Method of radial velocities for the estimation of aircraft wake vortex parameters from data measured by coherent Doppler lidar.

I.N Smalikho,V.A Banakh,F Holzäpfel,S Rahm

doi:10.1364/oe.23.0a1194

I.N Smalikho, V.A Banakh + Show 2 more

Open Access

https://doi.org/10.1364/oe.23.0a1194

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Abstract

The method of radial velocities (RV) is applied to estimate aircraft wake vortex parameters from measurements conducted with pulsed coherent Doppler lidar (PCDL). Operations of the Stream Line lidar and the 2-µm PCDL are simulated numerically to analyze the accuracy of the estimated wake vortex parameters with the RV method. The RV method is also used to estimate wake vortex trajectories and circulation from lidar measurements at Tomsk and Munich airports. The method of velocity envelopes and the RV method are compared employing data gathered with the 2-µm PCDL. The domain of applicability of the RV method is determined.

Highlights

The rotating air motion arising behind an aircraft can be dangerous for other flying vehicles encountering its wake zone [1]
We discuss the applicability and accuracy of the method for estimation of aircraft wake vortex parameters from the array of radial velocities measured by the Stream Line lidar and 2-μm pulsed coherent Doppler lidar (PCDL)
It is shown that the radial velocities (RV) method allows to estimate the position and circulation of aircraft wake vortices from raw data of the Stream Line lidar with an accuracy sufficient for the study of the spatial dynamics and evolution of wake vortices formed behind aircraft flying in the atmospheric surface layer

Summary

Introduction

The rotating air motion arising behind an aircraft can be dangerous for other flying vehicles encountering its wake zone [1]. The pulse repetition frequency of the Stream Line lidar is 30 times higher than that of the 2-μm PCDL This allows achieving the required measurement accuracy even at the low signal-tonoise ratio. The high SNR and the relatively long duration of the probing pulse leading to the insignificant (~0.6 MHz) instrumental broadening of the Doppler spectrum for the 2-μm PCDL [8] allows to apply the method of velocity envelopes (VE method) for the estimation of wake vortex parameters from lidar data [6] This method cannot be applied to the processing of data of the Stream Line lidar due to its low SNR. The wake vortex parameters estimated with the VE and RV methods are compared employing the 2-μm PCDL

Lidars and measurement strategy

RV method

Numerical simulation results

Field experiment results

Findings

Conclusions