交错波纹板原表面换热器通道内对流换热的数值研究

Numerical Study on the Characteristics of Convection Heat Transfer in Crossed-Corrugated Primary Surface Exchanger

对具有正弦波形通道交叉排列的原表面换热器多通道单元内三维稳态层流流动与换热特性进行了分析,利用数值模拟方法探讨了上下波纹板交错角θ、波纹相对节距P/H(波长/波高)及雷诺数Re对流动与换热性能的影响.结果表明:在入口段流动与换热性能的变化较大,此变化在沿主流方向第4个单元后基本消失;在水力直径基本相同的前提下,阻力系数f及平均努谢尔特数Nu随θ的增大而增大;f及Nu在P/H为1 5～3 1的范围内随P/H的增大而增大,在Re大于900及P/H为3 1～4 0时随P/H的增大却开始减小;壁面局部Nu的最大值发生在主流尾部以及与流体出口邻近的2个入口处附近,最小值在上下波纹板的接触点上产生.

Investigations on the three-dimensional steady laminar flow and heat transfer characteristics were conducted for the multi-channel with the sine-wave crossed corrugated primary surface. The effects of corrugation angle (θ), the ratio of the wave length P to height H(P/H), and Reynolds numbers (Re) on the flow and heat transfer performance were studied using numerical simulation. The results obtained show that the flow and heat transfer performance changes significantly in the entry region and this change disappears basically after the fourth cell number along the main flow direction. Under the condition of the same hydraulic diameter, Nusselt number (Nu) and friction factor (f) increase with increasing θ. In addition, Nu and f increase with P/H when P/H is between 1.5 and 3.1, and decrease with the increase of P/H when it is between 3.1 and 4.0 with the excess of Re over 900. The maximum of the wall surface local Nu is located near the main flow trailing position and at the entrances of the neighborhood outflows; the minimum of local Nu is obtained at these points where the top plate touches the bottom one.