【作者】 李国见；

【导师】 李建华；

【作者基本信息】 西北工业大学 ， 机械设计及理论， 2007， 硕士

【摘要】 指尖密封是继蓖齿密封和刷式密封之后出现的一种新型密封技术，主要应用于航空发动机的气流流路密封。最早提出的指尖密封属于接触式密封，指尖靴和转子相接触，指尖与转子间的接触磨损始终是接触式指尖密封面临的一个重要问题。为了解决这一问题，后来在接触式指尖密封的结构基础上又提出非接触式指尖密封。与接触式密封相比，其最大特点在于指尖具有“自浮性”，即指尖靴部与转子之间能保持一较小的具有承载能力的流体间隙，在指尖受到轴向和径向作用后密封的整体性能不会受到影响，因而在密封效果尤其是使用寿命方面具有明显的优势。 本文根据流体动压学原理，对指尖的靴部结构进行设计，由于其靴部特殊的结构，在靴部与转轴间形成楔型气膜，在转子的高速转动下，产生动压，使指尖靴部浮起，与转子保持一定的间隙，从而使转子与密封片之间没有摩擦。动压靴结构设计的成功与否主要通过动压靴能否“浮起”，气体的泄漏量以及动压靴对转轴跳动的“跟浮”性能来衡量，所以需要分析设计的动压型指尖密封系统是否满足上述性能。 动压型指尖密封系统的分析是典型的流固耦合问题。流固耦合力学的重要特征是两相介质之间的相互作用，固体在流体载荷作用下会产生变形或运动，而变形或运动又反过来影响流体，从而改变流体载荷的分布和大小。为此，本文利用有限元软件ANSYS与CFD软件CFX建立动压型指尖密封系统的数值模型，对动压型指尖密封系统进行流固耦合仿真分析，获得指尖密封系统在不同工况下的流场压力特性，指尖变形量以及气体泄漏量并对结果进行分析。分析结果表明流体具有很好的承载能力，能够“浮起”动压靴，而气体泄漏量又很小，证明了本文设计的动压型密封结构满足指尖密封系统的设计要求。 此外，本文还针对指尖密封在实际工作中，转轴有跳动的情况，建立动压型指尖密封系统的弹簧—质量—阻尼动力学模型，以此来分析动压靴对跳动的转轴的“跟浮”性能。分析结果表明，设计的动压靴对转轴有很好的“跟浮”能力，能够保证动压靴与转轴始终不接触。更多还原

【Abstract】 The finger seal is a new innovative seal after labyrinth seal and brush seal, and apples to the gas-path seal of Gas turbine engines. The designed early finger seal is contacting seal which finger root contacts to rotor. The contacting wear between finger root and rotor is an important problem. So a non-contacting finger seal has been designed later. Compared to contacting finger seal, the finger root of non-contacting finger seal have the capability of self-lifting, so a clearance which has carrying capacity can be obtained between finger root and rotor. Thus the seal capability and especially life of finger seal is an obvious advantage.Finger root based on hydrokinetics have been designed. Fluid film wedge have been formed because the peculiar structure of finger root, and it can brings hydrodynamic pressure which can lifts finger root by the high rotate speed of rotor. So the friction between finger root and rotor has been avoided. Whether the designed root is a good design can be estimated by the self-lifting capability of finger root, gas leakage and the following capacity of finger root to the motion of the rotor.The analyse to hydrodynamic finger seal system is a typical fluid - structure coupling problem. The character of fluid-structure coupling dynamics is the interaction between fluid and structure. Structure can displace by fluid load, and the displacement affects the fluid and changes the distributing of fluid load. So the numerical model of hydrodynamic finger seal system has been established by ANSYS and CFX. The fluid - structure coupling analyse to hydrodynamic finger seal system has been accomplished. The analyse result indicates that the fluid has a good lifting capability and is capable of lifting finger root, and gas leakage is small.In addition, a spring - quality - damper dynamic model of FS system is proposed to describe the dynamic running of FS system because the rotor is jumpy, and following capacity of finger root to the motion of the rotor has been analyzed. The analyse result indicates that the designed hydrodynamic finger root has a very good following capacity tothe rotor, and doesn’t contact to the rotor at all time.更多还原