涡量控制对自主推进俯仰振荡翼型推进效率的影响

用自适应多重网格法和浸没边界法对俯仰振荡翼型的自主推进进行了数值模拟.在研究翼型原地摆动和自主推进的基础上,提出了一种确定俯仰振荡翼型推力的新方法,在得到推进效率与斯特劳哈尔(Strouhal)数关系的同时,还得到了斯特劳哈尔数与雷诺数之间的关系.通过分析不同推进效率下涡量场的演化规律发现,当尾迹中有正负涡抵消时,推进效率就会降低;反之,若出现同号涡的合并时,推进效率就会提高,从而说明涡量控制过程对推进效率的影响起着决定性的作用.

Propulsion efficiency of self-propelled pitching oscillating foil under the influence of vortex control

The self-propulsion of pitching oscillating foil was numerically simulated using the adaptive multigrid and immersed boundary methods.A new method to determine the thrust of pitching oscillating foil was established on the basis of tethered and the self-propelled oscillating foil,providing the relationships of Strouhal number with both the propulsion efficiency and the Reynolds number. Finally,the relationship between vortex field and propulsion efficiency was analyzed,and it indicates that the vortex control process is one of the most important factors determining the propulsion efficiency: the propulsion efficiency decreases when positive vorticity merges into negative vorticity in the wake and increases when voticities with the same sign merges into each other.