基于流场探测的发动机喘振控制仿真研究

(1.西北工业大学 燃烧、热结构与内流场重点实验室,陕西 西安 710072; 2.西安航天动力研究所,陕西 西安 710100)

冲压发动机; 激波探测; 喘振控制; 仿真

Simulation research on ramjet buzz control based on flow field detecting technology
LIANG Junlong1, WANG Yufeng2, ZHANG Guitian1

(1. State Key Laboratory of Combustion, Thermal Structure and Inner Flow Field, School of Astronautics, Northwestern Polytechnical University, Xi'an 710072,China; 2. Xi'an Aerospace Propulsion Institute, Xi'an 710100,China)

ramjet; shock wave detection; buzz control; simulation

备注

为使冲压发动机性能最优并始终工作在安全状态,需要使其工作的喘振裕度最小且在喘振边界内。在喘振边界安装一种能够准确分辨超声速或亚声速流场状态的流场探测装置,控制进气道结尾激波位置。针对一维变截面流动控制方程,研究了流场探测装置的安装位置,以及激波越过流场探测装置后控制系统的减油规律。仿真研究结果表明,用试验数据修正理论仿真的方法可以准确地捕捉进气道结尾激波,同时根据某型冲压发动机的设计临界喘振裕度,确定了流场探测装置安装位置位于距进气道锥尖的距离; 进气道沿程压力跟随发动机燃油流量的变化而变化,压力波传播时间相对于燃油调节时间可以忽略; 由于进气道内激波前后运动存在明显的压力滞环现象,当激波越过喘振边界时,进气道出口压力会进一步上升,发动机喘振危险加大,应使用加速电磁阀快速减小燃油流量,控制激波回到安全区域。

In order to make the ramjet performance optimization and always work in a security state, the ramjet's buzz margin should be keep in minimum and within the buzz boundary. A flow field detecting device that can distinguish the supersonic or subsonic flow field status is installed in the buzz boundary to control shock wave location at the intake terminal. Aiming at the one-dimensional variable cross-section flow control equations, the installation position of the flow field detecting device and the fuel reduction law of the control system after the shock wave goes through flow field detecting device are studied in this paper. The simulation result indicates that the method to use the test data to correct theoretical simulation data can accurately catch the shock wave at intake terminal, and according to the critical buzz margin designed for a certain type ramjet, can determine the installation location of the shock exploring device. The pressure along intake changes with the variation of engine's fuel flow, pressure wave propagation time relative to the fuel regulating time can be ignored. As the existence of the pressure hysteresis phenomenon is obvious before and after the intake shock motion, when the shock goes through the buzz boundary, the pressure at intake exit will rise further, the engine buzz risk increases, and the acceleration electromagnetic valve should be adopted to quickly reduce fuel flow, so as to make the shock wave go back to a safe area.