MATHEMATICAL MODELING OF COMPLEX DYNAMIC PROCESSES DURING LIQUID-PROPELLANT ROCKET ENGINES START-UP

Abstract

A number of complex physical processes and phenomena occurring during the start-up of liquid-propellant rocket engines (LPREs) are considered. The characteristics of cavitating flows in LPRE pumps are determined using an experimental–computational approach, and a mathematical model of cavitating pumps is developed. For mathematical modeling of the delay in propellant gasification and the residence time of combustion products in LPRE gas paths, an approximate replacement of delay-differential equations in the dynamic model of gas paths by ordinary differential equations is employed. To describe wave processes in extended branched hydraulic lines of multi-engine systems, an approach based on the impedance method is used, which involves matching the frequency characteristics of hydraulic lines represented as distributed- and lumped-parameter systems. For a reconfigurable hydraulic system, several configurations corresponding to different stages of its operation are considered. In this regard, a mathematical model of dynamic processes in a check valve is developed, and its verification is performed using CFD simulation results of pressure distribution over the valve poppet surface. Mathematical modeling of LPRE start-up using the developed models makes it possible to refine the characteristics of the transient processes during engine start-up.