LAUSR

Abstract The inevitable boundary-layer transition and severe heating argumentation of Hypersonic Inflatable Aerodynamic Decelerator (HIAD) pose challenge for survivability of a Thermal Protection System (TPS). In the current study, the effects of sphere-cone angle on hypersonic heating and boundary-layer transition of stacked tori HIADs with 60°, 65° and 70° sphere-cone are demonstrated minutely by solving compressible Navier-Stokes equations with k-ω-γ transition model. Transition and heating augmentation triggered on the leeward where the shape deformation causes crossflows and local flow separations are sensitive to the cone angle. Smaller cone angle withstands severer heating flux. The study reveals that the first-mode disturbance and crossflow instability are dominators to the transition. Whereas the contribution of second-mode disturbance could be negligible. Larger cone angle postpones transition onsets as a result of weaker crossflow and more limited affected region of the first-mode disturbance. The 70° sphere-cone model, whose crossflow is lower than the critical value is only determined by the first mode, and thus has a quite smaller transition zone as compared to the other two models.