Patent Description:
Gas turbine engines include a number of features configured for providing desired fluid flow characteristics. Some turbomachines include a diffuser feature that diffuses fluid (e.g., air) received from a compressor wheel as the fluid flows downstream. Also, some turbomachines include a deswirl feature that deswirls the fluid as it flows further downstream, for example, to a combustion section of the engine. As such, particular flow characteristics can be provided that improve engine efficiency, etc..

However, these fluid flow features can suffer from certain disadvantages. For example, these features may include a relatively large number of parts and/or they can be relatively bulky and heavy. Also, assembling these structures can be difficult, inconvenient, and time consuming. Thus, manufacturing costs can be relatively high.

In addition, the aerodynamic performance of these fluid flow features may be deficient at some operating conditions. For example, unintended leakage may occur between assembled parts along the flow path, resulting in efficiency losses.

Hence, there is a need for an improved diffuser and deswirl fluid flow structure for a gas turbine engine that provides desired fluid flow characteristics. There is also a need for improved manufacturing methods for such a structure. Documents cited during prosecution include <CIT>; <CIT>; <CIT>; and <CIT>.

Aspects and preferred embodiments of the invention are defined in the appended claims. Disclosed herein is a diffuser and deswirl flow structure for a gas turbine engine defining a longitudinal axis. The fluid flow structure includes a plurality of tube structures that has an outer wall that is hollow and elongate and that extends between a first portion and a second portion of the respective one of the plurality of tube structures. The plurality of tube structures is disposed in an annular arrangement about the longitudinal axis. The flow structure also includes a plurality of flow passages extending through respective ones of the plurality of tube structures. The plurality of flow passages extend from the first portion to the second portion, respectively. The plurality of flow passages respectfully include a diffuser portion, which is proximate the first portion and configured to diffuse a fluid flow from a compressor wheel. The plurality of flow passages respectfully include a deswirl portion, which is proximate the second portion and configured to deswirl the fluid flow from the diffuser portion. The outer wall defines the diffuser portion and the deswirl portion. The outer wall is self-supporting.

Also, a tube structure for a flow structure of a gas turbine engine is disclosed. The tube structure is configured for annular arrangement with a plurality of additional tube structures about a longitudinal axis to define the flow structure. The tube structure includes an outer wall that is hollow and elongate and that extends between a first portion and a second portion along a tube axis. The tube structure also includes a flow passage extending through the tube structure along the tube axis from the first portion to the second portion. The flow passage includes a diffuser portion, which is proximate the first portion and configured to diffuse a fluid flow from a compressor wheel. The flow passage respectfully includes a deswirl portion, which is proximate the second portion and configured to deswirl the fluid flow from the diffuser portion. The outer wall defines the diffuser portion and the deswirl portion. The outer wall is self-supporting.

Furthermore, a method of manufacturing a diffuser and deswirl flow structure for a gas turbine engine defining a longitudinal axis is disclosed. The method includes forming a plurality of tube structures. The tube structures respectively include an outer wall that is hollow and elongate and that extends respectively between a first portion and a second portion. The plurality of tube structures are disposed in an annular arrangement about the longitudinal axis. The method also includes defining a plurality of flow passages extending through respective ones of the plurality of tube structures. The plurality of flow passages extend from the first portion to the second portion, respectively. The plurality of flow passages are defined to respectively include a diffuser portion, which is proximate the first portion and configured to diffuse a fluid flow from a compressor wheel. The plurality of flow passages are defined to respectively include a deswirl portion, which is proximate the second portion and configured to deswirl the fluid flow from the diffuser portion. The outer wall defines the diffuser portion and the deswirl portion. The outer wall is self-supporting.

Other desirable features and characteristics of the apparatus and method will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the preceding background.

The present disclosure will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein:.

The following detailed description is merely exemplary in nature and is not intended to limit the present disclosure or the application and uses of the present disclosure. All of the embodiments described herein are exemplary embodiments provided to enable persons skilled in the art to make or use the present disclosure and not to limit the scope of the present disclosure which is defined by the claims.

