Axisymmetric and Asymmetric Turbulent Shock Wave Boundary Layer Interaction at Mach 2.5

Axisymmetric and asymmetric shock wave boundary layer interactions are relevant to both internal and external supersonic and hypersonic applications such as inlets of scramjet engines. This paper reports on wall-resolved implicit large-eddy simulations of a canonical Mach 2.5 axisymmetric and asymmetric shock wave boundary layer interaction experiment at NASA Glenn Research Center. A conical shock wave was generated with a conical centerbody with a 16 degrees half-angle. The centerbody radii were 9.2% and 14.7% of the test section diameter. The conical shock wave interacted with the turbulent boundary layer on the inside surface of the cylindrical test section. Axisymmetric interactions were obtained when the centerbody was located in the center of the test section while asymmetric (swept) interactions were obtained when the centerbody was displaced from the test section centerline. Precursor Reynolds-averaged Navier-Stokes calculations provided the initial and boundary conditions for the implicit large-eddy simulations which considered only the interaction region to allow for a high grid resolution. The experimental Reynolds number based on diameter was Re-D = 4 Chi 10(6). The Reynolds number for the simulations was lowered to Re-D = 4 Chi 10(5) to keep the computational expense of the simulations within limits. For both centerbody radii, the turbulent boundary layer separated from the test section surface. For the larger centerbody radius, the expansion fan impacts the test section wall farther downstream and the downstream extent of the separated flow region is larger. Various sub-domains upstream of the interaction, within the interaction, and downstream of the interaction were analyzed with the proper orthogonal decomposition. The dominant modes for all three regions are streamwise coherent structures with Strouhal numbers based on separation length of 0.15 and below. Fourier spectra of the wall-pressure coefficient for the interaction region have peaks at Strouhal numbers based on separation length of 0.15 and 0.04. Preliminary results are presented for asymmetric interactions with a centerbody offset of one quarter and one third of the test section radius. These simulations are computationally more expensive as they required a computational domain that spanned half of the azimuth. Instantaneous flow simulations revealed a swept interaction with considerable cross-flow.