On the numerical simulation of thermal decomposition of hydrocarbon mixtures in channels of cooling systems of high-speed vehicles. Optimization of the fuel composition

A mathematical model of physical and chemical processes in a turbulent flow of mixtures of alkanes with the number of carbon atoms 0 < C < 9 in heated channels has been developed. The Navier-Stokes equations were used to describe the turbulent transfer, and a detailed kinetic mechanism served to describe the thermal decomposition of hydrocarbons. A detailed description of the developed model and the results of its verification based on experimental data is given. In the present paper, the model is used to numerically study the conjugate heat transfer in a plane heated channel of the cooling system of advanced ramjet aircraft engines on endothermic hydrocarbon fuels. A two-criterion optimization of the initial composition of endothermic hydrocarbon fuel was performed to obtain the maximum endothermic effect and energy content of the resulting hydrocarbon fuel mixture, further fed into the combustion chamber of the engine. The limitations in the optimization are the maximum permissible temperature of the heated channel walls (the condition of thermal resistance of the structure) and the maximum acceptable degree of decomposition of the hydrocarbon mixture, in excess of which the intensive formation of solid deposits begins on the washed channel walls.