Research On Contact Collision Characteristics For The Whole Circle Integrally Shrouded Blade

For the turbine machinery system, it is the serious threat to the safe of turbine system when the blade is failure. According to the relevant statistics, the blade malfunction is more than 40% of the total engine malfunction. Therefore, improving the reliability and stability of blade system is one of the investigation focuses. In the recent years, the Integrally Shrouded Blade (ISB) is using widely in the rotating machinery such as the steam turbine and aircraft engine.As a result of using ISB, the vibration energy of blade can be dissipated by the contact friction and impact between tips of the adjacent blades, so the vibration of blade can be reduced. In addition, the advantages of installation easily and repair conveniently is obvious.The normal collision and the tangential stick and slide of the tip interface of adjacent blades can result in the nonlinear dynamical behavior of blade. But nowadays the mechanism of the nonlinear behavior of ISB is not clear and the further research should be conducted. It is significant actually for the research that the service life of blade can be prolonged and the efficiency and reliability of the steam turbine can be increased.In this paper, 3D beam element of ANSYS software is employed to establish the discrete mesh of the blade. In the ISB group model with 5 blades the Hertz contact force model is used to describe the contact friction and impact between tips, and in the full circle model of ISB the penalty function is employed.In the investigation of the ISB group model, the vibration type graphs are given by the ANSYS modal analysis method,and the time history graph, phase diagram and spectrum diagram obtained by the ANSYS transient dynamics analysis method and the harmonic response analysis are used to study the nonlinear behavior of ISB group. In the full circle ISB model, the dynamical characteristic of the nodal diameter vibration is analyzed. The conclusions have important guiding significance for the analysis of the damping mechanism,optimization theory, the reliability design criteria.