Combustion chamber for gas turbine engines

Claim 1

In a combustion chamber for gas turbine engines, including an outer housing; at least one flame tube inserted in said housing so as to form an annulus between the outer housing and the flame tube; means for supplying secondary air into said annulus; and means for supplying a primary zone inside the flame tube with fuel-enriched combustion air; an improvement comprising: a. two independent fuel atomizer nozzles with respective mutually independently controllable fuel supplies in axial series arrangement within said flame tube so that combustion takes place entirely initially in a fuel-enriched combustion zone and thereafter in a second main combustion zone provided with a leaner amount of fuel in that sequence within the flame tube; b. an air infeed hood encompassing said fuel atomizer nozzles and the upstream end of said flame tube so as to form a combustion air passageway between said hood and the flame tube, said passageway communicating with the first and second combustion zones respectively through first helical apertures and second further apertures formed in said flame tube; c. said air infeed hood having a conically widening section, the fuel spray cone of the first of said two fuel atomizer nozzles extending within said combustion air passageway approximately parallel with said conically widening section of the air infeed hood, the spray cone of the second atomizer nozzle extending approximately parallel to the inner wall of a section of said flame tube which conically widens from the second atomizer nozzle so as to form the required space in the flame tube for the first combustion zone preceding the second main combustion zone, a cylindrical sleeve surrounding said second nozzle and connected to said conically widening section of the air infeed hood; d. said conically widening section of said air infeed hood having a smaller cone angle than said section of the flame tube such that said passageway narrows in a direction away from said second atomizer nozzle; e. said conical section of said air infeed hood having an end remote from said second atomizer and including a cylindrical portion extending from said end coaxially with said combustion zones and a radial portion on said cylindrical portion extending into said further apertures in said flame tube to divide these apertures into a first part communicating with the combustion air passageway between the flame tube and said hood and a second part communicating with the annulus between the flame tube and the housing such that secondary combustion products in said combustion air passageway which have passed said helical apertures are constrained to pass through said first part of said further apertures into said second combustion zone, while secondary air flowing in said annulus passes through said second part of said further apertures into said flame tube, said flame tube including a radial enlargement at the end of the conically widening section of the flame tube remote from the second atomizer nozzle.