Stabilization of combustion of kerosene-air mixture by hydrogen injection

Abstract

On aircrafts at high flight speeds, the ramjet engine (ramjet) is of greatest interest at present, the efficiency of which can be increased by using the thermochemical fuel conversion (TFC) technology. Some aspects of the operation of such an engine can be simulated numerically. In this work, a theoretical and experimental study of the processes in the combustion chamber is carried out, and a method is proposed for stabilizing the combustion of a kerosene-air mixture by injecting molecular hydrogen into a direct-flow combustion chamber. An experimental setup created at TsAGI was used, on which the influence of the hydrogen temperature, the location and size of the mass supply area on the combustion process was studied. For a theoretical study, the corresponding numerical technology was applied based on the Navier-Stokes equations using the Spal-rt-Allmares turbulence model, implemented in a complex of computer programs developed at the Research Institute of Mechanics of Moscow State University. Numerical modeling solved two problems. The first concerned the conditions for the ignition of molecular hydrogen supplied to the flow-type igniter, and the second - the conditions for the stabilization of the combustion of a kerosene-air mixture by a hydrogen flame. Based on the results of calculations, it was found that the ignition process is facilitated by an increase in the temperature of hydrogen and the power of its injection. The position and size of the hydrogen source is less influential. In the course of a comprehensive study by the method of a full-scale and computational experiment, the characteristic features of the flow structure in the channel, including the formation of a detonation wave, were revealed, and the possibility of controlling combustion by hydrogen injection was shown.