Grégoire Winckelmans

Simulation Methods for Aircraft Encounters with Deformed Wake Vortices

Simulation of aircraft wake-vortex encounters is regularly applied in the research toward revised aircraft separation minima. Most encounter flight simulation studies have used a pair of straight counter-rotating vortices. However, after being shed by the generating aircraft, the wake vortices begin to develop a growing deformation due to the long-wave Crow instability, especially under low-turbulent atmospheric conditions when vortices decay slowly. In this study, two methods for simulation of aircraft encounters with such perturbed wake vortices are described and compared. The first method uses a vortex simulation model, which is based on analytical models of the deformation that consider the large-scale vortex shapes. The second method applies vortex-velocity fields from high-fidelity large-eddy simulations. It offers the highest possible level of realism and is used as the reference. The resulting aircraft responses induced by wavy vortices and vortex rings are reproduced with good quality by the vort...

Development and assessment of a wake vortex characterization algorithm based on a hybrid lidar signal processing

Since air traffic is in constant expansion, a more efficient optimisation of the airports capacity is expected. In this context, the characterization of aircraft hazardous turbulences known as wake vortices with an operational vortex Lidar is one of the major issues for the dynamic distances separation. A study has been probed to develop a hybrid vortex algorithm , i.e that uses both the velocity envelopes and a parametric estimator in the interest of processing time as short as possible. The aim is to make this algorithm exploitable for operational projects. That is why a methodology has been set up to evaluate its precision and its robustness. The results of tests on simulated scenarios of different aircraft vortices and different weather conditions show that this algorithm is able to localize precisely wake vortices and to estimate accurately their circulation in a short time.

Analysis of extreme aircraft wake vortex circulations

Because of its take-off, an aircraft generates a wake essentially made of a pair of counter-rotating vortices notably characterized by their total circulation. In this test case, we analyze the evolution of wake vortex total circulation with the extreme value theory. It consists in estimating the probability that a wake vortex circulation exceeds a given threshold for a fixed set of CMC samples