Broadly, embodiments of the present disclosure include a gas turbine engine with a combination diffuser and deswirl flow structure. In some embodiments, the flow structure is a monolithic, unitary, one-piece structure that includes a plurality of tube structures that are connected together and arranged annularly about a central axis. An outer wall of the tube structures may define a respective flow passage (i.e., channel, duct, etc.) therethrough. The outer wall may extend continuously between the diffuser and deswirl portions of the flow structure. The diffuser and deswirl portions may be tailored for the particular compressor section for improved performance.

Also, the outer wall may include a number of features that improve the structural strength and robustness of the part. The flow structure may additionally include weight-saving features for improving fuel efficiency of the gas turbine engine.

Furthermore, one or more features are provided for facilitating manufacture of the diffuser and deswirl structure. In some embodiments, for example, the flow structure may be additively manufactured. The flow structure can, therefore, include features for facilitating additive manufacture. In addition, the outer wall of the flow structures may be configured to be self-supporting during the additive manufacturing process. As such, internal supports within the flow structure may be unnecessary, which provides weight savings, reduces material cost, and provides other benefits.

With reference to <FIG>, a partial, cross-sectional view of an exemplary gas turbine engine <NUM> is shown with the remaining portion of the gas turbine engine <NUM> being substantially axisymmetric about a longitudinal axis <NUM>, which also defines an axis of rotation for the gas turbine engine <NUM>. In the depicted embodiment, the gas turbine engine <NUM> is an annular multi-spool turbofan gas turbine jet engine within an aircraft (represented schematically at <NUM>), although features of the present disclosure may be included in other configurations, arrangements, and/or uses. For example, in other embodiments, the gas turbine engine <NUM> may assume the form of a non-propulsive engine, such as an Auxiliary Power Unit (APU) deployed onboard the aircraft <NUM>, or an industrial power generator.

In this example, with continued reference to <FIG>, the gas turbine engine <NUM> includes a fan section <NUM>, a compressor section <NUM>, a combustor section <NUM>, a turbine section <NUM>, and an exhaust section <NUM>. In one example, the fan section <NUM> includes a fan <NUM> mounted on a rotor <NUM> that draws air into the gas turbine engine <NUM> and compresses it. A fraction of the compressed air exhausted from the fan <NUM> is directed through the outer bypass duct <NUM> and the remaining fraction of air exhausted from the fan <NUM> is directed into the compressor section <NUM>. The outer bypass duct <NUM> is generally defined by an outer casing <NUM> that is spaced apart from and surrounds an inner bypass duct <NUM>.

In the embodiment of <FIG>, the compressor section <NUM> includes one or more compressors <NUM>. The number of compressors <NUM> in the compressor section <NUM> and the configuration thereof may vary. The one or more compressors <NUM> sequentially raise the pressure of the air and direct a majority of the high-pressure fluid or air into the combustor section <NUM>. In the combustor section <NUM>, which includes a combustion chamber <NUM>, the high-pressure air is mixed with fuel and is combusted. The high-temperature combustion air or combustive gas flow is directed into the turbine section <NUM>. In this example, the turbine section <NUM> includes three turbines disposed in axial flow series, namely, a high-pressure turbine <NUM>, an intermediate pressure turbine <NUM>, and a low-pressure turbine <NUM>. However, it will be appreciated that the number of turbines, and/or the configurations thereof, may vary. In this embodiment, the high-temperature combusted air from the combustor section <NUM> expands through and rotates each turbine <NUM>, <NUM>, and <NUM>. The combustive gas flow then exits the turbine section <NUM> for mixture with the cooler bypass airflow from the outer bypass duct <NUM> and is ultimately discharged from the gas turbine engine <NUM> through the exhaust section <NUM>. As the turbines <NUM>, <NUM>, <NUM> rotate, each drives equipment in the gas turbine engine <NUM> via concentrically disposed shafts or spools.

Referring now to <FIG>, the compressor section <NUM> will be discussed in greater detail according to example embodiments. As shown, one stage of the compressor section <NUM> may include a compressor wheel <NUM> (shown in phantom), which is supported for rotation about the axis <NUM>. The compressor wheel <NUM> may rotate within a shroud member (hidden in <FIG>), and an airflow may flow through a passage cooperatively defined by the shroud member and the compressor wheel.

