Papers by Keyword: Hypersonic Flow

Abstract: The authors present the results of investigations of degradation processes that occur in the structure of heat-resistant coating of the Si-TiSi₂-MoSi₂-B-Y system in hypersonic flows of air plasma. It is found that coating operating capacity at surface temperatures T_w ≤ 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 ≥ 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.

Abstract: Two efficient computational procedures based on the boundary layer equations and approximate relations areassessedin prediction of the laminar hypersonic flowfield for both the perfect gas and equilibrium air around the axisymmetric blunt body configurations. For the boundary layer procedure, the boundary layer equationsutilize the integral matrix solution algorithm for the blunt nose and after body region by using a space marching technique. The integral matrix procedure able us to create accurate and smooth results using the minimum grid in the boundary layer and minimize the computational costs. Applying the approximate method creates a robust and efficient code for heating calculations over the blunt bodies which flies in hypersonic regimes. These algorithms are highly appropriate to design of hypersonic reentry vehicles. The effects of real gas on the flowfield characteristics are also studied in two procedures.

Abstract: In this paper, a thermal protection system (TPS) of opposing jet combined with a forward-facing cavity in hypersonic flow was investigated numerically. The flow field parameters and heat flux distribution along the outer body surface are obtained. The thermal protection efficiency of the combined TPS and the single opposing jet TPS was compared. The numerical results shows that this combined TPS has a good effect on cooling the nose of hypersonic vehicle. The recirculation region plays an pivotal role for the reduction of heat flux. The exist of the cavity strengthen the cooling efficiency.