Dynamic modeling and analysis of the different cavity-type hydrostatic slide turntable system
In this paper, a nonlinear oil-film force model with velocity term for hydrostatic slide system with rectangular, sector and round chamber is established respectively, by eliminating the small amount after the dimensional analysis with the help of Navier-Stokes equation, and combining with the oil-film bearing model of Hydrostatic Slide System of constant oil supply. And the turntable dynamic equations of hydrostatic slide system with different chambers are formulated consequently. Furthermore, the analysis of dynamics properties of the hydrostatic slide turntable with the same oil chamber area is investigated by numerical simulation. This research provide theoretical bases of the further studying and improving of the rest aspects property of hydrostatic oil film-turntable system.
A novel nonlinear model of rotor/bearing/seal system and numerical analysis
Abstract A novel nonlinear model of rotor/bearing/seal system based on the Hamilton principle is proposed for steam turbine systems in power plants. The Musznyska model and unsteady bearing oil-film force model were applied to describe the nonlinear steam excitation force and oil-film force. The Runge–Kutta method was used to solve the motion equation of the rotor/seal/bearing system. The dynamic characteristics of the rotor/bearing/seal system were analyzed with bifurcation diagrams, time-history diagrams, trajectory diagrams, Poincare maps and frequency spectrums. The numerical analysis indicates that the seal force and the oil-film force influence the nonlinear dynamic characteristics of the rotor system. With the increase of rotation speed, the rotor system exhibits rich forms of periodic, double-periodic, multi-periodic, quasi-periodic and chaotic motion. The combined impact of steam excitation force and bearing oil-film force may cause a severe vibration which seriously affects the safety and stability of the rotor. The presented model provides a theoretic foundation for further research on the ultra-supercritical steam turbines.
Study on quantitative earthquake damage of Dujiangyan city, caused by 2008 MS=8.0 Wenchuan, China earthquake based on aerial imagery
The paper introduces quantitative earthquake damage estimation method based on remote sensing data. The quantitative remote sensing seismic damage index based on building damage extracted from the aerial image of Dujiangyan city proper, southwest China's Sichuan province, which acquired after 2008 Ms=8.0 Wenchuan earthquake. The actual seismic damage indices were determined by the ground-based investigation in the city proper. Then their quantitative relationship was established. The results indicate that it is possible to build quantitative model of remote sensing seismic damage, which will enhance significantly the practicality applying the remote sensing in emergency acquisition and analysis of seismic disaster.