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针对非加力状态下的无人机(UAV),建立了其蒙皮、尾喷口及尾焰辐射的理论计算模型,利用有限元分析方法求解了不同方位角、不同观测仰角的红外辐射计算公式。利用Fluent流场计算软件分析了尾焰的温度场、压力场及其中CO2及H2O组分的浓度场,并在尾焰红外辐射计算中利用分析数据的方法,这种计算较精确。采用工程中实际使用的中波红外和长波红外探测器的探测波段,利用LOWTRAN分析了其在不同观测仰角下的波段透射率。对于某一特定型号的无人机,实验结果证明,相对于8~10μm长波蒙皮辐射而言,中波3.7~4.8μm的蒙皮辐射可以忽略不计。中波的尾喷口及尾焰辐射随观测角度的变化规律与长波类似,在相同观测角度下,中波的尾喷口及尾焰辐射都分别大于长波,其中尾喷口辐射在方位角大于90°的前提下,要大于相同角度下的尾焰辐射。在大气衰减影响下,蒙皮辐射和尾焰红外辐射的最大值均出现在观测仰角45°、方位角90°附近。
Aiming at the unmanaged UAV, the theoretical calculation models of the skin, tail nozzle and tail flame are established. The calculation formulas of infrared radiation at different azimuth angles and elevation angles are solved by the finite element method . The temperature field and pressure field of the tail flame and the concentration field of CO2 and H2O components were analyzed by using Fluent flow field calculation software. The calculation method was more accurate by using the analytical data in the infrared radiation calculation of tail flame. Using the detection band of the medium-wave infrared and long-wave infrared detectors actually used in the project, the transmission of the band at different observed elevation angles was analyzed by LOWTRAN. For a certain type of UAV, the experimental results show that the radiation of 3.7 ~ 4.8μm in the middle wave is negligible compared to 8 ~ 10μm longwave skin radiation. In the same observation angle, the radiation of the tail-end and tail-end of the middle wave are respectively greater than that of the long-wave, and the radiation of the tail-throat at azimuth greater than 90 ° Under the premise of greater than the same angle of the tail flame radiation. Under the influence of atmospheric attenuation, the maximum values of the skin radiation and the tail flame infrared radiation all appear at the observation elevation angle of 45 ° and the azimuth angle of 90 °.