Research On The Thermal Bending Characteristics Of Rubbing Rotor For Steam Turbine

Vibration problems is a very common kind of problem to steam turbine during startup and operation process.There are a variety of reasons lead to severe vibration,one of which is the rubbing between the rotor and the stator of steam turbine.For large steam turbine units,the thermal impact of the rotor is often greater than the force impact when the rub impact occurs.The heat generated during rhe rubbing process will result in the bending of the rotor.In this paper,some characteristics of the frictional heat bending failure were obtained by doing some analysis about the temperature field and the vibration of the rotor using the finite element method,which have guiding significance to practical engineering problems.In this paper,a finite element model of a 660MW HP/IP turbo generator rotor was established based on the ANSYS and then the modal analysis was done using the model to verify the accuracy of the model.The temperature field of rub impact rotor was studied in this paper.First,the thermal-structure coupling analysis was done based on the finite element model.the model was used to analyze the effect of the friction coefficient,the clearance and the speed on friction heat;the thermal analysis of the same model was done to study the impact of thermal conductivity,heat capacity,environmental temperature and convection coefficient on the temperature field on occation that the friction was definite.The analysis about factors of the temperature field can provide reference to steam turbine design and actual operation to reduce the occurrence frequency of thermal-bending fault or the bending degree of steam turbine rotor.What's more,the vibration characteristics of rub impact thermal bending faults were studied.First,the unbalance vibration,thermal bending vibration and coupled vibration were analyzed to find the difference between the unbalanced and thermal bending faults,and then the influnces to these two kinds of vibration was researched through reducing the speed;the rub impact vibration was compared with the rubbing-thermal bending vibration to analyze the influnce of thermal bending;what's more,the transformation about the temperature field and the vibration was also analyzed after the rub impact disappeared.Finally,an engineering example was analyzed using numerical simulation conclusion.