Progress in shock wave/boundary layer interactions

Modern developments in shear-stress measurement ☆

Advances in CFD prediction of shock wave turbulent boundary layer interactions

Review and assessment of turbulence models for hypersonic flows

An assessment is given of existing shock wave/tubulent boundary-layer interaction experiments having sufficient quality to guide turbulence modeling and code validation efforts. Although the focus of this work is hypersonic, experiments at Mach numbers as low as 3 were considered. The principal means of identifying candidate studies was a computerized search of the AIAA Aerospace Database. Several hundred candidate studies were examined and over 100 of these were subjected to a rigorous set of acceptance criteria for inclusion in the data-base. Nineteen experiments were found to meet these criteria, of which only seven were in the hypersonic regime (M is greater than 5).

Supersonic and hypersonic shock/boundary-layer interaction database

Wall shear stress measurements beneath crossing-shock-wave/turbulent boundary-layer interactions have been made for three interactions of different strengths. The interactions are generated by two sharp fins at symetric angles of attack mounted on a flat plate. The shear stress measurements were made for fin angles of 7 and 11 deg at Mach 3 and 15 deg at Mach 3.85. The measurements were made using a laser interferometer skin-friction meter, a device that determines the wall shear by optically measuring the time rate of thinning of an oil film placed on the test model surface. Results of the measurements reveal high skin-friction coefficients in the vicinity of the fin/plate junction and the presence of quasi-two-dimensional flow separation on the interaction center line. Additionally, two Navier-Stokes computations, one using a Baldwin-Lomax turbulence model and one using a k-epsilon model, are compared with the experimental results for the Mach 3.85, 15-deg interaction case. Although the k-epsilon model did a reasonable job of predicting the overall trend in portions of the skin-friction distribution, neither computation fully captured the physics of the near-surface flow in this complex interaction.

Laser interferometer skin-friction measurements of crossing-shock-wave/turbulent-boundary-layer interactions

A detailed comparison of experimental and computational results on the flowfield structure of a Mach 4, 15-deg symmetric crossing-shock-wave/turbulent-boundary-layer interaction is presented. Experimentally obtained planar laser scattering images are compared with static-pressure contours predicted by the computation.

Structure of crossing-shock-wave/turbulent-boundary-layer interactions

A three-dimensional (3D) hypersonic crossing shock wave/turbulent boundary-layer interaction is examined numerically at Mach 8.3. The test geometry consists of a pair of opposing sharp fins of angle alpha = 15 deg, mounted on a flat plate. Two theoretical models are evaluated. The full (3D) Reynolds-averaged Navier-Stokes equations are solved using the Baldwin-Lomax and the Rodi (modified k-epsilon) turbulence models. Computed results for both cases show good agreement with experiment for flat plate surface pressure and for flowfield profiles of pitot pressure and yaw angle, indicating that the flowfield is primarily rotational and inviscid. Fair to poor agreement is obtained for surface heat transfer, indicating a need for more accurate turbulence models. The overall flowfield structure is similar to that observed in previous crossing shock interaction studies.

Computation of crossing shock/turbulent boundary layer interaction at Mach 8.3

A numerical study of the three-dimensional interaction between crossing shocks generated by symmetric sharp fins and a flat-plate turbulent boundary layer is presented. The full mean compressible Navier-Stokes equations, incorporating a turbulent eddy-viscosity model, are solved. Computed results for the flow past (11 deg, 11 deg) symmetric fins at a freestream Mach number Mw = 2.95 and Reynolds number Re^ = 2.5 X 10s (based on the undisturbed boundary-layer thickness 600) show general agreement with experimental measurements for flatplate surface pressure and surface flow visualization. Analysis of the computed flowfield reveals a complex interaction involving the "collision" of two slowly counter-rotating vortical structures generated by the initial shock/boundary-layer interaction due to each fin. Associated with the streamline structure of the interaction is the formation and growth of a region of low energy near the centerline, downstream of the crossed shocks. A "first look" at the shock structure of the interaction is provided.

Interaction Between Crossing Oblique Shocks and a Turbulent Boundary Layer

A combined theoretical and experimental study is presented for the interaction between crossing shock waves generated by (10 deg, 10 deg) sharp fins and a flat plate turbulent boundary layer at Mach 8.3. The theoretical model is the full 3D mean compressible Reynolds-averaged Navier-Stokes (RANS) equations incorporating the algebraic turbulent eddy viscosity model of Baldwin and Lomax (1978). A grid refinement study indicated that adequate resolution of the flow field has been achieved. Computed results agree well with experiment for surface pressure and surface flow patterns and for pitot pressure and yaw angle profiles in the flow field. The computations, however, significantly overpredict surface heat transfer. Analysis of the computed flow field results indicates the formation of complex streamline and wave structures within the interaction region.

N. Narayanswami

Papers

Laser interferometer skin-friction measurements of crossing-shock-wave/turbulent-boundary-layer interactions

Structure of crossing-shock-wave/turbulent-boundary-layer interactions

Computation of crossing shock/turbulent boundary layer interaction at Mach 8.3

Interaction Between Crossing Oblique Shocks and a Turbulent Boundary Layer

Investigation of a hypersonic crossing shock wave/turbulent boundary layer interaction