V型沟槽尖峰形状对减阻效果及流场特性影响的数值分析

The effects of the tip shape of V-groove on drag reduction and flow field characteristics by numerical analysis

采用雷诺平均N-S方程和RNGk-ε湍流模型计算V型沟槽面的湍流边界层流动和黏性阻力,研究了V型沟槽尖峰形状对减阻效果、湍流边界层内的速度分布以及沟槽壁面切应力的影响。计算结果表明,沟槽尖峰处的圆角半径越小其减阻效果越好,最大减阻率可达6.6%;沟槽斜面中下部的壁面应力随着圆角半径的减小而降低,但尖峰处的局部壁面应力会随之而增大。沟槽尖峰处生成的二次涡是产生并影响减阻效果的根本原因。

The flow in turbulent boundary layer and the viscous drag over V-groove surface are numerically simulated using the RANS formula and RNG k-ε turbulence model. The effects of the tip shape of V-groove on the drag reduction, the velocity profile in the turbulent boundary layer and shear stress on groove surface are studied. It is shown that, the smaller the fillet radius of the tip is, the better the effect of drag reduction is. And the best ratio of drag reduction that can be attained is 6.6%. As the fillet radius of the tip becomes smaller, the wall shear stress on the middle and low part of the groove surface becomes less, but the local wall shear stress on the tip becomes greater. The secondary vortices generated at the groove peaks are the fundamental reasons of the drag reduction, and the variation of the drag reduction is also caused by the secondary vortices.