昼夜温度变化对燃油箱空余空间氧浓度的影响

燃油箱空余空间氧浓度变化规律的确定是惰化系统的设计基础，但影响燃油箱空余空间氧浓度因素很多，当前人们对于昼夜温度变化这一实际现象还缺少必要的分析计算。为此，以某型飞机中央翼燃油箱为研究对象，依据FAR25适航条款中昼夜温度变化的相关规定，建立理论仿真模型，利用实验数据对模型进行验证，探讨燃油箱空余空间氧浓度与昼夜温度变化之间的对应关系，并分析昼夜温度变化范围、载油率、初始氧浓度、溶解氧析出等因素对燃油箱空余空间氧浓度的影响，提出满足适航条款要求的夜间停机前燃油箱初始氧浓度限值。研究结果表明:昼夜温度的变化范围、载油率、初始氧浓度等因素对燃油箱空余空间氧浓度变化规律影响程度有所不同；停机前燃油箱初始氧浓度限值应该低于最低氧浓度限值0.5%~1%。研究成果将对惰化系统设计、燃油箱可燃性暴露时间计算具有较好的参考价值。 

Influence of diurnal temperature changes on oxygen concentration in free space of fuel tank

The variation rule determination of oxygen concentration in the free space of fuel tank is the basis of the design of inerting system.However, there are many factors that influence the oxygen concentration in the free space of fuel tank. At present, people still lack the necessary analysis and calculation for the actual phenomenon of the diurnal temperature changes. Taking the central wing fuel tank in a certain airplane as the research object, based on FAR25 airworthiness clauses of diurnal temperature changes, this paper builds theory simulation model. The model is verified by experimental data, and the corresponding relationship between oxygen concentration of free space of fuel tank and temperature difference between day and night is discussed. The influence of the diurnal temperature range, oil load, initial concentration, dissolved oxygen precipitation and other factors on the fuel tank free space oxygen concentration is analyzed, and the initial oxygen concentration limit of fuel tank before shutdown at night that satisfies the requirement of airworthiness clauses is proposed. The study results show that the variation range of day and night temperature, oil load, initial oxygen concentration and other factors have different effects on the oxygen concentration in the free space of fuel tank. The initial oxygen concentration limit of the fuel tank before shutdown should be lower than the minimum oxygen concentration limit of 0.5% - 1%. The research results will be of good reference to the design of inerting system and the calculation of average flammability exposure time of fuel tank.