Tip Vortices of Isolated Wings and Helicopter Rotor Blades.

Thin layer Navier-Stokes equations are solved numerically for simulating the flowfields of isolated wings and helicopter rotor blades with a particular emphasis on understanding the formation and roll-up of tip vortices in subsonic and transonic flows. Several test cases consisting of wings and rotor blades of different planforms have been considered to examine the influence of the tip-cap shape, the tip-planform, the freestream Mach number, and the effect of centrifugal forces of rotation. A fairly good definition of the formation and roll-up of the tip vortex is demonstrated for all the cases considered here. Finally, the calculated lift, drag and pitching-moment coefficients agree well with the experimentally determined values, where available. Alternate methods of simulating the hovering rotor flowfields in blade-fixed mode that have the circulation distribution as hovering blade are explored. The results and discussion are presented. Keywords Viscous, Unsteady flows Zonal grid topology Thin layer Navier-Stokes Tip vortices Inertial reference frame Three-dimensional flow separation Steady flows, Fluid dynamics.