This airflow may be received by a diffuser and deswirl flow structure <NUM>, which is represented in <FIG> according to example embodiments. As shown, the flow structure <NUM> may be annular and substantially centered on the axis <NUM>. The flow structure <NUM> may include a forward side <NUM>, an aft side <NUM>, an inner radial portion <NUM>, and an outer radial portion <NUM>. The compressor wheel <NUM> is received within the flow structure <NUM> with the inner radial portion <NUM> facing the outer radial edge of the wheel <NUM>, with the forward side <NUM> and the forward face of the wheel <NUM> facing forward along the axis <NUM>, and with the aft side <NUM> and the aft face of the wheel <NUM> facing rearward along the axis <NUM>.

The flow structure <NUM> may include a plurality of tube structures <NUM>. The plurality of tube structures <NUM> may be disposed in an annular arrangement about the axis <NUM>. One of the tube structures <NUM> is shown in isolation in <FIG> according to example embodiments of the present disclosure.

As shown, the tube structure <NUM> may be an elongate member having a first portion <NUM> and second portion <NUM> that are separated longitudinally with a bend <NUM> disposed therebetween. The tube structure <NUM> may be hollow and may be defined by an outer wall <NUM>.

The first portion <NUM> may include and/or terminate at a first end <NUM>. The first end <NUM> may include a surface <NUM> that partly defines the inner radial portion <NUM> of the flow structure <NUM> (<FIG>). The surface <NUM> may be arcuate and curved about the axis <NUM>. The surface <NUM> may have concave curvature. Also, the surface <NUM> may be substantially ovate in shape. Additionally, the surface <NUM> may be open-ended for inletting flow into the tube structure <NUM>.

The second portion <NUM> may include and/or terminate at a second end <NUM> of the tube structure <NUM>. The second end <NUM> may partly define the outer radial portion <NUM> of the flow structure <NUM> (<FIG>). The second end <NUM> may be rectangular and may define a rectangular lip <NUM>. The second end <NUM> may be open-ended for outletting flow from the tube structure <NUM> as will be discussed in more detail below.

The tube structure <NUM> may define a longitudinal tube axis <NUM>. The tube axis <NUM> may intersect the first end <NUM>, extend along the first portion <NUM>, turn along the bend <NUM>, extend along the second portion <NUM>, and extend normal to the second end <NUM>. One or more segments of the outer wall <NUM> may be centered about the axis <NUM>. It will be appreciated that different embodiments of the tube structure <NUM> may have different shapes and configurations, and the tube axis <NUM> may extend in a number of directions without departing from the scope of the present disclosure. In some embodiments, for example, the tube structure <NUM> widens/enlarges in cross section as it extends along tube axis <NUM> from the first end <NUM> to the second end <NUM>. The tube structure <NUM> may widen in a first cross-wise direction <NUM> (i.e., a direction extending between a first side <NUM> and a second side <NUM> of the tube structure <NUM>). The tube structure <NUM> may also widen somewhat in a second cross-wise direction <NUM> (i.e., a direction normal to the first cross-wise direction <NUM> and the tube axis <NUM>).

As shown in <FIG>, the tube structures <NUM> may be attached together and arranged annularly about the axis <NUM>. The first sides <NUM> of the tube structures <NUM> may be attached to the second side <NUM> of the neighboring (i.e., adjacent) tube structure <NUM> in succession about the axis <NUM>. The tube structures <NUM> may be fixedly attached at the first ends <NUM> along the first and second sides <NUM>, <NUM>. The tube structures <NUM> may also be fixedly attached at the second ends <NUM> along the first and second sides <NUM>, <NUM>. Furthermore, as shown in <FIG>, there may be spaces <NUM> defined between the first portions <NUM> of the tube structures <NUM>. The spaces <NUM> may be generally triangular in shape when viewed axially and may define open space extending between the forward side <NUM> and the aft side <NUM>. These spaces <NUM> may provide weight savings for the flow structure <NUM>.

