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中国物理学会期刊

动量比及其调节方式对针栓喷注器喷雾特性的影响

CSTR: 32037.14.aps.68.20190671

Influence of momentum ratio and its throttling method on spray characteristics of pintle injector

CSTR: 32037.14.aps.68.20190671
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  • 对不同动量比下针栓喷注器的喷雾特性开展了试验研究. 以水为模拟介质, 分别通过增大氧化剂流量与减小燃料流量, 在0.16—0.99范围内增大局部动量比, 其中前者对应的总动量更高. 通过高速摄影结合激光相位多普勒技术(PDA)研究了不同工况下的喷雾边界、粒径分布及速度场. 结果表明, 工况变化直接影响喷雾形态, 并进一步影响其他喷雾特性. 对于同一局部动量比, 喷雾锥角一致, 但高总动量对应的喷雾下游范围更大. 随着外喷嘴流量增加, 喷雾上游出现空心区, 且其范围随局部动量比增大而增大. Sauter平均直径 (SMD)随局部动量比增加而增大, 变化范围则随总动量增高而扩大. 有空心区的喷雾SMD沿径向呈N形变化趋势, 喷雾外缘粒径最大; 实心喷雾SMD沿径向略有下降. 喷雾合速度取决于总动量, 合速度、轴向速度、径向速度均沿径向呈倒V形变化, 但轴向速度以下降趋势为主, 径向速度增加后缓慢减小或直接趋平. 局部动量比越高, 径向速度越高, 轴向速度越低. 此外, 空心区下方喷雾速度场由液膜主导.

     

    The spray characteristics of a liquid-liquid pintle injector under different momentum ratios are investigated experimentally in this paper. Water is used as a simulant medium for both the fuel and the oxidizer. By increasing the mass flow rate of the oxidizer or reducing the mass flow rate of the fuel, the local momentum ratio is increased from 0.16 to 0.99, wherein the responding total momentum obtained by the former throttling method is relatively high due to the higher mass flow rate of the fluid. The outer and inner spray boundary, droplet size distribution and the velocity field are studied by high-speed camera and phase Doppler anemometry (PDA). It is indicated that the spray pattern is affected by the operating conditions directly. The spray pattern is divided into the solid cone and the hollow-solid cone, generally. Furthermore, the spray pattern influences the other spray characteristics. Under the same local momentum ratio with different throttling methods, the spray angle is almost consistent, while the spray boundary in the far field is wider under the higher total momentum. With the increase of the mass flow rate of the outer injector, a hollow structure is generated in the near field of the spray, and its range expands with the increase of the local momentum ratio. The value of SMD increases with the local momentum ratio increasing. Under the same local momentum ratio, the variation range of SMD is wider under the higher total momentum. The variation trend of SMD in the radial direction differs from the spray pattern, too. The SMD of the hollow-solid spray displays as an " N” shape along the radial direction, and reaches its peak at the outer boundary. By contrast, the SMD of the solid spray decreases slightly in the radial direction and varies on a small scale. The value of the resultant velocity is determined by the total momentum, and the curves of all the resultant/axial/radial velocity display as an inverted " V” in the radial direction. Nevertheless, the trend of axial velocity in the radial direction is mainly decreasing, and the increasing stage only exists at the central spray. However, the radial velocity undergoes a slight decrease or levels off directly after reaching the peak. The higher the local momentum ratio, the larger the radial velocity is, while the lower the axial velocity. In addition, the velocity field below the hollow field is dominated by the liquid film, which is explained by analyzing the impinging process of the neighboring cloaks in this paper.

     

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