高雷诺数下并列双圆柱绕流的大涡模拟

Large eddy simulation of flow around two side-by-side circular cylinders at a high Reynolds number

摘要:

为澄清并列双圆柱结构发生偏向流现象的流场机理,采用大涡模拟（LES）方法,在高雷诺数下（Re=1.4×10⁵）研究了并列双圆柱的气动性能及其流场特性随圆柱间距比P/D（P为圆心间距,D为圆柱直径）的变化规律,重点探讨了小间距并列双圆柱的偏向流现象及其对圆柱气动性能的作用机理.研究结果表明:大涡模拟方法得到的气动力结果与文献风洞试验值吻合良好；随着并列双圆柱间距的增大,绕流场会呈现单一钝体、偏向流和平行涡街等多种流态结构；当P/D=1.1时,绕流场会间歇性地出现单一钝体和偏向流流态,两种流态的气动性能和流场特性有很大差异,圆柱的气动力会随时间发生剧烈变化,呈现非稳态特征；当P/D=1.2~1.5时,绕流场呈现偏向流流态,两个圆柱的气动力和尾流呈现不对称现象,偏向流的偏转方向会出现间歇性地变化,尾流涡脱强度弱,气动力脉动小；当P/D=2~4时,绕流场总体呈现平行涡街流态,尾流涡脱强度强,气动力脉动大,气动干扰减弱.

Abstract:

To clarify the mechanism that two side-by-side circular cylinders will experience biased flow patterns, flow and aerodynamics of two side-by-side circular cylinders of various center-to-center spacing ratios (P/D) were investigated using large eddy simulation (LES) at a high Reynolds number of 1.4×10⁵. Efforts were devoted to study the characteristics of the biased flow and its influences on the aerodynamics of the two cylinders. Results revealed that the present numerical results are in good agreement with those by the wind tunnel test. With the spacing increase, three flow patterns were found, i.e., single-bluff-body pattern, biased flow pattern, and parallel vortex street pattern. When P/D=1.1, the two cylinders underwent the single-bluff-body flow pattern and biased flow pattern intermittently. There was a significant difference between flow field characteristics and aerodynamics under these two flow patterns. When P/D=1.2~1.5, the two cylinders underwent biased flow pattern. The flow field of the wake region and the aerodynamic forces were asymmetrical for the two cylinders. The direction of the biased flow switched intermittently from one side to the other. The intensity of the vortex shedding was weak, and the magnitude of the fluctuating forces was low. When P/D=2~4, aerodynamic interference between two cylinders was weak and there were two vortex streets behind the two cylinders, which resulted in large fluctuating forces.