Radar Detection And Tracking Technology Of The Aircraft Wake Vortices

The wake vortices are the inevitable phenomena of aircraft lift. Compared with theambient atmosphere, the wake vortices have particular aerodynamic characteristics andradar characteristics. For the aerodynamics, the eddying motion of the atmosphere in thewake is very strong and irregular. It is one of the main factors related to aviation safety.For the radar detection, the wake vortices have relatively stronger detectability along withunique Doppler and spatial distribution characteristics. The wake vortices detection is anadvanced field of aviation safety and anti-concealed. Facing the need of aviation safety andanti-concealed, radar echo modeling of the vortices, radar detection, and tracking areinvestigated in the thesis. The main research results are listed as the following threeaspects:First, radar echo modeling of vortices in the condition of wet atmosphere is analyzed.Two kinds of the signal modeling methods are put forward. The pulse sequence in a CPIcan be obtained using the radar video frequency echo model, and the analytical expressionof the spectrum can be acquired using the statistics histogram method. The research resultsshow that the vortex echoes have unique Doppler-spread characteristics. It is identical tothe experiment results.Second, three vortices detectors are put forward based on the particular explorationand application situation. For the need of wake vortices surveillance in long dwell timecondition, a frequency-domain distributed target detector is put forward, and the analyticalexpressions of false alarm probability and detection probability in Gauss and Gammadistribution clutter are obtained. Simulation experiments show that through adaptivelyselecting the optimal number of detection cells, the detection performance of the proposedmethod is better than the conventional vortices detection method. For the need of wakevortices surveillance in short dwell time condition, an information geometry detector basedon short pulse sequence is put forward, and the detection performance in Gauss clutter wasanalyzed. Simulation experiments show that the detection performance of the informationgeometry method is better than the conventional coherent accumulation method. For theneed of wake vortices surveillance in the complex weather condition, a wake vorticesdetection method based on neural network is proposed. Through training theback-propagation network using the vortex spectrum characteristics, the method can detectthe wake vortices effectively in the complex weather clutter.Third, for the need of wake vortices surveillance using the mechanical scan Dopplerradar in the large airspace, based on the spatial linear distribution characteristics, a TBDmethod and a tracking method of airplane wake vortices are proposed. In TBD phase, firstof all, the frequency-domain low-threshold detection is carried out, so the range-angle-Doppler measurement space is reduced to two dimensions of range-anglespace. Then the system state function is set up based the spatial distribution characteristicsof detection points, and a new particle filter TBD method which combines amplitude andposition measurements is proposed. The TBD method tolerates high level of false alarms inpreprocessing, and achieves low false alarms through spatial accumulation. In trackingphase, a wake vortices tracking algorithm based on the spatial linear distribution model isput forward. Wake state parameters, such as center, slope angle, and length can beestimated by this algorithm. The influence of the wake measurement number variety iseliminated using the tracking method, and continuous tracking of the wake vortices isrealized also.Research results of this thesis are of important theory meaning and application valueto improve flight safety of fighter plane and civil aircraft, enhance fast takeoff of fighterplane in an emergency, and improve the detection performance of concealed targets.