Sundstrand Corporation

Steven A Sachrison

Jack R Shekleton

Michael W Sledd

In order to achieve ignition at altitude, particularly in relatively small combustors (10) with low fuel flow rates, a fuel injection system (20) includes an air nozzle (26), a fuel nozzle (28), and an air assist tube (34). The fuel nozzle (28) is disposed in a manner so as to direct fuel through the air nozzle (26) and includes a fuel metering orifice (30) or capillary tube (32) to control fuel flow therethrough. The air assist tube (34) is integrally associated with the fuel nozzle (28) downstream of the fuel metering orifice (30) or capillary tube (32) to accelerate fuel flowing through the fuel nozzle (28). With this arrangement, the air nozzle (26) may comprise an opening in a combustor wall (14) defining a combustion chamber (12) of a turbine engine combustor (10) wherein a combustor case (16) surrounds the combustor wall (14) to define an air flow path 18 in communication with a compressed air source whereby compressed air flows through the opening (26) and into the combustor (10) along with fuel from the fuel nozzle (28) and air from the air assist tube (34).

Air assist fuel injection system

Difficulties in achieving reliable starts in gas turbine engines operating at high altitude are avoided in a gas turbine engine including a rotary compressor (10), a rotary turbine wheel (12) coupled to the compressor (10) to drive the same, and a nozzle (42) for directing gases of combustion against the turbine wheel (12). An annular combustor (34) has an outlet (40) connected to the nozzle (42) and an opposed dome (38) that is axially spaced from the outlet (40). At least three sets of air injection openings (80, 92, 100) are axially spaced from one another with one set (82) in close proximity to the dome (38). Fuel injectors (86, 94) are associated with two of the sets (80, 92, 100), including the one set (80) and another of the sets (92) that is nearest the one set (80). The air injection openings of the sets (80 and 92) and the fuel injectors (86, 94) are constructed, arranged and sized so that the air/fuel ratio of air injected by each of the sets (80, 92) is no more than about 5/1 and the remaining set of air injection openings (100) is constructed, arranged and sized so that the total air/fuel ratio of air and fuel through all of the sets (80, 92, 100) and fuel injectors (86, 94) is approximately stoichiometric.

High altitude starting two-stage fuel injection apparatus

High altitude starting two-stage fuel injection

The problems of carbon build-up, poor fuel atomization, and fuel leakage in fuel injectors for turbine engines may be avoided if the fuel injector is fabricated by a method including the steps of: (a) providing a barrel (26) having an outlet end (44) adapted to be disposed in a turbine engine combustor (10), an inlet (46) adapted to be in fluid communication with the compressor of a turbine engine, an internal passage (40) extending between the inlet (46) and the outlet end (44) and a constriction (48) in the internal passage (40) between the inlet (46) and the outlet end (44) to define at least a partial venturi, (b) disposing a fuel tube (52) having a fuel injection end (54) within the internal passage (44), and (c) locating the fuel injector end (54) with respect to the constriction (48) at a position such that maximum fuel suction pressure is attained with a minimum reduction in air mass flow rate during operation of the injector.

Method of fabricating a fuel injector

Improved fuel atomization for turbine engines operating at low fuel flows and at high altitudes is accomplished in an engine 10 having an annular combustor 12 by utilizing fuel injectors 18 provided with fuel supply tubes 24 disposed within air tubes 20 wherein the fuel supply tubes 24 each have an exit orifice 26 internally of the corresponding air tube 20 and upstream of an exit orifice 22 thereof with a fuel impingement surface 28 being provided within the air tube 20 in confronting relation to the exit orifice 26 of the fuel supply tube 24 to produce a conical fuel film 36 subjected to pressurized air to enhance fuel atomization.

Turbine engine with pin injector

Improved fuel atomization for turbine engines operating at low fuel flows and at high altitudes is accomplished in an engine having an annular combustor 26 by utilizing start fuel injectors 46 provided with discharge orifices 56 and planar impingement surfaces 60 within the path of fuel discharged from the orifices 56 to provide flat sprays 62 that are generally tangential to the annular combustor 26 so as to be intercepted by an igniter 70 in a radial wall 34 of the combustor 26.

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LaJolla, CA, United States of America

Steven A Sachrison