Results of an experimental investigation related to near-field wing tip vortices are presented. The measurements were carried out using a PIV-system in T-1K wind tunnel of KNRTU-KAI. Q-criterion and crosssectional lines method were used to determine vortex core locations, which showed a good agreement. It is shown that the circulation of tip vortices remains constant at low to moderate angles of attack, and decreases in the stream-wise direction for higher angles of attack. It is also shown that the vortex core radius increases in the stream-wise direction, taking larger values at higher angles of attack.

The work documents recent experiments at the Kazan National Research Technical University named after A.N. Tupolev (KNRTU-KAI), related to helicopter acoustics. The objective is to measure near-field acoustics of rotors in hover and provide data suitable for CFD validation. The obtained set of data corresponds to a Mach-scaled rotor of known planform and the results are of high resolution. An advantage of the current dataset is that direct near-field acoustic data is made available and this allows for easy and direct comparisons with CFD predictions, without the need to use far-field aeroacoustic methods. Nomenclature