Krypton tagging velocimetry in a turbulent Mach 2.7 boundary layer

• Published in: Experiments in fluids 2016-05, Vol.57 (5), Article 62
• Main Authors: Zahradka, D., Parziale, N. J., Smith, M. S., Marineau, E. C.
• Format: Article
• Language: English
• Subjects: Engineering; Engineering Fluid Dynamics; Engineering Thermodynamics; Fluid- and Aerodynamics; Heat and Mass Transfer; Research Article
• ISSN: 0723-4864; 1432-1114
• DOI: 10.1007/s00348-016-2148-2

The krypton tagging velocimetry (KTV) technique is applied to the turbulent boundary layer on the wall of the “Mach 3 Calibration Tunnel” at Arnold Engineering Development Complex (AEDC) White Oak. Profiles of velocity were measured with KTV and Pitot-pressure probes in the Mach 2.7 turbulent boundary layer comprised of 99 % N 2 /1 % Kr at momentum-thickness Reynolds numbers of R e Θ = 800 , 1400 , and 2400. Agreement between the KTV- and Pitot-derived velocity profiles is excellent. The KTV and Pitot velocity data follow the law of the wall in the logarithmic region with application of the Van Driest I transformation. The velocity data are analyzed in the outer region of the boundary layer with the law of the wake and a velocity-defect law. KTV-derived streamwise velocity fluctuation measurements are reported and are consistent with data from the literature. To enable near-wall measurement with KTV ( y / δ ≈  0.1–0.2), an 800-nm longpass filter was used to block the 760.2-nm read-laser pulse. With the longpass filter, the 819.0-nm emission from the re-excited Kr can be imaged to track the displacement of the metastable tracer without imaging the reflection and scatter from the read-laser off of solid surfaces. To operate the Mach 3 AEDC Calibration Tunnel at several discrete unit Reynolds numbers, a modification was required and is described herein.