Patent Description:
Gas turbine engines typically include a fan section, a compressor section, a combustor section and a turbine section. In general, during operation, air is pressurized in the compressor section and is mixed with fuel and burned in the combustor section to generate hot combustion gases. The hot combustion gases flow through the turbine section, which extracts energy from the hot combustion gases to power the compressor section and other gas turbine engine loads. One or more sections of the gas turbine engine may include a plurality of vane assemblies having vanes interspersed between rotor assemblies that carry the blades of successive stages of the section. The design of the vanes may be based on the overall design of the gas turbine engine.

<CIT> discloses a non-uniform stator vane spacing in a compressor.

<CIT> Al discloses a blade grid for a turbomachine with adjacent blades having rear edges with different angles.

<CIT> discloses a stator vane assembly with the vanes having a strut being of asymmetric shape about an axis of a symmetric vane.

<CIT> discloses an asymmetric vane assembly for a gas turbine engine according to the preamble of claim <NUM>.

In a first aspect, the present invention provides an asymmetric vane assembly for a gas turbine engine according to claim <NUM>.

In various embodiments, each vane of the high count vane section and each vane of the low count vane section have substantially similar external airfoil shape. In various embodiments, the high count vane section and the low count vane section provide an operational performance substantially similar to an original vane assembly designed for the gas turbine engine and having uniformly distributed vanes. In various embodiments, the high count vane section occupies a first circumferential half of the asymmetric vane assembly, and the low count vane section occupies a second circumferential half of the asymmetric vane assembly.

In various embodiments, the first plurality of vanes in the high count vane section are evenly spaced apart such that a first distance is between any two adjacent vanes in the first plurality of vanes, and the second plurality of vanes in the low count vane section are evenly spaced apart such that a second distance is between any two adjacent vanes in the second plurality of vanes. In various embodiments, the first distance is less than the second distance.

In various embodiments, a gas turbine engine as claimed in claim <NUM> is also provided.

In various embodiments, a turbine section of a gas turbine engine as claimed in claim <NUM> is also provided.

In various embodiments, a number of vanes in the first vane section is a whole number of vanes and a number of vanes in the second vane section is a whole number of vanes.

It is to be understood that unless specifically stated otherwise, references to "a," "an," and/or "the" may include one or more than one and that reference to an item in the singular may also include the item in the plural.

The detailed description of various embodiments herein makes reference to the accompanying drawings, which show various embodiments by way of illustration. While these various embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that logical, chemical, and mechanical changes may be made without departing from the scope of the disclosure. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Also, any reference to attached, fixed, connected, or the like may include permanent, removable, temporary, partial, full, and/or any other possible attachment option. Cross hatching lines may be used throughout the figures to denote different parts but not necessarily to denote the same or different materials.

As used herein, "aft" refers to the direction associated with the tail (e.g., the back end) of an aircraft, or generally, to the direction of exhaust of the gas turbine engine. As used herein, "forward" refers to the direction associated with the nose (e.g., the front end) of an aircraft, or generally, to the direction of flight or motion.

In various embodiments and with reference to <FIG>, a gas-turbine engine <NUM> is provided. Gas-turbine engine <NUM> may be a two-spool turbofan that generally incorporates a fan section <NUM>, a compressor section <NUM>, a combustor section <NUM> and a turbine section <NUM>. Alternative engines may include, for example, an augmentor section among other systems or features. In operation, fan section <NUM> can drive coolant along a bypass flow-path B while compressor section <NUM> can drive coolant along a path of core airflow C for compression and communication into combustor section <NUM> then expansion through turbine section <NUM>. Although depicted as a turbofan gas-turbine engine <NUM> herein, it should be understood that the concepts described herein are not limited to use with turbofans as the teachings may be applied to other types of turbine engines including three-spool architectures.

Gas-turbine engine <NUM> may generally comprise a low speed spool <NUM> and a high speed spool <NUM> mounted for rotation about an engine central longitudinal axis A-A' relative to an engine static structure or engine case structure <NUM> via several bearing systems <NUM>, <NUM>-<NUM>, and <NUM>-<NUM>. It should be understood that various bearing systems <NUM> at various locations may alternatively or additionally be provided, including for example, bearing system <NUM>, bearing system <NUM>-<NUM>, and bearing system <NUM>-<NUM>.

