Dynamical Management of Boundary Layer with Manipulating Hierarchy Structure of Turbulent Eddy

通过在壁层中引入一对直径和强度随时间变化的流向涡，对壁面边界剪切流的管理进行了实验研究。重点考察了管理对湍流层级结构的影响在壁层的自相似性中的表现。在边界层、二维槽道流动和湍流壁面射流三种壁面湍流中进行了实验研究。从实验研究中获得的结论总结如下：1.结果表明：1.在逆压梯度作用下，边界层的壁层存在分层结构和壁面规律。在平面湍流壁面射流的内层引入了一对直径和强度随时间变化的流向涡。结果表明，在实际应用中管理是有效的，流向动量通量增加，并向t…输送。他的墙更多了。由直径和强度随时间变化的流向涡管理的壁面切变流动比没有随时间变化的流向涡恢复得更快。可以理解，随时间变化的流向涡类似于未受扰动的壁层中的湍涡。利用相平均技术和瞬时脉动速度分量的三重分解，详细研究了周期速度分量在动力学中的作用。对雷诺切应力和湍流能量方程中涉及的产生项的评估表明，周期分量对动量和能量平衡有相当大的贡献。通过三重分解对能量传输的研究表明，考虑大尺度运动的非局地效应的涡粘性模型是有效的。实验研究表明，考虑了分层结构的流向涡处理后，剪切层恢复到相似剖面的速度更快，同时增强了自由流流体的卷吸和向壁面的动量输送。较少

An experimental study has been made on management of wall bounded shear flows by introducing a pair of streamwise vortex, with temporal variation in diameter and strength, into the wall layer. The focus was placed to see what effects of the management on the hierarchical structure of turbulent eddy emerge in the self-similarity in the wall layer. Experimental work was made in three kinds of the wall turbulence, namely, boundary layer, two-dimensional channel flow, and turbulent wall jet. Concluding remarks obtained from the experimental study are summarized as follows.1. Under a adverse pressure gradient, hierarchical structure and existence of the wall law is confirmed in the wall layer of boundary layer.2. A pair of streamwise vortex with temporal variation in diameter and strength was introduced into the inner layer of plane turbulent wall jet. It is seen that the management is effective for use of practical application; streamwise momentum flux is increased and transported toward t … More he wall.3. The wall bounded shear flow managed by the streamwise vortex with temporal variation in diameter and strength recovers faster than the streamwise vortex without the temporal variation. It is understood that the streamwise vortex with temporal variation is resemble to turbulent eddies in undisturbed wall layer.4. Detailed study on the effect of periodic velocity components in dynamics was performed with phase averaging technique and triple decomposition of instantaneous fluctuating velocity components. Evaluation of production terms involved in Reynolds shear stress and turbulent energy equations shows considerable contribution of periodic component to momentum and energy balance.5. Investigation of energy transport with the triple decomposition suggests validity of eddy viscosity model considering non-local effect due to large scale motion.The experimental study shows that, with management of streamwise vortex considering the hierarchical structure, the shear layer recovers faster to similarity profile and enhances both entrainment of the free stream fluid and momentum transport toward the wall. Less