Flow measurement of synthetic jets in a boundary layer

M. Jabbal, S. Zhong

Research output: Chapter in Book/Report/Conference proceedingConference contribution


In this paper the results of an experimental investigation of the interaction of a synthetic jet with the near wall region of a boundary layer are presented. The purpose of this work is to quantify the impact of three main synthetic jet structures, namely hairpin vortices, stretched vortex rings and tilted vortex rings on a boundary layer and to assess and compare the potential flow separation control effectiveness of the different vortical structures. Centre and off-centre streamwise PIV measurements were carried out to obtain phase-averaged and long time-averaged velocity profiles to determine the impact of the synthetic jets. Flow control effectiveness was assessed via an analysis of the near wall fluid mixing, realised primarily by the measure of increase in wall shear stress produced by a passing structure. Both hairpin vortices and stretched vortex rings exhibit characteristics akin to a longitudinal vortex pair embedded in a boundary layer, inducing an upwash in fluid between the counter-rotating legs and a downwash outboard of the legs. Conversely, trailing secondary vortices associated with the tilted vortex rings induce a tertiary vortex pair in the near wall region with a common flow towards the wall. Spanwise wall shear stress measurements indicate that of the three cases, the stretched vortex rings have a greater near wall fluid mixing capability and thus potential for flow separation control.
Original languageEnglish
Title of host publicationCollection of Technical Papers - 37th AIAA Fluid Dynamics Conference|Coll. Tech. Pap. AIAA Fluid Dynam. Conf.
Number of pages15
Publication statusPublished - 2007
Event37th AIAA Fluid Dynamics Conference - Miami, FL
Duration: 1 Jul 2007 → …


Conference37th AIAA Fluid Dynamics Conference
CityMiami, FL
Period1/07/07 → …


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