The first ends <NUM> of the tube structures <NUM> may collectively define the inner radial portion <NUM> of the flow structure <NUM>. The second ends <NUM> of the tube structures <NUM> may collectively define the outer radial portion <NUM> of the flow structure <NUM>. The tube structures <NUM> may also collectively define the forward side <NUM> and the aft side <NUM> of the flow structure. As shown in <FIG>, the tube structures <NUM> may be arranged as eccentric spokes on the annular diffuser/deswirl flow structure <NUM>. The first portions <NUM> of the tube structures <NUM> may extend substantially radially with respect to the axis <NUM>. The bend <NUM> in the tube structures <NUM> may direct the second portions <NUM> of the tube structures <NUM> somewhat axially in the aft-facing direction with respect to the axis <NUM>.

In some embodiments, the diffuser/deswirl flow structure <NUM> may be a unitary, one-piece monolithic part. As such, the tube structures <NUM> may be integrally attached together to define the monolithic structure <NUM>. In some embodiments, the flow structure <NUM> may be formed via an additive manufacturing process such that the outer walls <NUM> of plural tube structures <NUM> are formed simultaneously and integrally attached. However, it will be appreciated that, in other embodiments, the tube structures <NUM> may be independently formed and then subsequently connected and arranged in the annular arrangement of <FIG>. In still other embodiments, the flow structure <NUM> may be a cast part that is integrally formed and monolithic. In further embodiments, parts may be assembled and fixedly attached together via brazing, using fasteners, or other attachments to define the flow structure <NUM>.

As mentioned above, the tube structures <NUM> may be hollow. As such, the flow structure <NUM> includes a plurality of flow passages <NUM>. The flow passages <NUM> may extend through respective ones of the plurality of tube structures <NUM> from the first end <NUM> to the second end <NUM>. The outer wall <NUM> may be hollow such that the interior defines the flow passage <NUM> for the respective tube structure <NUM>.

As shown in <FIG>, the flow passage <NUM> may include a first segment <NUM> that extends (substantially radially) through the first portion <NUM>. The first segment <NUM> may include an inlet <NUM> into the flow passage <NUM>. The inlet <NUM> may be a hole with a circular cross section. The inlet <NUM> may extend along and may be centered substantially on the tube axis <NUM>. In other embodiments, the axis of the inlet <NUM> may be slightly eccentric, disposed at an acute angle, etc. relative to the tube axis <NUM>. As shown in <FIG>, the surface <NUM> of the first end <NUM> may be disposed at an angle relative to the tube axis <NUM>; therefore, the inlet <NUM> may be ovate in shape where it intersects the surface <NUM>. The first segment <NUM> may also include an intermediate portion <NUM> (<FIG>), which gradually widens outward along the cross-wise direction <NUM>. The outer wall <NUM> may also have a constant wall thickness along the intermediate portion <NUM>.

Further downstream, the flow passage <NUM> may extend continuously through the bend <NUM> to open into a second segment <NUM> (<FIG>) that extends through the second portion <NUM>. The second segment <NUM> may widen slightly as it extends downstream. The second segment <NUM> may terminate at an outlet <NUM> defined by the lip <NUM>. The outer wall <NUM> may have a substantially constant wall thickness throughout the second segment <NUM>. Optionally, the second segment <NUM> may include one or more deswirl vanes <NUM> (<FIG>) for directing fluid flow out of the tube structure <NUM>. The deswirl vanes <NUM> may have a variety of shapes and configurations without departing from the scope of the present disclosure. For example, as shown, the deswirl vanes <NUM> may be flat with uniform thickness; however, in other embodiments, the vanes <NUM> may have nonuniform thickness, may have at least one contoured surface, etc..

The flow passage <NUM> may extend continuously from the first end <NUM> to the second end <NUM> of the respective tube structure <NUM>. The flow passage <NUM> may define a downstream direction along the tube axis <NUM> from the inlet <NUM> to the outlet <NUM>. Accordingly, the inlets <NUM> of the tube structures <NUM> may receive a fluid flow <NUM> (a compressed air stream indicated in <FIG>) from the compressor wheel <NUM>, that is directed along the axis <NUM> through the flow passage <NUM>, and that is outlet via the outlets <NUM> toward the combustor section <NUM>.

