Experimental Studies of Vortex Generators on the Wing Leading Edge

Аuthors

Volobuev R. A.^*, Galkin M. Y.^**, Kuznetsov A. V.^***, A. , Slitinskaya A. Y.^****

Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia

*e-mail: haruogawa.05@gmail.com
**e-mail: o9366891.953@gmail.com
***e-mail: alexkuzn@gmail.ru
****e-mail: flinas@yandex.ru

Abstract

Presently, various kinds of vortex generators are being actively employed on many aerial vehicles. Vortex generators create a vortex that interacts with both boundary layer and external airflow, mixing them and reducing thereby the height of the boundary layer. Vortex generators application refers to passive methods of the flow control. Vortex generators are being placed on the aircraft wings for the boundary layer separation protracting or preventing, flow-around improving at high angles of attack, and increasing maximum lift and critical angle of attack, as well as preventing harmful interference of the various aircraft structure parts.
The presented research work novelty lies in considering a new type of vortex generators (crescent-shaped vortex generators placed on the wing leading edge) and obtaining characteristics of their effectiveness with several different models. Experimental studies of the efficiency of vortex generators were conducted with eight models in the T-1 MAI Wind Tunnel. These are three wing compartments with various profiles, such as ND4, GA(W-1), GA(W-2); three wing compartments with the same profiles and crescent-shaped vortex generators installed on their leading edge. There was also one wing compartment with the ND4 profile with “classic” trapezoidal vortex generators mounted on the wing upper surface of the at 10% of its chord, as well as one aircraft model with a swept-back wing with the bolt-on vortex generators. 
In the course of the tests, the flow-around was being visualized by three methods, such as the mulberry method, the oiled dots method, and the oiled film method. The article demonstrates the necessity of accounting for the tufts effect on both flow-around and aerodynamic properties of the experimental model under study.
The visualization results demonstrate that the separation retard with the vortex generator installing. At the zero angle of attack, vortex tracks can be observed behind the “classic” vortex generators , which leads to the stronger increase in the drag coefficient during continuous flow-around and, as a result, to the decrease in maximum aerodynamic quality. At the same time, at high near-critical angles of attack, the separation area is much smaller, which leads to the significant increase in the maximum lift coefficient. The crescent-shaped vortex generators application on the wing leading edge at low angles of attack practically does not change the flow-pattern, however, it somewhat irons out the tear-off area development at the near-critical angles of attack. This effect affects beneficially on the piloting safety at low speeds and high angles of attack.
Application of the “classic” trapezoidal vortex generators placed on the wing upper surface led to a greater increase in the maximum lift coefficient than the installation of crescent-shaped ones placed on the wing leading edge of the, on the wing compartment with the ND4 profile at V = 48 m/s and Re = 1.24 · 106.
For the wing compartment with the GA(W-1) and GA(W-2) profiles, the efficiency of the crescent vortex generator on the wing leading edge is higher than on the wing compartment with the ND4 profile.
The section of local lift sliding at the intermediate angles of attack was eliminated by the crescent-shaped vortex generators placed on the wing leading edge of the training aircraft.

Keywords:

experimental studies of the vortex generators efficiency, of flow separation control passive methods, wing aerodynamic characteristics

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