Numerical Analysis of Hydrodynamic Performance of Finite Span Hydrofoil

对有限跨度水翼的水动力性能和流动情况进行了数值和实验研究。结果表明：升力体理论得到的升力、阻力和压力分布与实验结果吻合较好，除非在水翼表面发生较大的边界层分离。然而，该理论不能解释边界层及其与叶顶涡的关系等流动情况的细节。在低雷诺数为1000的情况下，进行了两种有限差分计算。选择了自由表面和空化条件等几种计算条件。并与实验结果进行了比较和讨论。为今后有限跨水翼的水动力研究指明了CFD研究的方向。对自由水面下的水翼进行了计算，结果表明水翼的起波作用和自由水面下升力的减小。结果表明，叶尖涡有两个核，分别由上下表面的两个边界层引起。计算了叶顶涡的上升过程和叶顶涡分离过程。计算得到的箔表面空化现象与实验结果相似，但由于雷诺数差异较大，无法得到定量的一致。测量结果表明，叶顶涡的半径很小，仅为最大弦长的1%，转速很高，可达均匀流速度的0.6倍以上。为了计算高雷诺数流动并对叶顶涡进行详细的讨论，除了湍流模型外，可能还需要一个解自适应网格、多网格系统或一些叶顶涡的建模。

Made were the numerical and experimental investigations on the hydrodynamic performance and flow situations of a finite span hydrofoil. The following results were obtained :The lift and drag forces and the pressure distribution obtained by the lifting body theory agreed well with those of the experiments unless the large boundary layer separation occurred on the hydrofoil surface.This theory, however, could not argue the details of the flow situations such as boundary layer and its relation to the tip vortex.Two kinds of finite difference calculations were made with a low Reynolds number of 1, 000. Some kinds of calculation conditions were selected such as with free surface and with cavitation. The results were compared and discussed in detail with the experimental ones. As a result the future works of the CFD research were clarified on the hydrodynamic study of finite span hydrofoils.The calculation of a hydrofoil under a free surface showed the wave-making due to the foil and the lift force decrease due to the free surface.It was shown that the tip vortex had two cores caused by the two boundary layers on the foil upper and lower surfaces, respectively. The rolling-up to the tip vortex and the tip vortex separation were also calculated.The calculated cavitation on the foil surface had similar appearance to that of the experiments although the quantitative agreement could not be obtained because of the large difference in the Reynolds numbers.The measurements showed that the tip vortex had a very small radius of 1% the maximum chord length and a high rotation speed of over 0.6 times the uniform flow velocity. A solution adaptive grid, multi-grid system or some modeling of the tip vortex might be required in addition to the turbulence model, in order to calculate a high Reynolds number flow and argue the tip vortex in detail.