EFFECT OF VORTEX SEPARATION ON LIFTING BODIES OF ELLIPTIC GROSS SECTION.
MASSACHUSETTS INST OF TECH CAMBRIDGE AEROPHYSICS LAB
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The lift on slender bodies at high angle of attack is strongly influenced by the separation of a pair of vortices from the lee side. Of the various possible methods for taking account of this vortex separation, that proposed by Bryson seems to incorporate the main features of the flow in the simplest mathematical form. In this model, the separated vortices are joined to the body by straight feeding sheets. Bryson gives solutions for the vortex strength and position as a function of time or distance along the body and calculates the resulting body normal force for circular cones and cylinders. These solutions are extended here to cambered bodies of elliptic cross section having arbitrary nose contour. Calculation of the development of the separated vortices requires specification of the angular position around the body at which the feeding sheet departs. The position of this separation line is determined here from a correlation of experimental results. An analytic procedure is also described, but its accuracy is considered to be inadequate. In order to complete the theory, the initial growth of the vortices as they first leave the surface must also be prescribed. Vorticity is assumed to accumulate within the boundary layer until it separates upon reaching a certain finite strength which depends on whether the boundary layer is laminar or turbulent at separation.
- Fluid Mechanics