Wake Encounter Severity Assessment Based on Validated Aerodynamic Interaction Models

Wake encounter severity criteria based on validated models are of great importance for any wake vortex related severity assessment. The aerodynamic interaction model “strip method” describes the vortex-induced aircraft reaction. The model quality is validated with wake encounter flight test data. Model shortcomings are improved with dedicated refinements. A simplified hazard area approach is developed employing validated simulation models. With one simple criterion, the roll control ratio, safe and undisturbed flight operations can be ensured. A limit value for manually flown (non fly-by-wire) aircraft is derived from piloted trials. With the simplified hazard area prediction method, this can be universally applied for wake vortex advisory systems like DLR’s wake vortex prediction and monitoring system

Impact of Wind and Obstacles on Wake Vortex Evolution in Ground Proximity

Data from different numerical simulations and field measurement campaigns are used to investigate aircraft wake vortex evolution in ground proximity. A new hybrid simulation method is employed to capture wake vortex evolution from early roll-up to final decay in ground proximity. The method is applied to investigate effects of very low flight altitudes and the sudden loss of lift during touchdown. The investigations also comprise a parameter study of vortex behavior at different wind directions and strengths (headwind, crosswind, and combinations thereof) where the vortices are generated at a height of one initial vortex separation above ground. Furthermore, it is shown that vortex decay in ground proximity can be accelerated by the installation of plate lines at distances of a few hundred meters from the runway threshold. Field measurement data gathered during the campaigns WakeMUC at Munich airport and WakeOP at special airport Oberpfaffenhofen corroborate and complement the findings of the simulations. Experiments and simulations demonstrate that plate lines appreciably accelerate wake vortex decay and interfere favorably with end effects. This way safety can be further increased during the flight phase with most reported encounters