有限长波浪形圆柱绕流数值模拟

为研究一端固定在壁面上,另一端为自由端的有限长波浪形圆柱的减阻抑振效果,对有限长波浪形圆柱进行了计算.首先,采用大涡模拟数值模型的方法,对雷诺数为3 900时的有限长直圆柱和不同波长、波幅组合后的12种有限长波浪形圆柱进行了计算;其次,针对计算结果进行后处理,得到并比较了不同组合形式下的有限长波浪形圆柱的升、阻力系数大小,结合升、阻力大小分析其减阻抑振效果;最后,对减阻抑振效果较好的组合形式进行流场分析并研究了有限长波浪形圆柱的减阻抑振机理.研究表明:在12种波浪形圆柱组合形式中,大多数组合形式都能减小圆柱受到的升力系数均方根值,起到抑振作用,减阻效果最好的组合形式阻力系数均值减小可达5.36%;有限长直圆柱与有限长波浪形圆柱周围有相似的流动特征,但波浪形圆柱由于马鞍面和节点面的存在,使流体在圆柱展向产生交互,削弱了圆柱后方尾涡的发展,从而起到减阻抑振的作用.所得结果可对有限长波浪形圆柱的减阻抑振效果进行比较全面的总结,对研究有限长波浪形圆柱的减阻抑振机理有一定的帮助.

Numerical simulation of flow around finite-length wavy cylinders

To study the drag reduction and vibration suppression effect of finite-length wavy cylinder which has a fixed end and a free end, the finite-length wavy cylinder was calculated. First, large eddy simulation numerical model was adopted to calculate finite-length straight cylinder and 12 finite-length wavy cylinders with different combinations of wavelength and amplitude at Re=3 900. Then, after post-processing the results, the lift and drag coefficients of the finite-length wavy cylinders with different combinations were compared, and corresponding drag reduction and vibration suppression effect was analyzed. Finally, flow field analysis was carried out on the combination forms with better drag reduction and vibration suppression effect, and the mechanism of drag reduction and vibration suppression of finite-length wavy cylinder was studied. Results show that for the 12 kinds of wavy cylinders, most of the wavy cylinder forms could reduce the root mean square value of the lift coefficient, which could suppress the vibration, and the best combination form reduced the mean drag coefficient by 5.36%. The flow characteristics around finite-length straight cylinder were similar with those around finite-length wavy cylinder. While due to the existence of saddle and nodal surfaces of wavy cylinder, the fluid interacted in the direction of the cylinder, weakening the development of the vortex behind the cylinder, which reduced the drag reduction and vibration suppression effect. The research results can summarize the drag reduction and vibration suppression effect of finite-length wavy cylinders, which is helpful to investigate the drag reduction and vibration suppression mechanism of finite-length wavy cylinders.