脊状表面减阻特性的风洞试验研究

Experiment Investigation on the Drag-reduction Characteristics above Riblet Surface in Wind Tunnel

利用热线风速仪,对光滑表面和多个脊状表面在低速风洞中进行了表面流场测试。基于测得的边界层速度分布数据,利用对数律区速度分布公式,编程分别计算出光滑表面和脊状表面的壁面摩擦速度和虚拟原点。研究发现,脊状表面最大减阻量达13.5%;有减阻效果的脊状表面使边界层速度曲线上移、湍流强度下降;与光滑表面相比,脊状表面的位移厚度和动量损失厚度明显减小,也表明脊状表面具有减阻效果;位移厚度和动量损失厚度减少量随槽间距s+的增加呈现先变大后变小的趋势,在s+=12时达到最大。

Exterior flow field measurement above smooth and different riblet surfaces was carried out in a low speed wind tunnel by means of hot-wire anemometry. Wall friction velocity and virtual origin of smooth and riblet surface were obtained respectively based on the measured velocity distribution and velocity distribution formula of logarithm region. Results show that drag reduction of the riblet surface can reach 13.5 percent; velocity distribution curve of boundary layer moves up and turbulent intensity descends evidently on riblet surfaces due to the drag reduction. Comparing with smooth surface, the displacement thickness and momentum thickness of riblet surface minish obviously, which bears out the drag reduction effect of riblet surface indeed. The decrement of displacement thickness and momentum thickness rises first and then falls along with the increase of space between grooves. The peak value appears when s^＋ = 12.