Hong Jie

Vibration Reduction Investigation of a Squeeze Film Damper With Valvular Metal Rubber

A new-style squeeze film damper with valvular metal rubber squeeze film ring (SFD/VMR) was designed to improve characteristics of the squeeze film force of the SFD. The immobile squeeze film ring of the SFD was replaced by the elastic squeeze film ring with the valvular metal rubber subassembly (VMR). When the unbalance force was smaller, the displacement of the journal changed little, and then the squeeze film force was smaller too, so as to the squeeze film ring of the SFD/VMR was nearly immobile. The working condition was similar with the SFD. When the unbalance force was larger, the displacement of the journal changed bigger, and then the squeeze film force rapidly increased, so as to the VMR deformed, which made the film thickness changed correspondingly, until it reached a balanceable state of the squeeze film force and elastic force of the VMR. Theoretical and experimental investigations showed that the SFD/VMR had optimal effect on reducing vibration, comparing with the SFD, because it could passively adjust the squeeze film clearance by taking advantage of the elastic deformation of the VMR. The SFD/VMR could control the squeeze film clearance in a suitable range, which made the characteristics of the squeeze film force of the SFD/VMR better than the SFD. The SFD/VMR could suppress the occurrence of the nonlinear vibration phenomenon markedly, such as bistable jump up.© 2006 ASME

Vibration Suppression of Additional Unbalance Caused by the Non-continuous Characteristics of a Typical Aero-Engine Rotor

The advanced aero engines have various features such as light weight, high efficiency and high power, so its rotor system is comparably weak, while the rotor often has to endure heavier weight loads. With loads of assembling and operating, the relative position between jointing interfaces will variate due to the relative slide of the interfaces and the changes of contact status. Dislocation of jointing interfaces can induce a deviation of the center of mass (CM) of the rotor system from its rotating axis, which implies an additional unbalance and may cause an engine vibration problem. In this article, a mechanism model is established to study the random influence of joints over the unbalance of rotor system. Then researchers use a typical aero-engine rotor as an example to investigate this topic. This study indicates that the additional unbalance of rotor system can be ascribed to the relative dislocation between jointing interfaces. The additional unbalance also shows a strong uncertainty due to the randomness of interfaces’ dislocation. Methods to control the technological parameters of joints should be utilized during the designing span of a rotor system in order to significantly depress the unbalance of rotor system and prevent engine from vibration effectively.