The tube structures <NUM> may condition, control, or otherwise affect the fluid flow <NUM> as it moves along the flow passage <NUM>. For example, as shown in <FIG>, the flow passage <NUM> may define a diffuser portion <NUM> and a deswirl portion <NUM>. The diffuser portion <NUM> may be proximate to and may extend through the first portion <NUM> of the tube structure <NUM>. The diffuser portion <NUM> may be configured for diffusing the fluid flow <NUM> (i.e., for slowing the high-velocity discharge from the compressor wheel <NUM> to increase the air pressure at a slower velocity). The shape, dimension, configuration, etc. of the inlet <NUM>, the intermediate portion <NUM>, and/or the bend <NUM> may be chosen for diffusing the fluid flow <NUM> during operation of the gas turbine engine <NUM>. The deswirl portion <NUM> may be proximate to and may extend primarily through the second portion <NUM> of the tube structure <NUM>. The deswirl portion <NUM> may be configured for reducing swirling within the flow <NUM> received from the diffuser portion <NUM>, thereby providing desired conditions within the flow <NUM> for the combustor section <NUM>. Thus, the shape, dimension, configuration, etc. of the bend <NUM>, the second segment <NUM>, the optional vanes <NUM>, and/or the outlet <NUM> may be chosen for deswirling the fluid flow <NUM> during operation of the gas turbine engine <NUM>.

The diffuser and deswirl flow structure <NUM> may be manufactured in many different ways without departing from the scope of the present disclosure. In some embodiments, the diffuser/deswirl flow structure <NUM> may be additively manufactured using any type of additive manufacturing process which utilizes layer-by-layer construction, including, but not limited to: selective laser melting; direct metal deposition; direct metal laser sintering (DMLS); direct metal laser melting; electron beam melting; electron beam wire melting; micro-pen deposition in which liquid media is dispensed with precision at the pen tip and then cured; selective laser sintering in which a laser is used to sinter a powder media in precisely controlled locations; laser wire deposition in which a wire feedstock is melted by a laser and then deposited and solidified in precise locations to build the product; laser engineered net shaping; Direct Metal Electron Beam Fusion (DMEBF); and other powder consolidation techniques. In one particular exemplary embodiment, direct metal laser fusion (DMLF) may be used to manufacture the flow structure <NUM>. DMLF is a commercially available laser-based rapid prototyping and tooling process by which complex parts may be directly produced by precision melting and solidification of metal powder (the "build material") into successive layers of larger structures, each layer corresponding to a cross-sectional layer of the flow structure <NUM>.

In some embodiments, a majority of the flow structure <NUM> may be formed using additive manufacturing processes, and additional features may be formed subsequently via other processes. For example, as represented in <FIG> and <FIG>, the flow structure <NUM> may be additively manufactured with the flow passages <NUM> partially formed (<FIG>), and the flow passages <NUM> may be completed by removing material (<FIG>) in a machining process.

More specifically, the flow structure <NUM> may be additively manufactured layer-by-layer such that the outer wall <NUM> progressively forms along a growth axis <NUM>. In some embodiments, the growth axis <NUM> may be substantially parallel to the longitudinal axis <NUM>. Also, in some embodiments, the growth axis <NUM> may be directed from the aft side <NUM> toward the forward side <NUM>. Accordingly, the outer wall <NUM> may be built layer-by-layer starting from a leading edge <NUM> to a trailing edge <NUM>. The leading edge <NUM> may correspond to the aft-most portion of the lip <NUM> of second end <NUM>. The trailing edge <NUM> may correspond to a forward-most ridge <NUM> of the flow structure <NUM>.

The tube structures <NUM> and/or other portions of the flow structure <NUM> may include features that facilitate the additive manufacturing process or otherwise improve manufacturing efficiency. For example, the outer wall <NUM> may include various features that cause it to be self-supporting. Stated differently, the outer wall <NUM> may be shaped, dimensioned, and configured to support itself such that internal supports, struts, braces, scaffolding, or other supporting structures extending within the outer wall <NUM> are unnecessary. As such, the internal flow passage <NUM> defined by the outer wall <NUM> may remain free of these obstructions.

