密封汽流激振下转子动力特性的时域分析

Time-domain analysis of rotordynamic characteristics with steam flow excited vibration in seal

针对汽轮机转子偏心导致的汽流激振问题和静偏心模型在转子动力特性研究中的缺陷,采用动网格技术模拟转子真实的三维涡动,在时域上对转子的动力特性进行研究。结果表明:转子涡动时,汽流激振力及其动力系数在时域上随位移呈三角函数变化,且径向力的方向随转子中心位置的变化发生改变。偏心率、涡动速度、自转速度和压比均影响转子动力特性。额定工况下,偏心率每增加10%,径向力与切向力平均增加约25~35 N。随着涡动速度的增大,切向力朝负方向增加,而直接阻尼和交叉阻尼减小。随着压比的增加,径向力增大而切向力减小。在一定范围内,较大的自转速度会使最大激振力的绝对值减小。

In order to solve the problem of steam flow excited vibration caused by rotor eccentricity in steam turbine and the defects of static eccentric rotor whirling motion model in rotordynamic characteristics study,the dynamic mesh was adopted to simulate the authentic rotor three-dimensional whirling motion in order to study rotordynamic characteristics in time domain.The results show that the exciting force and the rotordynamic coefficients present the trigonometric function changes while the rotor whirls,and the direction of radial force changes with rotor central position.The rotordynamic characteristics are influenced by the eccentricity,whirling speed,rotational speed and pressure ratio.Under rated condition,the radial force and tangential force increase about 25-35 N averagely with the 10%increase in eccentricity.As the whirling speed increases,the tangential force,direct damping and cross damping decrease.With the increase of pressure ratio,the radial force increases,while tangential force decreases.In a certain range,the absolute value of maximal exciting force decreases when the rotational speed becomes higher.