic coefficients were presented. The study supplied a reference approach for hydrodynamic coefficient test which could get rid of the limit of experiment condition and had great significance in the research of hydrodynamic performance of planing ship.
At present, research on hydrodynamic performance of planing ship still has many unsolved problems which are always sloved by ship model test. Maneuvering test on planing ship is limited by experimental conditions because of the high speed of planing ship. Research in this field is not enough. So by the use of computational fluid dynamics, motions of planing ship can be scientifically simulated and calculated., Results are in accordance with the practice by combining air and water in the study. The method used in this paper has great significance for further study of hydrodynamic performance of planing ship. With the development of numerical simulation technology, the numerical simulation method will be more and more used in the research about motions of planing ship. This paper investigates applications of numerical simulat..