某中央翼燃油箱惰化流场的数值模拟及特性分析

在不同富氮气体入口参数下,对某大型运输机中央翼燃油箱的惰化过程进行了数值模拟,研究了在不同流量和体积分数富氮气体条件下燃油箱的惰化规律.计算结果显示：当富氮气体中氮气体积分数为95%、体积流量分别为0.021,0.028m^3/s和0.042m^3/s时,燃油箱内平均氧体积分数随体积置换次数的变化曲线几乎完全重合;当富氮气体体积流量为0.042m^3/s、氮气体积百分比分别为92%,94%和98%时,燃油箱惰化率随时间的变化曲线重合.说明相同体积分数富氮气体条件下燃油箱惰化完成时所需富氮气体量与富氮气体流量无关,而富氮气体的流量直接决定了各舱室富氮气体的惰化率.通过对计算结果的分析,证明了利用缩比油箱去模拟真实油箱的惰化过程的合理性.为优化某运输机中央翼燃油箱惰化系统设计提供参考.

Numerical simulation and analysis of nitrogen-enriched air flow in a center wing tank

Under the different nitrogen-enriched air(NEA) parameters, the inerting process was studied by numerical simulation of a civil airplane center wing tank(CWT). The study show the inerting rule of the CWT under different flow rates and different oxygen concentration. The results show that, when the NEA containing volume fraction of about 95% of the nitrogen and the volume flow rate of the NEA are 0.021, 0.028m³/s and 0.042m³/s, the average oxygen volume fraction distribution versus volumetric tank exchange (VTE) are almost the same; when the volume flow rate of the NEA is 0.042 m³/s and the volume fraction of the nitrogen are 92%, 94% and 98%, the inerting ratio versus time are the same. It is conclusion that the inerting time of the CWT has nothing to do with the flow rate under the same oxygen concentration, and the flow rate of the NEA determines the inerting ratio of each bay. Based on comparative analysis of the numerical result, it proves that the shrink analogy method can be used to simulate the inerting process of the CWT. The research provides reference for optimizing the design of a transport airplane inerting system.