Combustion characteristics of swirl coaxial injectors at kerosene-rich conditions

Static and dynamic characteristics of fuel-rich combustion burning Jet A-1 and liquid oxygen have been experimentally studied in the present study. The combustion chamber pressures were varied up to 6.9 MPa with mixture ratios ranging from 0.25 to 0.36. Liquid fuel and oxygen are atomized using bi-liquid swirl coaxial injectors. Flow discharging through the injectors under combustion environment is hindered by flame anchoring at the exit of the oxidizer injector and it can be improved by the increase of the axial momentum of the oxygen flow. The space formed between the fuel and the oxidizer flows significantly affects flow discharging and dynamic characteristics of fuel-rich combustion. At the chamber pressures less than the critical pressure of oxygen, pressure waves at a frequency of 150 Hz are excited and their phases are identical in the combustion chamber. Their excitation is triggered by the inherent low-frequency pulsation of the oxidizer swirl injector with the contraction chamber and eventually, a pressure wave coupled to the Helmholtz mode of the combustion chamber becomes sustaining.