燃气-蒸汽弹射气液两相流场流动耦合特性研究

Study on flow coupling characteristics of gas⁃liquid two⁃phase flow field in gas⁃steam ejection

为研究燃气-蒸汽弹射中气液两相流场的流动耦合特性,基于Mixture模型和RNG k-ε湍流模型并结合自定义汽化凝结程序,建立了考虑汽化效应、组分输运和动网格影响的数值模型,并通过模拟发动机尾焰注水试验验证了模型的有效性。在此基础上对复杂波系的形成和气液流动耦合特性进行了分析,并研究了喷水孔直径对气液两相流场的影响。研究表明:因管道结构和水射流约束而产生的系列膨胀波与压缩波会在管道内相交反射形成波系,波系通过影响两相流的属性将内流场划分为不同的区域。在弯管内因离心力作用而形成的迪恩涡能增强湍流强度,提高水汽转换传质传热的效率,同时水射流对燃气流有较强的阻滞与挤压作用,两者会因能量的差异而在喷水管处相互挤压。喷水孔总面积相同时,直径越小,质量流率越小,水汽转换效率越高;直径越大,温度和压强的波动越大,导弹的运动越不平稳。研究结果可为燃气-蒸汽弹射的流场分析和结构设计提供参考。

In order to study the flow coupling characteristics of gas-liquid two-phase flow field in gas-steam ejection,a numeri-cal model which takes into account the effects of vaporization,component transport and dynamic mesh was established based on Mixture model and RNG k-εturbulence model,and combined with a self-defined vaporization condensation program.The effective-ness of the model was verified by tail-flame injection test of a simulated injector.On this basis,the formation of complex wave sys-tem and the coupling characteristics of gas-liquid flow were analyzed,and the influence of the diameter of the spout hole on the gas-liquid two-phase flow field was studied.The results show that a series of expansion waves and compression waves generated by pipe structure and water jet constraints can intersect and reflect in the pipe to form a wave system.The wave system divides the internal flow field into different regions by affecting the properties of the two-phase flow.The Dean vortex formed by centrifugal force in the elbow can enhance the turbulence intensity and improve the efficiency of water vapor conversion and mass transfer and heat transfer.At the same time,the water jet has a strong blocking and squeezing effect on the gas flow,both two will squeeze each other at the spray pipe due to energy difference.When the total area of the spout hole is the same,the smaller the diameter,the smaller the mass flow rate,and the higher the water vapor conversion efficiency.The larger the diameter,the greater the fluctuation in tempera-ture and pressure,and the more unstable the missile motion.The results can provide reference for flow field analysis and structural design of gas-steam ejection.