In particular, the outer wall <NUM> may self-support as it is built layer-by-layer during the additive manufacturing process. The wall <NUM> may form and grow at a slight angle relative to the growth axis <NUM> and may span gradually away from the axis <NUM> rather than spanning directly transverse to the growth axis <NUM>. As such, the wall <NUM> can support itself as it grows and is unlikely to collapse under its own weight. Also, there may be minimal build-up of the wall <NUM> parallel to growth axis <NUM>. This avoids heat build-up, warpage of the wall <NUM>, etc. during formation of the wall <NUM>.

The flow structure <NUM> may be additively manufactured using an additive manufacturing device <NUM> as represented in <FIG>. The additive manufacturing device <NUM> may include an emitter <NUM>. The emitter <NUM> may emit a laser, an electron beam, or other energy toward a support bed <NUM>. The emitter <NUM> may be operatively attached to an actuator <NUM> (e.g., one or more electric motors) in some embodiments for moving relative to the support bed <NUM>. The support bed <NUM> may support a collection of particulate material <NUM>. A condition of the material <NUM> may change as a result of exposure to the laser, electron beam, or other energy from the emitter <NUM>. The support bed <NUM> may be connected to an actuator <NUM>. The actuator <NUM> may selectively change elevation of the support bed <NUM>. The outer wall <NUM> may be formed layer by successive layer as the actuator <NUM> moves the support bed <NUM> until the outer wall <NUM> is completed. In some embodiments, the emitter <NUM>, the actuator <NUM>, and/or the actuator <NUM> may be in communication with a computerized device (not shown). The computerized device may include computerized memory (RAM or ROM) and a processor. The processor may send control signals to the emitter <NUM> and/or the actuator <NUM> based on CAD data that is stored in the memory. The CAD data can correspond to the flow structure <NUM>. Accordingly, the processor may control the emitter <NUM> and/or the actuator <NUM> to form the flow structure <NUM>.

In some embodiments, the material <NUM> may include a plurality of particles made from a metal alloy. The emitter <NUM> may emit focused energy at particular areas of the material <NUM>, causing adjacent particles to melt and fuse together to form the outer wall <NUM>. The actuator <NUM> may move the support bed <NUM> such that the outer wall <NUM> is formed layer-by-layer and grows along the axis <NUM>. Once formed, the flow structure <NUM> may be supported atop the support bed <NUM> as shown.

More particularly, during the additive manufacturing process, the lip <NUM> at the second end <NUM> of the tube structures <NUM> may be built initially. Then, the second portion <NUM> may be progressively built along the growth axis <NUM>. Eventually, an inner surface <NUM> of the bend <NUM> (<FIG>) may be formed. An aft facing surface <NUM> of the first portion <NUM> may be formed subsequently. Next, the first side <NUM> and the second side <NUM> may form progressively and simultaneously. Then, a first canted surface <NUM> and second canted surface <NUM> may form progressively and terminate at the ridge <NUM> (<FIG>). Thus, the ridge <NUM> may define the apex of the flow structure <NUM> when formed along the growth axis <NUM>.

In some embodiments of this additive manufacturing process, a solid blank end <NUM> (<FIG>) may be formed at the first end <NUM>. The solid blank end <NUM> may be cylindrical and may have a solid circular cross section taken perpendicular to the axis <NUM>. Subsequently, material may be removed from the flow structure <NUM> to form the inlets <NUM> (as shown in phantom in <FIG>). In some embodiments, for example, tooling <NUM> (e.g., a drill bit, mill bit, or electrical discharge machining (EDM) tooling) may be used to machine, cut, and remove material from the blank end <NUM> to form the inlet <NUM>. This machining step ensures that the inlets <NUM> are accurately formed in a controlled manner.

