Analysis of the possibility of improving rocket engine nozzles

Abstract

It is possible to significantly increase the impulse characteristics of the rocket engine due to the use of effective nozzles in which the flow of atmospheric air optimizes the jet. The purpose of the work is to analyze the characteristics of slotted nozzles, nozzles with ground and height contours, nozzles with a central body, nozzle blocks with nozzles covered by a common nozzle; research on ways to adjust the height of the nozzle; development of practical recommendations for the design of effective nozzles. The work uses the method of expert evaluations, the calculation and analytical method, and the method of retrospective analysis. Slotted nozzles with a high degree of expansion are able to significantly increase the value of the average thrust impulse of the rocket engine. When a rocket is launched from the Earth's surface, the separation of the gas flow occurs at the edge of the annular gap, i.e. earlier than in its absence. Therefore, part of the overexpanded flow zone disappears, and the nozzle momentum in the starting conditions increases. As a result of the ejection, air from the environment is added to the jet, which increases the thrust of the engine. However, slotted high-altitude nozzles with a smooth contour are impractical to use on the first stages of rockets due to the increased level of thrust losses due to flow dispersion. A significant reduction in the linear dimensions of the engine becomes possible when the annular cylindrical combustion chamber is placed inside the nozzle. Combustion products in such a chamber move from the mixing head in the direction of the slotted critical section, turn 180 degrees and flow out through the dish-shaped supersonic nozzle. A nozzle with a central body forms a jet that converges to the axis of symmetry, as a result of which a compact gas torch is formed. Self-adjustment of the nozzle with external expansion, that is, the calculated operating mode of the nozzle in a wide range of heights, is ensured by the presence of a free outer boundary of the jet stream. New variants of nozzle block schemes with an integral nozzle are considered.