【摘要】 蒸汽发生器管束在安装过程中与孔板和防振条之间存在一定间隙,称为间隙约束.当流速很大时管束发生流弹失稳而与间隙约束间发生碰撞磨蚀,影响装置运行的安全.以往的支撑模型大多采用了三次弹簧模型,该模型未考虑管与支撑的间隙和支撑阻尼.因此基于该模型,考虑间隙和支撑阻尼,提出了改进的间隙约束模型,从而建立了有间隙约束的悬臂管的动力学模型.通过求解方程观察到了分岔和混沌等有趣的非线性动力学行为,并对比了改进的间隙模型和三次弹簧模型,及支撑阻尼对管的非线性特性的影响.发现改进后的间隙约束模型比三次弹簧模型使得管振动表现出更复杂的非线性动力学行为,且考虑支撑阻尼后,第一叉型分岔点后的轨迹线发生一定程度改变且混沌运动提前发生.更多还原

【Abstract】 The main objective of this study is to determine the effects of nonlinear clearance constraint on the dynamic characteristics of steam generator tube.A modified constraint model considering the clearance size and the damping of constraint is proposed based on cubic spring model and the equation of motion of a cantilevered tube with nonlinear clearance constraint is established utilizing quasi-static fluid force coefficients of two-phase flow.After Galerkin discretization and Runge-Kutta algorithm numerical solution,modified constraint model and cubic spring model are compared and the effects of constraint damping on tube dynamic are discussed.Numerical solutions show that modified constraint model exhibits more complicated nonlinear behaviors than cubic spring model.Moreover,the clearance damping has effects on nonlinear dynamical behavior after 2 nd Pitchfork bifurcation point and chaotic motion occur earlier.更多还原