航空发动机静子支承刚性的一种传递矩阵算法

A Transfer Matrix Method for Calculation of Support Stiffness of Aeroengine Stator

本文建立了航空发动机静子支承刚性的一种传递矩阵算法.该方法不仅可以计算出发动机静子支承刚性,也可以计算出发动机主支承到发动机安装节的传递函数.发动机静子支承刚性是发动机整机及转子系统动力特性分析所必须的数据,通常由实测法获得,然而在不具备实测条件时,一种较有效的解析方法是必要的.本文对一实际发动机静子系统进行了分析计算,在实测飞机上发动机安装节处的动柔度矩阵的基础上,分析得出静子支承刚性和主支承到安装节的传递函数.

Support stiffness of stator is usually obtained through testing. There does exist a Finite Element Method (FEM) for its determination. The authors believe that existing FEM software can be used for this purpose. However the high complexity of the structure of the stator requires the FEM model to include various finite elements and boundary elements. As a result, a great number of degrees of freedom must be used and the amount of computation is unnecessarily large. In order to reduce the amount of computation, the authors present Transfer Matrix Method (TMM). The main features of TMM are: (1) The order of the equations of TMM is very low and the amount of computation is samll. TMM makes use of the boundary conditions of each node and transfers the parameters of state of each elements, described by the eight parameters of state of the characteristic section of the stator, to the said characteristic section by means of the corresponding transfer matrix. Thus, for every stator system, all degrees of freedom are essentially expressed implicitly by the eight parameters of state of the said characteristic section. TMM still gives results of about the same precision as FEM. (2) As compared with FEM, the effect of aircraft or test plateform can be more conveniently taken into account by the stiffness matrix K_m and transfer matrix T_m of TMM. A specific engine stator is analyzed in this paper. The results show that the support stiffness of the stator varies significantly with frequency ω. So the errors will be significant if static stiffness is used to analyze the dynamic characteristics of the staotr. All computations of this paper are completed on a micro-computer. The computation time of TMM is only several minutes.