Investigating lift increase and drag reduction for airfoils using discrete CFJ (Co-Flow Jet)

Continuous Co-Flow Jet (CCFJ) and Discrete Co-Flow Jet (DCFJ) are new near-the-wall flow control methods for airfoils and compared with CCFJ, DCFJ is more efficient. We mainly focus on flow control effect and mechanism of DCFJ using numerical simulation. For the same jet momentum coefficient, DCFJ airfoil can achieve up to a 9.2% increase of maximum lift and simultaneously reduce aerodynamic drag. For the same power consumption, DCFJ is more striking in drag reduction. The drag is reduced 35% compared with CCFJ at zero angle of attack. The aerodynamic performance of airfoil is enhanced significantly. Simulation results and their analysis indicate preliminarily that a DCFJ airfoil generates both streamwise and spanwise vortex structures to mix the high speed jet with main flow and boundary layer thoroughly. Because of this mixing, DCFJ is highly efficient and more effective for increasing lift and reducing drag.