Patent Description:
In a turbine engine, the areas surrounding the combustor have elevated temperatures because of the heat generated by the combustor as fuel is combusted therein. Transfer of such thermal energy may influence the function of components surrounding the combustor, such as fuel nozzles. For example, the structures defining passages via which fuel flows inside fuel nozzles may require particular thermal management consideration.

<CIT> discloses a fuel injector with an internally heat-shielded nozzle.

According to an aspect of the present invention, there is provided a fuel nozzle for a turbine engine as claimed in claim <NUM>.

Optionally, and in accordance with the above, the first stem end and the second stem end are respectively joined to the flange and to the tip by brazing, welding or soldering.

Optionally, and in accordance with any of the above, the first line end and the second line end are respectively fixedly joined to the flange and to the tip by brazing, welding or soldering.

Optionally, and in accordance with any of the above, the first stem end and the second stem end are respectively matingly received by the flange and the tip such that the stem chamber extends from inside the flange to inside the tip.

Optionally, and in accordance with any of the above, the first stem end and the second stem end are cylindrical in shape.

Optionally, and in accordance with any of the above, the stem has a constant wall thickness throughout a length thereof.

Optionally, and in accordance with any of the above, the peripheral wall has a thickness of between <NUM> and <NUM> at a location spaced away from the flange and from the tip.

Optionally, and in accordance with any of the above, an or the inner diameter of the peripheral wall is between <NUM> and <NUM>.

Optionally, and in accordance with any of the above, the stem has an opening defined in the peripheral wall at an intermediate location between the tip and the flange, the opening in fluid communication between the stem chamber and outside the fuel nozzle.

Optionally, and in accordance with any of the above, the opening is located closer to the flange than to the tip.

Optionally, and in accordance with any of the above, the opening has a cross-sectional area that is less than <NUM><NUM>.

According to another aspect of the present invention, there is provided a turbine engine as claimed in claim <NUM>.

Optionally, and in accordance with any of the above, the opening has a cross-sectional area of no greater than <NUM><NUM>.

Optionally, and in accordance with any of the above, the second stem end and the second line end are parallel to one another.

<FIG> illustrates a gas turbine engine <NUM> of a type preferably provided for use in subsonic flight, generally comprising in serial flow communication a fan <NUM> through which ambient air is propelled, a compressor section <NUM> for pressurizing the air, a combustor <NUM> in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, and a turbine section <NUM> for extracting energy from the combustion gases.

Referring to <FIG> and <FIG>, the gas turbine engine <NUM> has fuel nozzles <NUM> or injectors mounted between an annular case <NUM> of the gas turbine engine <NUM> and the combustor <NUM>. The case <NUM> surrounds a cavity E forming an air plenum, hereinafter "engine cavity E", around the combustor <NUM>. The combustor <NUM> defines a combustion chamber C circumscribed by radially inner and radially outer combustor liners of the combustor <NUM> inside the engine cavity E. <FIG> shows an embodiment of one of the fuel nozzles <NUM>. The illustrated nozzle <NUM> generally comprises a number of external parts secured together, namely, a flange <NUM> which is securable to the case <NUM>, a stem <NUM> adapted to be disposed inside the engine cavity E and extending from the flange <NUM>, and a tip <NUM> inside the engine cavity E located at the end of the stem <NUM>. The flange <NUM> is typically bolted to an exterior of the case <NUM>. The stem <NUM> is configured to structurally support the tip <NUM> on the flange <NUM>. A portion of the nozzle <NUM>, which may include a portion of the flange <NUM> and/or a portion of the stem <NUM>, extends from outside the case <NUM> to inside thereof via an opening defined in the case <NUM>. The tip <NUM> of the nozzle <NUM> is positioned so as to extend through a corresponding opening defined in a dome wall portion of the combustor <NUM>, and thus extends from outside the combustion chamber C to inside the combustion chamber C. The tip <NUM> may be monolithic or, as will be described further below, may comprise a plurality of components <NUM>', <NUM>" suitably assembled. In some embodiments, only one of such components <NUM>', <NUM>" extends through the opening of the combustor <NUM>.

