NUMERICAL DETERMINATION OF ACOUSTIC SPACE OSCILLATING GAS PARAMETERS IN CHAMBER OF A LIQUID FUEL POWER PLANT

Abstract

Modern space liquid launch vehicles that launch payload into orbit with lower environmental impact require the use of inexpensive, safe, and reliable propulsion systems. To meet these criteria as much as possible, the design of modern rocket engines is based on the use of advanced elements, materials, and technologies. To study the combustion chamber's dynamic instability, mathematical modeling of unsteady gas flow in the experimental power plant chamber for liquid fuel manufactured using additive technologies was performed. To compare the approaches, two-dimensional axisymmetric and three-dimensional non-symmetric flow problems were considered. The main aim of the article is the numerical study and comparative analysis of the nature of the combustion product flow and the spatial acoustic gas oscillation parameters in the liquid fuel power plant chamber manufactured using additive technologies. The numerical analysis of the combustion products flow parameters in the power plant chamber was performed using ANSYS Fluent finite element analysis and the LES – Large Eddy Simulation turbulence models and k-ε turbulence models. Based on the numerical study results of the power plant combustion chamber dynamics, it was determined that the combustion products' turbulent motion along the walls of the cylindrical chamber occurs with the formation of vortices that collapse periodically during the gas flow motion from the injector face to the throat section. Numerical results analysis indicates that the self-excited oscillation dynamic process develops in the power plant chamber, during which the combustion products pressure amplitude in the chamber can reach 2 bar – 3 bar (i.e., 10% – 15% of the static pressure). The numerical modeling results using the LES turbulence model demonstrated high convergence with the combustion chamber fire test data in terms of dominant frequency and amplitude characteristics. The verified model reproduces the asymmetric nature of self-excited oscillation combustion products and the associated vortex flow structure. The implementation of the proposed approach will allow for the optimization of power feed system design and significantly reduce the time required for full-scale development of modern engines.