Low speed spool <NUM> may generally comprise an inner shaft <NUM> that interconnects a fan <NUM>, a low pressure compressor section <NUM> and a low pressure turbine section <NUM>. Inner shaft <NUM> may be connected to fan <NUM> through a geared architecture <NUM> that can drive fan <NUM> at a lower speed than low speed spool <NUM>. Geared architecture <NUM> may comprise a gear assembly <NUM> enclosed within a gear housing <NUM>. Gear assembly <NUM> couples inner shaft <NUM> to a rotating fan structure. High speed spool <NUM> may comprise an outer shaft <NUM> that interconnects a high pressure compressor <NUM> and high pressure turbine <NUM>. A combustor <NUM> may be located between high pressure compressor <NUM> and high pressure turbine <NUM>. A mid-turbine frame <NUM> of engine case structure <NUM> may be located generally between high pressure turbine <NUM> and low pressure turbine <NUM>. Mid-turbine frame <NUM> may support one or more bearing systems <NUM> in turbine section <NUM>. Inner shaft <NUM> and outer shaft <NUM> may be concentric and rotate via bearing systems <NUM> about the engine central longitudinal axis A-A', which is collinear with their longitudinal axes. As used herein, a "high pressure" compressor or turbine experiences a higher pressure than a corresponding "low pressure" compressor or turbine.

The core airflow C may be compressed by low pressure compressor <NUM> then high pressure compressor <NUM>, mixed and burned with fuel in combustor <NUM>, then expanded over high pressure turbine <NUM> and low pressure turbine <NUM>. Turbines <NUM>, <NUM> rotationally drive the respective low speed spool <NUM> and high speed spool <NUM> in response to the expansion.

Gas-turbine engine <NUM> may be, for example, a high-bypass ratio geared aircraft engine. In various embodiments, the bypass ratio of gas-turbine engine <NUM> may be greater than about six (<NUM>). In various embodiments, the bypass ratio of gas-turbine engine <NUM> may be greater than ten (<NUM>). In various embodiments, geared architecture <NUM> may be an epicyclic gear train, such as a star gear system (sun gear in meshing engagement with a plurality of star gears supported by a carrier and in meshing engagement with a ring gear) or other gear system. Geared architecture <NUM> may have a gear reduction ratio of greater than about <NUM> and low pressure turbine <NUM> may have a pressure ratio that is greater than about five (<NUM>). In various embodiments, the bypass ratio of gas-turbine engine <NUM> is greater than about ten (<NUM>:<NUM>). In various embodiments, the diameter of fan <NUM> may be significantly larger than that of the low pressure compressor <NUM>, and the low pressure turbine <NUM> may have a pressure ratio that is greater than about five (<NUM>:<NUM>). Low pressure turbine <NUM> pressure ratio may be measured prior to inlet of low pressure turbine <NUM> as related to the pressure at the outlet of low pressure turbine <NUM> prior to an exhaust nozzle. It should be understood, however, that the above parameters are exemplary of various embodiments of a suitable geared architecture engine and that the present disclosure contemplates other turbine engines including direct drive turbofans. A gas turbine engine may comprise an industrial gas turbine (IGT) or a geared aircraft engine, such as a geared turbofan, or non-geared aircraft engine, such as a turbofan, a turboshaft, or may comprise any gas turbine engine as desired.

In various embodiments, fan <NUM>, low pressure compressor <NUM>, high pressure compressor <NUM>, low pressure turbine <NUM>, and high pressure turbine <NUM> may comprise one or more stages or sets of rotating blades and one or more stages or sets of stationary vanes axially interspersed with the associated blade stages but non-rotating about engine central longitudinal axis A-A'.

