Periodic and aperiodic flow patterns around an airfoil with leading-edge protuberances

The effects of leading-edge tubercles on dynamic stall

“…Several works have also shown this to create counter-rotating streamwise vortices above the suction surface (Favier et al 2012;Rostamzadeh et al 2014;Hansen et al 2016) (figure 13b, blue lines). We note that while some recent studies have shown that past the static stall angle an asymmetry may develop along the span (Cai et al 2017(Cai et al , 2019Perez-Torro & Kim 2017), that effect was not observed in the current study. It is unclear from the post-stall static studies whether the asymmetry was due to tubercle-to-tubercle variations or due to three-dimensional effects from the end walls.…”

A Review of Research Status and Scientific Problems of Floating Offshore Wind Turbines

“…Compared with the optimum section, the effect of the twist angle design on the power factor was more significant because it could acquire a larger pressure deviation. Cai et al [35] studied the flow patterns around the blade of a stall airfoil with a leading edge bulge, and found that with the increase of attack angle, the flow pattern between the bulges gradually changed to asymmetric and aperiodic. The flow direction vortices formed from the leading edge reduced the local effective angle of attack and delayed the stall phenomenon, but the hysteresis effect was reduced and the stall performance was improved.…”

Effects of smart flap on aerodynamic performance of sinusoidal leading-edge wings at low Reynolds numbers

“…More recently, the effects of different flow patterns and geometric parameters have been investigated. Effects of periodic and aperiodic flow patterns on leading-edge protuberance airfoils were studied by Cai et al 18 In another research, Cai et al 19 assessed aerodynamic performance of a single leading-edge protuberance NACA63 4 -021 airfoil at Re ¼ 1 � 10 5 . They demonstrated that the performance of the modified airfoil could be improved in the poststall region while it is declined in the prestall area.…”

“…Effects of periodic and aperiodic flow patterns on leading-edge protuberance airfoils were studied by Cai et al. 18 In another research, Cai et al. 19 assessed aerodynamic performance of a single leading-edge protuberance NACA63 4 -021 airfoil at Re = 1 × 10 5 .…”