振荡流下二维单椭圆柱体水动力特性研究

Study on Hydrodynamic Characteristics of Two-dimensional Single Elliptical Cylinder under Oscillatory Flow

椭圆柱体的流线型结构有助于降低应力集中,增强结构稳定性。为研究椭圆柱体在振荡流作用下的水动力特性,该文利用Fluent数值模拟了雷诺数Re=200,迎流角度θ=15°、30°、45°、60°、75°和90°,轴长比R_(A)=0.5、0.6、0.7、0.8和0.9的椭圆柱体绕流过程,分析了柱体的流场特性和水动力参数等变化规律。结果表明:振荡流正向来流时,小轴长比的椭圆柱体尾涡沿顺流方向发展,随着轴长比及迎流角度的增大,椭圆柱体尾涡的强度、尺寸、脱落周期和影响范围增大,柱体两侧脱落的涡对数量增多,尾流迹线增长,偏转角度增大;迎流角度θ=0°~90°时,随着θ的增大,椭圆柱体的拖曳力系数C_(D)不断增大,惯性力系数C_(M)先减小后增大,升力系数均方根C_(l-rms)先增大后减小,C_(M)和C_(l-rms)均在θ=45°时最大;θ≤30°时,椭圆柱体可发挥减阻效果。该研究结果可为相关工程设计提供参考。

The streamlined structure of an elliptical cylinder helps to reduce stress concentration and enhance structural stability.In order to study the hydrodynamic characteristics of an elliptical cylinder under oscillating flow,Fluent is used to numerically simulate the flow process around an elliptical cylinder with Re=200,flow angleθ=15°,30°,45°,60°,75°,90°and axial length ratio R_(A)=0.5,0.6,0.7,0.8,0.9.The flow field characteristics and hydrodynamic parameters of the cylinder are analyzed.The results show that when the oscillating flow flows forward,the wake of elliptical cylindrical with a small axial length ratio develops along the downstream direction.With the increase of the axial length ratio and flow angle,the strength,size,shedding period and influence range of the elliptical cylindrical wake increase,the number of shedding vortex pairs on both sides of the cylinder increases,the wake trace increases,and the deflection angle increases.Whenθ=0°-90°,withθincreasing,C_(D) of the elliptical cylinder increases continuously,CM decreases first and then increases,C_(l-rms) increases first and then decreases,and C_(M) and C_(l-rms) reach the maximum value whenθ=45°.Whenθ≤30°,the reduction effect of drag can be played.The results of this paper can provide reference for related engineering design.