窄流道内单个鱼鳞型凹坑影响流动与传热特性的数值研究

Numerical study of flow and heat transfer in dimpled channel with simple fish-scale cavity

基于水轮机上的鱼鳞坑磨痕,提出了应用于窄流道的鱼鳞形凹坑的设计思想,通过数值模拟研究了单个凹坑对窄流道流动与传热的影响,并和球形凹坑进行了对比。结果表明,鱼鳞形凹坑平板的传热特性明显要高于光滑平板,并且优于球形凹坑平板。与光滑平板的摩擦系数随着流体速度的提高而提高不同,凹坑平板的摩擦系数随流体速度的提高而降低。当通道进口速度较低时,鱼鳞凹坑平板的摩擦系数最高,然而随着进口速度的增大,其摩擦系数会逐渐低于球形凹坑平板,当进口速度增大到一定程度时,鱼鳞凹坑平板的摩擦系数将会低于光滑平板。

Based on fish-scale cavity on the blade of water turbine, the fish-scale cavity used on the dimpled channel was proposed. The numerical simulation was used to study the flow and heat transfer in a dimpled channel with the simple fish-scale cavity or spherical cavity. The computational results show that the wall heat transfer coefficient of the surface with the fish-scale cavity is higher than the one of the surface with the spherical cavity or the smooth surface. Compared with the friction coefficient of the smooth surface which would increase with the increase of the fluid velocity, the friction coefficients of the surfaces with different cavities will decrease with the increase of the fluid velocity. When fluid velocity is low, the friction coefficient of the surface with the fish-scale cavity is high. However, with the increase of fluid velocity, the gap between the surfaces with the fish-scale cavity and the spherical cavity will minished. Continuing to increase the fluid velocity, the friction coefficient of the surface with the fish-scale cavity will be lower than the one of the surface with the spherical cavity. When the fluid velocity increases to a special value, the friction coefficient of the surface with the fish-scale cavity will be lower than the one of the smooth surface.