The traditional manual detection of aircraft skin is subjective and inefficient. In order to achieve rapid damage detection, this paper proposes an aircraft skin damage detection and evaluation framework by combining gray level co-occurrence matrix (GLCM) and cloud model. In the experimental stage, the UAV picks up the damage image of the aircraft, and the texture feature data is output by using the GLCM algorithm. The introduction of the cloud model evaluation system makes the skin damage type be quickly judged. The results show that the proposed method has good recognition ability for aircraft skin damage, and the identification accuracy of the verification image set reaches 85%. In the validation image set, 50 % of the corrosion spalling images were judged to be normal, which may be due to the similarity of the two types of texture features, and also indicates that the initial stage of skin damage starts from pitting. When evaluating the damage image, 59 % of the cloud droplets fall in the normal level, indicating that the damage is not serious, and the damage maintenance of the aircraft can be delayed according to the usage.

为解决不规则燃油箱惰化时,出现的氧体积分数分布不均匀、惰化区域不充分的难题,以熵权改进优劣解距离(TOPSIS)理论为基础,提出一种适用于不规则油箱惰化系统的优化方法,并结合数值仿真方法进行综合评价,实现波音747飞机惰化系统进出口的优化设计.结果表明:根据熵权改进TOPSIS理论设计的惰化方案,不仅可以降低惰性气体流量需求,而且可以使得惰化空间氧体积分数分布更为均匀;优化后的波音747飞机惰化方案,综合性能指标提升22.67％,速度性指标提升2.97％,均匀性指标提升27.78％;单侧偏置惰化方案设计思路,可以增加流通路径、延长惰性气体存续时间,使得油箱惰化时氧气分布更为均匀、氧体积分数下降迅速.

Inert gas distribution has a great influence on the inerting effect, especially for the multiple-bay fuel tank. In order to find out the optimal scheme, an optimization method based on the entropy-weight improvement TOPSIS method is proposed, and an experimental system of inert gas distribution is established to measure the speed index and uniformity index. The results show that the position of the inlet and outlet has a significant effect on the overall inerting effect. The inerting scheme designed by the entropy-weight improvement TOPSIS method can not only reduce the flow demand of inert gas but also make the oxygen distribution more uniform. The optimization inerting scheme of the Boeing 747 aircraft has improved the average speed index by 3.01% and the average uniformity index by 26.18%. The smoke visualization experiment also showed that the scheme designed by the entropy-weight improvement TOPSIS method has the denser white smoke, which means that the scheme has better performance.

Using Tunable Diode Laser Absorption Spectroscopy (TDLAS)technology to accurately measure the oxygen concentration in the ullage of the aircraft fuel tank is of great significance to ensure the safety of the aircraft and improve the working quality of the aircraft onboard inerting system. This paper focuses on designing a smart sensor for the detection of oxygen concentration applied to airborne inerting systems, which can reduce random environmental noise and line shape errors during the flying process. First, a prototype including a laser emission module with wavelength modulation and temperature control, a multi-reflection long optical path absorption gas cell, and a high-precision signal extraction module are designed. Then, ground experiments at 294 K, and 1 bar are carried out. The oxygen inversion method is designed, the oxygen concentration results are obtained, and the lower detection limit (3.3 ppm) and detection accuracy (9.6 ppm) of the sensor are discussed. Thirdly, the change of absorption line profile influenced by the change of pressure is discussed. The series of oxygen concentration measurement experiments with variable pressure (274 k, 1-0.1 bar) was carried out. and the measurement error is below 1%. Finally, a second harmonic (2f)/first harmonic (1f) normalized method is proposed to eliminate the errors caused by laser attenuation and environmental vibration in oxygen measurement.

The accident of fuel tank explosion is an important factor affecting aircraft performance and reliability. Therefore, the inerting system of aircraft fuel tank has been developed in the past decades. The purpose is to reduce the oxygen concentration by filling the tank with nitrogen. In order to monitor the oxygen concentration in the tank, we use tunable diode laser absorption spectroscopy (TDLAS) to measure. Based on the commonly used Matlab numerical simulation module Simulink, this paper establishes the simulation model of intelligent oxygen concentration sensor, and carries out the simulation experiment of measuring oxygen concentration. We compare the influence of different temperature and pressure on the measurement results, and prove the necessity of temperature and pressure compensation. The experimental results show that TDLAS can obtain higher accuracy by adopting the second harmonic detection method under noisy conditions, and can adapt to the high temperature and high pressure environment of the fuel tank. In addition, the research results can provide a theoretical basis for the development of TDLAS based aircraft equipment.