串列布置下倒角柱体绕流数值模拟及水动力特性分析

Numerical Simulation and Hydrodynamic Characteristics Analysis of Flow Past Cylinder with Different Rounded Corners in Tandem Arrangement

为研究串列布置情况下,倒角变化对柱体绕流水动力特性的影响,该文采用大涡模拟方法研究了在雷诺数Re=3900和间距比L/D=3条件下,6种不同倒角(R^(+)=0.0、0.1、0.2、0.3、0.4和0.5)串列布置的柱体三维流场,模拟工作验证有效。分析了柱体后方水动力参数、瞬时流场和时均流场的变化情况,分析结果表明:随着倒角增大,上下游柱体的平均阻力系数C_(d-ave)变化趋势相反,上游柱体C_(d-ave)逐渐变小,而下游柱体的C_(d-ave)逐渐上升且均为负值;随着倒角增大,上下游柱体Sr数值相同并出现先增大后减少的趋势;两柱体之间的回流速度曲线下切深度明显增加,速度最小值出现处从下游柱体两侧向中心不断变化;串列布置下游柱体尾流宽度显著变小,在间距比L/D=3条件下,剪切层的初始分离均发生在上游柱体倒角转折处,并附着于下游柱体前端及两侧。该研究结果可为柱体绕流研究及相关工程应用提供参考。

In order to study the influence of rounded corner changes on the hydrodynamic characteristics of the flow around the cylinder under the condition of tandem arrangement,in the paper the large eddy simulation method is used to study the three-dimensional flow field of the cylinder with six different rounded corners(R^(+)=0.0,0.1,0.2,0.3,0.4,0.5)under the condition of Re=3900 and spacing ratio L/D=3.After the simulation is validated,the changes of hydrodynamic parameters,instantaneous flow field and time averaged flow field behind the cylinder are analyzed.The analysis results show that with the increase of rounded corners,the change trend of C_(d-ave)of the upstream and downstream columns is opposite,the C_(d-ave)of the upstream column gradually decreases,while the C_(d-ave)of the downstream column gradually increases and is negative.With the increase of rounded corners,the Strouhal value of the upstream and downstream cylinders is the same and increases first and then decreases.The undercut depth of the backflow velocity curve between the two cylinders increases obviously,and the position where the velocity minimum value appears continuously changes from both sides of the downstream cylinder to the center.The wake width of the downstream column in tandem arrangement is significantly reduced.In addition,when the spacing ratio L/D=3,the initial separation of the shear layer occurs at the corner of the upstream cylinder and attaches to the front and both sides of the downstream cylinder.The results of the paper can provide a reference for the study of flow around a cylinder and related engineering applications.