壁面的表面粗糙度引起的Stokes层亚临界不稳定性

发布时间：2018-05-06 06:24

本文选题：Stokes层 + 表面粗糙度　；参考：《航空动力学报》2016年10期

【摘要】：用数值模拟的方法研究了二维壁面的表面粗糙度下Stokes层的非线性亚临界不稳定性问题.发现当粗糙度高度极小时,响应系数曲线与线性情况就会产生较大偏离.随着粗糙度高度的增加,扰动1阶谱会出现亚谐波的成分,粗糙度高度的进一步增加使扰动1阶谱进入混乱阶段,显示出亚临界失稳的过程.根据粗糙度高度与扰动1阶谱演化的特征关系,定义了临界粗糙度高度,并给出临界粗糙度高度与雷诺数的关系曲线.结果表明:临界粗糙度高度随着雷诺数增大而减小.雷诺数为300左右时,微米量级的粗糙度高度就可能引起Stokes层的亚临界失稳,发生转捩,由此也可以给出实验中观测到的转捩通常都发生在雷诺数为300附近的原因.
[Abstract]:The nonlinear subcritical instability of Stokes layer under two-dimensional surface roughness is studied by numerical simulation. It is found that the curve of response coefficient deviates greatly from the linear condition when the roughness is extremely small. With the increase of roughness height, subharmonic components will appear in the disturbance first order spectrum, and the further increase of roughness height will lead the disturbance first order spectrum to a chaotic stage, which shows the process of subcritical instability. According to the characteristic relationship between the roughness height and the evolution of the first order perturbation spectrum, the critical roughness height is defined, and the relation curve between the critical roughness height and Reynolds number is given. The results show that the critical roughness height decreases with the increase of Reynolds number. When Reynolds number is about 300, the roughness height of micron may cause subcritical instability and transition of Stokes layer. Thus, the reason why the observed transition usually occurs near Reynolds number is given.
【作者单位】：天津大学机械工程学院力学系;淮阴工学院建筑工程学院;
【基金】：国家自然科学基金(11202147,11332007) 高等学校博士学科点专项科研基金(20120032120007)
【分类号】：O35

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