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The present paper examined experimentally the glide flight flow visualization and boundary layers of a bio-inspired corrugated dragonfly wing performing a comparison with the results obtained with a flat plate, at low to moderate range of chord Reynolds numbers. The experimental work is performed in an open-end low speed subsonic wind tunnel at different angles of attack ranging from 0 to 120 and Reynolds number 2.25×105. The boundary layer measurements were done at a fixed chord location (0.7 x/c) and three different semi span locations such as 30%, 60% and 90% of the wing’s semi span from the right side of the longitudinal axis of the wing. The flow patterns were visualized by using colored tufts, placed at different span locations. The flow reversal was observed at selected Reynolds numbers and angles of attack only. The boundary layer measurements demonstrated that there exists a clear distinction on the pressure and velocity parameters in all the three tested locations on both types of the wings. The corrugated wing showed significant delay in stall and flow separation compared with the flat plate. The visualization of flow in both wings showed that there subsists a spanwise flow moving from wing tip to root, indicating three dimensional natures of airflows.

No abstract

The present study investigates the flow behavior due to three different vertical canard locations on the scaled‐down model aircraft by using tuft flow visualization and boundary layer measurements. The aircraft is fabricated with wing airfoil S1223 modified and canard with N22 airfoil using laser cutting technique. Three different color tufts are pasted in wing and canard at 30%, 60%, and 90%. The assembled model is placed inside the subsonic wind tunnel with flow chord Reynolds number 3.8*106, which corresponds to 35 m s−1 of the flow velocity and zero‐degree angle of attack. The boundary layers are measured at 70% of the wing chord with 00 incidence angle at three different span locations, i.e., 30%, 60%, and 90% of the wingspan with varying vertical canard positions. The results are compared with wing alone and it is found that the high wing and high canard configuration are outperformed by providing minimum velocity gradient and hence minimum skin friction drag. The tuft flow visualization also shows the identical results as the boundary layer measurements results. The aerodynamic performance of the high wing high canard configuration is found to be promising, as the skin friction drag coefficient is found to be minimum.