旋转机械局部非线性大系统振动研究

Research results of theory and mothod of the nonlinear rotor dynamicsThe theory and mothod of nonlinear rotor dynamics for large scale steam urinerotor-nonstationary nonlinear oil film journal-foundation-soil integrated system with huge degreesof freedom is researched. The nonlinear time history and the followed bifurcation analysis withvarying parameter of rotating speeds are obtained and changed hesituation of Jeffecott rotor withfew DOF. Based on the modern theory of the nonlinear rotor dynamics, the bifurcation diagrams,Poincare maps, and power spectrum is used to analyze the nonlinear vibration behavior of thesystem. The bifurcation phenomenon, half or nearly half frequencies oil whirl and oil vibration.with some one of critical speeds of a 500 MW steam turbine are calculated from the numericalsimulation with different rotating speed. But the more complicated phenomenon such as chaosmotion etc. haven’t presented within the rotating speed 3,500 r/min. The software researched can.be used for system with local described nonlinearty, such as nonlinear oil film force, rubbing,crark and seals etc., which may be presented in engineering practice. The method also sutable fornonlinear response and phinonmina analisis in the researched air engines and hydroricgenerators.An on-line monitoring and fault diagnosis equipment of large-scale rotating machineryAn on-line monitoring and fault diagnosis system for a large-scale rotating machinery are.researched and designed successfully from the point of hardware design, software design andfinally assembly as a product set up on the factory. The operating experince proved the reliabilityand and anti-strong disturbins. It was an extending project of science and technology of Tsinghuauniversity from 2000.A new numerical integration method.A new method for solving accurate solution of the non-linear dynamic systems by numericalintegration method is established, By introducing the first approach Jacobi matrix existed for an.arbitrary autonomous or non-autonomous non-linear dynamic system, the nonlinear differentialequation is reconstructed as an equivalent non-linear ordinary ifferential equation. The uhamalconvolution integration gives the expression of precision solution in the time steps and convergesquickly with in given accuracy. Using step by step integration, the nonlinear responses is obtainedin time domain exactly. The Duhamel integration solutions are continuously satisfied systemdifferential equations, which differs from all of the traditional finite difference method satisfiedsystem equation at the end of time steps only. The truncation error is unlimited by original ofmethod and determined by the calculating accuracy with in given accuracy. To save the computingtime, the calculating the exponential function matrix ultiplications by itself are all avoid. Theunconditional stability has been easily proved. Thereconstructed equivalent non-lineardifferentialequation breakthrough the traditional iteration with linearized increment equations, it is simpleand has widely acceptability. The Duhamel integration breakthrough the traditional Euler's formof finite difference methods, which the truncation error is limited, the proposed method not onlyhas high accuracy, but also avoid all of the troubles presented in finite difference methods, theperiod elongation, artificial damping, overshoot and tability problem.

对旋转机械这类具有局部非线性的高自由度系统，研究准确、有效的降维理论，研究非线性振动的串、并行数值计算方法：计算系统非线性振动响应与全局性态。揭示由油膜轴承、密封及间隙等非线性特性引发系统振动的机理、特征。开展灵敏度分析，研究前述局部动力约束对系统振动性能的影响。在此基础上提出并发展高维强非线性耦合振动动力学理论。