Abstract
In order to clarify the dynamical switching mechanism of attachment jet by control jet in wall attachment device, the switching processes were observed by the visualization technique of flow pattern and pressure distribution applying Moire topography to free-surface water table.
The observation were performed at Froude numbers of 0.5 to 0.8, which correspond to Mach numbers of air jet, and at various control flow rate between 30 and 70 per cent of the attachment jet's supply flow rate. The similarities in static and dynamic bihavior of hydraulic and gaseous wall attachment devices were recognized.
It was found that the factors affecting the switching action are the initial deflection of the jet and decreasing or vanishing pressure gradient across the jet owing respectively to the momentum and the flow of the control jet. At high control flow rate, a storong vortex caused by control jet's entrainment kepps the attachment jet from switching in its earlier stage.
