Research On Flow Field And Dynamic Characteristics For Seal System Of Ultra-super Critical Steam Turbine

With the continuous development of our economy, power generation equipment isin rapidly expansion demand strategic transition period. The steam turbine generator setis moving in the direction of development of supercritical and ultra supercritical.Because of the higher rotor speed, greater scale and higher steam pressure, the resultingloss of steam and shafting instability caused by sealing force is more serious. Domesticand foreign researches in this area are limited. This paper mainly analyzes the questionsof the dynamic characteristic coefficient of labyrinth seal, the sealing mechanism oflabyrinth seal and the stability of labyrinth seal rotor system. Using FLUENT softwarein-depth analyzes the internal flow field of labyrinth seals. According to the results ofthe simulation, optimizes the sealing structure, makes an analysis of the labyrinth sealeffect on the stability of rotor bearing system. Provide guidance for the design of theseals for the turbine generator and installation.This paper analyzes the through type, interleaved type and ladder type. Anddetermine the flow form of through type finally. Through the comparison of the maincalculation method on leakage, iterative computing method is determined. Verify theaccuracy of the simulation calculation through the literature examples.A two-dimensional model of labyrinth seal is established. Analyzes the impact ofthe gap width, the cavity depth, the cavity width and tooth shape on the leakage of theseal. The best sealing structure parameters is obtained. Combining with the fluidmechanics, analyzes the flow field changing trend of the sealed chamber. Athree-dimensional model of labyrinth seal is established. Analyzes the impact of rotorspeed, pressure difference, rotor whirl speed, fluid pre-rotational speed and channellength on the leakage of the seal.A linear model of sealing force is established based on the optimized structure ofthe seal. Combining the calculation formula of the seal dynamic coefficients, analyzesthe effects of sealing clearance seal diameter, pressure difference and rotor speed on thestiffness and damping coefficient in detail. Study the effects of seal stiffness anddamping coefficient on the stability of rotor system to further improve the sealingstructure.Analyzes the impact of labyrinth seal on the critical speed, unbalance response andstability of rotor bearing system. Combined with the Q factor and the logarithmicdecrement, make stability evaluation of shafting after considering the seal.