Hydrodynamic phenomena can be analyzed by optical measurements of double refraction induced when a solution of large molecules is subjected to a shearing force. This paper deals with the analysis of flows in wall-attachment fluid amplifiers by the streaming birefringence method.
First, we study the fundamental flows in the fluid amplifiers, that is, the free jets, the jets attaching to parallel and oblique walls, the main jets with the control flows, and the flows into output ducts and vents. The core and the boundary of a jet can be clearly visualized by this method. In case of a free jet, it is shown that the length of jet core and the spreading angle of jet boundary depend on the Reynolds number. When the jet is attached to a side wall, two or three eddies can be observed in the bubble. The entrainment of jet on the bubble side is increased by the circulation in the bubble and by the control flows. When the jet flows into an output duct, reversed flows or eddies are observed at the entrance of the duct. The flows in the output duct with a vent are studied, too.
A wall-attachment fluid amplifier actuated by water was designed, referring to the results of fundamental experiments. The flows in the amplifier are complicated by the interference of the side walls and the splitter. The main jet is switched by eddies on the opposite side of the attached wall. In some cases, the eddies are composed of a largee one near the splitter and a small one near the main jet nozzle. The latter is important for an acceleration of switching. The switching time of the experimental device is about 10ms.
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