高雷诺数条件非线性弹簧下PTC圆柱流致振动数值模拟

Numerical simulation of FIV of PTC-cylinder with nonlinear springs at high Reynolds number

[目的]为了提高涡激振动圆柱发电装置的发电效率,研究在大范围雷诺数下非线性弹簧支撑的被动湍流控制圆柱的流致振动特性。[方法]利用FLUENT软件,结合动网格技术和用户自定义函数(UDF),选取Spalart-Allmaras湍流模型求解非稳态雷诺平均Navier-Stokes方程组,对线性弹簧和分段弹簧支撑的被动湍流控制(PTC)圆柱流致振动进行二维数值模拟研究,并将模拟结果和实验结果进行对比。[结果]与线性弹簧下相比,分段弹簧下圆柱的振幅明显增强,涡脱模式更加复杂。当第1段弹簧刚度和第2段弹簧相比较大时,分段弹簧的分段点越小,圆柱的振幅越大,振动频率越小,涡脱模式越复杂。[结论]非线性弹簧下圆柱的流致振动特性和线性弹簧下的有所不同,合理选择分段点可以有效地增强流固耦合作用,为提高能量转换装置的效率提供理论与技术支撑。

[Objective]This article studies the characteristics of the flow-induced vibration(FIV)of a cylinder with passive turbulence control and nonlinear springs in a wide range of Reynolds numbers in order to use the FIV of the PTC-cylinder to improve the efficiency of power generators.[Methods]The FIV of a PTCcylinder supported by linear and nonlinear springs is studied by solving the 2-D URANS equations in combination with the Spalart-Allmaras turbulence model with dynamic mesh and user-defined-function(UDF)in FLUENT.The numerical simulation results are compared with the experimental results.[Results]Compared with linear springs,the amplitude of a cylinder with piecewise-linear springs is enhanced significantly,and the vortex mode becomes more complicated.When the spring stiffness of the first segment is greater than that of the second segment,the amplitude of the cylinder becomes larger,the oscillation frequency becomes smaller and the vortex mode of the cylinder becomes more complicated as the piecewise point of the piecewise-linear function becomes smaller.[Conclusions]The FIV of a PTC-cylinder with nonlinear springs is different from that with linear springs.The fluid-structure interaction is enhanced effectively with the reasonable selection of the piecewise point,providing theoretical and technical support for improving the efficiency of hydrokinetic energy conversion devices.