晴空湍流对飞机的影响分析

Analysis of Influence of Clear Air Turbulence on Aircraft

摘要: 晴空湍流(Clear Air Turbulence，CAT)因其不可见性，民航飞机预报CAT十分困难，是影响航空安全的一重大隐患。为尽可能有效探测CAT，本文首先定量分析CAT对飞机的影响，研究了一种反应式的CAT检测方法，即基于飞机垂直加速度估计涡流耗散率(Eddy Dissipation Rate，EDR)来量化CAT强度，并给出检测流程。其次美国航空无线电技术委员会更新了机载气象雷达湍流检测的标准，其中将垂直载荷因子定义为检测依据，则可进一步具体分析EDR估计值和垂直载荷因子之间的关系，得出可将CAT对飞机的影响量化为垂直载荷因子。最后利用遭遇了CAT的某航班的真实ADS-B (Automatic Dependent Surveillance-Broadcast，广播式自动相关监视)数据求解EDR估计值，验证了以上理论分析的合理性，进而证明基于垂直载荷因子的CAT检测方法的合理性，可基于机载气象雷达实现更准确合理的CAT预报。晴空湍流对飞机的影响分析对晴空湍流的精确预报与检测有实际意义。

Abstract: It is very difficult for civil aviation aircraft to predict CAT (clear air turbulence), since the precipitation of CAT is lower than that of the convective turbulence. So CAT is a major hidden danger affecting aviation safety. In order to detect CAT as effectively as possible, firstly, the influence of CAT on the aircraft is analyzed in this paper, and a reactive CAT detection method is researched. This method is estimating the Eddy Dissipation Rate (EDR) based on the aircraft's vertical acceleration to quantify the CAT intensity. Then, the detection process is obtained. Secondly, The Radio Technical Commission for Aeronautics revised the specification of airborne weather radar detection turbulence, in which the vertical load factor is defined as the detection amount. The relationship between the EDR and the vertical load factor can be further analyzed in detail to conclude that the impact of the CAT on the aircraft can be quantified as the vertical load factor. Finally, the conclusion of the above theoretical analysis is verified to be correct, as the EDR is calculated using the real ADS-B (Automatic Dependent Surveillance-Broadcast) data which come from a flight that has encountered CAT. Furthermore, it is proved that the CAT detection method based on the vertical load factor is reasonable, and airborne weather radars can predict CAT more accurately and reasonably by using this method. The analysis of the impact of clear-air turbulence on the aircraft has practical significance for the accurate prediction and detection of clear-air turbulence.