the results infer that the jet's oscillation pattern is approximately sinusoidal with comparable residence and switching times.

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The presented study examines various methods for phase-averaging the naturally oscillating flow field of a scaled-up fluidic oscillator. No external trigger is employed to control the oscillation of the flow. Mathematical and signal conditioning approaches for phase-averaging the data are categorized and described. The results of these methods are evaluated for their accuracy in capturing the natural flow field. The respective criteria are based on the minimum fluctuation in oscillation period length, the conservation of velocity amplitudes, and the number of snapshots per phase-averaging window. Although all methods produce reasonable qualitative results, only two methods are identified to provide the desired quantitative accuracy and suitability for the investigated flow field. The first method is based on conditioning a time-resolved pressure signal from the feedback channels in the oscillator. An autocorrelation applied to the reference signal improves the period identification. The second method employs

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This experimental study investigates the flow field and properties of a sweeping jet emitted from a fluidic oscillator into a quiescent environment. The aspect ratio of the outlet throat is 1. Stereoscopic particle image velocimetry is employed to measure the velocity field plane-by-plane. Simultaneously acquired pressure measurements provide a reference for phase correlating the individual planes yielding three-dimensional, time-resolved velocity information. Lagrangian and Eulerian visualization techniques illustrate the phase-averaged flow field. Circular head vortices, similar to the starting vortex of a steady jet, are formed repetitively when the jet is at its maximum deflection. The quantitative jet properties are determined from instantaneous velocity data using a cylindrical coordinate system that takes into account the changing deflection angle of the jet. The jet properties vary throughout the oscillation cycle. The maximum jet velocity decays much faster than that of a comparable steady jet indicating a higher momentum transfer to the environment. The entrainment rate of the spatially oscillating jet is larger than for a steady jet by a factor of 4. Most of the mass flow is entrained from the direction normal to the oscillation plane, which is accompanied by a significant increase in jet depth compared to a steady jet. The high entrainment rate results from the enlarged contact area between jet and ambient fluid due to the spatial oscillation. The jet’s total force exceeds that of an idealized steady jet by up to 30 %. The results are independent of the investigated oscillation frequencies in the range from 5 to 20 Hz.

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