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On the length scales of hypersonic shock-induced large separation bubbles near leading edges

  • R. Sriram (a1), L. Srinath (a1), Manoj Kumar K. Devaraj (a2) and G. Jagadeesh (a1)

The interaction of a hypersonic boundary layer on a flat plate with an impinging shock – an order of magnitude stronger than that required for incipient separation of the boundary layer – near sharp and blunt leading edges (with different bluntness radii from 2 to 6 mm) is investigated experimentally, complemented by numerical computations. The resultant separation bubble is of length comparable to the distance of shock impingement from the leading edge, rather than the boundary layer thickness at separation; it is termed large separation bubble. Experiments are performed in the IISc hypersonic shock tunnel HST-2 at nominal Mach numbers 5.88 and 8.54, with total enthalpies 1.26 and $1.85~\text{MJ}~\text{kg}^{-1}$ respectively. Schlieren flow visualization using a high-speed camera and surface pressure measurements using fast response sensors are the diagnostics. For the sharp leading edge case, the separation length was found to follow an inviscid scaling law according to which the scaled separation length $(L_{sep}/x_{r})M_{er}^{3}$ is found to be linearly related to the reattachment pressure ratio $p_{r}/p_{er}$ ; where $L_{sep}$ is the measured separation length, $x_{r}$ the distance of reattachment from the leading edge, $M$ the Mach number, $p$ the static pressure and the subscripts $r$ and $e$ denote the conditions at the reattachment location and at the edge of the boundary layer at the shock impingement location respectively. However, for all the blunt leading edges $(L_{sep}/x_{r})M_{er}^{3}$ was found to be a constant irrespective of Mach number and much smaller than the sharp leading edge cases. The possible contributions of viscous and non-viscous mechanisms towards the observed phenomena are explored.

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Present address: Marie Curie Fellow in Aerospace Engineering (Aerospace Sciences), School of Engineering, University of Glasgow, Glasgow G12 8QQ, UK.

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Anderson, J. D. 1989 Hypersonic and High Temperature Gas Dynamics. McGraw-Hill.
Ball, K. O. W. 1971 Flap span effects on boundary-layer separation. AIAA J. 9 (10), 20802081.
Billig, F. S. 1967 Shock-wave shapes around spherical-and cylindrical-nosed bodies. J. Spacecr. Rockets 4 (6), 822823.
Bleilebens, M. & Olivier, H. 2006 On the influence of elevated surface temperatures on hypersonic shock wave/boundary layer interaction at a heated ramp model. Shock Waves 15 (5), 301312.
Borovoi, V. Y., Egorov, I. V., Skuratov, A. S. & Struminskaya, I. V. 2005 Interaction between an inclined shock and boundary and high-entropy layers on a flat plate. Fluid Dyn. 40 (6), 911928.
Borovoy, V. Y., Egorov, I. V., Skuratov, A. S. & Struminskaya, I. V. 2012 Two-dimensional shock-wave/boundary-layer interaction in the presence of entropy layer. AIAA J. 51 (1), 8093.
Chapman, D. R., Kuehn, D. M. & Larson, H. K.1957 Investigation of separated flows in supersonic and subsonic streams with emphasis on the effect of transition. NACA Tech. Rep. TN-3869.
Chen, X.-q., Hou, Z.-x., Liu, J.-x. & Gao, X.-z. 2011 Bluntness impact on performance of waverider. Comput. Fluids 48 (1), 3043.
Clemens, N. T. & Narayanaswamy, V. 2014 Low-frequency unsteadiness of shock wave/turbulent boundary layer interactions. Annu. Rev. Fluid Mech. 46, 469492.
Coleman, G. T. & Stollery, J. L. 1972 Heat transfer from hypersonic turbulent flow at a wedge compression corner. J. Fluid Mech. 56 (04), 741752.
Creager, M. O.1957 Effects of leading-edge blunting on the local heat transfer and pressure distributions over flat plates in supersonic flow. NACA Tech. Rep. TN 4142.
