Narrow Results

The prediction of heat transfer for blunt bodies in hypersonic flows remains a great challenge. In particular, the uncertainties are larger in the leeside due to the complexity of the wake flow. Generally, the heat transfer is over-predicted using the Reynolds-averaged Navier–Stokes (RANS) models. In this paper, the improved delayed detached eddy simulation (IDDES) method is used to simulate the Mach 6 flow around a scaled spherical capsule model. In addition, a low dissipative WENO scheme is used for inviscid fluxes and dual-time stepping method is applied for time advancement. Results are compared to experimental data for mean and instantaneous heat transfer in the leeside of the aftbody. It is shown that the integrated error is 75.49% for RANS while 35.69% for IDDES method. Moreover, the multi-scale structures in the separation region are also resolved well by the IDDES method.

Inviscid and viscous boundary layer stabilities in hypersonic flows, which are different from those in low speed flows, are investigated, and have actually multiple unstable modes due to inherent mathematic characters. Numerical integration with the singularity point is implemented by expanding calculation region onto the complex plane, and can avoid the difficulty in solving the inviscid stability equations. The high accurate numerical method of the parabolic stability equation (PSE) is used in spatial marching to solve the viscous stability equations. Computed results show good agreement with relevant data.

In this paper, we present the results of investigations of degradation processes that occur in the structure promising high-temperature anti-oxidizing of heat-resistant coating of the Si–TiSi₂–MoSi₂–B–Y system in hypersonic flows of air plasma. The coating is designed to protect a wide range of heat-resistant materials (carbon–carbon and carbon–ceramic composites, coal–graphite materials, alloys based on Nb, Mo, W, etc.). It is found that the coating operating capacity at surface temperatures $T_w\le$ 1820–1830^∘C is provided by the structural-phase state of its microcomposite main layer and formation on the coating surface of a heterogeneous passivating protective film. It is based on borosilicate glass reinforced by rutile microneedles. The mechanism of coating destruction at $T_w\ge$ 1850–1860^∘C is erosion loss of oxide film as well as generation and growth of gas-filled cavities at the “coating main layer–oxide film” interface. As the pressure of saturated vapor of gaseous oxidation products (SiO, CO, MoO₃ and B₂O₃) exceeds that of the ambient, the oxide film integrity is disrupted and oxidation process becomes active. The rates of erosion loss and sublimation grow as operating temperature increases and ambient pressure decreases.

In this paper, we establish the global existence and stability of a multidimensional conic shock wave for three-dimensional steady supersonic flow past an infinite cone. The flow is assumed to be hypersonic and described by a steady potential flow equation. Under an appropriate boundary condition on the curved cone, we show that a pointed shock attached at the vertex of the cone will exist globally in the whole space.