A first side 30a of the flange <NUM> generally faces away from the combustor <NUM>, whereas a second side 30b of the flange <NUM> generally faces the stem <NUM> and the combustor <NUM>. A first side 40a of the stem <NUM> generally faces the flange <NUM>, whereas a second side 40b of the stem <NUM> generally faces the tip <NUM>. A first side 50a of the tip <NUM> generally faces the stem <NUM>, whereas a second side 50b of the tip <NUM> generally faces the combustor <NUM>.

In operation, fuel is supplied to at least one fuel passage <NUM>, <NUM>' of the flange <NUM> (or flange passage <NUM>, <NUM>') of the illustrated nozzle <NUM>, in this case from a manifold (not shown) of the engine <NUM> in fluid communication with a plurality of the fuel nozzles <NUM> of the engine <NUM>. The at least one fuel passage <NUM>, <NUM>' is defined by the flange <NUM> so as to suitably condition the flow of fuel downstream of the manifold. The fuel exits the fuel nozzle <NUM> at the tip <NUM> via at least one fuel passage <NUM>, <NUM>' thereof (or tip passage <NUM>, <NUM>'), from which it is injected into the combustor <NUM> and ignited to generate heat. The at least one fuel passage <NUM>, <NUM>' is defined by the tip <NUM> as to suitably condition the flow of fuel as it flows therein and/or exits therefrom, for example to incorporate air with the fuel so as to generate a spray.

The fuel nozzle <NUM> is configured to provide suitable fluid connection(s) between the fuel passage(s) <NUM>, <NUM>' of the flange <NUM> and the fuel passage(s) <NUM>, <NUM>' of the tip <NUM>. The fuel nozzle <NUM> comprises at least one fuel line <NUM>, <NUM>' extending lengthwise, at least partially, inside the stem <NUM>. Each one of the at least one fuel line <NUM>, <NUM>' has two opposite ends, namely a first end 60a, <NUM>'a in fluid communication with a corresponding one of the at least one fuel passages <NUM>, <NUM>' of the flange <NUM>, and a second end 60b, <NUM>'b in fluid communication with a corresponding one of the fuel passages <NUM>, <NUM>' of the tip <NUM>. Depending on the embodiment, the first end(s) 60a, <NUM>'a and/or the second end(s) 60b, <NUM>'b may extend outside the stem <NUM>. The fuel nozzle <NUM> may be referred to as a "simplex" nozzle if it includes a sole fuel line <NUM>, or as a "duplex" nozzle if it includes a pair of fuel lines <NUM>, <NUM>'. Fuel nozzles <NUM> having more than two fuel lines, and a corresponding number of fuel passages <NUM>, <NUM>, are contemplated.

The flange <NUM> can define one or more flange cavities <NUM>, <NUM>, for example one such cavity <NUM> located on the second side 30b of the flange <NUM> for receiving the stem <NUM>, and at least one other such cavity <NUM> located on the first side 30a of the flange <NUM> in fluid communication with the at least one fuel passage <NUM>, <NUM>'.

The tip <NUM> can define one or more tip cavities <NUM>, <NUM>, <NUM>', for example one such cavity <NUM> located on the first side 50a of the tip <NUM> for receiving the stem <NUM>, and at least one other such cavity <NUM>, <NUM>' located on the second side 50b of the tip <NUM> in fluid communication with the at least one fuel passage <NUM>, <NUM>'.

