TRAILING-EDGE JET CONTROL OF LEADING-EDGE VORTICES OF A DELTA-WING

The effect of using a trailing-edge Set to control the leading-edge vo rtices of a delta wing is investigated experimentally in a water towin g tank facility, The Reynolds number, based on the freestream velocity and the root chord, is 9.8 x 10(3), Both static and dynamic (pitching -up) conditions are tested, For the dynamic cases, the wing is pitched from 10- to 45-deg angle of attack with pitch rates varied from 0.043 to 0.26. From the dye flow visualization, it is shown that a downward vectored trailing-edge jet can significantly delay the vortex breakdo wn on a delta wing, Strong asymmetric breakdown of the leading-edge vo rtices can be induced by arranging the vectored jet in an asymmetric c onfiguration, Transient pitching motion delays the onset of the vortex breakdown, The initial delay is independent of the pitch rate, Also, the use of jet control is found to be effective for the dynamic cases, During the initial pitching-up period, the use of jet control has a d ominant influence on the propagation of the vortex breakdown, In gener al, with jet control, the propagation of the vortex breakdown slows do wn, From instantaneous particle image velocimetry measurements, a quas iperiodic variation of the leading-edge vorticity field is detected be fore the vortex breakdown, This variation appears to relate to the str ong interaction between the separating shear layer, the secondary vort ex, and the primary vortex, Along the vortex axis, the velocity distri bution changes from a jet-type profile to a wake-type profile, signify ing the onset of vortex breakdown.