Study of cooling coatings based on natural materials

Studies of the maximum heating loads for cooling systems coatings made from natural materials have been conducted. To investigate cooling coatings based on natural materials, an experimental setup including a coating spraying tool has been developed. The conditions for spraying the material onto the heating surface, as well as the design principles for nozzles and combustion chambers, have been established. In the area of the steam-generating surface’s limiting state, shielded from burnout by cooling, these investigations are practically significant. Cooling systems with porous coatings have been developed, which make it possible to prevent the development of fractures in the coatings of chambers and nozzles through the use of thermodynamic and acoustic screens from three heating sources, as well as devices for spraying coatings with detonation high-temperature flares emanating from nozzles and combustion chambers that are cooled by capillary-porous coatings. High-speed filming and holography were used during the investigation. Heat fluxes, temperatures, flow rates, and pressures of liquid and gas flows were measured. The degree of unaccounted flow at different pressures was determined. A model of the interaction of an axisymmetric supersonic detonation jet of gases from the thermal tool normal to the coating has been constructed. Thermodynamic characteristics of oxygen-kerosene burners for the generation of supersonic high-temperature detonation flares by spraying of coatings from powders of natural materials have been established, and the granulometric composition of materials has been determined. Hydrodynamic operating modes of the burners were selected for specific heat fluxes in the range of (2·10 6 ÷ 2·10 7 ) W/m 2 from the jet torch into the coating. The oxidizer-to-fuel ratio varied between 0.3÷0.8; the jet torch temperature was (850÷3000)°C; the jet length was (0÷0.16) m; the jet radius was (3÷10) ·10 -3 m, and the burner axis angle to the coating was (90÷0) degrees. Capillary-porous and flow-through cooling systems showed high reliability, with the former reducing coolant consumption by up to 80 times.