变循环发动机稳态控制规律设计的新方法

An Innovative Method for Design of Steady State Control Law for Variable Cycle Engines

关键词:  逆算法  核心机驱动风扇  变循环发动机  稳态控制规律

Key words:  Reverse method  Core driven fan stage  Variable cycle engine  Steady state control law

摘要:

变循环发动机(VCE)具有较多的可调参数，为了进行变循环发动机的多变量稳态控制规律优化设计，提出了用于变循环发动机稳态控制规律优化设计的一种新方法-逆算法。该方法基于敏感性系数矩阵，采用可调参数替换传统部件级性能计算模型中的独立变量，在给定变循环发动机主要状态参数和部件参数的条件下，实现了可调参数的求解，进一步完成发动机稳态控制规律的优化设计。对比表明，逆算法的计算精度和收敛速度与传统算法一致，收敛性得到了改善。对带有核心机驱动风扇(CDFS)的双外涵变循环发动机亚声速巡航的节流状态控制规律优化后，使得巡航推力下的安装耗油率比定几何的双外涵和单外涵发动机分别下降7.8%和16.4%，而地面安装耗油率最大降低约3.4%。结果表明，逆算法是变循环发动机稳态控制规律优化设计的一种有效途径。

Abstract:

Variable cycle engine (VCE) has several variable geometry parameters. In this paper，a new method called ‘Reverse Method’ was developed to design the multiple variable steady state control law for VCEs. Based on the sensitivity matrix，the variables of the component based performance model were replaced with variable geometric parameters. Thus the state factors and components parameters were given while the variable geometric parameters were iterated during the procedure of engine off-design balancing which allows the optimal design of VCE steady state control law. Results showed that the ‘Reverse Method’ has the same accuracy and rate of convergence as the conventional component based model，while its astringency is better. The subsonic cruise control law for a dual-bypass VCE is optimized employing the ‘Reverse Method’ to minimize the installed specific fuel consumption (SFC). Optimization results showed 7.8% and 16.4% reduction in installed SFC compared to the fixed geometry dual-bypass mode and the single-bypass mode respectively. By using this optimized control law，the sea level installed SFC was decreased by 3.4%. It can be concluded that the ‘Reverse Method’ is a practical way to design the optimal steady state control law for VCEs.