Fuel Injection and Flame Stabilization in a Liquid-Kerosene-Fueled Supersonic Combustor

Investigations on combustion enhancement and stabilization of liquid kerosene using five different integrated fuel-injection/cavity-based flameholder configurations were conducted in a model combustor of cross sections 51 x 70 mm. The entry Mach number was fixed at 2.5, whereas the ranges of total pressure and stagnation temperature varied were 1.0-1.3 MPa and 1700-1900 K, respectively. Pure liquid atomization and barbotaged atomization with either air or hydrogen were compared based on spray-structure visualization and combustion-performance assessment. The effects of kerosene injection angle and cavity configuration on both flame holding and mixing enhancement were also investigated. Experimental results showed that the average increase in combustion efficiency using hydrogen barbotage is 15 to about 20 percent as compared to the use of pure liquid atomization, for the conditions investigated. Cavity configuration with combined open-closed cavities was demonstrated to have better combustion performance than the single-cavity module. It was also shown that kerosene injection location and injection scheme have strong effects on the minimally required pilot hydrogen equivalence ratio. The present results further substantiate our previous finding that there existed a local high-temperature region, which would be the major factor in promoting the ignition and the subsequent flame holding of the kerosene combustion. (Author)