a combustor system for a miniature gas turbine engine includes fuel injection via orifices which direct fuel into fuel - air injection tubes which feed a fuel - rich mixture of fuel and air into a leading end of the combustor liner to form a primary burning region . fuel system pressures are kept low and controlled by control of the fuel injection port size and number . fuel breakup is via airblast and tube wall impingement . the fuel - air injection tubes are directed circumferentially , radially outward and toward the front end of the combustor . air is fed into the combustor such that two distinct burning regions are created . each region approximates a “ well - stirred reactor ” and the combination of the two regions results in an efficient use of combustion volume .