Annotation: At Yuzhnoye State Design Office, the Cyclone-4 launch vehicle 3rd stage engine has been developed and is under testing. For adjustment of the engine and test bench systems, in the first firing tests the radiation-cooled nozzle extension was replaced with a steel water-cooled one. It was planned to start the engine with water-cooled nozzle extension without vacuumizing and without gad dynamic pipe, which conditioned operation with flow separation at the output edge of water-cooled nozzle extension. Therefore, the calculation of flow in the nozzle with water-cooled extension, flow separation place, and thermal load on watercooled nozzle extension during operation in ground conditions is an important task. Selection of turbulent flow model has a noticeable impact on prediction of flow characteristics. The gas dynamic analysis of the nozzle with water-cooled extension showed the importance of using the turbulent flow model k-ω SST for the flows with internal separation of boundary layer and with flow separation at nozzle section. The use the flow model k-ω SST for calculation of nozzle with flow separation or with internal transitional layer allows adequately describing the flow pattern, though, as the comparison with experimental data showed, this model predicts later flow separation from the wall than that obtained in the tests. The calculation allows obtaining a temperature profile of the wall and providing the recommendations for selection of pressure measurement place in the nozzle extension for the purpose of reducing sensors indication error. With consideration for the special nature of the nozzle extension wall temperature field, the cooling mode was selected. The tests of RD861K engine nozzle with water-cooled extension allow speaking about its successful use as a required element for testing engine start and operation in ground conditions without additional test bench equipment.

Annotation: This article considers the practical data on parts (specimens) manufacturing from powder metal material 316L using the innovative method of selective laser melting; the comparative study of the structure and physical and mechanical properties of 316L material, the combined influence of heat treatment and specimen orientation relative to the arrangement plate on the physical and mechanical properties and structure of specimens made of 316L alloy. Results are presented of the following: comparative study of the physical and mechanical properties and structure of specimens, manufactured using the selective laser melting technologies with horizontal and vertical placement relative to the arrangement plate; dependence of the ultimate strength and unit elongation on the annealing temperature. The possibility and suitability of the selective laser melting technology to manufacture parts and space-rocket hardware are evaluated. Experimental study of the specimens heat treatment conditions after selective laser melting enabled the definition of the optimal condition for the 316L alloy and have shown that heat treatment of the manufactured specimens under the heating at 1230 °С with the subsequent tempering at the temperature of 510 °С gives the homogeneous structure to the material of specimens made of alloy 316L, its dendritic structure, inherent in the specimen material in its initial condition, disappears after selective laser melting. Results of the mechanical tests of the obtained specimens have shown that the technology of selective laser melting provides development of products made of powder metal material 316L with optimal complex of physical and mechanical properties. It is shown that transition to the selective laser melting technology will enable production of the aerospace products, in particular geometrically-complex parts made of powder metal material 316L, in one technological cycle, excluding cutting, punching, refinement, cropping, welding, manufacturing of special tools or stamps