高雷诺数下错列双圆柱气动干扰的机理研究
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摘要
为了进一步澄清小间距错列双圆柱的气动干扰机理,该文采用大涡模拟方法,在高雷诺数下(Re=1.4×105),研究了间距为2倍圆柱直径的错列双圆柱的气动性能和流场特性随风攻角的变化规律,分析了两个圆柱气动力系数相关性,探讨了下游圆柱气动力与流场结构的内在联系,对下游圆柱平均升力的流场机理提出了新的解释。研究表明,大涡模拟得到的结果与风洞试验值吻合良好;下游圆柱的气动性能、流场结构和两个圆柱气动力相关性均会随风攻角发生剧烈变化;风攻角在0°~10°时,下游圆柱受平均负阻力作用,其原因分别为两圆柱间的回流区和间隙流;风攻角在10°附近时,下游圆柱受很大平均升力作用,风压停滞点偏移、两圆柱间高速间隙流、下游圆柱间隙侧剪切层的提前分离和再附是平均升力出现的三个因素。
To clarify the mechanism of aerodynamic interference between two closely spaced staggered circular cylinders, a large eddy simulation(LES) method is adopted to investigate the flow structure and aerodynamics of the two cylinders at a high Reynolds number(Re=1.4×105). The ratio of center-to-center pitch(P) to the diameter of the cylinder is P/D=2. The correlations of aerodynamic coefficients between the two cylinders are analyzed, and the relationship between the aerodynamic forces and the flow structure is discussed as well. A new explanation is proposed for the mechanism of the large net lift on the downstream cylinder. It is revealed that the present numerical results are in a good agreement with those by a wind tunnel test. For small incidence angles(0°~10°), the downstream cylinder experiences a mean negative drag force, which is induced by the recirculation flow and the gap flow between the two cylinders. For the incidence angles of around 10°, the downstream cylinder is subject to a large mean lift, which is ascribed to the combined effects of three factors, i.e. the shift of stagnation point, the high-speed gap flow between the two cylinders, and the early separation and reattachment of shear layer of the downstream cylinder.
To clarify the mechanism of aerodynamic interference between two closely spaced staggered circular cylinders, a large eddy simulation(LES) method is adopted to investigate the flow structure and aerodynamics of the two cylinders at a high Reynolds number(Re=1.4×105). The ratio of center-to-center pitch(P) to the diameter of the cylinder is P/D=2. The correlations of aerodynamic coefficients between the two cylinders are analyzed, and the relationship between the aerodynamic forces and the flow structure is discussed as well. A new explanation is proposed for the mechanism of the large net lift on the downstream cylinder. It is revealed that the present numerical results are in a good agreement with those by a wind tunnel test. For small incidence angles(0°~10°), the downstream cylinder experiences a mean negative drag force, which is induced by the recirculation flow and the gap flow between the two cylinders. For the incidence angles of around 10°, the downstream cylinder is subject to a large mean lift, which is ascribed to the combined effects of three factors, i.e. the shift of stagnation point, the high-speed gap flow between the two cylinders, and the early separation and reattachment of shear layer of the downstream cylinder.
引文
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[3]Zhou Y,Alam M M.Wake of two interacting circular cylinders:A review[J].International Journal of Heat&Fluid Flow,2016,62:510―537.
[4]Sumner D.Two circular cylinders in cross-flow:A review[J].Journal of Fluids&Structures,2010,26(6):849―899.
[5]Zdravkovich M M.The effects of interference between circular cylinders in cross flow[J].Journal of Fluids&Structures,1987,1(2):239―261.
[6]张军锋,葛耀君,赵林.群塔布置对冷却塔整体风荷载和风致响应的不同干扰效应[J].工程力学,2016,33(8):15―23.Zhang Junfeng,Ge Yaojun,Zhao Lin,et al.Interference effects on global wind loads and wind induced responses for group hyperboloidal cooling towers[J].Engineering Mechanics,2016,33(8):15―23.(in Chinese)
[7]Sumner D,Richards M D,Akosile O O.Two staggered circular cylinders of equal diameter in cross-flow[J].Journal of Fluids&Structures,2005,20(2):255―276.
[8]Ting S K,Wang D J,Price S J,et al.An experimental study on the fluid elastic forces for two staggered circular cylinders in cross-flow[J].Journal of Fluids and Structures,1998,12(3):259―294.
[9]Gu Z,Sun T.On interference between two circular cylinders in staggered arrangement at high subcritical Reynolds numbers[J].Journal of Wind Engineering and Industrial Aerodynamics,1999,80(3):287―309.
[10]Alam M M,Sakamoto H,Zhou Y.Determination of flow configurations and fluid forces acting on two staggered circular cylinders of equal diameter in cross-flow[J].Journal of Fluids&Structures,2005,21(4):363―394.
[11]Alam M M.Lift forces induced by phase lag between the vortex shedding from two tandem bluff bodies[J].Journal of Fluids&Structures,2016,65:217―237.
[12]Afgan I,Kahil Y,Benhamadouche S,et al.Large eddy simulation of the flow around single and two side-by-side cylinders at subcritical Reynolds numbers[J].Physics of Fluids,2011,23(7):525―338.
[13]Tong F,Cheng L,Zhao M.Numerical simulations of steady flow past two cylinders in staggered arrangements[J].Journal of Fluid Mechanics,2015,765:114―149.
[14]贾晓荷,刘桦.双圆柱绕流的大涡模拟[J].水动力学研究与进展,2008,23(6):33―40.Jia Xiaohe,Liu Hua.Large eddy simulation of flow around two circular cylinders[J].Chinese Journal of Hydrodynamics,2008,23(6):33―40.(in Chinese)
[15]Kitagawa T,Ohta H.Numerical investigation on flow around circular cylinders in tandem arrangement at a subcritical Reynolds number[J].Journal of Fluids&Structures,2008,24(5):680―699.
[16]Cantwell B J,Coles D.An experimental study of entrainment and transport in the turbulent near wake of a circular cylinder[J].Journal of Fluid Mechanics,1983,136(1):321―374.
[17]Achenbach E.Distribution of local pressure and skin friction around a circular cylinder in cross-flow up to Re=5×106[J].Journal of Fluid Mechanics,1968,34(4):625―639.
[18]Nishimura H,Taniike Y.Aerodynamic characteristics of fluctuating forces on a circular cylinder[J].Journal of Wind Engineering&Industrial Aerodynamics,2001,89(7):713―723.
[19]Kiya M,Suzuki Y,Arie M,et al.A contribution to the free-stream turbulence effect on the flow past a circular cylinder[J].Journal of Fluid Mechanics,1982,115(115):151―164.
[20]Surry D.Some effects of intense turbulence on the aerodynamics of a circular cylinder at subcritical Reynolds number[J].Journal of Fluid Mechanics,1972,52(3):543―563.
[21]Norberg C.Fluctuating lift on a circular cylinder:review and new measurements[J].Journal of Fluids&Structures,2003,17(1):57―96.