剪切稀化Carreau-Yasuda流体激励下圆柱两自由度涡激振动机理研究  

Mechanism of Vortex-induced Vibration of Cylinder with Two Degrees of Freedom under Shear-thinning Carreau-Yasuda Fluid Excitation

作　　者：张旭炎 马希 何涛[1] Zhang Xuyan;Ma Xi;He Tao(School of Civil Engineering,Shanghai Normal University,Shanghai 201418,China)

机构地区：[1]上海师范大学建筑工程学院,上海201418

出　　处：《水动力学研究与进展（A辑）》2024年第4期483-492,共10页Chinese Journal of Hydrodynamics

基　　金：上海市自然科学基金面上项目(19ZR1437200)。

摘　　要：剪切稀化是重要的一类广义牛顿流体行为,在生物医药、食品化工等领域已有广泛应用。剪切稀化流体激励下的单圆柱单自由度涡激振动已有诸多研究,但鲜有涉及剪切稀化流体作用下两自由度圆柱涡激振动现象。该文选用Carreau-Yasuda本构模型,运用边线型光滑有限元法(Edge-based Smoothed Finite Element Method,ES-FEM)研究剪切稀化行为对单圆柱两自由度涡激振动特性的影响。研究发现:低时间常数下,随着折合流速U_r增加,剪切稀化流体中的圆柱振荡将加快趋于稳定,但随时间常数增加,加速效应减弱。在不同时间常数下,圆柱质心均呈经典“8”字型自限振荡,且高时间常数下轨迹杂乱。在U_r=6条件下,对两自由度下不同时间常数的圆柱尾涡模式进行模拟,模拟结果显示:0.8≤Cu≤80时捕捉到2S尾涡;80≤Cu≤160范围内则为2P模式。在不同时间常数区间释放流向自由度后发现,不同时间常数下,流体对剪切速率变化敏感性不同,高时间常数区间内流向自由度对尾流区黏度场有明显扰动。该研究结果将为广义牛顿流体作用下的钝体振动抑制及能量收集提供借鉴。Shear thinning is an important generalized Newtonian fluid behavior,which is widely used in biomedicine,food chemical industry and other fields.The vortex-induced vibration of a single cylinder with one degree of freedom under shear-thinning fluid excitation has been studied extensively,but the phenomenon of vortex-induced vibration of a cylinder with two degrees of freedom under shear-thinning fluid excitation is rarely involved.In this thesis,the Carreau-Yasuda constitutive model is used to study the influence of shear thinning behavior on the vortex-induced vibration characteristics of a single cylinder with two degrees of freedom by using the Edge-based Smoothed Finite Element Method(ES-FEM).It is found that at low time constant,the cylinder oscillation in shear thinning fluid will accelerate and tend to be stable with the increase of reduced flow velocity U_(r),but the acceleration effect will weaken with the increase of time constant.At different time constants,the center of mass of the cylinder shows classical"g"self-limited oscillation,and the trajectory is messy at high time constants.Under the condition of U_(r)=6,the cylindrical vortex mode with different time constants in two degrees of freedom is simulated,and the 2S vortex is captured when 0.8<Cu<80.In the range of 80<Cu≤160,it is 2P mode.After releasing the streamwise degrees of freedom in different time constant intervals,it is found that the fluid has different sensitivity to the shear rate change under different time constants,and the streamwise degrees of freedom in high time constant intervals significantly perturb the wake viscosity field.The research results of vibration characteristics will provide reference for blunt body vibration suppression and energy harvesting under generalized Newtonian fluid.

关 键 词：边线型光滑有限元法 剪切稀化 涡激振动 广义牛顿流体 

分 类 号：O37[理学—流体力学]