无导叶对转涡轮多重碰摩耦合的非线性动力学研究

The sealing system of vaneless-counter-rotating-turbine is so complicated that several kinds of rubs, including radial/axial rubs at the seals between rotor and stator, radial/axial rubs at the seals between dual rotors, and rubs at tip seals, will happen in the system. The coupling of different kinds of rubbing may lead to more complex dynamical behaviors, which can seriously affect the safety and reliability of the system. Thus this research project plans a study for the influences of seal structrual parameters, temperature and rotational speed on the responses, as well as the influences of typical rubs (such as rotor-rotor rubbing between counter-rotating dual rotors, tip rubbing of a blade rotor-casing system, and etc.) and the coupling of rubs on the responses. Firstly, the model of vaneless-counter-rotating-turbine is established considering the coupling of rubs and the influences of temperature and centrifugal force on clearence of the seals. Then typical rubs are investigated analytically. In the following, based on the analytical conclusions, numerical studies are conducted for the response of coupled rubbing. Finally, a rubbing test rig of vaneless-counter-rotating-turbine is build for the experimental verification of the analytical and numerical results. With the help of this investigation, connections can be built between seal structrual parameters, temperature, rotational speed, rubbing types and dynamical behaviors to give theoretical references for the parametric design and fault diagnosis of vaneless-counter-rotating-turbine system.

无导叶对转涡轮的密封系统结构复杂，会发生包括转-静级间密封的径向/轴向碰摩、转-转级间密封的径向/轴向碰摩以及叶尖密封的碰摩等多种不同类型的碰摩，多重碰摩的耦合使得系统的动力学行为变得异常复杂，严重影响了系统安全可靠的工作。本申请拟对无导叶对转涡轮密封结构参数及温度、转速对系统响应的影响规律和典型碰摩（对转双转子转-转碰摩、叶轮转子叶尖-机匣碰摩等）以及多重碰摩的耦合对系统响应的影响规律进行研究，首先考虑多重碰摩耦合和温度、离心力对密封间隙的影响建立无导叶对转涡轮动力学模型，然后基于简化模型对典型碰摩进行解析的机理分析，在机理研究结论的指导下通过数值计算研究多重碰摩耦合的动力学响应，最后建立无导叶对转涡轮碰摩实验台，对机理和数值研究的结论进行实验验证。通过研究建立密封结构参数、转速、温度、碰摩类型与系统响应振幅和动力学特性的联系，为无导叶对转涡轮密封的参数化设计和故障诊断提供理论依据。

无导叶对转涡轮的密封系统结构复杂，会发生包括转静碰摩、转转碰摩以及叶尖密封的碰摩等多种不同类型的碰摩，多重碰摩的耦合使得系统的动力学行为变得异常复杂，严重影响了系统安全可靠的工作。本项目针对无导叶对转涡轮多重碰摩耦合的非线性动力学进行研究，取得了如下成果：.针对变间隙转子碰摩开展研究，分析了碰摩的约束分岔特性，转迁集和分岔图表明，系统将出现19种分岔形式，对应某些参数域，系统会发生共振区后不脱离碰摩或者在共振区不发生碰摩，而在最高转速碰摩的现象，是变间隙转子特有的。研究了全周碰摩稳定性，发现对应某些参数将发生二次碰摩失稳。.研究了叶轮转子耦合碰摩。考虑叶片离心刚化效应及与机匣的Hertz接触变形，推导了新的叶尖碰摩模型。研究发现碰摩响应频率包括工频、反进动频率及其线性组合，叶片的接触将导致边频出现。当反向进动频率相对转速线性变化时，边频和转速及叶片数目的线性组合有关。碰摩初期，响应在周期和混沌运动之间多次切换，碰摩后期为混沌运动，研究了周期运动的稳定性，同数值结果对比后发现对应某些转速，周期响应和混沌响应共存。研究了叶尖和蓖齿耦合碰摩动力学，发现耦合响应在周期和混沌运动发生多次转换，耦合碰摩也存在周期1响应和其他周期响应及混沌响应共存现象。.针对双转子耦合碰摩开展研究，研究了同向和对转双转子转转碰摩，同向转转碰摩特征为：碰摩初期响应从周期1到周期2，到周期4，然后回到周期2，三维谱图上频率成分均沿左上-右下方向倾斜。对转转转碰摩，碰摩初期响应从周期1到周期2，又到周期1，频域上出现一个明显的反进动成分。研究了双转子转转/转静耦合碰摩，发现耦合碰摩处分岔图上出现波动现象，对于同向旋转耦合碰摩，倾斜频率成分不再出现，只有固有频率和工频为主的混沌响应。研究了双转子转转/叶尖耦合碰摩，叶尖碰摩响应特征并不明显，因此今后研究可采用等效当量刚度模型简化计算。