Abstract: A gas-turbine engine combustion system has a combustor with a burner head having both pilot gas and pilot liquid-fuel injection arrangements, the pilot gas arrangement comprising an annular gallery communicating with a downstream face of the head and a deflecting arrangement adjacent the gallery for directing the pilot gas-fuel towards a longitudinal axis of the combustor and over a central part of the downstream face. The combustion system is designed so that, during both gas- and liquid-fuel operations, the flame front face is located close to the burner head and, during liquid-fuel operation, air is forced across the downstream face to cool the head. Advantageously, the cooling air is made to replace the pilot gas-fuel in the annular gallery, so that it is deflected, like the gas-fuel, and contacts the central part of the downstream face. The burner head also features main gas and liquid-fuel injection arrangements, these communicating with one or more passageways in a radial swirler attached to the head.

Abstract: The arrangement comprises a swirler for producing at least one air stream for mixing with a supply of fuel but wherein the supply of fuel is initially injected into at least one zone adjacent a respective air stream but shielded (by 26) therefrom whereby fuel-rich pockets of fluid are formed in the zone(s). The pockets ensure flame stability at least at lower power settings. The zone is defined by a wall of the swirler. The fuel is injected through nozzles. Additional nozzles for supplementary supply of fuel may be provided in a block. A plate is arranged between the block and the swirler.

Abstract: A method for effecting combustion of carbonaceous fuel is operative to sustain the combustion at a predetermined rate or rates of total fuel demand, the fuel being distributed between two combustion stages to make up the required total feed rate. Thus one portion, usually about 20-70 percent, of the total fuel is fed to a thermal combustion stage. Sufficient air is supplied simultaneously to the thermal combustion stage, preferably about 125 to 185 percent of the stoichiometric amount of air, to effect substantially complete combustion of that portion of the fuel and produce a heated effluent. An additional amount of relatively cool air is mixed with this effluent, and the resulting cooled mixture continues through the mixing zone, the additional air being sufficient to inhibit preburning of the remaining portion of the fuel which is added downstream in the mixing zone.