STREAMWISE VORTEX PRODUCTION BY PITCHED AND SKEWED JETS IN A TURBULENT BOUNDARY-LAYER

Weak longitudinal (streamwise) vortices produced by the interaction of simple, round wall jets with a two-dimensional now comprising a turbulent boundary layer were studied experimentally. Like the jets used in the vortex generator jet (VGJ) method of stall control, the jets in this study were pitched up at 45 deg and skewed relative to the freestream as they entered from the wall. Skew angles of 90-45 deg produced the strongest vortices, and vortex strength increased with jet speed over the range studied, VR = U(j)/U(infinity) = 0.7 to 1.3. It is shown through comparison to other work that the vortices produced by the jets are similar to weak vortices produced by a solid vortex generator, but different from a strong vortex from a larger solid generator.