The maximum skin friction and flow field are experimentally measured on a planar impinging gas jet using oil film interferometry (OFI) and particle image velocimetry (PIV), respectively. A jet nozzle width of W = 15 mm, impingement ratios H/W = 4, 6, 8, 10, and a range of jet Reynolds numbers Rejet = 11,000–40,000 are tested to provide a parametric map of the maximum skin friction. The maximum skin friction predictions of Phares et al. (2000, “The Wall Shear Stress Produced by the Normal Impingement of a Jet on a Flat Surface,” J. Fluid Mech., 418, pp. 351–375) for plane jets agree within 5% of the current OFI results for H/W = 6, but deviates upward of 28% for other impingement ratios. The maximum skin friction is found to be less sensitive to changes in the impingement ratio when the jet standoff distance is roughly within the potential core length of the jet. PIV measurements show turbulence transition locations moving toward the nozzle exit with increasing Reynolds number, saturation in the downstream evolution of the maximum axial turbulence intensity before reaching a maximum peak upon impingement, followed by sudden damping at the plate surface. As the flow is redirected, there is an orthogonal redistribution of the fluctuating velocity components, and local peaks in both the axial and transverse turbulence intensity distributions at the plate locations of the maximum skin friction.
The Maximum Skin Friction and Flow Field of a Planar Impinging Gas Jet
Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received February 6, 2017; final manuscript received April 27, 2017; published online July 18, 2017. Assoc. Editor: John Abraham.
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Ritcey, A., McDermid, J. R., and Ziada, S. (July 18, 2017). "The Maximum Skin Friction and Flow Field of a Planar Impinging Gas Jet." ASME. J. Fluids Eng. October 2017; 139(10): 101204. https://doi.org/10.1115/1.4036717
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