【作者】 鹿世化；

【导师】 刘卫华；

【作者基本信息】 南京航空航天大学 ， 人机与环境工程， 2012， 博士

【摘要】 油箱燃爆是飞机事故的主要原因之一，现有研究表明，利用机载制氮系统产生的富氮气体对油箱进行惰化是保证飞机油箱安全、抑制油箱燃爆最经济、最有效的方式之一。该惰化方式可通过对燃油洗涤和油箱上部气相空间冲洗惰化技术来实现，其中，燃油洗涤主要应用于军用飞机，而冲洗惰化则广泛适用于民用飞机。所谓冲洗惰化就是将富氮气体冲入到油箱气相空间，并使得气相空间氧气浓度维持在燃油燃烧极限以下。本文结合国产大飞机燃油箱惰化技术研究任务需要，对民用飞机惰化流场及惰化效果影响因素开展了较为深入的研究。其具体内容包括：（1）在对燃油中氧氮溶解特性研究的基础上，建立了适用范围更广的燃油冲洗惰化模型，通过与实验对比验证了所建模型的正确性；并应用数值积分的方法研究了冲洗过程中的氧浓度变化规律。（2）采用数值模拟方法分别对单舱和多舱油箱惰化空间的氧浓度变化规律进行了研究，并探讨了如流量、氮气浓度、流速等因素对油箱惰化效果的影响；在此基础上，提出了舱内氧浓度“最大值”、“惰化完成百分比”等评估指标，完善了惰化效果评价体系；建立三维数学模型，结合国产大飞机油箱结构，就多隔舱油箱冲洗过程进行了仿真研究，获得了各油箱隔舱在不同时刻时的氧浓度分布情况等详细信息。（3）首先以单舱油箱的冲洗惰化过程为例，将单舱油箱的进出口之间的通道命名为“主流道”，并认为最佳的冲洗效果是主流道应占据尽可能多的舱内面积（体积），对冲洗过程中流场变化机理进行了研究；然后，对具有代表意义的多隔舱油箱进行了多算例计算；在此基础上，提出了具有普适意义的多隔舱油箱气流优化的设计原则，并将该原则应用于大飞机油箱惰化气体流动路线的设计之中，获得了较好的效果。（4）建立了实验装置，开展了一系列实验研究工作。其中：气体流动的可视化实验验证了文中对于流体流动计算方法的有效性；液体冲洗示踪实验建立了流体冲洗过程的定性认识；液体冲洗时浓度的定量测量实验为流体的示踪以及浓度测量，特别是瞬态的浓度测量提供了一个良好的思路，实验结果进一步证实了文中提出的惰化气体流动方式优化设计原则。本文研究结果可为大型民用飞机燃油箱惰化系统设计提供有益的参考。更多还原

【Abstract】 Fuel tank blasting is one of the main reasons of aircraft accident. The existing studies haveshown that using Nitrogen Enriched Air (NEA) generated by On-Board Inert Gas Generation system(OBIGGS)to inert fuel tank is one of the most economical and effective ways of safety protection forfuel tank.This contains two ways: fuel scrubbing and ullage washing, while fuel scrubbing is mainly usedin military aircraft, ullage washing is widely used in civil aircraft.The so-called ullage washing refers to displace NEA on the fuel tank ullage to make andmaintain the oxygen concentration lower than the fuel burning limit.Taking the needs of domestic aircraft fuel tank inerting technology research into account, thispaper carry out a more in-depth study on the inerting flow field and influencing factors of the civilaircraft. The specific contents include:(1)Characteristics of oxygen and nitrogen dissolved in fuel are systematically summarized andtheoretical models of fuel washing applicable to a wider range are established. By comparing with theexiting experiment, the validity of the model has been verified. Numerical integration methods areused to study the variation of the oxygen concentration during the washing process.(2)By means of numerical simulation, the oxygen concentration variation of the single-bay andmulti-bay fuel tank inerting space is studied. The impact of factors such as flow rate, concentration ofNEA, velocity of NEA on fuel tank inerting is discussed. On this basis, new indices,“maximumoxygen concentration” and “percentage of inerting completion” are proposed to improve theevaluation system of inerting. Three-dimensional mathematical models, which combined withdomestic aircraft fuel tank structure, are built to carry out a study of washing process of the multi-bayfuel tank. Detailed information of oxygen concentration distribution in each bay at different times isobtained.(3) Taking a single-bay fuel tank ullage washing for example, a new concept------“mainstream”isdefined as the channel between inlet and outlet. Meanwhile, the optimal “mainstream” should occupythe area (volume) of the bay as much as possible. The Mechanism of flow changing during ullagewashing has been studied. Several numerical examples of a typical multi-bay tank inerting arecalculated. An airflow optimized design principles, which is of universal applicability, is put forwardand used in the airflow design of the aircraft fuel tank inerting and good results are achieved.(4) A series of experiment are carried: The gas flow visualization experiments verify the validityof the fluid flow calculation method; Liquid washing tracer experiments establish the qualitative understanding of the fluid washing process; The quantitative measurement of liquid concentrationprovide a good idea for tracer experiments of fluid and liquid concentration measurement, inparticular for transient concentration measurement. The experimental results further validate theproposed optimization principle.The results of this study provide a useful reference for large civil aircraft fuel tank inertingsystem design.更多还原