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边界层控制:从微扰到改造

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在大雷诺数下,边界层是把双刃剑.为了保持并增强它的有利效应(如附着边界层提供的升力),并抑制它的有害效应(如摩阻、失稳和转捩成湍流、分离导致的失速和非定常旋涡流动、噪声、气动加热等),一百多年来,边界层控制一直是流动控制研究的首要任务.21世纪以来,在高性能生物流动的启发下,人们开始对边界层本身的改造,使之变成外部势流和固壁之间的低剪切隔离层,从而回归能达到极高升阻比的无旋绕流,即逼近Lighthill提出的所谓"d'Alembert定理"(而不是d'Alembert佯谬)这个战略目标.本文阐述控制和改造的物理基础,介绍了在第一阶段用微激振控制边界层分离与分离流的案例,以及在第二阶段用柔壁行波和超疏水微结构把边界层改造成低剪切隔离层的进展.同时解释了不失速的高升力产生机制.
Boundary Layer Control:from Perturbation to Transformation
At large Reynolds numbers,the boundary layer is a double-edged sword.In order to maintain and enhance its valuable beneficial effects(such as the lift provided by the attached boundary layer)and suppress its harmful effects(such as friction drag,instability and transition to turbulence,stall and unsteady vortical flow due to separation,noise,aerodynamic heating,etc.),boundary layer control has been the primary task of flow control research for more than 100 years.Since the 21st century,inspired by high-performance biological flows,people have embarked on a more physically thorough journey:The boundary layer itself is transformed into a low-shear isolation layer between the external potential flow and the solid wall,so as to return to the irrotational flow with extremely high lift-drag ratio,that is,to approach the strategic goal of the so-called"d'Alembert theorem"proposed by Lighthill(rather than the d'Alembert paradox).Based on the author's experience and understanding,this paper expounds the physical basis of the aforementioned two stages of research.The case of controlling boundary layer separation and separated flow by micro-excitation in the first stage is reviewed,and the progress of boundary layer transformed into low-shear isolation layer by flexible-wall traveling wave and superhydrophobic microstructure in the second stage is reviewed.The mechanism of high lift without stall is also addressed.

boundary layer control and transformationmicro excitationcontrol of boundary vorticity fluxd'Alembert theoremseparated flowflexible-wall traveling wavesfluid roller bearingsStokes layersuperhydrophobic microstructureshigh lift without stall

杨延涛、朱金阳、吴介之

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北京大学 工学院,北京 100871

电力规划设计总院, 北京 100120

边界层控制和改造 微激振 边界涡量流控制 d'Alembert定理 分离流 柔壁行波 流体滚动轴承 Stokes层 超疏水微结构 不失速高升力

2024

10.20118/j.issn2097-258X.2024.02.001

气动研究与试验

气动研究与试验

ISSN：
年,卷(期)：2024.2(2)
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