Davies, W. R. & Bernstein, L. 1969 Heat transfer and transition to turbulence in the shock-induced boundary layer on a semi-infinite flat plate. J. Fluid Mech. 36 (01), 87112.
Davis, J. P. & Sturtevant, B. 2000 Separation length in high-enthalpy shock/boundary-layer interaction. Phys. Fluids 12 (10), 26612687.
Delery, J. & Coet, M. C. 1991 Experiments on shock-wave/boundary-layer interactions produced by two-dimensional ramps and three-dimensional obstacles. In Hypersonic Flows for Reentry Problems, pp. 97128. Springer.
Délery, J. & Dussauge, J. 2009 Some physical aspects of shock wave/boundary layer interactions. Shock Waves 19 (6), 453468.
Délery, J. & Marvin, J. G.1986 Shock-wave boundary layer interactions. Tech. Rep. AGARD-AG-280.
Eckert, E. R. G. 1955 Engineering relations for friction and heat transfer to surfaces in high velocity flow. J. Aero. Sci. 22 (8), 585587.
Elfstrom, G. M. 1972 Turbulent hypersonic flow at a wedge-compression corner. J. Fluid Mech. 53 (1), 113129.
Erdem, E., Kontis, K., Johnstone, E., Murray, N. P. & Steelant, J. 2013 Experiments on transitional shock wave–boundary layer interactions at mach 5. Exp. Fluids 54 (10), 122.
Fay, J. F. & Sambamurthi, J.1992 Laminar hypersonic flow over a compression corner using the hana code. AIAA Paper 92-2896.
Gadd, G. E., Holder, D. W. & Regan, J. D. 1954 An experimental investigation of the interaction between shock waves and boundary layers. Proc. R. Soc. Lond. A 226, 227253.
Hayakawa, K. & Squire, L. C. 1982 The effect of the upstream boundary-layer state on the shock interaction at a compression corner. J. Fluid Mech. 122, 369394.
Holden, M. S. 1970 Boundary-layer displacement and leading-edge bluntness effects on attached and separated laminar boundary layers in a compression corner. I-theoretical study. AIAA J. 8, 21792188.
Holden, M. S. 1971a Boundary-layer displacement and leading-edge bluntness effects on attached and separated laminar boundary layers in a compression corner. II-experimental study. AIAA J. 9 (1), 8493.
Holden, M. S. 1971b Establishment time of laminar separated flows. AIAA J. 9 (11), 22962298.
Humble, R. A., Elsinga, G. E., Scarano, F. & Van Oudheusden, B. W. 2009 Three-dimensional instantaneous structure of a shock wave/turbulent boundary layer interaction. J. Fluid Mech. 622, 3362.
John, B. & Kulkarni, V. 2014 Effect of leading edge bluntness on the interaction of ramp induced shock wave with laminar boundary layer at hypersonic speed Comput. Fluids 96, 177190.
Katzer, E. 1989 On the lengthscales of laminar shock/boundary-layer interaction. J. Fluid Mech. 206, 477496.
Krek, R. M. & Jacobs, P. A.1993 Stn, shock tube and nozzle calculations for equilibrium air. Tech. Rep. Research Report No. 2/93, The University of Queensland.
Krishnan, L., Yao, Y., Sandham, N. D. & Roberts, G. T. 2005 On the response of shock-induced separation bubble to small amplitude disturbances. Mod. Phys. Lett. B 19, 14951498.
Lewis, J. E., Kubota, T. & Lees, L. 1968 Experimental investigation of supersonic laminar, two-dimensional boundary-layer separation in a compression corner with and without cooling. AIAA J. 6 (1), 714.
Mallinson, S. G., Gai, S. L. & Mudford, N. R. 1996a High-enthalpy, hypersonic compression corner flow. AIAA J. 34 (6), 11301137.
Mallinson, S. G., Gai, S. L. & Mudford, N. R. 1996b Leading-edge bluntness effects in high enthalpy, hypersonic compression corner flow. AIAA J. 34 (11), 22842290.
Mallinson, S. G., Gai, S. L. & Mudford, N. R. 1997a Establishment of steady separated flow over a compression–corner in a free–piston shock tunnel. Shock Waves 7 (4), 249253.
