Patent ID: 6772595
Filing Date: 2004-08-10
Classification: F23R

Abstract:
An improved low emission (NOx) combustor for use with gas turbine engine comprising:a liner having a first generally annular wall and including a premix chamber for mixing fuel and air and a combustion chamber for combusting said fuel and air, said premix chamber in communication with said combustion chamber, said first generally annular wall having at least one first aperture and at least one second aperture, said second aperture being radially outward of said premix chamber; a venturi having a second generally annular wall that includes a first converging wall and a first diverging wall, said first converging wall abutting said first diverging wall at a first plane, said first plane generally perpendicular to said first generally annular wall, said venturi further containing a throat portion at said first plane, said throat portion being positioned between said premix chamber and said combustion chamber, said second generally annular wall being radially inward from said first generally annular wall and having an aft end adjacent said at least one first aperture, said venturi having a third generally annular wall being radially outward of said second generally annular wall and radially inward of said first generally annular wall, said third generally annular wall including a second converging wall and a second diverging wall, said second converging wall connected to said second diverging wall at a first region of curvature proximate said first plane and having a first radius R1, said second convergent wall having a first convergent member and a second convergent member, said second diverging wall having a first divergent member and a second divergent member, wherein said second convergent member and said second divergent member are located adjacent said first region of curvature, said first divergent member oriented at an angle &agr;1 relative to said first plane, said second divergent member oriented at an angle &agr;2 relative to said first plane, said first convergent member oriented at an angle &agr;3 relative to said first plane, and said second convergent member oriented at an angle &agr;4 relative to said first plane, wherein &agr;21 and &agr;43, thereby forming a first region of reduced cross sectional area A1 between said first diverging wall and said second divergent member and a second region of reduced cross sectional area A2 between said first converging wall and said second convergent member; a passageway for flowing cooling air through said venturi, said passageway extending from said at least one first aperture to said at least one second aperture, said passageway including a first portion radially inward from said third generally annular wall and radially outward from said second generally annular wail, and said passageway including a second portion radially outward from said first portion of said passageway, said second portion extending from said passageway first portion to said at least one second aperture, and said first aperture being radially outward from said first portion, and said first portion of said passageway having a second region of curvature with radius R2 proximate said throat; a plurality of raised ridges fixed to said second generally annular wall extending into said first portion of said passageway; and, a blocking ring extending from said aft end of said second generally annular wall to said first generally annular wall in sealing contact therewith, said blocking ring preventing cooling air that is in said first portion of said passageway from flowing directly into said combustion chamber without flowing through said second portion of said passageway; wherein said passageway is in fluid communication with said at least one first aperture and said at least one second aperture, said passageway communicates with said premix chamber through said at least one second aperture, and cooling air, after being heated by cooling said venturi, exits from said passageway into the premix chamber thereby increasing the efficiency of the combustion process and reducing NOx emissions.