Inyoung Yang , Kyungjae Lee , Sanghun Lee, Yangji Lee
DOI Number XXX-YYY-ZZZ
Conference Number HiSST 2018-0983
In this research, the ignition characteristics of the liquid kerosene in a model supersonic combustor was explored with the assist of atomization, pilot gaseous hydrogen, and fuel heating. The supersonic combustor model contains two fuel injector sets, each of the sets consists of one main liquid hydrocarbon injector and one pilot gaseous hydrogen injector. A simple orifice-type injector or a gasblast-type injector was used as the main injector. For the gas-blast-type injector, the gaseous hydrogen is supplied and mixed with the main liquid fuel in a small chamber in the injector, acting as the atomization assist. The hydrogen also becomes the ignition source in this case. For the orifice-type injector, there is no atomization assist besides the main transverse supersonic airflow. A simple orificetype is used for the pilot injector. A regenerative heat exchanger was installed on the combustor model optionally. The purpose of the heat exchanger was to heat up the main kerosene fuel before it was provided through the injectors. The tests were performed in a continuous-type, direct-connected combustor test facility. The air flow speed at the inlet of the model was Mach 2.0, the air total temperature was 1,100 K, and the air total pressure was 500 kPa(abs). Test variables were the different atomization/piloting scheme as described above, as well as the flow rate of the main and the pilot fuel and the main fuel temperature. The orifice-type injector couldn’t provide enough level of atomization for the ignition and flame holding of the main liquid fuel under the supersonic flow condition. The gasassist-type, in contrast, was able to maintain supersonic combustion when assisted by hydrogen. In either case of using the hydrogen as the atomizing gas or pilot fuel, the ignition and flame holding was possible, provided that the hydrogen flow rate was equal to or more than 0.8 g/s. For the main fuel injectors of larger injection holes, the ignition was marginal even with the hydrogen flow rate over 0.8 g/s. In this case, main fuel heating was helpful for the ignition, even though the temperature was still below the boiling temperature.