Qualitative and Quantitative Visualization of Wake Vortices in Industrial Test Facilities

Abstract

Increasing security demands of air traffic control require an improved understanding of the wake vortex behavior behind transport aircraft. The persistence of aircraft trailing vortices determines the minimum distance between successive landing air-liners (between 3 and 6 miles, depending on weight of aircraft) and thus limits the passenger rate of an airport. The risk of such wake vortices increases with the aircraft's weight, so that in the case of wide-bodied aircraft the advantage of a higher passenger capacity is partly lost by the delayed landing of the following air-liner. In most cases experimental simulations of the wake vortex problems are carried out in a wind tunnel, where however the length of the test section determines, how far behind the plane the vortices can be investigated. The standard measuring techniques for wind tunnels can be applied (flow visualization by means of smoke, measurement of velocity fields by means of 5 hole probes etc.).