Abstract: Laminar flow characteristics of helical ducts with right-angled isosceles triangle cross section is investigated numerically with CFD software. The velocity fields of fully developed laminar flow are obtained. The effects of dimensionless curvature ratio d and dimensionless torsion l on the intensity of secondary flow and flow resistance are analyzed. The results indicate that the steady flow structure of secondary flow on the cross section perpendicular to helix has two vortexes within d=0.021~0.083 and Re=100~1000. Both the secondary flow intensity and flow resistance rise with increasing of Reynolds number and d. In the range of study, l has little effect on the intensity of secondary flow and the flow resistance. The flow resistance of the triangular helical duct is smaller than that of the half-coil helical duct when they have the same structural parameters and Reynolds number, and with increasing of Re, the difference between them increases as well. In the range of Re, the friction factor of triangular helical duct is 84.1%~99.5% as much as that of half-coil helical duct.

Key words: helical duct, triangle cross section, secondary flow, flow characteristic

摘要： 应用CFD软件对直角三角形螺旋流道内层流流体的流动特性进行了数值模拟，得到了充分发展条件下流体的速度场，分析了无量纲曲率d、无量纲挠率l对二次流强度和流体流动阻力的影响. 结果表明，当d=0.021~0.083且Re=200~1000时，流体流过该螺旋流道产生的二次涡为稳定的两涡结构；随Re及d增大，二次流强度增强，流体阻力系数也相应增大；在研究范围内，l对二次流强度及流体流动阻力的影响不大；当结构参数及Re取值相同时，三角形螺旋流道的阻力比半圆形螺旋流道小，且随Re增大，二者的差值增大，在所计算的Re范围内三角形螺旋流道的阻力系数为半圆管螺旋流道的84.1%~99.5%.

关键词: 螺旋流道, 三角形截面, 二次流动, 流动特性