长拉杆-止口连接弯曲刚度损失及对转子系统振动响应影响

Bending stiffness loss of rod-rabbet joints and its effect on vibration response of rotor systems

航空燃气轮机为了实现高负荷、轻质化的追求,在转子结构设计中,趋向于提高转速和加大长径比。这使得转子系统弯曲模态临界转速降低,转子在工作转速范围内不可避免会产生一定的弯曲变形。转子弯曲变形会影响连接结构界面接触特性的变化,使其连接结构局部弯曲刚度产生损失。因此,对于工作转速靠近弯曲临界的高速转子系统,需要考虑连接结构界面接触状态变化对转子系统振动特性的影响。以高负荷的长拉杆-止口连接转子系统为对象,分析连接界面接触应力分布特性,提出连接结构弯曲刚度损失修正方法,以此为基础建立界面连接转子动力学模型。通过对止口连接三级轴流压气机转子结构动力学特性的仿真和试验研究表明,在靠近弯曲振型临界转速下,转子连接界面接触状态的变化会产生弯曲刚度损失,对转子动力学特性具有显著影响。

With the pursuit of higher output power and light weight of the aero-engine structure,the stiffness of the rotor structure has to be weakened,while the operational speed of the rotor is increased.These changes induce large bending deformation on the rotor in operation.The rotor structure system with multiple joints will experience a sudden change in contact characteristics at the joint interface when the rotor is exerted by the bending moment,and this sudden change will weaken the bending stiffness of these joints.Therefore,in the design span of the high-speed rotor system,the bending stiffness loss of the joint structure must be considered.In this paper,the contact status and stress distribution of the rod-rabbet joint interfaces are analyzed,followed by the establishment of the bending stiffness model of the joint.Based on the bending stiffness model,the dynamics of a typical rotor system is investigated.The simulation result reveals that the stiffness loss of the joints can significantly affect the dynamic characteristics of the rotor system,hence verifying the correctness of the bending stiffness loss model of the joint.