圆柱体减阻技术及其机理初步研究

利用氢气泡显示技术观测空心圆柱体在开有不同数目的细缝以及细缝在不同的攻角情况下的流态,对此类空心圆柱体的减阻机理进行了初步探讨.细缝是否改变了圆柱体的尾迹流场是其能否减阻的主要判据,据此得到细缝的攻角 α满足|α|≤60°时可以降低圆柱体的阻力,且当|α|=20°时,效果最佳.此时位于下游的细缝将产生明显的二维射流,极大地影响尾迹的流态.而当细缝的攻角满足70°≤|α|≤90°时,细缝对阻力几乎没有影响. 

Drag Reduction Technique of Cylinder and Mechanism Research

The hydrogen bubble flow visualization technique has been used to study the flow around a hollow circular cylinder with several splits and the drag reduction mechanism. The experiments cover the cylinder with different number and arrangement of splits, different angle of attack. The primary criterion of drag reduces is whether the splits change wake of the hollow cylinder. According to this criterion, the experimental result indicates when the attack of a split is in the range of |α|≤60°, the cylinder possesses drag reduction characteristics, and the optimum angle of attack is 20°. Under this condition, a two-dimensional jet flow is visible in the downstream split, which affects the wake flow pattern. However, when the attack of the split is equal to 70°≤|α|≤90°, the split can hardly affect the drag of the cylinder.