The effects of the upstream location of a single continuous control jet (i.e., within the main jet nozzle) on an axisymmetric free jet, at Reynolds numbers of 6600 and 26 500, were investigated experimentally using PIV. The control jet was oriented perpendicular to the main jet flow and its momentum coefficient was varied for each Reynolds number. The resultant mean flow field and the turbulent stresses were examined in two planes, along and across the control jet's line of action. When the control jet is located near the main jet exit plane, the main jet is vectored away from the control jet due to the direct impact of the control jet. Conversely, with the control jet located farther upstream (i.e., into the nozzle), the main jet is drawn back toward the control jet, which may be as a result of a virtual modification of the nozzle shape. Furthermore, the direction of the main jet can also be controlled by varying the momentum coefficient of the control jet at a fixed upstream location. Finally, the effectiveness of the control jet in altering the main jet flow was found to be more pronounced when the interaction occurs at a lower Reynolds number, which is more susceptive to disturbances.
Journal of Turbulence, Volume 8, Issue 21, 2007.