With A Slender Shaft Of The Power Turbine Rotor Dynamic Characteristics Analysis

With the development of modern aviation industry, the aero-engine turbo-rotor not only demands high speed, long and thin shape, high efficiency, but also demands lower noise and vibration. Rotor dynamic design is one of the most important aspects of aero-engine design. Rotor dynamic analysis is the first step of rotor dynamic design. The Transfer Matrix Method (TMM) and the Finite Element Method (FEM) are two ordinary calculating methods for rotary system.Firstly the MATLAB codes of TMM for rotor critical speed computation is programmed. With both TMM program and FEM software SAMCEF/ROTOR, the rotor dynamics model of WW turbo-shaft was built, and the critical speeds were calculated. After comparing and analyzing the two results, it can be concluded that the two results were consistent. And the harmonic response and the transient response of the turbo-shaft rotor were calculating.At last this paper discussed the influence of the rotor's structural parameters on the turbo-shaft rotor's dynamics character, such as the critical speed by the rigidity of the fifth elastic bearing, the bend rigidity of the spline and the length of the branch's structure; the influencing regularity of the transient responses by the rigidity of the fifth elastic bearing, the nominal gap between the shaft and the stator of the squeeze-film damper, inlet and outlet pressure, the unbalance.Based on the computations, following conclusions can be drawn.1. The critical speeds of the turbo-shaft are influenced obviously by the rigidity of the fifth elastic bearing and the length of the branch's structure;2. The spline can be regarded as a rigid coupling part if it's bend rigidity is very large;3. The gap between the shaft and the stator of the squeeze-film damper is the mainly factor of the damper's vibration-proof effectiveness;4. The damper's vibration-proof effectiveness is independent of the inlet and outlet pressure of the squeeze-film damper;5. The response of the turbo-shaft is linear with the unbalance in a special interval.