Patent ID: 8099960

Claim:
A fuel-air mixer, comprising: an annular shroud having a circular cross section defined by a wall, the annular shroud having an axial axis extending along an axial direction, a radial axis extending along a radial direction, and upstream and downstream end portions; a first swirler disposed at the upstream end portion of the annular shroud; a second swirler disposed at the upstream end portion of the annular shroud outwardly from the first swirler in the radial direction; a hub separating the first and second swirlers, the hub being configured to allow independent rotation of first and a second portions of a first gas stream entering the annular shroud at the upstream end portion thereof, the first and second portions of the first gas stream being rotated by the first and second swirlers, respectively, in which the hub is further configured such that the first and second portions of the first gas stream accumulate at a region adjacent a wall of the annular shroud; a center body extending along the axial axis of the annular shroud; a fuel shroud disposed at the upstream end portion of the annular shroud outwardly from the second swirler in the radial direction and circumferentially around the annular shroud, the fuel shroud being configured to inject a fuel into the annular shroud to be mixed with the first and second portions of the first gas stream and a second gas stream upstream of a combustion chamber; and a third radial swirler is disposed downstream of the first and second swirlers, the third swirler having an axial and radial gap adjacent the wall of the annular shroud and being configured to introduce the second gas stream from a region outside the wall of the annular shroud to the first and second portions of the first gas stream to allow an independent rotation of the first and second gas stream and the fuel from the fuel shroud wherein the second gas stream enters the annular shroud at a region adjacent and within the wall of the annular shroud.