Co-Flowing Jet (CFJ) is considered one of the most significant active flow controls techniques used to migrate airfoil vortices and delay stall phenomenon. This research presents a computational investigation of the S809 airfoil equipped with CFJ to predict the optimum configuration for improved aerodynamic performance. The effect of injection angles, suction location, and injected mass flow rates (mo) were analyzed. Several suction slots were studied at different locations of (60, 70, 80 and 90) %C for various injection angles of 48°, 58°, 68°, 78° and 88°. The most effective combinations of suction location and injection angle that achieves the maximum (Cl/Cd) ratio were determined and then analyzed for different injected (mo) of 2.5%, 5% and 7.5%. The results indicate that the highest lift-to-drag ratio (Cl/Cd) is achieved with a suction slot at 80%C and an injection angle of 78°. Increasing the injected mass flow rate beyond 2.5% showed negligible improvement in airfoil performance. Furthermore, a CFJ turn-off condition was evaluated to assess the jet channel effect, revealing a 42% reduction in lift, increased drag, and earlier stall occurrence at an attack angle of 16.24°. Overall, the findings confirm that CFJ significantly enhances the aerodynamic characteristics of wind turbine airfoils under optimal configurations.
Farghaly et al. (2026) studied this question.