Effects of Unsteady Deformation of a Flapping Wing on Its Aerodynamic Forces
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摘要: 通过在动态变形网格上求解N-S方程的方法,研究了昆虫拍动翅的非定常变形对其气动力的影响.其中,拍动翅的扭转变形对气动力影响很小,拱形变形则会产生显著的影响,扭转和拱形组合变形的效果与拱形变形单独的效果基本相同.在6%拱形和20度扭转组合变形的情况下(此为对大量昆虫观察所得到的典型值),相对于无变形平板翅,升力增加了10~20%,升阻比增加了约10%.翅膀的变形可增大最大升力系数;同时,可减小飞行的能耗,例如,对于做悬停飞行的熊蜂,其翅膀的动态变形(6%拱形和20度扭转组合变形)使其飞行中的能耗比无变形情况降低了约16%.Abstract: The effects of unsteady deformation of a flapping model insect wing on its aero dynamic force production were studied by solving the Navier-Stokes equations on a dynamically deforming grid. Aerodynamic forces on the flapping wing are little affected by consider abletwist, but are affected by camber deformation; the effect of combined camber and twist deformation is similar to that of camber deformation. With a de formation of 6% camber and 20 degrees twist (typical values observed forwings of many insects), lift is increased by 10~20% and lift-to-dragratio by around 10% compared with the case of rigid flat-plate wing. As a result, the deformation canincrease the maximum lift coefficient of aninsect, and candecrease its power requirement of flight, e. g., for a hovering bumblebee with dynamically deforming wings (6% camber and 20 degrees twist), aerodynamic power required is de creased by about 16% compared with the case of rigid wings.
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Key words:
- insects /
- wing deformation /
- unsteady aerodynamic forces /
- computational fluid dynamics
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