|Cross-sectional distributions of time-averaged properties. Left column: baseline JICF (no tab); middle column: two stationary tabs (placed symmetrically); right column: tabs oscillating at 7.5 Hz.|
Ivana Milanovic, professor of mechanical engineering, CETA, published the research paper "Control of a jet-in-cross-flow by periodically oscillating tabs" in Physics of Fluids. The paper was co-authored with Dr. Khairul Zaman of NASA Glenn Research Center.
Physics of Fluids is published by the American Institute of Physics with the cooperation of The American Physical Society Division of Fluid Dynamics. The journal is devoted to the publication of original theoretical, computational, and experimental contributions to the dynamics of gases, liquids, and complex or multiphase fluids.
A technique for active control of a jet-in-cross-flow (JICF) is explored in this study. Two triangular tabs are placed at the 90 deg. and 270 deg. edges of the jet orifice, relative to the direction of the cross-flow. An asymmetry in the placement of the two tabs is reversed periodically. This causes a profound oscillation of the flow field that persists as far downstream as permitted by the measurements in the facility (100 orifice diameters). The kidney-shaped cross-section of the JICF is seen to tilt side-to-side periodically. The flow mechanism apparently involves a direct perturbation of the counter-rotating streamwise vortex pair of the flow.