当量比对连续旋转爆轰燃烧室特性的影响

为了探究当量比对甲烷-空气连续旋转爆轰燃烧室（CRDC）特性的影响，利用二维可压缩欧拉方程对CRDC进行了数值研究，分析了爆轰波的发展过程和贫燃熄火过程，对比了不同工况下CRDC特性参数的变化情况。结果表明:CRDC起爆后燃烧场在由不稳定状态到相对稳定状态的过程中发生了2次碰撞，当进气当量比较低时，CRDC未能完全发生2次碰撞过程就已经熄爆。随着进气当量比的降低，爆轰波传播速度、轴向平均速度、出口平均温度、出口平均总压均呈下降趋势；增压比随当量比降低而减小的根本原因在于旋转爆轰燃烧过程和等压燃烧过程的熵增差减小，使吉布斯自由能增量差减小。CRDC的燃料驻留时间处于亚毫秒量级，燃烧热效率保持在99%以上。 

Influence of equivalence ratio on characteristics of continuously rotating detonation combustor

Based on two-dimensional compressible Euler equation, a series of numerical studies were conducted to investigate the effect of equivalence ratio on continuously rotating detonation combustor (CRDC) using methane-air mixture. The developing process and lean-burn extinction process of detonation wave were researched, and the influence of inlet equivalence ratio on performance parameters was analyzed in detail. Results showed that, after ignition, two collisions happened in the developing progress of CRDC from the unstable state to the relatively stable state. Extinction happened in CRDC without happening of two collisions when the inlet equivalence ratio was too low. With the decrease of inlet equivalence ratio, the detonation wave propagation velocity, axial average velocity, outlet average temperature and outlet average total pressure all showed a downtrend. The fundamental reason for the downtrend of the pressurization ratio was that the decrease of entropy increase difference between the rotating detonation combustion process and the isobaric combustion process resulted in the decrease of the Gibbs free energy increment. The fuel residence time was at sub-millisecond level and the thermal efficiency was kept more than 99%.