Experimental study on controlling wake vortex in water towing tank

An experimental study was carried out to establish a self-destructing vortex wake. Sets of horizontal tail plains were employed to generate additional vortex sheet interacting with the wing vortex sheet of a rectangular wing. The study was made in the water towing tank in Gottingen (WSG), which was instrumented with 2D/3C PIV system, balance and flow visualisation devices. The tailoring of 4 vortices wake systems was achieved by varying horizontal tail plains with different aspect ratios with various incidences, generating various destabilising effects. The study exhibited that the interaction of tail vortices with tip vortices may result in a promising self-destructive mechanism within the wake system in the sense that the vortex core experiences an instability and decay abruptly. Typically, the wake vortex cores could be destabilised by as early as in 30 wing spans downstream with suitable tail settings, instead of more than 100 wing spans for that of a "clean model". The possible influence from the finite movement in the water tank due to transient processes of the model (end-effect) was investigated. The influence of the bottom and side wall effects was estimated from comparison of results from a larger water towing tank (HSVA).