CRITICAL WAKE VORTEX ENCOUNTER SCENARIOS KRITISCHE EINFLUGBEDINGUNGEN IN EINE WIRBELSCHLEPPE

SUMMARY A simulation-based method was developed to investigate the hazard of Wake Vortex Encounters (WVEs). This paper describes an important part of this method: the determination of worst-case WVE conditions, which is referred to as Worst-Case Search (WCS). The WCS results permit to reduce time and costs of WVE hazard related piloted simulator tests and allow the comparison of the hazard that vortices of different generator aircraft exert on a follower aircraft. The WCS is based on a high fidelity, offline simulation of the follower aircraft that includes the interacting wake vortex, a hazard criterion that rates the severity of each WVE, and a pilot model. It can be formulated as an optimisation problem that is solved with the optimisation tool MOPS (Multi Objective Parameter Synthesis). MOPS varied the encounter geometry until the simulation yields maximum values of the WVE hazard criterion. Worst-case encounter conditions for different parameters were investigated and sensitivity studies performed. The influence of the height above ground, the core radius, and the models for the wake vortex velocity profiles on the severity of a WVE was examined. To demonstrate the capability of the method, a comparison of the hazard of a WVE behind two different heavy transport aircraft for a 20t aircraft was made. The WCS method proved its applicability and delivered the worst-case encounter geometry.