Simulation of a fluidic oscillator for active flow control of boundary layer separation

Abstract

The main purpose of this study is to analyze the different types of flow regimes that can be found on a two-dimension fluidic oscillator at low Reynolds number. First of all, there is a description on what types of fluidic actuator there are; the one chosen for this study is a symmetric fluidic oscillator with feedback path. The characteristics of the internal flow and the jet expelled from the fluidic oscillator, which can be found in this study, have been extracted from computational results. This computational results have been obtained using an open source spectral elements code, which specific variables are found in this study. It has been found that in a range of Reynolds number from 50 to 100, there are four types of flow regimes: stationary symmetric jet, stationary asymmetric jet, oscillating asymmetric jet and oscillatory jet. The characteristics of each flow regime have been analyzed in this study, as well as it has been made a discussion between the obtained solutions, in order to obtain the final conclusions. When analyzing the interaction between the mixing chamber and the feedback channel in the oscillatory jet, it has been found that the oscillation starts when more fluid enters either feedback channel, when this fluid leaves the feedback channel to reincorporate to the mixing chamber it pushes the main jet to the opposite wall. Then, more fluid enters the other feedback channel and when it enters the mixing chamber pushes the main jet to the opposite side, this process repeats indefinitely and periodically; this oscillation is transmitted outside the mixing chamber to the outlet of the oscillator expelling the main jet in an oscillatory motion. The flow is also measured by probes inside the oscillator, which give additional comprehension of the behavior inside the fluidic oscillator. In addition, the forces applied to the flow diverter and the inner blocks are analyzed to quantify the dynamics of the oscillation in the mixing chamber and the outlet of the fluidic oscillator.