八重准周期排列的短沟槽结构减阻机理分析

设计构建了一排和三排阵列的八重准周期短条纹沟槽减阻结构,以及作为对比研究的无序和周期结构,并采用雷诺Navier-Stokes方程和RANGκ-ε湍流模型,系统计算了这些结构表面的湍流边界层状态和总应力,模拟结果显示:八重准周期沟槽结构相对于周期和无序结构具有更优的减阻效应,且为三排阵列时的减阻效果明显优于单排阵列,这一结果得到了减阻实验的验证,通过分析比较不同结构的流体边界层特性发现,八重准周期结构可有效抑制附面层的涡强度,减小湍流耗散速率,保持流体条纹相的稳定性,结合二维光栅的夫琅禾费衍射波模型分析表明,八重准周期结构可减弱衍射谱在大角度方向上的谱强度,揭示出该结构抑制流体相干扰动波扩展的物理机制,并与流场分析结果相符合。

Drag reduction mechanisms of 8-fold quasi-periodic short groove structures

We design two types of 8-fold quasi-period short groove structures which are arranged in single row and three rows respectively The flow field in the turbulent boundary layer and the total stress over these groove surfaces are numerically simulated by using Reynolds average Navier-Stokes equation and turbulence model. It is shown that the 8-fold quasi-periodic structure has good drag reduction effect compared with the periodic and disorder structures, especially for structure arranged in three rows. The results are also confirmed by the sheer stress measurements which are performed on substrates with the designed structures. By analyzing the distribution of flow field, we find that the quasi-periodic structure effectively inhibits the intensity of vortex, reduces the turbulent dissipation rate, and keeps the stripe phase stable. Furthermore, by using the two-dimensional grating model, it is found that the 8-fold quasi-periodic structure can reduce spectrum intensity in the large angle direction, revealing that the inhibition of the extension of coherence disturbance waves is responsible for the drag reduction effect, which is also confirmed by the flow field analysis.
Keywords： groove structure vortex strip phase 8-fold quasi-period