Simulation investigation on flow and combustion characteristics in a high temperature rise combustor based on RQL under different primary holes spacing

In order to achieve the good unification of combustion performance and low emission of high temperature rise combustor, RQL technology was applied to the design of high temperature rise combustor in this paper. Three-dimensional physical models of combustor were set up by referring to the structure and size of experimental model, and the influence of primary holes spacing on the flow and combustion characteristics were studied by using simulation under the conditions of room temperature and atmospheric pressure. The simulation results show that with the increase of primary holes spacing, the angle of primary jets gradually inclines to the upstream, and the vortex centers of local recirculation in rich zone approach to the primary jets. Meanwhile, the number of local recirculation zones in the quench zone also varies with the primary holes spacing. The optimum design of primary holes spacing not only improves the mixing effectiveness of airflow in the quench zone, but also enhances the combustion in rich zone. The optimum holes spacing is related to the combustor height and the momentum flux ratio of primary jets to mainstream. In addition, under the optimum structure of primary holes spacing (Case-3 model), the range of local hot spots at outlet was smallest, the combustion efficiency and the emission index of NO at the equilibrium of kinetic rate of chemical reaction were about 0.06% higher and 12% lower than the other two models, but the formation of soot and CO along the rich zone were slightly higher.