Developing high-velocity atmospheric aircraft equipped with ramjet engines, which use atmospheric air as the oxidizer, is an important component of aerospace technology prospects. These craft may be employed to quickly deliver payloads over intercontinental distances and as boosters for spacecraft injection into orbit. A characteristic feature of high-velocity atmospheric aircraft is a presence of sharp aerofoil edges subjected to highly oxidative airflow. This means that actual implementation of numerous hypersonic atmospheric aircraft projects largely depends on whether it is possible to develop materials that could remain stable in an oxidative atmosphere at temperatures of 2000--2500 °C. We estimated the thermal state of a structural component in the shape of a blunted wedge made out of promising refractory ceramics under flight conditions at an altitude of 22 km and a velocity of Mach 7

The efficiency and maximum height, speed and duration characteristics of the flight path of high-speed atmospheric aircraft are largely determined by the temperature regime of the most heat-stressed structural elements, suchas the edges of airframe airfoils. Their active thermal protection systems contribute to solving a number of complex scientific and technical problems, the most promising and simple solution being heat-resistant inorganic materials of the oxide class. However, their use for the structural design of the edge as a monolithic structural element is difficult both in terms of technology and strength characteristics, especially in the heat shock mode. In this regard, a promising solution is an edge in the form of a core made of heat-resistant and heat-conducting materials with a high-temperature oxide ceramic lining, which protects from the environmental oxidative effects and provides the permissible temperature regime of the core due to thermal resistance determined by the thickness of the lining. The study examines the temperature conditions of the wedge-shaped edge with a heat-conducting core and a heat-resistant ceramic lining. When choosing materials for the core and lining, it is important to preliminary calculate and estimate the parameters of the edge performance, taking into account the data on the thermophysical and physicomechanical properties of the materials. The study comparatively analyzes the thermal state of a prefabricated wedge with a heat-conducting core made of hafnium boride, which is an advanced heat-resistant material, and molybdenum and nickel, which are more technological and cheap metal materials, with a lining of oxide heat-resistant ceramics

One of the features of high-velocity atmospheric aircraft is the presence of thin aerofoils with edges characterised by a small blunt radius, subjected to high-temperature aerodynamic heating at temperatures of up to 2000 -- 2500 °C. In order to ensure correct operation of both the power plant producing thrust in such vehicles, assumed to be a supersonic combustion ramjet, and respective aerodynamic controls, the components subjected to high-velocity air flows must retain their geometric stability. A way to ensure their performance is to use methods and means of thermal protection, as well as materials that are resistant to high temperatures in an oxidising atmosphere, while one of the promising trends is employing refractory oxide materials such as oxides of aluminium, zirconium and hafnium. Since this class of materials has low thermal conductivity, large temperature gradients develop in the vicinity of the surface being heated, resulting in temperature stresses, all of which designers should take into account. We analysed the temperature state in a model of an acute zirconium oxide wedge featuring a small blunt radius, subjected to a high-velocity air flow. To reduce the edge temperature and temperature gradients, we propose a design solution implemented as a thermally conductive core lined with a thin layer of zirconium oxide. We consider using aluminium oxide and hafnium boride as core materials

The paper considers the possibility of using refractory oxide materials in thermal protection designed for those structural components of high-velocity atmospheric aircraft that are subjected to significant thermal loading. We present numerical analysis results concerning the thermal state of an acute wedge with a blunted edge positioned in a high-velocity airflow and made of aluminium and zirconium oxides. We studied a wedge featuring a small blunt radius at a range of altitudes and determined which flight velocities do not lead to the aerodynamic heating temperature in the wedge exceeding the melting point of its materials.