An investigation of a supersonic fluidic oscillator generating pulsations in chambers during pressurization

A load-type supersonic fluidic oscillator has potential application for introducing small oscillations in the chamber of a superplastic forming process to improve performance. This paper presents a study of a special bistable load-type supersonic fluidic oscillator capable of simultaneously producing self-sustained oscillations in two gas pressure chambers during their filling at high-pressure. The experimental portion of the work verifies the robust nature of the device performance. Distinct differences, however, are observed compared to those previously shown for a similar prototype supplying pressure fluctuations to a single chamber at low pressure. It is also found that a three-dimensional computational fluid dynamics model is required to accurately simulate the transient filling process of the current oscillator facility, unlike the previous case. This leads to an unaffordable computational cost. To address this issue, a low-order fluid circuit model is developed. This simplified approach is based on a quasi-steady assumption and is of the same form as the one which accurately predicts the performance of the previous prototype. The model is numerically empirical in that the model parameters are determined using steady state 3D-CFD analysis rather than physical experiments. The circuit model combined with a lumped parameter numerical model of tank filling with realistic heat transfer to the surroundings provides an accurate and rapid prediction of the transient performance of the device. Also, the usefulness of the circuit model as an industrial design tool is demonstrated by predicting the effect of two design changes.

Automated summary

This paper presents a study of a special bistable load-type supersonic fluidic oscillator capable of producing self-sustained oscillations in two gas pressure chambers. The experimental portion verifies the robust nature of the device performance and shows distinct differences compared to a similar prototype. A three-dimensional computational fluid dynamics model is required to accurately simulate the transient filling process, leading to an unaffordable computational cost. To address this issue, a low-order fluid circuit model is developed, which provides an accurate and rapid prediction of the transient performance.