喷射压力对同轴旋转射流喷雾锥角影响的实验研究

Experimental Study on Effects of Injection Pressure on Spray Cone Angle of Coaxial Swirl Injector

关键词:  双组元空间推进器  同轴旋流喷注器  喷雾锥角

Key words:  Bipropellant space thruster  Coaxial swirl injector  Spray cone angle

摘要:

为了研究同轴旋转射流喷雾锥角的变化规律，设计了喷雾实验装置和同轴旋流喷注器。采用水和乙醇分别代替氧化剂和燃料，利用高速摄影系统对喷雾过程进行观测，分析不同喷射压力下喷雾锥角的变化规律。实验结果表明:内外两路同时喷雾时，喷雾锥角随着外路喷射压力的增加而增大，锥角值从81.6°增加至102.3°；但内路喷射压力增加后，喷雾锥角反而减小，从102.5°降低到94.8°。这个变化规律与单路旋流喷嘴的情况有所不同。将实验结果与通过动量定理推导出的理论公式进行对比，发现喷射压力小于0.2MPa时，实验值与理论公式吻合较好；随着喷射压力的增加，喷孔内液体的湍动能对喷雾锥角的影响逐渐增加，导致实验值与理论公式的偏差逐渐增大，喷射压力增加至0.6MPa时，实验值比理论值大10°左右。实验还研究了内路出口缩进对喷雾锥角的影响，结果显示随内路出口缩进长度的增加，喷雾锥角呈现先减小后增大的变化趋势。

Abstract:

To investigate the spray cone angle variation of coaxial swirling jet，the spray experiment device and the coaxial swirl injector were designed. Water and ethanol were used in place of the oxidant and fuel. The spray process was observed with high speed photography system，and the variation of spray cone angle under different injection pressure was analyzed. The results indicated that，when the inner and outer sprays were injected together，the spray cone angle increased with the increase of outer injection pressure，the cone angle value increased from 81.6° to 102.3°，but the spray cone angle decreased when the inner injection pressure increase，reduced from 102.5° to 94.8°. This variation is different from that of the single swirl injector. The experimental results were compared with the theoretical formula derived from the momentum theorem. The experimental values were in good agreement with the theoretical formula when the injection pressure was less than 0.2MPa. When the injection pressure increased，the deviation between the experimental value and the theoretical formula was gradually expanded because the effects of the turbulent kinetic energy of the liquid in the nozzle on the spray cone angle become larger. When the injection pressure increased to 0.6MPa，the experimental value is about 10° higher than the theoretical value. The experiment also studied the effects of recess length of inner injector on the spray cone angle，the results indicated that，with the increase of the recess length，the spray cone angle showed a trend of decrease first and then increase.