Still referring to <FIG>, the stem <NUM> has a hollow stem body <NUM> (hereinafter "body") that in this case is monolithic, and extends peripherally so as to circumscribe a stem chamber <NUM> inside which the at least one fuel line <NUM>, <NUM>' extends, while providing structure to the stem <NUM>. The at least one fuel line <NUM>, <NUM>' is spaced from the inner wall of the hollow stem body <NUM> by an annular insulating gap. Hence, in addition to supporting the tip <NUM>, the stem <NUM> provides thermal insulation to the at least one fuel line <NUM>, <NUM>'. Stated otherwise, the stem <NUM> serves a dual function as it is both a support for the tip <NUM> and a heat shield for the at least one fuel line <NUM>, <NUM>'. As such, surrounding the stem <NUM> with a dedicated heat shield is not necessary in most embodiments. The body <NUM> is elongated, and extends lengthwise from a first end 42a of the stem <NUM>, also referred to as a proximal end 42a (i.e., the end that is the closest to the flange <NUM>) to a second end 42b (i.e., the end that is the furthest from the flange <NUM>), also referred to as a distal end 42b. The stem body <NUM> extends proximate to the flange <NUM> along a first stem axis, such that it is matingly connected to the flange <NUM> along the first stem axis. In this case, the first stem end 42a is matingly received by the flange cavity <NUM> defined on the second side 30b of the flange <NUM>. The flange <NUM> may be said to seal the stem chamber <NUM> from the engine cavity E. The stem body <NUM> extends proximate to the tip <NUM> along a second stem axis, such that it is matingly connected to the tip <NUM> along the second stem axis. In this case, the second stem end 42b is matingly received by the tip cavity <NUM> defined on the first side 50a of the tip <NUM>. The tip <NUM> may be said to seal the stem chamber <NUM> from the combustion chamber C and from the engine cavity E. Depending on the embodiment, the stem body <NUM> may be said to follow a certain path as it extends lengthwise. In the present embodiment, the first stem axis and the second stem axis are collinear, and thus correspond to a same axis A. Also, in this embodiment, the stem body <NUM> fully extends along the axis A, and thus follows a linear path. In other embodiments, at least a portion of the stem body <NUM> may follow a non linear path. In some such embodiments, the first stem axis and the second stem axis may be at an angle relative to one another.

As mentioned hereinabove, the stem body <NUM> is hollow, and may thus be said to include a peripheral wall having an outer surface 42c (i.e., a surface exposed at least in part to the engine cavity E) and an inner surface 42d (i.e., a surface circumscribing the stem chamber <NUM>). The stem body <NUM> may be cylindrical in shape, and thus may extend axially and circumferentially relative to the axis A, with the outer surface 42c and the inner surface 42d being spaced by a thickness T relative to the axis A, i.e., in this case a radial thickness, that is the same at the first stem end 42a, at the second stem end 42b, and at either axial position therebetween. Stated otherwise, the stem body <NUM> may have an outer diameter and an inner diameter (shown at D) that are constant throughout its length. Other configurations are contemplated for the peripheral wall.

The stem <NUM> and the at least one fuel line <NUM>, <NUM>' are sized and arranged relative to one another so as to provide suitable insulation to the at least one fuel line <NUM>, <NUM>' from the high temperatures in effect in the vicinity of the fuel nozzle <NUM> as the engine <NUM> operates. For instance, the temperature inside the engine cavity E around the combustor can attain <NUM> F, or approximately <NUM> C, whereas it may be desirable to maintain the stem chamber <NUM> at a temperature of about <NUM> F, or approximately <NUM> C, to minimize adverse heating of the fuel as it flows inside the at least one fuel line <NUM>, <NUM>'. In order to provide a suitable air gap around the at least one fuel line <NUM>, <NUM>', the inner diameter D of the of the peripheral wall of the stem body <NUM> is between <NUM> and <NUM> times an outer diameter d of the at least one fuel line <NUM>, <NUM>'. In some embodiments, the inner diameter D may be of between about <NUM> inch and <NUM> inch, for example <NUM> inch, i.e., between about <NUM> and <NUM>, for example <NUM>. In some such embodiments, the outer diameter d may be of between about <NUM> inch and <NUM> inch, for example <NUM> inch, i.e., between about <NUM> and <NUM>, for example <NUM>.

Still referring to <FIG>, in order to hinder the transfer of heat toward the fuel flowing inside the at least one fuel line <NUM>, <NUM>', a portion of the volume circumscribed by the outer surface 42c of the stem body <NUM> that is occupied by air (i.e., unoccupied by either of the stem body <NUM> nor the at least one fuel line <NUM>, <NUM>') may be maximised while maintaining the requisite structural integrity of the stem <NUM> as it holds the tip <NUM> relative to the flange <NUM>. To this end, the thickness T of the peripheral wall of the stem body <NUM> may be much smaller than the inner diameter D. For example, the thickness T may be of between about <NUM> inch and <NUM> inch, for example <NUM> inch, i.e., between about <NUM> and about <NUM>, for example <NUM>. In embodiments, the thickness T is at least at a location that is spaced away from the flange <NUM> and from the tip <NUM>. The peripheral wall may have multiple thicknesses at respective lengthwise locations. A thickness of the at least one fuel line <NUM>, <NUM>' may be of between about <NUM> inch and <NUM> inch, for example <NUM> inch, i.e., between about <NUM> and <NUM>, for example <NUM>. An inner diameter of the at least one fuel line <NUM>, <NUM>' may be of between about <NUM> inch and <NUM> inch, i.e., between about <NUM> and <NUM>.