With reference now to <FIG> and still to <FIG>, a portion of an engine section <NUM> is shown in accordance with various embodiments. Engine section <NUM> may be a fan section <NUM>, a compressor section <NUM> or a turbine section <NUM>. Engine section <NUM> is illustrated in <FIG>, for example, as a turbine section. It will be understood that the vane assemblies in this disclosure is not limited to the compressor section, and could extend to other sections of the gas turbine engine <NUM>, including but not limited to the fan section <NUM>.

Referring to <FIG>, engine section <NUM> may include alternating rows of rotor assemblies <NUM> and vane assemblies <NUM> that carry airfoils that extend into the core flow path C. For example, the rotor assemblies <NUM> may carry a plurality of rotating blades <NUM>, while each vane assembly may carry a plurality of vanes <NUM> that extend into the core flow path C. Vanes <NUM> may be arranged circumferentially about engine central longitudinal axis A. Blades <NUM> may rotate about engine central longitudinal axis A-A', while vanes <NUM> may remain stationary about engine central longitudinal axis A-A'. Blades <NUM> create or extract energy (in the form of pressure) from the core airflow that is communicated through engine section <NUM> along the core flow path C. Vanes <NUM> direct the core airflow to blades <NUM> to either add or extract energy.

Vane <NUM> may comprise a leading edge <NUM> and a trailing edge <NUM>. Leading edge <NUM> and trailing edge <NUM> may be configured to direct airflow through engine section <NUM>. In various embodiments, vane assembly <NUM> may increase pressure in engine section <NUM>, and straighten and direct air flow. Vane <NUM> may comprise, for example, an airfoil body <NUM>.

In various embodiments, vanes <NUM> may be made of a metal, such as titanium or high-grade aluminum, a metal alloy such as stainless steel, or a composite material such as a fiber composite material. The vanes <NUM> may be resistant to heat. In various embodiments, the properties of materials use to form vanes <NUM> are compatible with the temperatures and pressures encountered during operation of engine section <NUM>. In various embodiments, a vane <NUM> may be resistant to temperatures experienced in the engine section <NUM>.

Vane <NUM> may be configured to interface with an engine case structure <NUM> disposed radially outward of vane <NUM>. Engine case structure <NUM> provides the support for the vane <NUM> such that loads on vane <NUM> transfer to the engine case structure <NUM>. Vane <NUM> may also be configured to be coupled to platform <NUM>. Platform <NUM> may be an annular structure located around engine central longitudinal axis A-A' and attached to vane <NUM> and other vanes.

Vane <NUM> may be part of a vane assembly. The vane assembly may be designed specifically for the gas-turbine engine <NUM>. In various embodiments, after testing the gas-turbine engine <NUM>, the vane assembly may be adjusted to introduce asymmetry. Asymmetry may be used to interrupt forced response on adjacent blade rows and reduce stress. In order to create asymmetry, the vane assembly may be adjusted on an ad-hoc basis by adjusting the orientation of some of the vanes, adjusting spacing between the vanes, and/or removing some of the vanes. For purposes of creating asymmetry, the adjustments may be made on a circumferential half of the vane assembly only. However, this ad-hoc adjustment of the vane assembly to introduce asymmetry may result in a vane assembly that has a different aerodynamic profile. As used herein, "original vane assembly" refers to the symmetrically or uniformly distributed vane assembly designed for the gas-turbine engine <NUM>.

<FIG> illustrates an axial view of an asymmetric vane assembly <NUM>. The asymmetric vane assembly <NUM> may be a continuous annular shaped structure, or may be made of multiple vane sub-assemblies connected together. The asymmetric vane assembly <NUM> is divided into a first section <NUM> and a second section <NUM>. The first section <NUM> may include a first plurality of vanes 358A equally spaced apart a first distance 356A. The second section <NUM> includes a second plurality of vanes 358B equally spaced apart a second distance 356B. The asymmetric vane assembly <NUM> is located circumferentially around engine central longitudinal axis A-A'. Accordingly, the first plurality of vanes 358A and the second plurality of vanes 358B are located radially around engine central longitudinal axis A-A'. The distance <NUM> between vanes is shown in <FIG> as being the distance between the leading edges of two adjacent vanes or the trailing edges of adjacent vanes. In various embodiments, the distance <NUM> may be referred to as pitch. The pitch may represent the fraction of the circular vane assembly occupied by a section divided by the number of vanes in the section.

