Investigation of Vortex-Dominant Flow of a Diamond Wing with an Airfoil Cross-Section Canard at Low Angles of Attack: An Experimental Study

Abstract

In this experimental article, the effects of the canard on the flow of a diamond wing at low angles of attack have been investigated. For this purpose, two diamond wing models with LEX are used. An airfoil cross-section canard is installed at the wing apex of one of the models, and the other is without the canard. The investigated diamond wings’ span and chord length were 234 mm and 175 mm, respectively, with a sharp leading edge. Pressure and vorticity distributions on the upper surface of the wing were obtained using a five-hole probe. A hotwire anemometer was used for measuring turbulence intensity and velocity fluctuations on the wing’s upper surface and the wake region. The wind tunnel free stream velocity was 12.5 m/s, corresponding to Re 2.16 × 105, based on the model length. Low Reynolds smoke flow visualization was conducted to better understand and observe the canard’s vortical flow. The results reveal, at α 5°, a coherent LEV is formed over both models, which is enlarged by shedding toward the wing’s trailing edge. The shedding of the vortices to the trailing edge of the wing caused a pressure drop at the vortex core; however, this process is stronger for the model equipped with a canard. With increasing the angle of attack, the suction pressure increases, and the vortices cover a wider area over the wing. Velocity fluctuations at the LEV core showed that the u is higher for the wing equipped with a canard compared to the simple diamond wing for all span-wise sections. The dominant peak of PSD at the LEV core occurred in st 0.64 and st 1 for the model without a canard and the model equipped with a canard, respectively