迷宫密封对高参数转子系统稳定性的影响分析及公理设计方法应用

Investigation on Influences of Labyrinth Seal on Stability of High-Parameter Rotor System and Application of Axiomatic Design Method

针对高参数汽轮机,研究迷宫密封汽封力和轴承油膜力作用下的转子系统稳定性问题。首先基于两控制体模型对各级密封的动特性进行计算,并与6瓦可倾瓦轴承进行对比,发现高压缸围带密封的交叉刚度已达107N/m,与轴承相当或更大,表明密封相比轴承是稳定性的主导因素。然后采用有限元方法将实际转子进行模化,根据建立的转子轴承密封系统动力学模型,对不同密封间隙和转速下的系统动力学特性进行计算分析,表明：考虑密封力后系统的最小对数衰减率min下降很大但对临界转速影响不大。间隙对min的影响存在区域性,在小于设计间隙（0.5~0.8 mm）范围选择合适的间隙可使系统的泄漏特性和稳定性最优。最后针对4种密封耦合设计方案,采用公理化方法研究其概念设计过程中的知识表达、知识融合及优化决策,表明该方法的简明和有效性。

The rotor system＇s dynamic stability of high-parameters steam turbine under the combined action of oil-film force and labyrinth seal force was researched.The improved two-control-volume bulk-flow model was used to compute the dynamic coefficients of multi-stage labyrinth seals,and the results show that the cross-stiffness of high pressure cylinder shroud seals has reached about 107N/m,which is equal or even higher than the six-pad tilting bearing＇s cross-stiffness,this indicate that seal is the dominant factor of system＇s dynamic stability.The rotor system was modeled by finite element method and then the rotor-bearing-seal dynamic model was built to calculate the influence of seal clearance and rotating speed on rotor system dynamic performance,the analysis results indicate that the logarithm decrement（？min） of the rotor system decreased rapidly in considering of the sealing force,but the critical speed of rotor system is influenced weakly,while,the ？min is influenced by the seal clearance regionally,proper choice of seal clearance in range of 0.5 mm to 0.8 mm which is less than the design clearance（0.8mm）,can optimize the leakage and stability of the system.The concept design knowledge representation and scheme optimization for coupling design was accomplished by axiomatic design（AD）theory,which takes four schemes of seal design as the case,and this indicate that the AD method is simple and effective.