液氧煤油补燃发动机泵间管路高温富氧燃气掺混冷凝特性数值研究

Numerical Study on Mixing Condensation Characteristics of High Temperature Oxygen Enriched Gas in Pipe Between Turbopump for Liquid Oxygen/Kerosene Staged Combustion Cycle Engines

针对液氧煤油补燃发动机液氧预压泵和主泵间管路富氧燃气掺混冷凝现象,建立了大过热度下富氧燃气和液氧两相流动掺混冷凝特性的全三维数值仿真方法,并以常温制冷剂R123为工质,通过气液掺混冷凝实验验证了数值仿真模型对管内两相流型和气液再液化性能的精确预测能力。仿真结果表明:弯管段气液两相在离心力作用下发生横向相对流动,强化了相间热质交换;在较低的液体流速(1m/s)下,气体水平注入管路后形成一个与气孔相连接的局部气腔,注气速率低于80m/s时,气腔一侧贴在管路内壁上,注气速率超过100m/s后气腔脱离管路内壁面。气相在气腔下端被撕裂成离散的气泡,随液体向下游流动并逐渐冷凝。在实际工况下管路的富氧燃气没有全部完成再液化过程,此时流体状态会对液氧主泵造成气蚀影响。

Aiming at mixing condensation phenomenon of high temperature oxygen enriched gas in a pipe between a reloading pump and a main pump for liquid oxygen/kerosene staged combustion cycle engines,a full three-dimension numerical calculation method on mixing condensation characteristics of oxygen enriched gas and liquid oxygen two phase-flow under large super-heat degree was developed. Experiment study of gas-liquid mixing condensation with refrigerant R123 as working medium was conducted to verify accuracy and reliability of the numerical model. Calculated results show that lateral relative flow of the gas-liquid two-phase occurs in the elbow section under the action of centrifugal force,which enhances the heat and mass transfer between the two phases. Under lower liquid velocity of 1 m/s,a local gas cavity connected with the gas hole is formed after the high temperature oxygen enriched gas is injected into the pipe horizontally. When the gas injection rate is lower than 80 m/s,one side of the gas cavity is attached to the inner wall of the pipe. When the gas injection rate exceeds 100 m/s,the gas cavity could leave the inner wall of the pipe. The gas phase is torn into discrete bubbles at the lower end of the gas cavity and it gradually condenses with the liquid flowing downstream. As a result,it is found that the oxygen enriched gas in the outlet of pipe is not fully re-liquified in this actual working condition,and this flow state may cause cavitation effect on the main liquid oxygen pump.