The Effect of Scale and Working Fluid on Sweeping Jet Frequency and Oscillation Angle

Brian T. Bohan, Air Force Institute of Technology
Marc D. Polanka, Air Force Institute of Technology

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This study was conducted to quantify in a controlled manner the effect of oscillator scale and working fluid on oscillator performance. The performance parameters of interest include the oscillation frequency and oscillation spread angle. Three scale models were manufactured with model attributes identical except for scale with models at two times and three times a baseline scale. Four working fluids were tested including helium, ethylene, carbon dioxide, and propane to generate a range of densities and viscosities. The frequency and oscillation angle measurements were obtained using high-speed video recordings of visible schlieren imagery. Trends in frequency were observed and quantified for each oscillator scale and working gas as a function of mass flowrate. This paper shows that these values could all be nondimensionalized with the data collapsing to a single Strouhal number between 0.015 and 0.018 depending on surface roughness, independent of the Reynolds number. This result expands on the authors' previously published work and confirms the previous finding that reveals the geometry and fluid properties also scale and collapse.
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