Developments in the ESA boundary layer identification and transition zone detection code

Abstract

Different correlations for boundary layer transition exist within literature. However, they often require boundary layer parameters (like displacement and momentum thickness) which are not automatically provided by standard CFD tools. To tackle this problem, the boundary layer identification and transition zone detection (BLITZ) code was developed. This work presents different improvements to the tool to further extend its capabilities and improve its accuracy. To ensure faster analysis of flight vehicles, parallelization is implemented combined with a new streamline tracing and interpolation methodology. Additionally, a blending methodology between the laminar and turbulent field solution is developed based on an intermittency factor to provide a better representation of the real flow acting on the vehicle. Together with the implementation of a standalone monitoring property calculation algorithm, it is now possible to make an improved estimate of the total heat load into the vehicle as well as the aerodynamic forces exerted on it considering the evolution of the transitional flow regime. Further, improvements on the boundary layer edge detection, streamline tracing and pressure gradient calculation are implemented. The results are validated on flat plate cases with and without pressure gradient. Finally, a first validation based on launch data found in the literature is provided. Consequently, an analysis of different possible fairing geometries is given to show the impact of continuity in radius of curvature on the boundary layer transition.