回转体微沟槽面湍流边界层流动实验测量

Experimental measurement of the turbulent boundary layer flow of gyroidal objects with microgrooves surfaces

为了揭示具有减阻功能的沟槽面湍流边界层与光滑面湍流边界层流动的差异,结合粒子图像测速技术对流场无干扰及高精度全场测量的技术优势,在拖曳水池中,采用随车式PIV测量系统,开展了水下回转体分别粘贴微沟槽薄膜和光滑薄膜时的壁面湍流边界层流动显示及速度测量试验,对比分析了微沟槽薄膜湍流边界层和光滑薄膜湍流边界层的速度、速度梯度和流线分布图,说明了微沟槽对湍流边界层流动特征的影响规律:微沟槽薄膜有利于保持回转体壁面边界层流动的稳定,能够减少壁面涡的强度和发生频率,并降低近壁面区的速度梯度.

This paper compares the differences in turbulent boundary layer flow over grooved surfaces with reduced-drags function and smooth surfaces. Flow visualization and velocity measurement experiments on the turbulent boundary layer flow around the smooth and grooved surfaces of gyroidal objects were carried out in a towing tank by using a PIV measurement system mounted on the towing carriage. The patterns of velocity, velocity gradient, and streamline of the turbulent boundary layer around the grooved surface were compared with those around the smooth surface. The research results show that microgroove surfaces help maintain stability of the boundary layer flow of a gyroidal object, by decreasing the intensity and the occurring frequency of surface vortex, as well as reducing the velocity gradient near the surface. These results can be used to analyze the influence of microgrooves on the characteristics of the turbulent boundary layer in depth.