Papers by Author: Chun Yu Zhao

Abstract: The dynamic model of vibrating system with two motors is established. Through dynamic analysis, the equations of frequency capture of the vibrating system and the conditions of implementing stable self-synchronous operation are obtained. Then the vibrating system is optimization designed based on the conditions of implementing stable self-synchronous operation. The simulation program with proper parameters of vibrating system is run, and the results show that the system is in a good synchronous state. Computer simulations demonstrate that the vibrating system realizes speed synchronization and phase synchronization. The results verify the effectiveness of the optimization design.

Abstract: Structural damage often happens in rotating machinery such as steam engines, aircraft engines, and compressors due to the high-speed rotating of the shaft. The most common structural damages in rotating machinery are rotor shaft crack, rotor to stator rub, and bolts looseness and so on. In the present paper, the model based identification method is used to detect single structural damage such as crack, rotor to stator rub, pedestal looseness, and also, coupling fault such as rotor to stator rub and crack, crack and pedestal looseness. Utilizing the characteristic that equivalent loads of rub forces are internal forces, and the equivalent loads of the crack are external moments, the coupling faults of crack and rub-impact and crack and pedestal looseness are analyzed and exampled. The merit of the method is that it is an online diagnosis method, which provides early warning of machine failure. Theoretical simulation and laboratory testing are conducted to validate the method.

Abstract: A continuum model of the evolution of air ingestion and entrainment for open-ended squeeze film dampers is proposed in this paper. Hydrodynamic lubrication theory is extended to lubrication with mixture of a Newtonian liquid and an ideal gas. The solution to the universal Reynolds equation is determined numerically using a control volume method (Elrod algorithm) and the forth-order Range-Kutta method. This method conserves mass throughout the computational domain including air ingestion and entrainment. Excellent agreement is found with the experimental works of Diaz and San Andrès for the squeeze film damper [1, 2].