壁面微结构流动控制技术的减阻机理研究

On the mechanism of drag reduction of wall microstructure flow control technique

为了研究壁面微结构流动控制技术的减阻效应及其产生的原因,利用循环管路系统的方形管道进行了压降测定试验,并利用粒子成像测速仪测量了边界层内部结构和对应的参数。试验采用了沟槽和肋条两种不同类型的微结构壁面,每种形状的微结构各有3种不同的结构尺寸。试验研究结果表明:在一定的无量纲宽度s+范围内,6种不同的微结构壁面都具有减阻效果;减阻率随着s+的增大,呈现先增大后减小的趋势,其中沟槽壁面2的减阻效果最好,最大减阻率为9.90%;壁面微结构通过影响流场内部的涡结构、湍流脉动、雷诺切应力和平均流速等使得不同壁面微结构具有减阻效果。

In the present work drag reduction and its causes of wall microstructure flow control techniquehave been investigated experimentally. Pressure drop tests were carried out on a closed rectangular ductand particle image velocimetry was used to measure inner structure and corresponding flow parameters ofboundary layer. Plates with micro-grooves or micro-riblets were fixed as the floor of the duck pipe. The re-sult shows that a notable decrease in drag reduction for microstructure surfaces can be seen at a certainrange of s＋. The dag reduction rate increased first then decreased with the increase of s＋,and a maximumrag-reduction of nearly 9.9 percent was acquired over the micro-grooves surface B. Microstructure can thick-en the boundary layer and weaken turbulent fluctuation intensity. What＇s more,Reynolds shear stress,androot-mean-square velocity both decreased.