側壁付着形素子における内部流の不安定現象

抄録

In a wall-attachment fluid amplifier, there are cases which the internal flow becomes unstable and the jet is not stably attached to the one of walls. The case of the large scale model is reported previously, this unstable phenomenon is an oscillation with almost constant periods. And those periods are longer than those of other types of fluidic oscillators previously reported. For a small scale amplifier model that is onefifth of the previous large scale model, geometrical shapes in the fluid amplifier occuring the oscillation are measured and relations between the velocity of the main jet at the nozzle exit and frequencies are examined. By use of the theory of the attached jet and the analysis of the switching mechanism, the oscillation process is modeled by dividing into three processes, geometrical shapes occuring the oscillation and frequencies are calculated and compared with experimental ones. Geometrical shapes occuring the oscillation in the small scale model is different from those in the large scale model reported before. Oscillating frequencies in the small scale model are higher than those in the large scale model and they are same order as those of the load-type fluidic oscillator. It is found that the frequency is easy to vary by changing the velocity of the main jet.