7-Cone-cylinder flare analysis

Numerical investigation of the transition process and boundary layer separation on a hypersonic cone-cylinder-flare geometry

Clément Caillaud*,1, Mathieu Lugrin 2, Sébastien Esquieu 1

1CEA-CESTA, 15 Avenue des Sablières, Le Barp, France

2DAAA, ONERA, Paris Saclay University, F-92190 Meudon – France



Characterizing the boundary layer transition to turbulence around realistic hypersonic vehicles is a challenging task due to the numerous parameters that affect the process.

To address this challenge, the cone-cylinderflare (CCF) geometry has been designed to provide a flow topology that captures various transition mechanisms observed on reentry objects. These mechanisms encompasses the absolute and convective instabilities and are dependent on the free stream conditions.

A numerical investigation of such instabilities around the CCF common research model is presented.These computations are in relation with a recent experimental campaign performed in the R2Ch hypersonic wind tunnel at ONERA.

The current investigations mainly aims at probing the instabilities that may take part in the transitional process. Using a global linear stability analysis, convective and absolute instabilities will be discussed for the sharp and blunt geometries at two Mach numbers: M= 6.0 and M= 7.0. Validation of the numerical results against the experimental data will be provided.

Furthermore, the physical mechanisms driving these instabilities growth will be discussed in detail by using a sensitivity analysis of the linearised dynamics. These results aim at paving the way for future non-linear simulations.