Ocean Engineering ( IF 5 ) Pub Date : 2021-04-01 , DOI: 10.1016/j.oceaneng.2021.108901 Xiao-Dong Bai , Ji-Sheng Zhang , Jin-Hai Zheng , Yong Wang
To promote energy extraction efficiency, an active deformation method to implant an elastic airbag at the leading edge of flapping wings is proposed in this study. The charging and discharging processes of the airbag are accomplished by sinusoidally adjusting the local deformation angle. We investigated numerically the effect of both the reduced frequency and the local deformation amplitude on the energy extraction efficiency with the chord based Reynolds number . Our results show that as the reduced frequency increases, the energy extraction efficiency of flapping wings with various local deformation first rises and then drops with a maximum energy efficiency around 0.4. Energy extraction efficiency via local deformation of the leading edge can be enhanced up to 25%, compared with the non-deformed flapping wing in the lower reduced frequency range. Analysis on flow field and the working coefficients indicates, due to the airbag deformation, the leading edge vortex is more closely attached to the suction side of the flapping wing with larger local deformation elastic airbag ( =20 and 25), inducing more preferable pressure distribution and higher power coefficients with less oscillation throughout the motion cycle.
中文翻译:
具有主动弹性安全气囊变形的前襟翼的能量提取性能
为了提高能量提取效率,本研究提出了一种主动变形方法,在襟翼的前缘处植入弹性气囊。通过正弦调整局部变形角度可完成安全气囊的充放电过程。我们从数值上研究了降低频率的影响 和局部变形幅度 基于和弦的雷诺数的能量提取效率 。我们的结果表明,随着频率的降低 增加,具有各种局部变形的襟翼的能量提取效率 首先上升,然后下降,最大能效约为0.4。与较低频率范围内未变形的襟翼相比,通过前缘局部变形的能量提取效率可提高高达25%。对流场和工作系数的分析表明,由于气囊变形,前缘涡流更紧密地附着在襟翼的吸入侧,而局部变形弹性气囊更大( = 20 和25),从而在整个运动周期内产生更佳的压力分布和更高的功率系数,并且振动更少。