Development of a separation vortex in a supersonic flow around a dihedral model for the angle of attack within α = 0 – 24°

The emergence and development of a vortex system during separation of a supersonic airflow on a rib of a dihedral model with the opening angle of 270° was studied in details. The appearance of a separation vortex above the side face was detected for a flow with an angle of attack α = 1°. For a case with α > 2°, boundary-layer separation occurs near the rib of the corner configuration. With an increase in pressure drop between the top and side faces of the model, the separation flow size grows and at an angle α = 3.7° a new vortex is observed (a secondary vortex). For a flow with an angle of attack α = 8°, a third vortex is clearly observed. This vortex is located above the secondary vortex and it has a minor influence on the pressure distribution and the limiting streamlines behavior on the side face. The flow at this angle of attack α results in repeated separations for thin boundary layers (near the configuration rib and beneath the enlarged secondary vortex). Within the tested interval of the angle of attack α = 8° – 24°, the sizes of those local separations remain almost the same. It was shown that analysis of limiting streamlines patterns and the surface pressure distribution cannot fully elucidate the actual structure of a complex vortex system without gaining some additional data.