Numerical study of the impact of operating modes and design parameters of a low-thrust thermocatalytic liquid-propellant rocket engine on its thermal state during operation

Аuthors

Tsyrendorzhiev E. S.

State Scientific Center of the Russian Federation “Keldysh Research Center”, Moscow, Russia

e-mail: tsyrendorzhiev.es@gmail.com

Abstract

The study presents a numerical investigation of thermal processes occurring in the combustion chamber of a low-thrust liquid-propellant thermocatalytic rocket engine. The research focuses on understanding how various operational and design parameters influence heat accumulation and distribution within the porous catalyst bed which plays a critical role in the efficiency and reliability of such propulsion systems.

A detailed physical mathematical model of unsteady filtration combustion using Representative Elementary Volume approach was employed. The model accounts for both homogeneous and heterogeneous chemical reactions, as well as heat and mass transfer phenomena between internal and surface gas phases, and the porous matrix. The simulations were performed using the OpenFOAM computational platform leveraging the finite volume method and PISO/SIMPLE algorithms for pressure-velocity coupling and transient flow resolution.

Numerical experiments demonstrate that increasing the initial temperature of the porous catalyst bed reduces the rate of the thermal energy accumulation and limits peak temperature due to proximity to adiabatic temperature of the monofuel decomposition. The relationship between propellant mass flow rate and accumulated energy is found to be nonlinear: exceeding a critical threshold additional increases in flow rate yield diminishing returns due to convective heat losses and limited heat transfer efficiency in the reaction zone. Variation in bed porosity reveals an optimal range where both decomposition efficiency and heat retention are maximized. Lower porosity enhances reaction intensity but reduces the medium’s ability to retain heat, whereas higher porosity improves heat storage but can lead to inefficient decomposition. The study also explores the effect of fuel injection schedules. Results indicate that pulsed operation leads to strong thermo-cycling loading of the catalyst bed, potentially accelerating material degradation and reduce operational lifespan.

The results provide valuable insight into the thermal behaviour of a low-thrust liquid-propellant thermocatalytic rocket engines under variable operating conditions. They provide a foundation of the optimization of the engine geometry, designing efficient propellant supply strategies and development of adaptive control algorithms that enhance thermal stability, operational reliability and catalyst longevity under cyclic or continuous operation.

Keywords:

low-thrust liquid rocket engine, model of the thermal regime of a rocket engine, filtration combustion, computer simulation, coupled heat exchange

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