Langley Research Center Workshop
CFD Validation of
Woodlands Hotel and Conference Center
Williamsburg, Virginia, USA
Case 2 (Introduction)
In Case 2, a zero-mass-flux, or synthetic, jet issues from a circular orifice and interacts with the turbulent boundary layer that has developed on a splitter plate mounted in an atmospheric wind tunnel. The flow is conceptually similar to that documented in Schaeffler (2003). The orifice has a diameter of 0.250 inches (6.35 mm). Being a synthetic jet, the flow through the orifice and out into the outer flowfield alternates between an exhaust and a suction cycle, driven by the expansion and contraction of a cavity internal to the actuator.
The volume changes in the internal cavity are accomplished by replacing one of the rigid walls of the cavity, the wall opposite the orifice exit, with a deformable wall. This flexible wall is driven by a bottom-mounted moveable piston. The piston is driven electro-mechanically.
The tunnel medium is air at sea level, and the tunnel is operating such that the Mach number in the test section, over the plate, is approximately M=0.1. The tunnel dimensions at the test section are 15.0 inches (381.00 mm) wide by approximately 9.8 inch (249 mm) high (distance from the splitter plate to the top wall). The height of the top wall is adjusted down the length of the test section to yield a flow with an approximately zero streamwise pressure gradient. The orifice is located under a fully developed turbulent boundary layer, whose approximate thickness (delta) at the orifice is somewhat greater than 20 mm. All of the experimental data are phase averaged with respect to the drive signal of the actuator.
The above animated GIF image shows are how fluid particles move through the phase-averaged flowfield. Simulated particles move as the actuator goes through its cycle. (From Schaeffler (2003).)
Schaeffler, N. W. and Jenkins, L. N., "Isolated Synthetic Jet in Crossflow: Experimental Protocols for a Validation Dataset," AIAA Journal, Vol. 44, No. 12, 2006, pp. 2846--2856.
Schaeffler, N. W., "The Interaction of a Synthetic Jet and a Turbulent Boundary Layer," AIAA Paper No. 2003-0643, 2003.
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