叶轮转子的碰摩是旋转机械的常见故障，严重的碰摩可能导致转子失稳、叶片断裂等后果。本文针对叶轮转子-机匣的碰摩进行研究，将叶片简化为一端固支的悬臂梁，考虑其在旋转状态下的离心刚化效应，机匣的局部变形采用Hertz模型表征，推导了叶片-机匣接触力的表达式，分析了叶片长度、截面惯性矩、叶片截面积和转速对接触力的影响，结果表明当叶片长度越小、截面惯性矩越大、转速越高接触力越大。基于所得的接触关系，给出了叶轮转子碰摩力模型，对叶轮转子碰摩的稳态响应进行数值模拟，结果表明系统在碰摩时的响应频率主要包括转速激励频率、反向进动频率及其线性组合，叶片的扰动将导致主要响应频率附近出现边频，边频在不同转速情况下存在多种不同形式。当反向进动频率相对于转速近似线性变化时，边频和转速与叶片数目线性相关。
Abstract
As a kind of common failure of the rotating machines, rubbing could lead to catastrophic consequences such as instability of the rotor or blade damages. Rubbing between blades and casing is investigated in this paper. The blades are simplified as cantilever beams with centrifugal stiffening effect, while the blade/casing contact is modeled by Hertz contact force and an expression of blade/casing contact force has been derived. Based on the derived expression, influence of various parameters to the contact force is analyzed, such as the rotating speed, cross section of blade, length of blade and bending stiffness of blade. The results show that blade with shorter length and larger moment of inertia or under higher rotating speed will lead to greater contact force on the casing. Meanwhile, a blade-rotor/casing rubbing model is derived with the given expression of contact force and numeric simulations with this model are also conducted. The results show that the responses on the spectrum consist of synchronous frequency, reverse precession frequencies and their linear combinations. It is also observed that the blades can lead to side frequencies near the main frequencies. Different kinds of side frequencies are observed under different angular speeds. When the reverse precession frequencies are nearly linear with the angular speed, the side frequencies are also linear with the angular speed as well as the number of blades.
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参考文献
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