Observations of attachment jet's switching action by applying Moire topography to free-surface water table

Abstract

In order to clarify the dynamical switching mechanism of attachment jet by control jet, the switching process was observed by the visualization technique of flow pattern and pressure distribution applying Moire topography to free-surface water table.
The observations were performed at Froude numbers of 0.5 to 0.8, which correspond to Mach numbers of air jet, and at various control depths between 30 and 80 per cent of the attachment jet's supply depths.
It was found that the factors affecting the switching action are the initial deflection of the jet and vanishing, occasionaly reversing pressure gradient across the jet owing respectively to the momentum and the flow of the control jet. A strong vortex caused by control jet's entrainment keeps the jet from switching in its earlier stage.