Combustor for a gas turbine engine

Claim 1

A combustor in a gas turbine engine of the type including a reverse flow annular combustor, the combustor having an inner cylindrical wall, an outer wall concentric with the inner wall about a combustor axis, and an annular dome connecting the inner wall and outer wall, the outer wall having a first cylindrical wall portion adjacent the dome and having a predetermined diameter, a second outer wall portion adjacent the first wall portion and remote from the dome, the second wall portion terminating in a third wall portion of cylindrical shape and of reduced diameter compared to the diameter of the first wall portion such that the second outer wall portion is frusto-conical; the dome, first and second outer wall portions define the primary combustion zone, and the third outer wall portion defines the secondary zone, the engine including a casing surrounding the reverse flow combustor and defining an annular air passage for compressor delivered air with the outer wall of the combustor; fuel injector means disposed on the second wall portion, and directed towards the dome, compressor delivered air intake means adjacent said fuel injector means, the cross-sectional area of the annular air passage at the first wall portion being less than the cross-sectional area of the annular passage at said third wall portion thereby creating a pressure head such that compressor delivered air is directly injected into the primary zone with the fuel by virtue of intake means being provided adjacent the fuel injector means.