Effects of CoFlow-Jet Active Flow Control on Airfoil Stall

Abstract

An active flow control method as CoFlow-Jet (CFJ) is implemented on the NACA 0024 airfoil at the chord-based Reynolds number of 1.5×105. For this purpose, an in-house solver based on the Reynolds averaged Navier-Stokes equations in two-dimensional, incompressible and unsteady form with the SST-k-ω turbulence model is prepared. Several levels of jet momentum coefficient (Cμ) are studied to achieve a proper momentum coefficient for each angle of attack (α). The findings demonstrate that at Cμ=0.06, the lift coefficients at low attack angles (up to α =15̊) dramatically increase. Furthermore, the dynamic stall at the given Reynolds number and with the lowered frequency of 0.15 is explored. In the instance of Cμ=0.07, the lift coefficient curve does not show a noticeable stall feature compared to Cμ=0.05, suggesting that a more powerful stronger jet can entirely control the dynamic stall. The impact of raising the Reynolds numbers from 0.5 × 105 to 3 × 105 on this active flow control is also explored. The lift coefficient improves at all Reynolds numbers studied as Cμ increases, with the highest performance achieved at α = 15̊.