Cavity staging in a combustor

A gas turbine engine combustor assembly comprising:

• a combustor downstream of a compressor, the combustor disposed axially about a central axis and including a combustor liner having defined therein a combustion chamber for the downstream flow of a main fluid;
• an annular trapped vortex cavity located at an upstream end of the combustor liner and defined between an annular aft wall, an annular forward wall, and a circular radially outer wall formed therebetween, the annular trapped vortex cavity including a cavity opening at a radially inner end of the cavity spaced apart from the circular radially outer wall and extending between the annular aft wall and the annular forward wall;
• at least one additional trapped vortex cavity located on the combustor liner and spaced axially downstream from the upstream annular trapped vortex cavity, the at least one additional trapped vortex cavity defined between an annular aft wall, an annular forward wall, and a circular radially outer wall formed therebetween, the at least one additional annular trapped vortex cavity including a cavity opening at a radially inner end of the cavity spaced apart from the radially outer wall and extending between the annular aft wall and the annular forward wall;
• a plurality of fuel injectors and a plurality of air injectors disposed in the circular radially outer wall of one or more of the annular trapped vortex cavities, the plurality of fuel injectors and a plurality of air injectors configured tangentially relative to the circular radially outer wall to provide for an injection of air and fuel to form an annular rotating trapped vortex of a fuel and air mixture within a respective annular trapped vortex cavity, and
• wherein the annular rotating trapped vortex of the fuel and air mixture at the cavity openings of the annular trapped vortex cavities is substantially perpendicular to the downstream flow of the main fluid.

A gas turbine engine comprising:

• a compressor section;
• a combustor section;
• a turbine section, wherein the compressor section, the combustor section and the turbine section are configured in a downstream axial flow relationship about a central axis, the combustor section comprising a combustor assembly comprising:
• a combustor including a combustor liner having defined therein a combustion chamber for the downstream flow of a main fluid;
• at least two annular trapped vortex cavities located on the combustor liner and staged axially spaced apart, each of the at least two annular trapped vortex cavities defined between an annular aft wall, an annular forward wall, and a circular radially outer wall formed therebetween;
• a cavity opening at a radially inner end of each of the at least two annular trapped vortex cavities spaced apart from the radially outer wall and extending between the aft wall and the forward wall;
• a plurality of fuel injectors and a plurality of air injectors disposed in the radially outer wall of one or more of the at least two annular trapped vortex cavities, the plurality of fuel and air injectors configured tangentially relative to the circular radially outer wall to provide for an injection of air and fuel to form an annular rotating trapped vortex of a fuel and air mixture within a respective annular trapped vortex cavity, and
• wherein the annular rotating trapped vortex of the fuel and air mixture at the cavity opening of each of the at least two annular trapped vortex cavities is substantially perpendicular to the downstream flow of the main fluid.