The Time-Resolved Internal and External Flow Field Properties of a Fluidic Oscillator

The time-resolved natural flow field of a fluidic oscillator

“…The instantaneous properties of the jet (e.g., jet velocity and jet width) may also be evaluated in the external flow field. Gaertlein et al (2014) suggested that the jet width is increasing with radial distance at a higher rate than a corresponding steady jet. At the same time, the jet's velocity is decaying faster with radial distance.…”

“…However, these observations are solely based on two-dimensional flow field data which neglects a potential meandering of the jet in and out of the laser plane. Gaertlein et al (2014) also estimate the entrainment of the jet by introducing an effective jet depth based on the conservation of momentum. Although this estimation suggests that the oscillating jet entrains substantially more fluid than a steady jet, its accurate quantitative determination requires three-dimensional flow field information.…”

“…They also noted the challenges of triggering into the natural oscillations of the device. The precursor of the current study was presented by Gaertlein et al (2014) with a preliminary analysis of the time-resolved internal and external flow field of a fluidic oscillator. Numerical studies have been sparse because they are burdened by the absence of a suitable data set for proper validation.…”

Experimental Investigation of Compressibility Effects in a Fluidic Oscillator

“…In order to lower the oscillation frequency in experimental studies investigating the time-resolved flow field, either the working fluid is changed to water 7 or the exiting velocity is reduced to the incompressible regime by increasing the oscillator's size. 8 However, both measures also omit the effects caused by compressibility. The few studies done in the compressible regime either investigate the global effects without the detailed flow field 4 yielding merely qualitative results 9 , or are numerical studies without experimental validation.…”

Drag reduction on a rectangular bluff body with base flaps and fluidic oscillators

“…Previous investigations on the particular oscillator design were conducted by Gaertlein et al (2014) and Ostermann et al (2015a). The experimental work of Gaertlein et al (2014) and Ostermann et al (2015a) provided a comprehensive description of the phase-averaged internal and external flow field for an oscillating jet in a quiescent environment. Ostermann et al (2015b) examined and discussed various phase-averaging methods of the naturally oscillating flow field.…”