Document Type : Original Article
Authors
1 Department of Mechanical Engineering, University of Birjand, Birjand, Iran
2 Faculty of Mechanical Engineering, Malek-Ashtar University of Technology, Esfahan, Iran
Abstract
In this research, the effects of canard flow on a diamond wing equipped with LEX, same as new-generation fighters, have been investigated, using a closed-circuit wind tunnel. All tests were performed at a speed of 12.5 meters per second, which is equivalent to Reynolds number 214000 based on model length. The pressure measurement is conducted by the five-hole probe, which is normalized by the dynamic pressure of the free stream velocity in four cross-sections over the wing. The results showed that at a low angle of attack, a strong vortex is produced at the leading-edge of the wing, called the leading-edge vortex. As the leading-edge vortex moves downstream, the diameter of its core and distance from the wing surface increases. At higher angles of attack, LEX, canard and body vortices are also present, which combine with the leading-edge vortex and cover a large cross-flow area over the wing. At these angles of attack, the movement of the vortical flow downstream leads to an increase in the pressure coefficient of the vortex core, which indicates the beginning of instability and vortex breakdown. The results showed that the pressure increase in the vortex core was not sudden and this results in that the breakdown phenomenon in the diamond wing equipped with LEX and canard occurs slowly.
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