Research on complex flow structures at the base of high-speed conical flow with an angle of attack

Under non-zero angle of attack, the near-wake flow of a conical shape vehicle loses its axisymmetric nature, and the flow structure significantly differs from that under the condition of zero angle of attack. In the present study, we selected a reference state from the Reentry-F flight experiment of an altitude of 37.5 km and Mach number of 19.13, and conducted a numerical study on the laminar near-wake flow structure of a 5° half-cone angle circular cone. Influences of the angle of attack, Mach number, Reynolds number, etc., on the near-wake flow structures, pressure and heat flux on the base surface were analysed. The results indicated that, in contrast to the conical shape at zero angle of attack, the recirculation region at non-zero angles of attack displayed an irregular shape, and its length decreased significantly, up to 44.6%. As the angle of attack increased, the near-wake vortices and the leeward vortices of the forebody could interact with each other, which results in a trend of decreasing-increasing-decreasing of the recirculation zone length. The non-dimensional pressure and peak values of the Stanton number showed a decreasing-increasing trend with the increase of the angle of attack. As the Mach number increases, the flow compressibility got stronger, leading to a monotonic decrease in the length of small-scale vortex surfaces and wave structures in the recirculation zone, while the dimensionless peak pressure increased monotonically, and the peak Stanton number decreased monotonically. The influence of Reynolds number on the wave structures was relatively small. As the unit Reynolds number increased, the viscous effect weakened, resulting in an increase in the leeward depression of the recirculation zone and a monotonic increase in the length of the recirculation zone, with both the dimensionless peak pressure and Stanton number decreasing monotonically.