PIV Investigation into the Evolution of Vortical Structures in the Zero Pressure Gradient Boundary Layer

Experimental investigation has been carried out towards understanding the complex fluid dynamics involved in the interaction of vortical structures with zero pressure gradient boundary layer. A laminar boundary layer is produced on the flat plate placed in the water flume and the synthetic jet actuator is deployed on top of the plate at a definite distance from the leading edge. The synthetic jet actuator has been designed in such a way that the to and fro motion of the diaphragm is maneuvered at will by varying the operating parameters to produce the typical streamwise vortical structures namely hairpin and tilted vortices. PIV measurements are made on the streamwise plane normal to the plate to evaluate their interaction with the near wall fluid.

Authors:

• Ishtiaq A. Chaudhry
• Zia R. Tahir

Keywords:

• Boundary layer
• synthetic jet actuator
• flow separation control
• vortical structures.

References:

[1] Acarlar, M.S. and Smith, C. R.; A study of hairpin vortices in a laminar
boundary layer, Part 2. Hairpin vortices generated by fluid injection;
Journal of Fluid Mechanics, Vol. 175, 1987.
[2] Glezer, A.; The formation of vortex rings; Phy. of Fluids, V. 31,9, 1988.
[3] Guo, F and Zhong, S.; A PIV investigation of the characteristics of
micro-scale synthetic jets; The Aer. Journal, l. 111, No. 1122, 2007.
[4] Ishtiaq A. Chaudhry, Shan Zhong: Understanding the interaction of
synthetic jet with the flat plate boundary layer; ICARME, Trivandrum,
India, May 2012.
[5] Jabbal, M. and Zhong, S.: The near wall effect of synthetic jets in a
boundary layer; Int. J. of Heat and Fluid Flow, V 29, issue 1, 2008.
[6] Tang, H; Performance modelling of synthetic jet actuators for flow
separation control; PhD thesis, School of Mechanical, Aerospace and
Civil Engineering, University of Manchester, UK, 2006.
[7] Zhou, J. Zhong, S. "Coherent structures produced by the interaction
between synthetic jets and a laminar boundary layer and their surface
shear stress patterns". Computers and Fluids. Vol. 39. Issue 8. 2010.