Abstract
The effects of some geometric peculiarities of wall-attachment fluidic devices on the attaching jet flow and the switching mechanism were experimentally made clear. And the propriety of the analytical model which has been used for the theoretical study of these devices was investigated.
In this experiment, a large scale model was operated with air and water. In the case of water, the flow pattern was visualized by means of polystyrene granules.
The experimental results can be summarized as follows:
(1) An analytical model of a jet flow attached to a sufficiently long wall, which has been used generally, is not applicable to the case of a relatively short wall length or vent distance and considerably large offset, because the jet flow is affected by the wall end or the vent.
(2) An attaching jet flow never separates from a sufficiently long side wall with a vent, unlike the case of a relatively short wall, though the attachment point moves discontinuously from the upstream wall to the downstream one of the vent by a continuous increase of the control flow rate.
(3) Therefore, the switching mechanism of the vent type device is always the opposite wall switching. But the switching mechanism of this case is more complex in comparison with the case of the device without a vent. In this case the vent effects on the attaching jet have to be considered.
(4) From the view point of the switching of the jet, the shorter vent distance is desirable, but from the view point of the output characteristics of the device, the vent distance has a lower limit in relation to the vent width to shut out the flow through the vent in the no load condition.
