Development of Strategies for Flow Management and/or Re-arrangement

许多工业产品都含有流动系统，其性能会影响产品的整体性能，特别是其运行的能源成本。能源成本的降低可以通过适当控制/管理/重新安排这些系统内的流量来实现。目前的工作集中于开发利用弱执行器模式的控制技术，这些弱执行器模式独立地无关，但如果以空间模式布置，则可以以决定性的方式影响流动。由于执行机构系统产生分布式强迫，因此确定它们最有效的模式并确定这些模式可以实现什么是这项工作的目标。层流、过渡流和湍流是以被动技术为目标的，因为它们很简单，而且没有容易发生故障的运动部件。*将考虑使用能够产生所需分布强迫的各种物理现象。这包括表面地形的设计、表面加热/冷却模式的确定、表面蒸腾模式的调查以及表面振动模式的研究。强迫产生了直接的流动响应，即空间调制，这可能导致其本身的减阻。同样的强迫可以产生间接的响应，其中流动调制改变流动的稳定性，并且系统分叉到具有非常小的外部激励的新状态。将确定这两种类型的答复以及在什么条件下可以取得什么成果。*拟议的工作分为六个主题。第一个主题将决定层流-湍流转变过程对分布表面存在的容忍度。第二个主题将确定在层流和湍流中可以产生较小摩擦阻力的表面地形。第三个主题将确定既能减少摩擦阻力又能控制层流-湍流转变的表面地形。第四个主题将使用加热和波纹模式来控制对流换热，目标是更高效的热交换器。第五个主题将着眼于使用表面粗糙度和加热模式控制相变过程，目标范围从控制翼型结冰到极热表面的冷却。第六个主题将确定如何利用表面振动模式来达到减阻和开发替代推进方案的目的。主题(A)-(C)将使航空航天工业受益，从而提高其竞争力。主题(D)-(E)将使能源和加工业受益，有可能导致新产品的开发。主题(E)将协助参与开发水艇的实体，消除一些限制推进的因素。

Many industrial products contain flow systems whose performance affects the overall product capabilities, especially the energy cost of their operation. Reduction of the energy cost may come through the proper control/management/re-arrangement of flows within these systems. The present work is focused on the development of control techniques taking advantage of patterns of weak actuators which are individually irrelevant but can affect the flow in a decisive manner if arranged in spatial patterns. Since systems of actuators produce distributed forcing, identifying their most effective patterns and determining what can be achieved with these patterns are the goals of this work. Laminar, transitional as well as turbulent flows are targeted with priority given to passive techniques due to their simplicity and lack of failure-prone moving parts.*** The use of various physical phenomena capable of producing the desired distributed forcing will be considered. This includes the design of surface topography, determination of patterns of surface heating/cooling, investigation of patterns of surface transpiration as well as studies of patterns of surface vibrations. The forcing creates a direct flow response, i.e. spatial modulations, which may lead to the drag reduction by itself. The same forcing may create an indirect response where the flow modulations change the flow stability and the system bifurcates to a new state with a very minimal external actuation. It will be determined what can be achieved with both types of responses and under what conditions.*** The proposed work is divided into six themes. The first theme will determine the tolerance of the laminar-turbulent transition process to the presence of distributed surface. The second theme will identify surface topographies which can produce smaller friction drag in laminar as well as in turbulent flows. The third theme will identify surface topographies which both reduce frictional drag and control the laminar-turbulent transition. The fourth theme will use heating and corrugation patterns to control convective heat transfer with the more efficient heat exchangers being the goal. The fifth theme will look at the control of phase change processes using surface roughness and heating patterns with goals ranging from the control of airfoil icing to cooling of extremely hot surfaces. The sixth theme will determine how patterns of surface vibrations can be harnessed for drag reduction purposes and development of alternative propulsion schemes. Themes (a)-(c) will benefit the aerospace industry, resulting in the increase of its competitiveness. Themes (d)-(e) will benefit the energy and processing industries, potentially leading to the development of new products. Theme (e) will assist entities involved in the development of water crafts, removing some of the propulsion limiting factors.