Research On Stability Simulation Analysis And Optimization Method Of Steam-turbine Rotor-bearing System

As a kind of significant equipment in electric power system,steam-turbine unit must run in security and reliably.Steam-turbine rotor is the main part of the unit, some instability accidents frequently happen because of complex working condition. Up to now,some steam-turbine accidents happen because of the rotor instability which causes greatly economic lost.There are many factors that result in rotor instability,for example,if the starting speed and the running speed are up to critical rotation speeds will cause serious instability phenomenon,rotor blade and impeller are affected by changing steam-excited force will cause intense vibration,and the rotor will become instable when affected by bearing nonlinear oil film force.Rotor instability will direct influence rotor's life,so it's greatly significant to enhance rotor's life and reliability by studying steam-turbine rotor stability.The C50-8.83/0.98 steam-turbine rotor-bearing system in Wuhan Steam-turbine Company was referred in the thesis,the virtual prototype of steam-turbine is modeled based on multi-body dynamic theory and higher rotor system dynamic theory.Critical rotation speeds were calculated by using modal solution technology in stead of Prohl Law.The virtual prototype which affected by steam-excited vibration is simulated, and the rule is found.Bearing is one of the most important factors which affect rotor stability.The change of bearing nonlinear oil film force will bring on oil film whirl.Based on bearing nonlinear mode expressions,the parameters which were defined in the virtual prototype were studied.The rule of bearing oil film force imbalance response was simulated and analyzed.In the end,the optimization of rotor stability is realized by using virtual prototype parameters design method,which provides a new method to solve optimization problem of complex mechanism system.The research conclusion was confirmed in enterprise's manufacture practice,and some analysis data about rotor characteristic in specific simulation environment also instruct the design and manufacture process.The research conclusion in thesis was confirmed in the steam turbine project between Wuhan Steam-turbine Company and Wuhan University of Technology Digital Manufacture Laboratory.At present,the critical rotation speeds was concerned mostly in the steam-turbine factory,the critical rotation speeds of virtual prototype are consistent with the prototype's,the conclusion of steam-excited vibration unbalanced respond can reasonably explain steam-turbine rotor's resonance effect under certain working condition.By analyzing the bearing dynamic characteristic influence to the rotor stability in the bearing film vibration research,the equipment can be forecasted whether it runs in security and reliably according to the bearing dynamic characteristic.Meanwhile,the rotor-bearing stability optimization result can help further improve the C50-8.83/0.98 steam-turbine rotor in this factory.