The vanes of the asymmetric vane assembly may be located around the engine central longitudinal axis A-A' such that the first plurality of vanes 358A are not downstream from the second plurality of vanes 358B and the second plurality of vanes 358B are not downstream from the first plurality of vanes 358A. That is, a reference point on a particular vane may be coplanar with corresponding respective reference points in the other vanes. For example, the first plurality of vanes 358A and the second plurality of vanes 358B may each be arranged such that a leading edge of a particular vane is located on a common plane as the respective leading edges of the other vanes. In another example, the first plurality of vanes 358A and the second plurality of vanes 358B may each be arranged such that a midpoint of a particular vane is located on a common plane as the respective midpoints of the other vanes.

The first section <NUM> is a high count vane section and the second section <NUM> is a low count vane section. The high count vane section includes a greater number of vanes than the low count vane section. As shown in <FIG>, the first section <NUM> includes <NUM> vanes and the second section <NUM> includes <NUM> vanes. Since the first section <NUM> includes more vanes 358A than the second section <NUM> does, the first distance 356A between the vanes in the first section <NUM> may be less than the second distance 356B between the vanes in the second section <NUM>. The distance between vanes, as used herein, may refer to the distance between adjacent vanes at corresponding parts of the adjacent vanes. For example, the distance between a first vane and a second vane may be measured between a most radially inward location of the first vane and a most radially inward location of the second vane. Alternatively, the distance between the first vane and the second vane may be measured between a most radially outward location of the first vane and a most radially outward location of the second vane.

The design of asymmetric vane assembly <NUM> is such that it has an equivalent operation as the original vane assembly designed for the gas-turbine engine <NUM>. That is, the asymmetric vane assembly <NUM> and the original vane assembly may be interchanged without significant effect on performance of the gas-turbine engine <NUM>. The total number of vanes in the original vane assembly may be different from the total number of vanes (e.g., number of vanes 358A in the first section <NUM> and number of vanes 358B in the second section <NUM>) in the asymmetric vane assembly <NUM>.

A number of vanes in the first plurality of vanes 358A may be greater than a corresponding portion of the original vane assembly. For example, if the first section <NUM> occupies half of the asymmetric vane assembly <NUM> circumferentially and there are <NUM> vanes 358A in the first section <NUM>, there may be less than <NUM> vanes in a circumferential half of the original vane assembly. In this example, there may be <NUM> equally spaced apart vanes in the original vane assembly, resulting in <NUM> vanes per circumferential half of the original vane assembly.

A number of vanes in the second plurality of vanes 358B may be less than a corresponding portion of the original vane assembly. For example, if the second section <NUM> occupies a circumferential half of the asymmetric vane assembly <NUM> and there are <NUM> vanes 358B in the second section <NUM>, there may be more than <NUM> vanes in a circumferential half of the original vane assembly. In this example, there may be <NUM> equally spaced apart vanes in the original vane assembly, resulting in <NUM> vanes per circumferential half of the original vane assembly.

While the asymmetric vane assembly <NUM> is shown as having a first section <NUM> occupying a top circumferential half of the asymmetric vane assembly <NUM> and a second section <NUM> occupying a bottom circumferential half of the asymmetric vane assembly <NUM>, the rotational orientation of the first section <NUM> and the second section <NUM> of the asymmetric vane assembly <NUM> is immaterial. For example, instead of the first section <NUM> being located on a top circumferential half of the asymmetric vane assembly <NUM>, and the second section <NUM> being located on a bottom circumferential half of the asymmetric vane assembly <NUM> (as shown in <FIG>), the first section <NUM> may be located on a right hand side and the second section <NUM> may be located on a left hand side, or vice versa, or any location therebetween.

