基于相干测风激光雷达的湍流预警算法研究

发布时间：2018-03-16 16:02

本文选题：湍流　切入点：激光雷达　出处：《中国民航大学》2017年硕士论文　论文类型：学位论文

【摘要】：湍流是一种国际上公认的严重影响飞行安全的大气现象,具有尺度小、强度大、时间短等特点。目前实际应用的基于激光雷达的纵向速度结构函数预警算法对小尺度湍流容易造成漏报,因此进一步研究有效的湍流预警算法尤为重要。此外选择合适的激光雷达扫描模式来提供有效风速数据以及对风速数据的处理也很重要。湍流对起飞离场和着陆进场过程中的飞机危害极大,因此选择具有针对性的下滑道扫描,这种扫描模式的扫描周期短,进而提高了预警率。首先,对下滑道扫描得到的径向风速数据进行质量控制,将扫描区域分成多个重叠的子扇区并筛选下滑道附近的子扇区,计算每个雷达测量点的脉动速度。其次对脉动速度使用预警算法对湍流进行探测,找到湍流的发生位置以及强度报告给飞行员。主要预警算法包括三种:标准偏差、谱宽、速度结构函数。对这三种算法都进行了研究,结果表明标准偏差需要经过大量的实验来确定阈值,谱宽算法还需要经过大量实验来评估。而速度结构函数算法已经被应用在实际机场中,并且经过实际应用表明湍流预警率得到了很大提高。相对于原算法的基于纵向结构函数检测,提出了将下滑道扫描与横向结构函数相结合的预警算法,将计算的结构函数与Von Karman模型预测的结构函数拟合得到涡流耗散率,并以国际民航组织规定的湍流阈值来判断湍流强度。使用激光雷达实测数据验证了该方法的有效性,对提高湍流预警率和实际应用是有重要意义的。
[Abstract]:Turbulence is an internationally recognized atmospheric phenomenon that seriously affects flight safety. It has a small scale and high intensity. At present, the longitudinal velocity structure function early warning algorithm based on lidar is easy to cause underreporting for small scale turbulence. Therefore, it is very important to further study the effective turbulence early warning algorithm. In addition, it is very important to select the appropriate lidar scanning mode to provide the effective wind speed data and to deal with the wind speed data. Turbulence is very important for take-off, departure and landing. Aircraft in the approach process are extremely harmful, Therefore, select the targeted glide path scanning, the scanning period of this scanning mode is short, and then improve the early warning rate. First, the quality control of the radial wind speed data obtained from the glide path scanning is carried out. The scanning region is divided into several overlapping sub-sectors and the sub-sectors near the glide channel are screened to calculate the pulsating velocity of each radar measurement point. The main early warning algorithms include three kinds: standard deviation, spectrum width, velocity structure function. All three algorithms are studied. The results show that the standard deviation needs a lot of experiments to determine the threshold value, and the spectral width algorithm needs a lot of experiments to evaluate the threshold, while the velocity structure function algorithm has been applied to the actual airport. The practical application shows that the turbulence warning rate has been greatly improved. Compared with the original algorithm based on longitudinal structure function detection, a new early warning algorithm combining glide path scanning and transverse structure function is proposed. The calculated structure function is fitted to the structure function predicted by the Von Karman model, and the eddy current dissipation rate is obtained, and the turbulence intensity is judged by the turbulence threshold prescribed by ICAO. The validity of the method is verified by using the measured data of lidar. It is of great significance to improve the early warning rate of turbulence and its practical application.
【学位授予单位】：中国民航大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN958.98

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