轴系稳定性与支承轴承的关系

本文研究了大型旋转机械转子轴承系统的稳定性与每个支承轴承的关系,建立了轴承对整个轴系稳定性的贡献系数。贡献系数最大的轴承对稳定性的贡献最大;贡献系数最小的轴承是轴系中最危险的轴承。油膜失稳或油膜振荡往往由这个轴承首先激发。轴系稳定性主要取决于系统中敏感轴承的动特性系数。适当地改变这些轴承的结构型式或设计参数可以显著地提高轴系的稳定性裕度。分别对一个5支承的模型转子系统以及国产200MW汽轮发电机组进行了数值计算,结果表明本文的计算结果与机组的实测结果比较一致。此外还讨论了国产200MW机组轴承的改造方案,提出将发电机转子的两个轴承改换为椭圆轴承,不但可以有效地提高机组的稳定性,而且改造费用最低。

Relationship between Rotor-Bearing System Stability and Supporting Bearings

The relationship between the rotor-bearing system stability of a large rotating machinery and the supporting bearings is investigated. The contribution factor of the bearings to the system stability is established. The bearing with the largest contribution factor gives the greatest contribution to the system stability. The bearing with the smallest contribution factor is considered as the most dangerous one, and oil whirl or oil whip is always first aroused by it. The rotor-bearing system stability mainly depends on the dynamic characteristic performance of the sensitive bearings. Appropriate readjustment in the type or design parameters of these bearings will result in large improvment in stability margin. Numerical examples are carried out for a model rotor-bearing system with five bearings in a domestic 200MW turbine generator set, which shows that the calculated results are in good agreement with those measured for some actual rotating machinery. Furthermore.the scheme to reconstruct the domestic 200MW turbine generator set is discussed,which discloses that it will not only bring about large increase in the stability but also reduce the cost of reconstruction to a minimum for us if two supporting bearings of the generator are changed into elliptical bearings.