Behavior of Vortex System Behind Cruciform Wings - Motions of Fully Rolled-Up Vortices.

摘要

The motions of four fully rolled-up vortices representing the vortex system trailing behind cruciform wings are studied by theoretical and visual- flow methods. The analysis applies throughout the Mach number range. Equations are developed for the three-dimensional paths traced by the vortices behind a cruciform wing banked 45 deg and calculations are made of the distance behind the wing at which the upper two vortices pass through the lower two. It is found that this 'leapfrog' distance depends upon the lift coefficient, aspect ratio, and span loading of the cruciform wing, and that for low-aspect-ratio cruciform wings leapfrogging may occur within two chord lengths of the trailing edges. The various types of vortex motion to be expected throughout the angle of attack range are considered in some detail, and the interaction of the two vortex sheets shed from the cruciform wing is taken into account. Results of some water tank studies are also presented and compared with the theory.