环形截面螺旋管道内二次流动特性的研究

从曲线柱坐标系下的N-S方程出发，以曲率和挠率为小参数，采用摄动法求解了环形截面螺旋管道内的黏性流动，给出了完全二阶摄动解，结果表明：当挠率为零时，二次流表现为上下对称的四个涡；当挠率不为零，涡的对称性遭到破坏，二次涡的强度和个数受De数和环形截面内外径之比δ的影响，轴向速度最大值在De数较小时靠近管道的内侧，随着De数的增加，其最大值向外侧移动。

THE RESEARCH ON THE CHARACTERISTICS OF THE SECONDARY FLOW IN A HELICAL ANNULAR PIPE

In this paper, following the un-simplified N-S equation in a curvilinear coordinate system, We obtain the perturbation solutions of axial and secondary flow in a helical annular pipe. For a curved annular pipe with zero pitch, four symmetrical vortexes appear in the annular cross section they are symmetrical up and down, but for a helical annular pipe , the symmetry is destroyed by the effects of torsion, the intensity and numbers of the secondary flow vortexes are affected by Dean number and the ratio of the inner and outer circle radius (5) of the annular pipe. The maximum of the axial velocity appears near the inner bend when Dean number is small and the maximum moves toward the outer bend with De number increasing. By integrating the perturbation solutions of the axial velocity, the volume flux equation for the fluid flow in helical annular duct is got, the equation indicates that the torsion has an effect to decrease the volume flux in a curved annular duct.