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首页> 外文期刊>Journal of Bionics Engineering >The Mechanism of Drag Reduction around Bodies of Revolution Using Bionic Non-Smooth Surfaces
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The Mechanism of Drag Reduction around Bodies of Revolution Using Bionic Non-Smooth Surfaces

机译:仿生非光滑表面在旋转体周围的减阻机理

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摘要

Bionic non-smooth surfaces (BNSS) can reduce drag. Much attention has been paid to the mechanism of shear stress reduction by riblets. The mechanism of pressure force reduction by bionic non-smooth surfaces on bodies of revolution has not been well investigated. In this work CFD simulation has revealed the mechanism of drag reduction by BNSS, which may work in three ways. First, BNSS on bodies of revolution may lower the surface velocity of the medium, which prevents the sudden speed up of air on the cross section. So the bottom pressure of the model would not be disturbed sharply, resulting in less energy loss and drag reduction. Second, the magnitude of vorticity induced by the bionic model becomes smaller because, due to the sculpturing, the growth of tiny air bubbles is avoided. Thus the large moment of inertia induced by large air bubble is reduced. The reduction of the vorticity could reduce the dissipation of the eddy. So the pressure force could also be reduced. Third, the thickness of the momentum layer on the model becomes less which, according to the relationship between the drag coefficient and the momentum thickness, reduces drag.
机译:仿生非光滑表面(BNSS)可以减少阻力。人们对肋状筋减少剪切应力的机理给予了很多关注。旋转体上的仿生非光滑表面降低压力的机理尚未得到很好的研究。在这项工作中,CFD仿真揭示了BNSS减少阻力的机制,这可能以三种方式起作用。首先,旋转物体上的BNSS可能会降低介质的表面速度,从而防止横截面上的空气突然加速。因此,不会严重干扰模型的底部压力,从而减少了能量损失并减少了阻力。第二,仿生模型引起的涡度变小,因为通过雕刻避免了微小气泡的增长。因此,减小了由大气泡引起的大惯性矩。涡度的降低可以减少涡流的耗散。因此,压力也可以减小。第三,模型上动量层的厚度变小,根据阻力系数和动量厚度之间的关系,减小了阻力。

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