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陈国孝, 刘喆, 邵传平. 旋转振荡板尾流的控制研究. 力学学报, 2021, 53(7): 1856-1875. DOI: 10.6052/0459-1879-20-423
引用本文: 陈国孝, 刘喆, 邵传平. 旋转振荡板尾流的控制研究. 力学学报, 2021, 53(7): 1856-1875. DOI: 10.6052/0459-1879-20-423
Chen Guoxiao, Liu Zhe, Shao Chuanping. Investigations on the control of wakes downstream of a rotary oscillating plate. Chinese Journal of Theoretical and Applied Mechanics, 2021, 53(7): 1856-1875. DOI: 10.6052/0459-1879-20-423
Citation: Chen Guoxiao, Liu Zhe, Shao Chuanping. Investigations on the control of wakes downstream of a rotary oscillating plate. Chinese Journal of Theoretical and Applied Mechanics, 2021, 53(7): 1856-1875. DOI: 10.6052/0459-1879-20-423

旋转振荡板尾流的控制研究

INVESTIGATIONS ON THE CONTROL OF WAKES DOWNSTREAM OF A ROTARY OSCILLATING PLATE

  • 摘要: 桥跨结构发生颤振时的旋涡尾流可由二维强迫旋转振荡板绕流模拟. 在弦厚比B/H = 5的振荡板两侧对称地放置两个宽度比均为b/H = 0.33的窄条, 对尾流的锁频旋涡脱落进行控制. 采用数值模拟和实验验证方法, 对旋涡场、尾流平均和脉动速度, 以及板所受扭转力矩和升力进行研究, 研究的振幅范围β = 0° ~ 10°, 振频范围feH/V = 0 ~ 0.0857, 雷诺数Re = VH/V = 2800. 窄条位置分为板的前缘、中央和尾缘3种, 控制参数为窄条横向坐标y/H. 根据实验结果, 当窄条位置y/H在一定范围, 振幅β = 0° ~ 7.5°, 振频feH/V = 0 ~ 0.08时, 有控制和无控制尾流脉动速度功率谱主峰的比值远低于1, 最低可达0.3左右. 根据数值模拟结果, 当中央控制件位于y/H = ±1附近时, 在振幅β = 0° ~ 7.5°, 和一定频率范围内, 脉动扭转力矩均方根和升力均方根都有大幅下降, 最多可分别降低43%和80%. 引入第一和第二涡黏系数, 将尾流无规则脉动形成的湍流法向和切向应力, 分别与扰动速度幅值的法向和切向梯度相联系, 得到线性稳定性方程. 稳定性分析表明, 施加控制后, 最大扰动放大因子ωi max大幅降低, 扰动增长的频率范围显著收窄. 窄条改变尾流速度剖面形状并增大湍流涡黏系数, 从而减弱尾流的不稳定性.

     

    Abstract: The vortex wake of a flutter bridge deck can be simulated by the flow across a forced rotary oscillating plate. Two narrow strips of width ratio b/H = 0.33 are set symmetrically on the upper and lower sides of an oscillating plate of chord to thickness ratio B/H = 5, to suppress synchronized vortex shedding in the wake. The method of numerical simulation and experimental validation is used, and the ranges of amplitude and frequency of oscillation investigated are β = 0° ~ 10° and feH/V = 0 ~ 0.0857 respectively, and the Reynolds number Re = VH/ V = 2800, where V is velocity of on-coming flow. Three kinds of stream-wise strip positions, i.e. the front edge, mid-chord and trailing edge of the plate are studied respectively, with transverse location y/H of the strip as varying parameter. The results of experiment demonstrate that, in a certain range of strip location y/H, and β = 0° ~ 7.5°, feH/V = 0 ~ 0.08, the peak to peak ratio of power spectra of fluctuating velocities in the wakes with and without control can be much lower than 1, and the minimum is about 0.3. The results of simulation show that, in β = 0° ~ 7.5° and a certain range of feH/V, the root mean square values of fluctuating torque and lift of the plate can be considerably reduced, and the top reductions are 43% and 80% respectively, if the mid-chord strip position is in the vicinity of y/H = ±1. The 1st and 2nd eddy viscosity coefficients are introduced to link the normal and shear turbulent stresses in the wake with the gradients of amplitudes of the perturbation velocities, and a linear stability equation is derived. Stability analysis indicates that, the maximum amplification factor of perturbation ωi max can be drastically reduced, and the frequency range of perturbation with maximum growth rate is substantially narrowed by the control. The application of the strips alters the velocity profiles and promotes the eddy viscosity, therefore weakens the instability of the wake.

     

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