Summary: The work sets up the problem of gaseous fuel combustion in a ground-based gas turbine engine combustion chamber and presents the results of a numerical study. It is assumed that the gas-air mixture is a single-phase multicomponent reactive flow. The Reynolds averaged Navier-Stokes equations were used to describe the turbulent flow in the combustion chamber. The SST turbulence model was used to close the averaged system. A combined EDM/FRC combustion model was used to determine the formation rate of mixture components. Based on comparing the results of preliminary calculations and experiments, it was suggested that the difference in obtained data is due to manufacturing tolerance and the heat-protective coating on the walls of the flame tube. In order to confirm this suggestion, the geometry of the computational domain was changed based on the air flow rate obtained in the aerodynamic tests. Then the parameters of the mathematical model were adjusted both on the initial and on the refined geometry. A technique was proposed for adjusting the mathematical model taking into account three parameters: the turbulent Prandtl and Schmidt numbers and the coefficient limiting the burning rate. The mathematical model was verified by results of experiments on three design versions of the flame tube. The results of calculations using refined data showed that a change in geometry made it possible to more correctly describe combustion in a turbulent flow: the results on average nonuniformity of the temperature field nearly coincide with the experimental data. By adjusting the geometry of the computational domain, it was possible to establish the location and magnitude of the maximum nonuniformity of temperature. The developed adjusted mathematical model for describing the combustion of gaseous fuel in the combustion chamber of a gas turbine engine is suitable for further optimization of the combustion chamber design.