Abstract: Wake vortices, especially large-scale tip vortices generated by airplanes, are hazardous for following aircraft. This article tries to explore a way to accelerate wake vortex decay through the jets spouted out of the aeroengine. In the experiment, a simplified aircraft model (with tail wing) is employed to construct a 4-vortex wake system consisting of a pair of tip vortices and a pair of counter rotating tail plane vortices. Without external disturbance, effects of vortices generated by the tail plane with different configurations acting on tip vortices differ: some tail plane vortices can lead to the acceleration of tip vortex disintegration, while others cannot. The influence of jets with different intensities on different 4-vortex systems is studied. As a contrast, a 2-vortex systems (without tail wing) with and without jets are also observed. The experiment is carried out in a water towing tank. A stereo particle image velocimetry (SPIV) system is employed to observe and measure a series of sections which are perpendicular to the towing direction and distributed uniformly between the tailing edge of the main wing and the position of 45 spans downstream. The result indicates that, when the jet is acting on the vortex directly, the effect depends on the original distance and relative strength between them; when the jet is acting on the overall 4-vortex wake system, the interruption caused by the jet can accelerate the destruction of various 4-vortex systems to a certain degree. The key is how to use jets to optimize the interaction mechanism of disturbance to the tip vortex, rather than merely the intensity of jets.

Key words: fluid mechanics, aircraft, wake, jet, stereo particle image velocimetry