基于航迹优化的变几何冲压发动机控制规律设计方法

Design Method of Control Law of Variable-Geometry Ramjet Based on Trajectory Optimization

关键词:  变几何  冲压发动机  控制规律  设计方法  航迹优化

Key words:  Variable geometry  Ramjet  Control law  Design method  Trajectory optimization

摘要:

宽速域的高超声速飞行需求对冲压发动机的变几何控制提出了更高的要求。基于高斯伪谱航迹优化方法，通过耦合变几何冲压发动机的控制变量及飞行器攻角变化率，将宽速域变几何冲压发动机的控制规律设计问题转换为特定飞行器的多变量最优航迹求解问题，建立了变几何亚燃冲压发动机的飞行器/推进系统匹配分析方法，实现了典型变几何冲压发动机的控制规律优化设计。研究结果表明：进排气无级可调冲压发动机最经济爬升轨迹相比最快爬升增加16.3%时间，节省7.8%燃油消耗，两种航迹状态下进气道均接近于临界状态，差异主要来自于油气比控制规律不同；喷管喉道面积两级可调冲压发动机通过动态调整进气道出口正激波位置及燃烧室油气比，亦可实现宽速域内的快速爬升，此时最经济航迹下燃油消耗较无极可调方案多20.8%，时间增加5.6%。

Abstract:

The requirement of hypersonic flight in the wide speed range puts forward higher requirements for the variable geometry control of the ramjet engine. Based on the trajectory optimization method of the Gauss pseudospectral， by coupling the control variables of the variable geometry ramjet and the rate of change of the aircraft’s angle of attack， the control law design problem of the wide-speed range variable geometry ramjet is converted into the multi-variable optimal trajectory solution of a specific aircraft problem. To solve the problem， a matching analysis method of the aircraft/propulsion system of the variable geometry ramjet is established， and the optimal design of the control law of the typical variable geometry ramjet is realized. The research results show that the most economical climb of the ramjet engine with an infinitely adjustable nozzle increases the time by 16.3% compared with the fastest climb and saves 7.8% of fuel consumption. Under the two-optimization goals， the inlet is close to the critical state， and the difference mainly comes from the different control law of the fuel-air ratio. The ramjet of the two-stage adjustable nozzle dynamically adjusts the position of the positive shock wave at the outlet of the inlet and the fuel-air ratio of the combustion chamber， which can also achieve a rapid climb at a wide speed range. At this time， the fuel consumption under the most economical climb is 20.8% more than the infinitely adjustable solution， and the time increases by 5.6%.