中文摘要：

自行设计制造了一台低Re数循环水洞试验台,收缩段采用维辛斯基（Witozinsky）曲线设计。变频电机调速,试验段流速范围0 2～1.0 m/s。用一维LDV系统测量了水洞试验段入口中心处的流速和湍流度随电机频率的变化,和来流速度为U∞=0.26 m/s的平板湍流边界层速度和湍流度分布;并用PIV系统检测边界层内层低速条带结构。试验结果表明,试验段入口湍流度随着流速增大而下降,放置于试验段的平板其边界层已达到充分发展状态,并且检测到其底层低速条带结构,试验台可用于湍流边界层流动结构测试研究。

英文摘要：

A low Re recycled water tunnel with a 1.5 m-long working section of 0.3 m×0.3 m is designed,manufactured and tested.The contraction section adopts the Witozinsky curve.The velocity in test section can be changed in the range of U_∞=0.2 to 1.0 m/s by a variable-frequency pump.A Laser Doppler Velocimeter（LDV） is used to determine the relation curve between the pump running frequency and the mean velocity and longitudinal turbulence intensity at inlet center of the test section.Furthermore,for a turbulent boundary layer developed from a flat plate placed in the test section,the mean velocity and longitudinal turbulence intensity distribution in normal direction are measured by the LDV,and the low-speed streaks in the buffer layer are investigated with a Particle Image Velocimeter（PIV）.The results indicate that the mean velocity in the test section has an approximately linear relation with the pump running frequency.The longitudinal turbulence intensity decreases with increasing velocity,when U_∞0.7 m/s,the turbulence intensity is less than about 2.6%.A fully developed flat plate turbulent boundary layer flow is obtained in the water tunnel,and its low-speed streaks at buffer layer are studied by PIV.