<FIG> also show certain features that allows the outer wall <NUM> to be self-supporting. For example, as shown in <FIG>, the tube structure <NUM> may define a first cross section <NUM> in the first portion <NUM>, proximate the first end <NUM>. The first cross section <NUM> may be a teardrop-shaped cross-sectional profile. More particularly, at the first cross section <NUM>, the aft facing surface <NUM> and the first and second sides <NUM>, <NUM> may be contoured about the axis <NUM>. The first and second canted surfaces <NUM>, <NUM> may be flat and may be joined at the ridge <NUM> such that the surfaces <NUM>, <NUM> are canted (i.e., sloped, pitched, angled, etc.) relative to the growth axis <NUM>. The tube structure <NUM> may maintain the teardrop-shaped cross section <NUM> along the axis <NUM> but may gradually transition to a second cross section <NUM> (<FIG>), which is proximate the bend <NUM>. The second cross section <NUM> may be a house-shaped cross-sectional profile. More particularly, at the second cross section <NUM>, the aft facing surface <NUM> may be substantially flat, the first and second sides <NUM>, <NUM> may be flat and may extend transversely to the aft facing surface <NUM>. Also, at the second cross section <NUM>, the first and second canted surfaces <NUM>, <NUM> may be flat and may be joined at the ridge <NUM>. The first and second canted surfaces <NUM>, <NUM> and ridge <NUM> may extend continuously between the first and second cross sections <NUM>, <NUM>. The outer wall <NUM> may be continuous such that there is a smooth and gradual transition from the first cross section <NUM> to the second cross section <NUM> and, further downstream, to the rectangular second portion <NUM>. It will be appreciated that the outer wall <NUM> may have other cross-sectional shapes without departing from the scope of the present disclosure. In some embodiments, the outer wall <NUM> may include at least one cross sectional shape that is asymmetrical.

Furthermore, the tube structures <NUM> may exhibit a lean or tilt in the first portion <NUM> relative to axis <NUM>. In other words, a part of the axis <NUM> extending through the first portion <NUM> may be oriented at non-orthogonal angle relative to axis <NUM>. In some embodiments, the lead/tilt may cause the bend <NUM> to be disposed further forward in aft direction than the first end <NUM>.

Because the wall <NUM> forms and grows at a slight angle relative to the growth axis <NUM> and spans gradually away from the axis <NUM> rather than spanning directly perpendicular to the growth axis <NUM>, the wall <NUM> may support itself and collapse is unlikely. Also, the wall <NUM> is unlikely to build-up heat and warp during formation because there is minimal build up directly parallel with the growth axis <NUM>. It will also be appreciated that the optional vanes <NUM> are included for providing aerodynamic benefits (i.e., for directing fluid flow) instead of for providing structural support of the outer wall <NUM>. The outer wall <NUM> can support itself in embodiments where the vanes <NUM> are omitted. Thus, it will be appreciated that the outer wall <NUM> can be considered "self-supporting" with or without the vanes <NUM>.

In summary, the combination diffuser and deswirl flow structure <NUM> of the present disclosure may provide advantageous aerodynamic performance for improving performance of the gas turbine engine <NUM>. The structure <NUM> may be compact and lightweight. Also, the structure <NUM> may be strong and robust. Furthermore, the structure <NUM> may be manufactured efficiently.

Claim 1:
A diffuser and deswirl flow structure for a gas turbine engine (<NUM>) defining a longitudinal axis (<NUM>), the fluid flow structure comprising:
a plurality of tube structures (<NUM>), obtained by an additive manufacturing process, including an outer wall (<NUM>) that is hollow and elongate, and that extends between a first portion (<NUM>) and a second portion (<NUM>) of the respective one of the plurality of tube structures, the plurality of tube structures disposed in an annular arrangement about the longitudinal axis;
a plurality of flow passages (<NUM>) extending through respective ones of the plurality of tube structures, the plurality of flow passages extending from the first portion to the second portion, respectively;
the plurality of flow passages respectfully including a diffuser portion (<NUM>), which is proximate the first portion and configured to diffuse a fluid flow from a compressor wheel (<NUM>), the plurality of flow passages respectfully including a deswirl portion (<NUM>), which is proximate the second portion and configured to deswirl the fluid flow from the diffuser portion;
the outer wall defining the diffuser portion and the deswirl portion; and
the outer wall being self-supporting, meaning that the outer wall is shaped, dimensioned and configured to support itself during the additive manufacturing process such that no supporting structures extending within the outer wall are required.