轴向长度对旋转爆震发动机的影响

Influence of axial length on rotating detonation engine

采用9组分19步基元反应模型,不考虑黏性、热传导和扩散效应等对流动的影响,对以氢气和氧气为反应混合物的旋转爆震发动机内流场进行计算,研究轴向长度对发动机性能的影响.研究表明:在一定范围内轴向长度对发动机比冲影响很小,轴向长度过长时会降低发动机比冲.轴向长度对爆震波的压力形成影响很大,轴向长度过小时,爆震波压力不高,过大时,会导致斜激波压力衰减.随着轴向长度的增加,由于膨胀的作用,出口的压力不断降低,轴向长度为200mm时,出口的平均速度最大,此时发动机比冲也达到最大值;周向速度明显减小,降低了周向速度对发动机的不利影响;推力密度峰值逐渐下降;激波前后密度差逐渐减小,这使发动机的推力偏心矩也不断降低,从而可有效地减小角散布等不利影响.

Based on 9 species and 19-step reaction,without consideration of the effect of viscosity,heat transmission and diffusion on flow,mixtures of hydrogen and oxygen were used to simulate rotating detonation engine flow field to research the effect of axial length on engine performance.Research show that：within a certain range,axial length has little influence on specific impulse of engine,but if axial length is too long,it will decrease specific impulse of engine;axial length has great influence on detonation pressure and temperature;if axial length is too little,the pressure of detonation wave is not high;if axial length is too long,the oblique detonation may decay;with the increase of axial length,the pressure of outlet continues to decrease owing to expansion;when axial length is 200 mm,the average speed and specific impulse of engine reach the maximum value;azimuthal velocity decreases obviously cuttingdown the harmful influence on engine;the maximum thrust density decreases gradually;density difference in before and after shock wave decreases gradually,so that the thrust eccentricity could continue to decrease,thus effectively reducing angle scatter harmful influence.