Carrier-based aircraft steam catapult system with feedback linearization control

To study the states' change of accumulator and cylinder in steam catapult aircraft launch, aiming at the nonlinear coupling characteristics of the cylinder system, considering the flashing phenomenon in the steam accumulator, the pressure change of chamber with rod and without rod in the steam cylinder, and the relationship between launching valve's core displacement and flow area, the steam accumulator and launching valve mathematical model, cylinder thermodynamic model and the aircraft six degrees of freedom dynamics model were established, and the launching valve controller of steam catapult system was accomplished. The simulation finds that the pressure-drop steam catapult system was extremely small, almost negligible in the catapult period; moreover, because of the nonlinear and coupling characteristics of the cylinder system, the traditional control method cannot accomplish a stable launching valve, whose opening degree experiences strong mutations when opened and closed. Based on the feedback linearization theory, the steam cylinder model can be completely linearized and can decouple cylinder state variables, contributing to the design of the launching valve controller. The simulation shows that using the feedback linearization method, the launching valve regulator can perform in a stable manner, achieving acceptable acceleration tracking effect during the catapult process. © 2016, Editorial Department of Journal of HEU. All right reserved.