High-Fidelity Numerical Simulation of Hypersonic Three-Dimensional Shock/Boundary Layer Interactions
Abstract
The present report summarizes the main activities carried out within the research project. The main research line focuses on the effects of a crossflow on the interaction between a turbulent boundary layer and an oblique shock. The activity relies on three sets of direct numerical simulations, with different boundary layer Mach numbers (supersonic/hypersonic conditions) and shock strengths. A statistically quasi-three-dimensional configuration is considered to isolate the crossflow effect on mean flow properties, mean turbulent stresses and large-scale unsteadiness. The numerical analysis reveals that the size of the separation bubble increases with the skew angle, as a result of both earlier flow detachment and delayed reattachment. Strong non-equilibrium conditions are observed after reattachment, where the flow relaxes towards a zero-pressure-gradient state. In this region, standard gradient viscosity hypothesis fails in predicting the mean turbulent stresses, and the mean flow direction strongly deviates from the inviscid solution. Those effects appear to be more severe in the supersonic flow case, than in the hypersonic one. The supersonic flow cases present evidence, for large enough domain widths, of spanwise large-scale rippling of the instantaneous flow separation line. These ripples are advected in the spanwise direction at a fraction of the mean spanwise velocity component; their wavelength scales fairly well with the mean separation length. Based on these results, a predictive formula of the frequency band of large-scale unsteadiness with the skew angle is obtained. In agreement with the literature, it is found that the typical frequency increases with the skew angle. A parallel research activity deals with the assessment of turbulent inflow conditions for the simulations of supersonic and hypersonic boundary layers. Two main classes of inflow conditions, based on recycling/rescaling (RR) and digital filtering (DF) approaches, are considered.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 13, 2022
- Accession Number
- AD1192161
Entities
People
- Sergio Pirozzoli
Organizations
- Sapienza University of Rome