Abstract
A study was made of the wall pressure fluctuations in the reattachment region of a supersonic free shear layer. The free shear layer was formed by the separation of a Mach 2.9 turbulent boundary layer from a backward facing step. Reattachment occurred on a 20° ramp. By adjusting the position of the ramp, the base pressure at the step was set equal to the freestream pressure, and the free shear layer formed in the absence of any turning. An array of flush-mounted, miniature, high-frequency pressure transducers was used in the vicinity of the reattachment region to make multichannel measurements of the fluctuating wall pressure. Contrary to previous observations of this flow, the reattachment region was found to be highly unsteady, and the pressure fluctuations were found to be large. The overall behavior of the wall pressure loading is similar in scale and magnitude to the unsteadiness of the wall pressure field in compression ramp flows at the same Mach number. Rayleigh scattering was used to visualize the instantaneous shock structure in the streamwise and spanwise direction. Spanwise “wrinkles” on the order of half the boundary layer thickness were observed on the shock sheet.
Similar content being viewed by others
References
Baca, B. K. 1981: An experimental study of the reattachment of a free shear layer in compressible turbulent flow. M. Sc. Dissertation, Princeton University, Princeton, N.J. 08544, USA
Briedenthal, R. 1981: Structure in turbulent mixing layers and wakes using a chemical reaction. J. Fluid Mech. 109, 1–24
Brown, G. L.; Roshko, A. 1974: On density effects and large-scale structure in turbulent mixing layers. J. Fluid Mech. 64, 775–781
Dolling, D. S.; Brusniak, L. 1987: Separation shock motion in fin, cylinder, and compression ramp-induced turbulent interactions. AIAA Pap. 87-1368
Dolling, D. S.; Dussauge, J.-P. 1989: Fluctuating wall-pressure measurements. Chapter 8, AGARDogaph 315
Dolling, D. S.; Murphy, M. T. 1983: Unsteadiness of the separation shock wave structure in a supersonic compression ramp flowfield. AIAA J. 21, 1628–1634
Hanley, R. D. 19785: Effects of transducers flushness on fluctuating surface pressure measurements. AIAA Pap. 75-534
Hayakawa, K.; Smits, A. J.; Bogdonoff, S. M. 1984: Turbulence measurements in a compressible reattaching shear layer. AIAA J. 22, 889–895
Poggie, J.; Smits, A. J.; Glezer, A. 1992: The dynamics and control of fluctuating pressure loads in the reattachment regions of a supersonic free shear layer. AIAA 30th Aerosp. Sci. Meet., January 6–9, 1992
Schewe, G. 1983: On the structure and resolution of wall-pressure fluctuations associated with turbulent boundary layer flow. J. Fluid Mech. 134, 311–328
Selig, M. S.; Andreopoulos, J.; Muck, K. C.; Dussauge, J. P.; Smits, A. J. 1989: Turbulence structure in a shock-wave/turbulent boundary layer interaction. AIAA J. 27, 862–869
Settles, G. S.; Williams, D. R.; Baca, B. K.; Bogdonoff, S. M. 1982: A study of reattachment of a free shear layer in compressible turbulent flow. AIAA J. 20, 60–67
Smith, M. W.; Smits, A. J.; Miles, R. B. 1989: Compressible boundary layer density cross sections by UV Rayleigh scattering. Opt. Lett. 14, 916–918
Spina, E. F. 1988: Organized structures in a supersonic turbulent boundary layer. Ph.D. Thesis, Princeton University, Princeton, N.J. 08544, USA
Wegener, P. P.; Stein, G. D. 1968: Light-scattering experiments and theory of homogeneous nucleation in condensing supersonic flow. 12th Int. Symp. Combust., 1183–1191
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Shen, Z.H., Smith, D.R. & Smits, A.J. Wall pressure fluctuations in the reattachment region of a supersonic free shear layer. Experiments in Fluids 14, 10–16 (1993). https://doi.org/10.1007/BF00196982
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00196982