Mallinson, S. G., Gai, S. L. & Mudford, N. R. 1997b The interaction of a shock wave with a laminar boundary layer at a compression corner in high-enthalpy flows including real gas effects. J. Fluid Mech. 342, 135.
Miller, D. S., Hijman, R. & Childs, M. E. 1964 Mach 8 to 22 studies of flow separations due to deflected control surfaces. AIAA J. 2 (2), 312321.
Moffat, R. J. 1988 Describing the uncertainties in experimental results. Exp. Therm. Fluid Sci. 1 (1), 317.
Munikrishna, N.2007 On viscous flux discretization procedures for finite volume and meshless solvers. PhD thesis, Indian Institute of Science.
Murray, N., Hillier, R. & Williams, S. 2013 Experimental investigation of axisymmetric hypersonic shock-wave/turbulent-boundary-layer interactions. J. Fluid Mech. 714, 152189.
Needham, D. A.1965 Laminar separation in hypersonic flow. PhD thesis, Imperial College London.
Needham, D. A. & Stollery, J. L.1966 Boundary layer separation in hypersonic flow. AIAA Paper 66-455.
Pirozzoli, S. & Grasso, F. 2006 Direct numerical simulation of impinging shock wave/turbulent boundary layer interaction at m = 2. 25. Phys. Fluids 18 (6), 065113.
Rudman, S. & Rubin, S. G. 1968 Hypersonic viscous flow over slender bodies with sharp leading edges. AIAA J. 6 (10), 18831890.
Schetz, J. A. & Fuhs, A. E. 1921 Handbook of Fluid Dynamics and Fluid Machinery. John Wiley and Sons.
Settles, G. S. & Bogdonoff, S. M. 1982 Scaling of two- and three-dimensional shock/turbulent boundary-layer interactions at compression corners. AIAA J. 20 (6), 782789.
Shende, N. & Balakrishnan, N. 2004 New migratory memory algorithm for implicit finite volume solvers. AIAA J. 42 (9), 18631870.
Spaid, F. W. & Frishett, J. C. 1972 Incipient separation of a supersonic, turbulent boundary layer, including effects of heat transfer. AIAA J. 10 (7), 915922.
Srinivasan, S., Tannehill, J. C. & Weilmuenster, K. J.1986 Simplified curve fits for the thermodynamic properties of equilibrium air. NASA Tech. Rep. Report No. 1181.
Sriram, R.2013 Shock tunnel investigations on hypersonic impinging boundary layer interaction. PhD thesis, Indian Institute of Science.
Sriram, R. & Jagadeesh, G. 2014 Shock tunnel experiments on control of shock induced large separation bubble using boundary layer bleed. Aerosp. Sci. Technol. 36, 8793.
Sriram, R. & Jagadeesh, G. 2015a Correlation for length of impinging shock-induced large separation bubble at hypersonic speed. AIAA J. 53 (9), 27712776.
Sriram, R., Ram, S. N., Hegde, G. M., Nayak, M. M. & Jagadeesh, G. 2015b Shock tunnel measurements of surface pressures in shock induced separated flow field using mems sensor array. Meas. Sci. Technol. 26 (9), 095301.
Stewartson, K. & Williams, P. G. 1969 Self-induced separation. Proc. R. Soc. Lond. A 312, 181206.
Swantek, A. B. & Austin, J. M. 2015 Flowfield establishment in hypervelocity shock-wave/boundary-layer interactions. AIAA J. 53 (2), 311320.
Toro, E. F., Spruce, M. & Speares, W. 1994 Restoration of the contact surface in the hll-riemann solver. Shock Waves 4 (1), 2534.
Venkatakrishnan, V. 1995 Convergence to steady state solutions of the euler equations on unstructured grids with limiters. J. Comput. Phys. 118 (1), 120130.
Verma, S. B. & Manisankar, C. 2012 Shockwave/boundary-layer interaction control on a compression ramp using steady micro jets. AIAA J. 50 (12), 27532764.
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