In some embodiments, the stem <NUM> may have an opening <NUM> defined in the peripheral wall at a location where the outer surface 42c is exposed to the engine cavity E, with the opening <NUM> extending through the peripheral wall from the inner surface 42d to the outer surface 42c. The opening <NUM> is thus in fluid communication between the stem chamber <NUM> and the engine cavity E, and more specifically a portion of the engine cavity E that is outside the combustor <NUM>. By way of the opening <NUM>, the pressure inside the stem chamber <NUM> may tend to equilibrate with that of the engine cavity E. The opening <NUM> is sized so as to be small relative to the stem chamber <NUM> so as to prevent ingress of hot air into the stem chamber <NUM>. For example, the opening <NUM> may have a cross-sectional area that is of less than about <NUM> % of an area of the outer surface 42c that is exposed to the engine cavity E. In embodiments, the opening <NUM> has a cross-sectional area that is no greater than about <NUM> square inches, i.e., no greater than about <NUM><NUM>. In embodiments, the opening <NUM> is cylindrical in shape. In some such embodiments, the opening <NUM> may have a diameter of between about <NUM> inch and <NUM> inch, i.e., between about <NUM> and <NUM>. Also, the opening <NUM> may be located closer to the flange <NUM> than to the tip <NUM>, such that it is spaced away from the heat source (i.e., the combustor <NUM>) and thus less susceptible to let heat enter the stem chamber <NUM>. In embodiments, the opening <NUM> is a sole opening defined in the peripheral wall. In embodiments, more than one opening <NUM> is provided in the peripheral wall.

Components of the fuel nozzle <NUM> interfacing one another may be fixedly joined, i.e., permanently joined or in a manner not intended to be disjoined, by various suitable means. For example, the first stem end 42a and the second stem end 42b may be respectively fixedly joined to the flange <NUM> and to the tip <NUM> by brazing, welding or soldering. Likewise, the first line end(s) 60a, <NUM>'a and the second line end(s) 60b, <NUM>'b may be respectively fixedly joined to the flange <NUM> and to the tip <NUM> by brazing, welding or soldering. Advantageously, the fuel nozzle <NUM> may be arranged such that brazing can be used to fixedly join multiple components of the fuel nozzle <NUM> in one heating operation or, stated otherwise, so that multiple joints of the fuel nozzle <NUM> may be brazed at once. It should be noted that the opening <NUM> may serve as a vent during a heat treatment cycle, for example a brazing cycle, so that pressures inside and outside the stem chamber <NUM> may equilibrate, and/or for gasses generated or used during the heat treatment cycle to evacuate from the stem chamber <NUM>. Fitment of any two components of the fuel nozzle <NUM> may refer to the secure, yet non permanent assembly of such two components, in some cases with a brazing media (e.g., paste, powder, or preform material) disposed at the interface therebetween. For example, the first stem end 42a may be fitted to a complementary shape of the flange <NUM>, for example the flange cavity <NUM>, whereas the first line end(s) 60a, <NUM>'a may be fitted to complementary shape(s) of the flange <NUM>, for example distal portion(s) of the fuel passages <NUM>, <NUM>'. The second stem end 42b may be fitted to a complementary shape of the tip <NUM>, for example the tip cavity <NUM>, whereas the second line end(s) 60b, <NUM>'b may be fitted to complementary shape(s) of the tip <NUM>, for example proximal portion(s) of the fuel passages <NUM>, <NUM>'. In the depicted embodiment, the outer surface 42c of the stem body <NUM> interfaces a radially inner surface of the flange <NUM> at the first stem end 42a, and interfaces a radially inner surface of the tip <NUM> at the second stem end 42b. As such, the first and second stem ends 42a, 42b are respectively recessed in, or matingly received by, the flange <NUM> and the tip <NUM>, such that end portions of the stem chamber <NUM> may be said to be located inside the flange <NUM> and inside the tip <NUM>. Stated otherwise, the stem chamber <NUM> may extend from inside the flange <NUM> to inside the tip <NUM> In other embodiments, the inner surface 42d of the stem body <NUM> may interface a radially outer surface of the flange <NUM> and/or a radially outer surface of the tip <NUM>. The fuel nozzle <NUM> may be arranged so as to facilitate the simultaneous fitment of the stem <NUM> and of the at least one fuel line <NUM>, <NUM>' to the flange <NUM> and/or to the tip <NUM>. For example, upon the flange <NUM> being fitted onto the stem <NUM> and onto the at least one fuel line <NUM>, <NUM>', the first stem end 42a and the first line end(s) 60a, <NUM>'a may extend parallel to one another, and/or the second stem end 42b and the second line end(s) 60b, <NUM>'b may extend parallel to one another. Upon the tip <NUM> being fitted onto the stem <NUM> and onto the at least one fuel line <NUM>, <NUM>', the second stem end 42b and the second line end(s) 60b, <NUM>'b may extend parallel to one another, and/or the first stem end 42a and the first line end(s) 60a, <NUM>'a may extend parallel to one another. The at least one fuel line <NUM>, <NUM>' is cylindrical in shape. In some such embodiments, the stem <NUM> and the at least one fuel line <NUM>, <NUM>' are all cylindrical in shape, and extend parallel to one another upon the nozzle <NUM> being assembled.

