基于改进牛顿法的航空发动机起动建模技术

为进行涡扇发动机起动过程性能仿真研究,在发动机慢车以上部件级模型的基础上,通过指数外推法获得低转速部件特性,在建立起动附件模型的同时,修正起动过程各部件总压恢复系数,从而建立起包含地面起动过程的全状态性能模型。在求解发动机各部件共同工作非线性方程组时,采用基于传统牛顿拉夫森迭代求解方法的改进方法,即在第1次完成中心差分得到Jacobian矩阵后,使用修正项迭代更新上一步的Jacobian矩阵。结果表明:该建模方法可以有效地建立起动过程性能模型,并大幅改善模型的执行效率、提高模型仿真求解速度。

Sub-idle Modeling of Aeroengine Based on Improved Newton's Method

In order to perform the performance simulation of aeroengine starting process, the component characteristics of low speed were obtained through the exponential extrapolation on the basis of component level model which was above idle region, and a full state performance model including ground starting process was finally established with modeling of starting accessories and modification of the total pressure recovery coefficient of each component. An improved Newton iterative method was adopted when solving the nonlinear equations of aeroengine different components. The Jacobian matrix was obtained by central difference for only one time, and it was updated iteratively with a modified term obtained over last iteration. The result shows that the modeling method can effectively establish the starting process model, and greatly improve the efficiency and speed of model simulation