An Investigation of a Newly Developed Bistable Load-Type Supersonic Fluidic Oscillator for Generating Large-Amplitude Pressure Pulsations

Abstract

Unique aspects in the development of bistable load-type fluidic oscillators that satisfy the requirement of producing large-amplitude pressure fluctuations during the charging of vessels for potential implementation in industrial processes such as the superplastic forming process are addressed in this paper. A pseudo-3D computational fluid dynamic model is shown to be capable of accurately predicting the experimental values of the dimensionless frequencies and pressure fluctuation amplitudes as well as the experimental Schlieren images of the flow field obtained over a wide range of operating conditions. The pseudo-3D model is also used to provide details of the fluid motion in the oscillator which could not be measured experimentally when investigating the operation of the device. The flow switching mechanism is identified as a consequence of a reduction of the flow deflection angle due to the increase of the downstream pressure load by the charging of feedback tanks. Some examples of the usefulness of the model as a cost-effective industrial design tool are also demonstrated. The effects of changing the number and size of the feedback tank volumes on the device frequency and amplitude of the oscillation are clearly shown using dimensionless variables.