10.14279/DEPOSITONCE-8173
Woszidlo, Rene
Rene
Woszidlo
Ostermann, Florian
Florian
Ostermann
Nayeri, Christian Navid
Christian Navid
Nayeri
Paschereit, Christian Oliver
Christian Oliver
Paschereit
The time-resolved natural flow field of a fluidic oscillator
Technische Universität Berlin
2015
Article
532 Mechanik der Fluide, Mechanik der Flüssigkeiten
particle image velocimetry
proper orthogonal decomposition
deflection angle
separation bubble
supply rate
Technische Universität Berlin
Technische Universität Berlin
2019-02-07
2019-02-07
2015
en
0723-4864
https://depositonce.tu-berlin.de//handle/11303/9072
1432-1114
The internal and external flow field of a fluidic oscillator with two feedback channels are examined experimentally within the incompressible flow regime. A scaled-up device with a square outlet nozzle is supplied with pressurized air and emits a spatially oscillating jet into quiescent environment. Time-resolved information are obtained by phase-averaging pressure and PIV data based on an internal reference signal. The temporal resolution is better than a phase angle of 3°. A detailed analysis of the internal dynamics reveals that the oscillation mechanism is based on fluid feeding into a separation bubble between the jet and mixing chamber wall which pushes the jet to the opposite side. The total volume of fluid transported through one feedback channel during one oscillation cycle matches the total growth of the separation bubble from its initial size to its maximum extent. Although the oscillation frequency increases linearly with supply rate, sudden changes in the internal dynamics are observed. These changes are caused by a growth in reversed flow through the feedback channels. The time-resolved properties of the emitted jet such as instantaneous jet width and exit velocity are found to oscillate substantially during one oscillation cycle. Furthermore, the results infer that the jet’s oscillation pattern is approximately sinusoidal with comparable residence and switching times.