Oblique-mode breakdown in hypersonic and high-enthalpy boundary layers over a blunt cone

The nonlinear analyses of the hypersonic and high-enthalpy boundary-layer transition had received little attention compared with the widely-studied linear instabilities. In this work, the oblique-mode breakdown, as one of the most available transition mechanisms, is studied using the nonlinear parabolized stability equations (NPSE) with consideration of the thermal-chemical non-equilibrium effects. The flow over a blunt cone is computed at a free-stream Mach-number of 15. The rope-like structures and the spontaneous radiation of sound waves are observed in the schlieren-like picture. It is also illustrated that the disturbances of the species mass and vibrational temperature near the wall are mainly generated by the product term of the wall-normal velocity disturbance and the mean-flow gradient. In comparison to the CPG flow, the TCNE effects destabilize the second mode and push upstream the N factor envelope. The higher growth rate of the oblique wave leads to stronger growth of the streamwise vortices and harmonic waves.

Experimental investigation of blunt cone model at hypersonic Mach number 7.25

Experiments were carried out in hypersonic shock tunnel in Defence Research and Directorate Laboratory at hypersonic Mach number of 7.25 using an 11.37° apex-angle blunt cone model. Heat flux measurement was carried out on cone model at different angles of attack with angle of rotation ϕ = 0° to 360° in steps of 45° with vacuum sputtered platinum thin film sensors. The measured experimental value of heat transfer data at stagnation point was compared with theoretical value estimated Fay and Riddell correlation. As angle of rotation was increased from ϕ = 0° to ϕ = 180°, the shock wave became closer to model surface due to high density ratio across the shock wave and consequently heat transfer rate became higher.