Abstract

A parametric experimental study was performed with sweeping jet actuators (fluidic oscillators) to determine their effectiveness in controlling flow separation on an adverse pressure gradient ramp. Parameters that were investigated included actuator placement (that is, pitch and spreading angles, streamwise location) and actuator size. Microvortex generators were also used to provide a reference control case for comparisons. Surface pressure measurements and surface oilflow visualization were used to characterize the effects of these parameters on the actuator performance. Two-dimensional particle image velocimetry measurements of the flowfield over the ramp and hot-wire measurements of the actuator’s jet flow were also obtained for selective cases. The results suggest that an actuator with a wider jet spreading (110 versus 70 deg) placed closer (2.3 versus 7 boundary-layer thickness upstream) to the flow separation location provides better performance. Different actuator sizes obtained by scaling down the actuator geometry produced different jet spreading. Scaling down the actuator (based on the throat dimensions) from $6.4 \times 3.2 mm$ to $3.8 \times 2 mm$ resulted in similar flow control performance; however, scaling down the actuator further to $2 \times 1 mm$ reduced the actuator efficiency by reducing the jet spreading considerably. The results of this study provide insight that can be used to design and select the optimal sweeping jet actuator configuration for flow control applications.

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Volume 56, Number 1January 2018

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Acknowledgments

The author would like to thank the NASA Fixed Wing Project for funding this research and the following individuals for their support: Catherine McGinley, Luther Jenkins, John Lin, Latunia Melton, and Charlie Debro.

Received26 October 2016
Accepted11 August 2017
Published online13 September 2017

Effects of Sweeping Jet Actuator Parameters on Flow Separation Control

Abstract

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