摆动方式对水翼输入功率的影响

利用投影浸入边界法,研究了不同主动摆动方式对水翼输入功率的影响。计算模型采用二维NACA0012翼型,雷诺数Re=800。最大摆角θ0=75°,摆动频率f的变化范围为0.1Hz~0.2Hz,非正弦摆动参数β的变化范围为1~3。首先,研究摆动频率f和非正弦摆动参数β对平均输入功率的影响,研究发现,平均输入功率随着f和β值的增加而增加,但当f0.16 Hz,β2.5时,平均输入功率急剧增加。其次,在摆动频率f=0.16 Hz时,研究不同非正弦摆动参数β下力矩系数、输入功率系数以及升阻力系数随时间的变化规律,研究发现,随着β值的增加,峰值输入功率也逐渐增加,而且β值影响峰值输入功率出现的位置。最后,研究不同β值下,变化的尾流发展对输入功率的影响,认为水翼上下表面产生的后缘涡与升阻力有关系,水翼上表面的负涡对水翼摆动产生阻力,而下表面的负涡对水翼摆动产生升力,从而对水翼摆动的输入功率产生影响。

Effects of different flapping ways on input power of a hydrofoil

A projected immersed boundary method is used to simulate a flapping foil ,w hich is a two-dimensional NACA0012 hydrofoil with Reynolds number Re=800 .The influence of the input power in different flapping ways is studied .The maximum pendulum angleθ0 is 75° ,the frequency f is from 0 .1 Hz to 0 .2 Hz and the non-sinusoidal pendulum parameter is from one to three .The results show that , firstly ,the averaged input-power coefficient increases with parameters f and β,however ,it undergoes a rapid ascent when f >0 .16 Hz ,β>2 .5 .Secondly ,the maximum input-power coefficient also increases with βat f=0 .16 Hz ,moreover ,the location of maximum input-power coefficient is related to β.Finally , lift force and drag force are connected with trailing edge vortex .Specifically ,the negative vortex on the top surface produces resistance ,and the negative vortex on the bottom surface induces lift force ,which affects the input power of the flapping hydrofoil .