Mode transition of fuel control test in a dual-mode combustor

Abstract

Ignition combustion test in dual-mode combustor with fuel flow rate change was carried out in a direct-connected wind tunnel facility that supplied airflow with total temperature of 880K, total pressure of 8atm and Mach number of 2.0. According to the wall pressure of combustor measured through the test, the distribution of other airflow parameters in the combustor was obtained by calculating with a one-dimensional analysis method, and the mode transition process in the condition of fuel flow rate change was studied. In addition, the position that the airflow in the isolator accessed to the subsonic velocity and the location of “choked thermal throat” at the combustor downstream were determined by analyzing of pressure distribution in the combustor. The results indicated that sole hydrogen combustion brought a supersonic combustion mode, then combined combustion of hydrogen and kerosene induced a subsonic combustion mode and combustion-induced pressure disturbance had been spread to the entrance to the combustor. In cases of sole kerosene combustion and the fuel equivalence ratio being kept at 0.53 and 0.61 respectively, both were in the subsonic combustion mode. Gradual increment of the fuel equivalence ratio was accompanied by enlarging subsonic combustion area. In case of combined combustion of hydrogen and kerosene, and improving kerosene flow rate, supersonic combustion mode was transformed to a subsonic one in a gradual manner.