超静定转子系统不对中动力学的理论与实验研究

Theoretical and experimental study on dynamics of a statically indeterminate rotor system with misalignment

不对中是多支承转子系统最常见的故障之一,超静定转子系统(SIRS)由于结构的特殊性而对支点的不对中表现得更加敏感。航空发动机低压转子经常采用三支点支承的方式,当套齿连接结构径向定位间隙较小时,就会构成了一个含有3个弹性支承的超静定转子系统。结合力法和达朗贝尔虚功原理,推导了尾部支承不对中情况下超静定转子系统的动力学方程和解析解,计算获得了其振动响应。以航空发动机超静定转子系统为研究对象,对其完全对中和尾部支点不对中状态展开解析模型推导和实验验证工作。理论和实验结果均表明,该系统由于支点的不对中不仅会对转子的转子产生动态附加激励,还会引起系统2X振动响应和内“8”字形响应轴心轨迹,理论和实验结果吻合良好。该研究对超静定转子系统动力学不对中情况下的响应计算及实验研究有较强的指导价值。

Misalignment of a multi-support rotor system is one of the most common fault conditions.A low-pressure rotor system of aero-engine uses spline joint for connecting,which constitutes statically an indeterminate rotor system(SIRS)with three elastic supports.The inherent defect of SIRS is extremely sensitive to misalignment.In this paper,an analytical dynamic model of SIRS was derived using a combination of the force method and the virtual work principle about the D’Alembert principle under alignment and misalignment of turbine back support conditions,and misalignment dynamic loads were detailed derived to determine the natural frequency and vibration responses.In this paper,the aeroengine hyperstatic rotor system was taken as the research object,and the analytical model derivation and experimental verification were carried out for its complete alignment and tail fulcrum misalignment and both theoretical and experimental results agree well.As a result,with the increase of misalignment,frequency multiplication components occur,2X component and increase linearly,the orbits change from ellipse to inside“8”shape.Due to the structural particularity of SIRS,the appearance of TBS misalignment which generates the dynamic external excitations,makes the response of low-pressure turbine more severely.