The first section <NUM> and the second section <NUM> may be divided into multiple sections and distributed circumferentially around the asymmetric vane assembly <NUM> in alternating fashion. For example, a top half 360A of the asymmetric vane assembly <NUM>, as divided by line <NUM>, may have a first high count vane section, a first low count vane section, a second high count vane section, and a second low count vane section, each occupying a quarter of the top half 360A. Likewise, the bottom half 360B of the asymmetric vane assembly <NUM> may have its own first high count vane section, a first low count vane section, a second high count vane section, and a second low count vane section, each occupying a quarter of the bottom half 360B. In general, the first section <NUM> may be distributed circumferentially into multiple subsections, and the second section <NUM> may be distributed circumferentially into multiple subsections, with each subsection having a whole number of vanes. Further, the first section subsections may, in aggregate, occupy a circumferential half of the asymmetric vane assembly <NUM>, and the second section subsections may, in aggregate, occupy another circumferential half of the asymmetric vane assembly <NUM>.

In various embodiments, the number of vanes within each section are a whole number of vanes. For example, if the asymmetric vane assembly <NUM> has a total of <NUM> vanes, then the total number of vane sections would be a factor of <NUM>. Stated another way, total vanes divided by vane sections yields a whole number, in accordance with various embodiments. In various embodiments, the asymmetric vane assembly <NUM> is divided into halves and the number of vanes in each half is a whole number. That is, in these embodiments, a vane section occupies exactly <NUM> circumferential degrees of the asymmetric vane assembly.

While <FIG> illustrates the first section <NUM> as having more vanes than the second section <NUM>, in various embodiments, the second section <NUM> may have more vanes than the first section <NUM> and the second section <NUM> may occupy more of the circumferential portion of the asymmetric vane assembly <NUM> than the first section <NUM>. For example, the vanes 358A of the first section <NUM> may be spaced apart a first distance 356A and the vanes 358B of the second section <NUM> may be spaced apart a second distance 356B, with the first distance being less than the second distance. Thus, if the first section <NUM> and the second section <NUM> occupied equal circumferential portions of the assembly <NUM>, the first section <NUM> would have more vanes 358A than the second section <NUM>. However, if the second section <NUM> occupied a greater circumferential portion of the assembly <NUM> than the first section <NUM>, the second section <NUM> may contain a greater number of vanes 358B than the first section <NUM>. This arrangement would still achieve the asymmetric design desired, while having a substantially similar operational performance as an original vane assembly designed for the gas-turbine engine <NUM>.

In addition to the number of vanes being adjusted, the orientation of the vanes is also adjusted. <FIG> illustrates a radial cross-sectional view of vane <NUM> of the original vane assembly, vane 358A of the first (high count) section <NUM>, and vane 358B of the second (low count) section <NUM>. The vanes <NUM>, 358A, and 358B each have a leading edge side <NUM> and a tail edge side <NUM> and air flowing in core air flow path C travels from the leading edge side <NUM> to the tail edge side <NUM>. In addition, each of the vanes <NUM>, 358A, and 358B are connected to platform <NUM>, which is similar to platform <NUM> of <FIG>.

As shown in <FIG>, each of the vanes <NUM>, 358A, and 358B have substantially similar external airfoil shape <NUM> and similar internal core geometry <NUM>. The internal core geometry <NUM> includes air flow paths for air to flow within the vanes <NUM>, 358A, and 358B. Having substantially similar vanes allows for the asymmetric vane assembly <NUM> to more easily have equivalent operation as the original vane assembly. In addition, having substantially similar internal vane structure or core geometry allows for a more efficient manufacturing of the asymmetric vane assembly <NUM>, as the same internal tooling, cores, and baffles used in the original vane assembly may be used throughout the asymmetric vane assembly <NUM>.

The first section <NUM> has more vanes than the second section <NUM> does. Accordingly, the orientation of each vane in the first section <NUM> and the second section <NUM> may be adjusted to achieve equivalent operation as the original vane assembly.

