Research on Cold Flow Mixing Characteristics of Kerosene Pyrolysis Gas in Rotating Detonation Combustor

Abstract

In order to study the cold flow mixing characteristics of kerosene pyrolysis gas in the rotating detonation combustor,the injection and mixing process of kerosene pyrolysis gas in the small hole-annular slot injection structure was studied by two-dimensional large eddy simulation using OpenFOAM. According to the numerical simulation results, the flow field structure of the cold flow field in the combustor and the location of the area which is capable of detonation were systematically described. The effects of different injection pressure (keeping the equivalence ratio unchanged), different injection position and injection angle of pyrolysis gas on the mixing effect were compared and analyzed. The mixing degree of pyrolysis gas and air is quantitatively evaluated by the mixing non-uniformity. The results show that the entrainment of large scale turbulent vortex structure caused by Kelvin-Helmholtz(K-H)instability is the main mechanism for the mixing of kerosene pyrolysis gas and air. The upper and lower limits of one-dimensional detonation equivalence ratio of kerosene pyrolysis gas/ air calculated by the finite rate model and one-step chemical reaction mechanism are 2.9 and 0.4 respectively. When the injection temperature of air and pyrolysis gas are 300 K and 720 K respectively,the mixing effect decreases with the increase of injection pressure. The injection position of pyrolysis gas is far away from the inlet of combustor,the mixing effect is improved. The injection angle of pyrolysis gas and air changes from the same direction to the opposite direction,the mixing effect is improved.