| Popis: |
A numerical study was conducted to investigate the effect of an array of zero-mass "synthetic" jets on the aerodynamic characteristics of the NACA-0012 airfoil. Flowfield predictions were made using a modified version of the NASA Ames "ARC2D" unsteady, two-dimensional, compressible Navier-Stokes flow solver. An unsteady surface transpiration boundary condition was enforced over a user-specified portion of the airfoil's upper or lower surface to emulate the time variation of the mass flux out from and into the airfoil's surface. Here, a sinusoidal function which describes the approximate time behavior of the mass flux across the airfoil's surface was used. Our numerical results have indicated that zero-mass jets can, with the careful selection of their peak amplitude and frequency, enhance the lift characteristics of airfoils (helicopter rotor blades, wings, etc.). Effects of the jet peak suction and blowing velocities, oscillation frequency and, jet placement on the time histories of the sectional lift, drag and moment are presented for two angles of attack and one free stream Mach number. Flowfield results which provide more insight into the mechanics of the interaction between the array of jets and the developing boundary layer over the airfoil are presented. |