As shown in <FIG>, the vane 358A of the first section <NUM> of the asymmetric vane assembly <NUM> may be a rotation of vane <NUM> from the original vane assembly, relative to the platform <NUM>. Vane <NUM> may be oriented in an original, baseline position. The vane 358A may be rotated in a first direction 394A (e.g., counterclockwise, as shown in <FIG>). The vane 358B of the second section <NUM> of the asymmetric vane assembly <NUM> may be a rotation of vane <NUM> from the original vane assembly, relative to the platform <NUM>. The vane 358B may be rotated in a second direction 394B (e.g., clockwise, as shown in <FIG>). The second direction 394B may be opposite the first direction 394A.

As illustrated in <FIG>, axis <NUM> represents the orientation of vane <NUM> of original vane assembly, axis 318A represents the orientation of vane 358A from the asymmetric vane assembly <NUM>, and axis 318B represents the orientation of vane 358B of the asymmetric vane assembly <NUM>. The vane 358A from the first section <NUM> of the asymmetric vane assembly <NUM> may be rotated a first rotation angle 320A and the vane 358B of the second section <NUM> of the asymmetric vane assembly <NUM> may be rotated a second rotation angle 320B. The first rotation angle 320A and the second rotation angle 320B may be equal amounts, but in opposite directions. The first rotation angle 320A and the second rotation angle 320B may be different amounts, and in opposite directions.

The first rotation angle 320A and subsequent orientation of the vane 358A may be referred to as an open position and the second rotation angle 320B and subsequent orientation of the vane 358B may be referred to as a closed position. There may be more vanes 358A in the first section <NUM> as compared to a corresponding circumferential section of the original symmetric vane assembly. Accordingly, the vanes 358A are in the open position to accommodate for the increased number of vanes. There may be fewer vanes 358B in the second section <NUM> as compared to a corresponding circumferential section of the original symmetric vane assembly. Accordingly, the vanes 358B are in the closed position to accommodate for the decreased number of vanes. The aggregate airflow passing through the asymmetric vane assembly <NUM> is substantially the same as the aggregate airflow passing through the original symmetric vane assembly. This substantial equivalence in aggregate airflow may be referred to as operational performance. Operational performance may also include efficiency or any performance metrics or measurements associated with a vane assembly working in conjunction with other parts of the gas-turbine engine <NUM>.

The first rotation angle 320A, the second rotation angle 320B, and the number of vanes in the first section <NUM> and the number of vanes in the second section <NUM> may all be determined based on the original vane assembly and the gas-turbine engine <NUM>. Therefore, the first rotation angle 320A, the second rotation angle 320B, and the number of vanes in the first section <NUM> and the number of vanes in the second section <NUM> may vary from gas-turbine engine to gas-turbine engine, and even from section to section within the same gas-turbine engine.

Benefits and other advantages have been described herein with regard to specific embodiments. However, the benefits, advantages, and any elements that may cause any benefit or advantage to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the disclosure.

In the detailed description herein, references to "various embodiments", "one embodiment", "an embodiment", "an example embodiment", etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic.

Claim 1:
An asymmetric vane assembly (<NUM>) for use in a gas turbine engine (<NUM>), the asymmetric vane assembly comprising:
a high count vane section (<NUM>) including a first plurality of vanes (358A); and
a low count vane section (<NUM>) including a second plurality of vanes (358B), a total number of vanes in the first plurality of vanes being greater than a total number of vanes in the second plurality of vanes;
wherein the first plurality of vanes are oriented in an open position;
wherein the second plurality of vanes are oriented in a closed position; and
wherein the first plurality of vanes (358A) and the second plurality of vanes (358B) are each coupled to a platform (<NUM>) and arranged radially around a central axis (A-A'),
wherein the first plurality of vanes being oriented in the open position comprises the first plurality of vanes being angled at a first angle (320A) in a radial cross-sectional view of the vane relative to the platform, and
wherein the second plurality of vanes being oriented in the closed position comprises the second plurality of vanes being angled at a second angle (320B), different to the first angle, in a radial cross-sectional view of the vane relative to the platform;
characterized by:
each vane of the high count vane section and each vane of the low count vane section having similar internal core geometry (<NUM>), wherein the internal core geometry (<NUM>) includes air flow paths for air to flow within the vanes (358A, 358B).