Dynamic Modeling of the Blade-Rotor-Shaft-Bearing System with SFD

Abstract

There are often a large number of blades on the rotating shafts of rotating machinery such as steam turbine engines, aero engines, and compressors. In actual work, forces are transferred between the shafting and the blades. However, most of the current researches separate the blade from the rotor-bearing system, and study the vibration characteristics of the blade system and the nonlinear behavior of the rotor system separately. As a result, the interaction between the blade and the rotor-bearing system is fragmented, and the coupling vibration between the blade-disk-bearing system is ignored, which will inevitably affect the accuracy of the analysis. With the gradual increase of modern rotating machinery's high speed, light structure and the gradual increase of blade length, the degree of coupling between the blade and the rotor-bearing system has become tighter. Therefore, it is necessary to study the coupling effect of blade, disc and rotor vibration. At the same time, there are a lot of nonlinear phenomena in the rotor during operation. However, there are still relatively few studies on the nonlinearity of the blade-rotor-bearing system. A research project was carried out to create a dynamic equation of a blade-rotor-bearing-shaft system. Firstly, the model of a BRSB system is developed with consideration the rubbing between the blade-tip and casing by using contact dynamics theory. Next, Timoshenko beam elements are adopted to simulate the shaft and the blade, and shell elements to simulate the disk, and spring-damping elements to simulate the ball bearings. This dynamic modelling has certain significance in analysing the nonlinear characteristics and improving the stability of the rotor system.