Numerical Investigation Of Two-Dimensional Blade Vortex Interaction

Two computer codes which predict pressures both on and off an airfoil surface subjected to a passing vortex, were employed to predict the unsteady flowfield of four airfoils; the Sikorsky SC1095 and SSC-A09, NACA 64A006 and Bell 540 (OLS). The two codes which are two-dimensional and unsteady are: ATRAN2, which solves the small disturbance equation and EULER2, which solves the Euler equations. The studies main objective was to predict the off-surface pressure changes induced by the passing vortex in an attempt to relate the magnitude of these pressure changes with the airfoils geometry and freestream conditions. This was accomplished by a parametric study of the effects of Mach number, angle of attack, vortex miss distance and computational grid size on numerical predictions. The study showed the magnitude of the induced pressure changes to be sensitive to both. airfoil geometry and freestream conditions. In addition a strong correlation was observed between events on the airfoil surface and the magnitude of the propagated pressure changes. The numerical methods, once correlated with experimental data, will be useful tools for the design of an airfoil less sensitive to the unsteady effects of a passing vortex.