变截面U形通道内肋高对换热特性影响的实验

采用实验方法研究了在定常状态下,肋的高度对横肋变截面U形通道内的换热特性的影响.通道内肋间距为15 mm,肋的宽度均为2 mm,肋的高度分别为1,1.5,2 mm和2.5 mm.雷诺数在12 000到56 000之间变化,采用单元分析法,以相同形状的无肋通道作为基准,研究了肋的高度对肋间距为15 mm通道的换热效果及阻力影响,得到了包括几何参数在内的经验关联式.结果表明,有肋的通道换热都得到了增强;肋高度的变化对变截面蛇形通道换热的影响不是单调的,而是呈多峰分布;肋的高度对阻力系数的影响却是随着肋高的增大而增大的.

Experimental study of heat transfer in snake-shaped variable cross-section channels with different ribs heights

The influence of the rib heights on heat transfer characteristics in U-shaped variable cross-section channels was experimentally studied in the steady state.The design parameters include:relative roughness pitch 15 mm,rib width 2 mm,and relative roughness heights 1 mm,1.5 mm,2 mm,and 2.5 mm,respectively,and Renault number from 12 000 to 56 000.Based on ribless channel of the same shape,the influence of rib heights on heat transfer effect and resistance of a channel with 15 mm pitch was studied,so an empirical relational expression comprising geometrical parameters was obtained.The experimental results show that,the heat transfer of ribbed channel will be improved;the influence of the rib heights on the heat transfer of U-shaped variable cross-section channel is not monotone,but distributed with multi peak values.The influence of rib heights on the resistance coefficient increases with the rib heights.