Features of the development of acoustic oscillations in the combustion product flow in power plant chambers when using propellant components derived from lunar regolith

Working processes in combustion chambers of various power plants (thermal power and marine plants, aircraft and rocket engines) are traditionally improved along a number of lines. Ensuring the thermoacoustic stability of power plants in their operating modes is one of the most important conditions for the efficient functioning of the combustion chamber. In situ Lunar Resource Utilization (ISLRU) is a technology that allows one to significantly accelerate space exploration. The expected increase in lunar exploration activity in the near future rises interest in in situ lunar resources (ISRU), especially those that can be used in the production of propellant components on the lunar surface, such as magnesium (Mg) and aluminum (Al), which are abundant in lunar regolith. The main focus is on the fundamental feasibility of these projects and the reliability of using these metals as the main propellant types in rocket propulsion systems (based on a solid or a hybrid propellant) specially designed for the implementation of lunar missions. However, significant gaps still exist in understanding how these metals will be extracted from regolith and integrated into the propellant section of the combustion chamber and what thermodynamic and other characteristics of the combustion products will be, given the poor mixing and incomplete combustion of this type of propellant. The most critical operating conditions of solid-propellant rocket propulsion systems are often due to the development of dangerous dynamic processes characterized by excess values of operational parameters. The use of a propellant from lunar regolith may result in pressure surges and a sharp increase in the local temperature of the combustion products, which may result in a structural failure of the combustion chamber and a critical behavior of the propulsion system, to the point of combustion termination. This paper presents the numerically found thermodynamic characteristics of a propulsion system that uses a metallized propellant close in characteristics to substances obtained from lunar regolith and the results of a preliminary analysis of experimental and calculated parameters of acoustic oscillations (thrust, dynamic pressure components, and axial velocity) and shows the development of vortex formation in the combustion product flow.