The flange <NUM>, the stem <NUM>, the tip <NUM> and/or the at least one fuel line <NUM>, <NUM>' are constructed of material(s) that are suitable for the joining means employed to assemble the nozzle <NUM>. For example, in the case of brazing, such material(s) are metallic materials having a melting temperature that is higher than that of the brazing media. In some embodiments, the material(s) have a melting temperature that is of at least <NUM>,<NUM> F (<NUM>,<NUM> C). The material(s) of which the stem <NUM> and/or the at least one fuel line <NUM>, <NUM>' may have particularly desirable properties in accordance with the dual function of the stem <NUM>, for example high rigidity and low thermal conductivity.

At least in some embodiments, the stem <NUM> and/or the at least one fuel line <NUM>, <NUM>' are obtained from standardized structures requiring minimal machining steps before being assembled so as to form the nozzle <NUM>. For instance, the stem <NUM> and/or the at least one fuel line <NUM>, <NUM>' can be made of tubing, in some cases having nominal dimensions that are readily available off-the-shelf. In some embodiments, a sole machining step to which the stem <NUM> and/or the at least one fuel line <NUM>, <NUM>' is/are submitted is lengthwise cutting. According to one aspect, the stem body <NUM> can be provided in the form of an outer tube and the at least one fuel line <NUM>, <NUM>' can be provided in the form of internal tube(s) inside the outer tube, thereby forming a nested tube arrangement.

Claim 1:
A fuel nozzle (<NUM>) for a turbine engine (<NUM>), comprising:
a flange (<NUM>) defining at least one flange passage (<NUM>,<NUM>');
a tip (<NUM>) spaced from the flange (<NUM>) , the tip (<NUM>) defining at least one tip passage (<NUM>, <NUM>');
a stem (<NUM>) provided in the form of a straight tube having a first stem end (42a) fixedly joined to the flange (<NUM>) and a second stem end (42b) fixedly joined to the tip (<NUM>), the stem (<NUM>) having a peripheral wall extending lengthwise along a linear path between the first stem end (42a) and the second stem end (42b) and peripherally around a stem chamber (<NUM>), the second stem end (42b) received into a cavity (<NUM>) defined in the tip (<NUM>), the tip (<NUM>) sealing the stem chamber (<NUM>) at the second stem end (42b); and
at least one fuel line (<NUM>,<NUM>') extending at least partially inside the stem chamber (<NUM>) and having a first line end (60a,<NUM>'a) fluidly connected to the at least one flange passage (<NUM>,<NUM>') and a second line end (60b,<NUM>'b) fluidly connected to the at least one tip passage (<NUM>,<NUM>'), wherein the at least one fuel line (<NUM>,<NUM>') is cylindrical in shape and spaced from an inner surface (42d) of the peripheral wall by an annular insulating gap,
characterised in that:
the first stem end (42a) and the second stem end (42b) are coaxial; and
an inner diameter (D) of the peripheral wall is between <NUM> and <NUM> times an outer diameter (d) of the at least one fuel line (<NUM>,<NUM>').