Hypersonic shock wave and turbulent boundary layer interaction in a sharp cone/flare model

A direct numerical simulation of hypersonic Shock wave and Turbulent Boundary Layer Interaction(STBLI)at Mach 6.0 on a sharp 7.half-angle circular cone/flare configuration at zero angle of attack is performed.The flare angle is 34.and the momentum thickness Reynolds number based on the incoming turbulent boundary layer on the sharp circular cone is Re θ=2506.It is found that the mean flow is separated and the separation bubble occurring near the corner exhibits unsteadiness.The Reynolds analogy factor changes dramatically across the interaction,and varies between 1.06 and 1.27 in the downstream region,while the QP85 scaling factor has a nearly constant value of 0.5 across the interaction.The evolution of the reattached boundary layer is characterized in terms of the mean profiles,the Reynolds stress components,the anisotropy tensor and the turbulence kinetic energy.It is argued that the recovery is incomplete and the near-wall asymptotic behavior does not occur for the hypersonic interaction.In addition,mean skin friction decomposition in an axisymmetric turbulent boundary layer is carried out for the first time.Downstream of the interaction,the contributions of transverse curvature and body divergence are negligible,whereas the positive contribution associated with the turbulence kinetic energy production and the negative spatial-growth contribution are dominant.Based on scale decomposition,the positive contribution is further divided into terms with different spanwise length scales.The negative contribution is analyzed by comparing the convective term,the streamwise-heterogeneity term and the pressure gradient term.

Characteristics of reattached boundary layer in shock wave and turbulent boundary layer interaction

The reattached boundary layer in the interaction of an oblique shock wave with a flatplate turbulent boundary layer at Mach number 2.25 is studied by means of Direct Numerical Simulation(DNS).The numerical results are carefully compared with available experimental and DNS data in terms of turbulence statistics,wall pressure and skin friction.The coherent vortex structures are significantly enhanced due to the shock interaction,and the reattached boundary layer is characterized by large-scale structures in the outer region.The space-time correlation of fluctuating wall shear stress and streamwise velocity fluctuation reveals that the structural inclination angle exhibits a gradual decrease during the recovery process.The scale interactions are analyzed by using a twopoint amplitude modulation correlation.A possible mechanism is proposed to account for the strong amplitude modulation in the downstream region.Moreover,the mean skin-friction is decomposed to understand the physically informed contributions.Unlike the upstream Turbulent Boundary Layer(TBL),the contribution associated with the Turbulence Kinetic Energy(TKE)production is greatly amplified,while the spatial growth contribution induced by the pressure gradient largely inhibits skin-friction generation.Based on bidimensional empirical mode decomposition,the turbulence kinetic energy production contribution is further split into different terms with specific spanwise length scales.