Characteristics of Modified Fluidic Oscillator with Adjustable Flow Parameters

The presented experimental study investigates the inner fluid mechanics and the oscillation patterns of a modified fluidic oscillator. The design is based on a fluidic oscillator with two feedback channels, but the feedback channels are removed. The fluid used to switch the main jet is supplied externally through fast-switching valves into short remains of the feedback channels. This enables the independent control of main mass flow, feedback channel mass flow, and frequency. Pressure measurements inside the mixing chamber give insight into the internal fluid dynamics. The external velocity field is measured using a particle image velocimetry system. Mean velocity fields and phase-averaged jet deflection angles enable a detailed analysis of the oscillation patterns. When gradually reducing the mass flow through the valves, the oscillation transitions from consistent to intermittent and eventually to a nonoscillating state. An in-depth analysis shows that the fluid volume of the feedback channel is driving the oscillation. The amount of volume necessary for an oscillation depends on the inner geometry of the fluidic oscillator. These results are expected to be applicable on an unmodified fluidic oscillator with feedback channels because the decisive internal flow mechanics are presumably the same in both devices. The modified fluidic oscillator can create a wide variety of different oscillation patterns and therefore enables systematic investigations of oscillation patterns with just one device. Changing the oscillation frequency or the main jet velocity results in different oscillation patterns. When both parameters are changed simultaneously to maintain a constant Strouhal number, the oscillation pattern remains the same.