不同截面形状微肋片内流动阻力特性

Resistance characteristics of micro pin fins with different cross-section shapes

以去离子水为工质,实验研究了横截面形状为圆形、椭圆及菱形的叉排微肋片组成的流道内的流动阻力特性。结果表明,3种形状肋片流道内压降随流量增大而增大。受微/小尺度下层流边界层的影响,流量较低时微肋形状对流动影响较弱,椭圆形肋片与菱形肋片内压降几乎相同,而圆形截面肋片内由于流动距离较长导致流动阻力最大;当流量较大时,椭圆形肋片内压降最小。Re较小时,长短轴一致的菱形肋片内的流动阻力系数f比椭圆形肋片略低,但在Re较高时,椭圆形肋片内的f值仍然最低。研究还表明,在现有各种关联式中,只有菱形微肋片关联计算值与本实验值较吻合。

The de-ionized water, used as the working fluid, flowed through the channel fitted with staggered array of micro pin-fins in circular, diamond, and ellipse shapes and the resistance characteristics were investigated experimentally. The investigation shows that the pressure drop increases with the flux with these three micro pin-fin groups. When the flux is very small, ellipse and diamond shape micro pin-fin groups present almost the same pressure drop because the influences of the shape of micro pin-fin on the flow is weakened by the laminar boundary layer, while the flow resistance of circular pin fins is maximal due to the longer flow distance. The pressure drop of the ellipse shape micro pin-fin is minimal compared with other two shapes of pin fins when the Reynolds number is relatively large. At low Re, the friction factor of diamond shape micro pin-fins with the same major axis and minor axis as the ellipse shape micro pin-fins is slightly smaller than that of ellipse shape pin-fin. The study also shows that the calculation values from the correlation related to the diamond shape micro pin-fins agree with experimental data among the three shapes of micro pin-fins.