Frequency Studies and Scaling Effects of Jet Interaction in a Feedback-Free Fluidic Oscillator

摘要

The work presented in this paper focuses on understanding the effects of scaling on fluidic oscillator performance, with a particular emphasis on the relationship between flow rate and oscillation frequency. The jet interaction feedback-free type of fluidic oscillator used in this investigation is a strong candidate for a flow control actuator, as it has high bandwidth, no moving parts, and high momentum capability. The aim of this study is to understand the basic fluid dynamics of fluidic oscillators, as well as to provide an engineering database of information for future oscillator designs. Results presented in this paper detail the frequency response of the fluidic oscillator under various geometric and supply fluid conditions. Scaling studies were performed in order to establish the operating range of the device. Oscillators were built and tested with different fluids in gas and liquid phases over a range of magnitude in flow rate and frequency response. Frequency maps of the oscillator response indicate a flow field that is rich in high-frequency content, with up to the 7~(th) harmonic visible in the spectra. Three different flow regimes were observed with particle image velocimetry with a refractive index matched fluid. An interesting mode-hopping behavior was also observed which varied with the size of the oscillator, aspect ratio, and test fluid.