人工糙管中湍流运动特性的研究——Ⅰ.时均速度分布与脉动速度

Turbulent Flow in Artificially Roughened Pipes

以热线风速仪测定了横肋管中时均速度、脉动速度的均方根值。横肋管的几何参数:峰高0.01～0.04,间距10～40,Re=20000～70000。实验结果给出时均速度沿径向、轴向分布,脉动强度沿径向分布,同时获得湍流能谱。分析了粗糙对这些量的影响,粗糙可使湍流强度增大40～50%,而湍流尺度则有所减小,速度分布u^+服从对数律, u^+=2.5lny^++B B值随峰高变化(式中y^+为无因次距离;B为常数)。

Mean and turbulent flow parameters of air flow in traverse ribbed pipes were measured by using hot-wire anemometer. Data were taken over a wide range of roughness dimension k/d=0.01～0.04, s/k=10～40. Re=20000～70000. The experimental results include velocity distribution along pipe diameter and along pipe axis, intennsity profile and energy spectrum; The influences of the geometry of roughness element on quanties mentioned above were analysed. The results indicate that the intensity of turbulence is 40～50% larger in the repeated rib pipes than in smooth pipes and the scales of turbulence appear to be smaller. Typical volocity profiles in the region above the roughness element can be described as following formulau^+=2.5lny^++Bthe value of B is dependent on rib height.