地面停放低温液氧贮箱热物理过程研究
Research on the Thermal Physical Process of Cryogenic Liquid Oxygen Tank in Ground Parking

针对低温推进剂箱体射前停放阶段,采用CFD技术数值研究了某低温液氧贮箱在地面停放阶段所经历的开口放置及高温气氧预增压过程。详细分析了该过程中箱体的压力变化、气液相变以及热分层现象。通过与相关试验结果对比,验证了本数值模型的有效性。计算结果表明:在液氧箱体开口停放阶段,在外部漏热下,箱体内部将出现剧烈的沸腾相变现象,并伴随着大量气泡的产生。随着时间的增加,用于低温流体相变的热量主要来自于外部漏热,此时相变过程主要发生在气液界面。在约150 s时,相变强度逐渐趋于稳定。经过250 s的地面开口停放,蒸发气体排放量约6.88 kg。当低温箱体封闭,预增压过程开始,箱体压力将在所设定的压力上下限内波动变化。由于气相过热、液相过冷,在整个过程中气相都处于冷凝状态。随着高温气体的注入,气相质量呈现波动变化,由15.84 kg增加到27？？27 kg。液相质量则近似线性增加,由最初的12 243？？10 kg增加到12 303？？95 kg。气液界面以下的液相呈现出较好的温度分层,气相温度分布则受增压气体影响较大,产生了一定的扰动。
The computational fluid dynamics (CFD) was used to investigate the pressurization process of cryogenic liquid oxygen tank including the open parking and pre？？pressurization stages in the ground parking before launch. The tank pressure change, liquid？？vapor phase change and fluid thermal stratification were analyzed in detail. The present CFD model was proven to have effective prediction ability in comparison with the experimental results. The results showed that under the external heat leakage, the intensive boiling phase change occurred in the tank with a large amount of gas bubbles moving upwards in the fluid during the ground open parking stage. As the heat used to generate phase change became less and mainly from the external heat leakage, the phase change intensity became weak and tended to stable in about 150 s, with the phase change focused on the interface. The total evaporation loss was about 6？？88 kg for 250 s ground open parking. When the cryogenic liquid oxygen tank was locked and the ground pre？？pressurization started, the tank pressure fluctuated between the maximum and minimum pressure limits. As the ullage was superheated and the liquid was subcooled, the ullage condensation appeared in the whole pre？？pressurization process. With the high temperature gas injecting into the tank, the ullage mass presented fluctuation change, with the value increasing from 15？？84 kg to 27？？27 kg. While the liquid mass displayed an almost linear increasing tendency, and rose from 12 243？？10 kg to 12 303？？95 kg. An obvious thermal stratification appeared in the liquid region below the liquid？？vapor interface, while the ullage was largely influenced by the injection gas with some disturbances