翼尖形状对小展弦比摆翼水动力性能的影响

In this paper, some oscillating foil propulsors with an aspect ratio of 2 and different wing tip structures were designed. The numerical method was used to study the effects of different wing tip shapes on thrust, efficiency and wake structure of oscillating foil. Different mesh topology, time step, turbulence model and convergence of computation were verified to ensure the reliability of the numerical simulation method. As can be seen from the results of verification, the mesh subdivision and time step have a great influence on the simulation results of flow separation, which further affect the efficiency of the propulsor. Then different wing tip shapes were studied firstly, the vertical tip, the round tip and the endplate tip were compared in next progress. The results indicate that the endplate can reduce the tip vortex loss, but the driving force of propulsors increases at the same time, so the improvement of the endplate tip foil is not achieved as expected. Furthermore, there is a regular phenomenon that with the increase of yaw angle amplitude, the peak efficiency of propulsor improves first and then decreases. It is found that the elliptical hydrofoil has the best performance when compared among the different wing tip contraction forms. The efficiency of this shape of propulsor is about 3% higher than those of other shapes, reaching 76.5%. In short, the more acute the tip contraction is, the worse the performance of propulsor is.