汽轮机转子-机匣系统碰摩的分叉现象分析

The Bifurcation Phenomena of Impact/Rub Rotor-stator box System in Steam Turbine

提高汽轮机热效率的有效途径是采用超超临界压力。压力的提高使得作用在转子—机匣上的激振力将显著增大,有必要对气流激振力作用下的转子-机匣系统的非线性动力学特性进行研究。本文采用双控体模型,以汽轮机转子—机匣系统为研究对象,将转子和机匣作为统一的弹性体,采用四阶Ruge-Kutta法进行数值仿真,来研究在密封气流激振力以及机匣体振动的双重作用下的转子与机匣的碰摩运动,揭示了转子与机匣碰摩的分叉动力学特性。给出了气流激振力作用前后的碰磨转子系统响应的分叉图、轨迹图、相轨迹图和Poincare映射图。着重讨论了输入气压和转子转速等决定气流激振力大小的因素对碰磨转子分叉特性的影响。对提高超超临界汽轮机的可靠性提供了有意义的参考。

Thermal power unit adopting ultra-super critical pressare is an important method to increase its thermal efficiency. Along with the increasing of the steam para metes, the flow induced force acting on the rotor of a power unit is enlarged significantly. As a result, it is necessary to analyze the nonlinear dynamic characteristics of a rotor-box system under the action of flow induced force. In this paper, the numerical method is used to analyze the bifurcation characteristics of a rubbing rotor with flow induced force and box＇s vibration as its excitation, while the flow induced force is received from two-control-volume model. From which, the bifurcation characteristics of impact/rub acted on that rotorstator box system is discovered. Meanwhile, the orbits and Poincare maps are provided that befor and after the flow induced force is gived to the system. It is emphasized that the effect on the bifurcation characteristics of a rubbing rotor from the factor of air pressure and rotor＇s rotating speed. It has a significant value for both theory and practice about the design of thermal power unit.