Patent Description:
A gas turbine engine typically includes a fan section, a compressor section, a combustor section, and a turbine section. Air entering the compressor section is compressed and delivered into the combustion section where it is mixed with fuel and ignited to generate a high-energy exhaust gas flow. The high-energy exhaust gas flow expands through the turbine section to drive the compressor and the fan section.

Components in the path of the high-energy gas flow through the turbine section experience high temperatures and pressures. The gas path through the turbine section is typically defined by blade outer air seals proximate a rotating airfoil and static vane stages. Cooling air is supplied to components exposed to the high-energy gas flow. Seals are provided between the blade outer air seals and platforms of the vane stages to contain the cooling air and prevent leakage into the gas path. Seals that are not seated properly or fail to accommodate relative movement between components may enable some cooling air to escape into the gas path and reduce engine efficiency. Moreover, poor sealing can enable high-energy gas flow to leak past the seals, thereby further affecting engine efficiency. Further, deflections of rails of platforms for vanes may compromise structural capability and overall life of the components.

<CIT> discloses vanes mounted to an outer casing via a support ring having an annular main body, an aft wall and a forward wall. In one embodiment the support ring includes a strong backing plate that spans between forward and aft walls. The backing plate may be provided with spaced apart corrugations.

According to a first aspect, vane assemblies are provided. The vane assemblies include a platform, an airfoil extending from a first side of the platform, a forward rail extending from a second side of the platform and arranged along a forward side of the platform, and an aft rail extending from the second side of the platform and arranged along an aft side of the platform. At least one support beam is provided extending in a forward-aft direction between the forward rail and the aft rail and separated from the platform by a first distance. The at least one support beam has a thickness in a radial direction of <NUM>% or less of a total radial extent from the platform to an outer diameter edge of at least one of the forward rail and the aft rail. The at least one support beam has a thickness in a circumferential direction of <NUM>% or less of a total circumferential extent of vane assembly, to define an unobstructed space to permit a cooling flow to flow into the vane assembly in a radial direction to provide cooling to the platform, the forward rail and the aft rail.

Optionally, the vane assemblies may include that the at least one support beam comprises a first support beam and a second support beam separated by the unobstructed space which is defined between the first support beam and the second support beam.

Optionally, the vane assemblies may include that the at least one support beam is formed from a material different from the forward rail and the aft rail.

Optionally, the vane assemblies may include that the at least one support beam is formed from a material that is the same as that of the forward rail and the aft rail.

Optionally, the vane assemblies may include that the at least one support beam is integrally formed with each of the forward rail and the aft rail.

Optionally, the vane assemblies may include that the at least one support beam includes filleted surfaces at locations where the at least one support beam connects to at least one of the forward rail and the aft rail.

Optionally, the vane assemblies may include that the at least one support beam is welded to each of the forward rail and the aft rail.

Optionally, the vane assemblies may include that the at least one support beam is brazed to each of the forward rail and the aft rail.

Optionally, the vane assemblies may include that the forward rail includes a forward hook configured to engage with a portion of a turbine case.

Optionally, the vane assemblies may include that the at least one support beam comprises at least two support beams that occupy a combined thickness in the radial direction of <NUM>% or less of the total radial extent from the platform to an outer diameter edge of at least one of the forward rail and the aft rail and a combined thickness in the circumferential direction of <NUM>% or less of the total circumferential extent of vane assembly.

In accordance with some embodiments, gas turbine engines are provided. The gas turbine engines include a turbine case and a vane assembly. The vane assembly includes a platform, an airfoil extending from a first side of the platform, a forward rail extending from a second side of the platform and arranged along a forward side of the platform, and an aft rail extending from the second side of the platform and arranged along an aft side of the platform. At least one support beam is provided extending in a forward-aft direction between the forward rail and the aft rail and separated from the platform by a first distance. The at least one support beam has a thickness in a radial direction of <NUM>% or less of a total radial extent from the platform to an outer diameter edge of at least one of the forward rail and the aft rail. The at least one support beam has a thickness in a circumferential direction of <NUM>% or less of a total circumferential extent of vane assembly.

Optionally, the gas turbine engines may include that the at least one support beam comprises a first support beam and a second support beam separated by a void in a direction between the first and second support beams.

Optionally, the gas turbine engines may include that the at least one support beam is formed from a material different from the forward rail and the aft rail.

Optionally, the gas turbine engines may include that the at least one support beam is formed from a material that is the same as that of the forward rail and the aft rail.

Optionally, the gas turbine engines may include that the at least one support beam is integrally formed with each of the forward rail and the aft rail.

Optionally, the gas turbine engines may include that the at least one support beam includes filleted surfaces at locations where the at least one support beam connects to at least one of the forward rail and the aft rail.

Optionally, the gas turbine engines may include that the at least one support beam is welded to each of the forward rail and the aft rail.

Optionally, the gas turbine engines may include that the at least one support beam is brazed to each of the forward rail and the aft rail.

Optionally, the gas turbine engines may include that the forward rail includes a forward hook configured to engage with a portion of the turbine case.

Optionally, the gas turbine engines may include that the at least one support beam comprises at least two support beams that occupy a combined thickness in the radial direction of <NUM>% or less of the total radial extent from the platform to an outer diameter edge of at least one of the forward rail and the aft rail and a combined thickness in the circumferential direction of <NUM>% or less of the total circumferential extent of vane assembly.

In one disclosed embodiment, the engine <NUM> bypass ratio is greater than about ten (<NUM>:<NUM>), the fan diameter is significantly larger than that of the low pressure compressor <NUM>, and the low pressure turbine <NUM> has a pressure ratio that is greater than about five <NUM>: <NUM>. The geared architecture <NUM> may be an epicycle gear train, such as a planetary gear system or other gear system, with a gear reduction ratio of greater than about <NUM>:<NUM>. It should be understood, however, that the above parameters are only exemplary of one embodiment of a geared architecture engine and that the present disclosure is applicable to other gas turbine engines including direct drive turbofans.

For vanes within the compressor and/or turbine sections, forward and aft rails may be susceptible to large deflections due to height and loading conditions associated therewith. The large deflections can drive high steady stresses into certain areas of the part that compromise the structural capability and overall life metric of the vane assemblies. Embodiments of the present disclosure are directed to structural ties between the outer diameter forward and aft rails of vane platforms. The structural ties are provided in the form of support beams that mechanically connect the forward and aft rails at the outer diameter thereof. Although the rails tend to deflect toward each other under loading, the structural beams are provided to resist the deflections and prevent fatigue due to the deflections. A reduction in the deflections of the rails can reduce peak stresses in the part and can improve the structural capability and overall life metric of the vane assemblies.

Referring to <FIG>, a schematic illustration of a cross-section of a turbine section <NUM> of a gas turbine engine that may incorporate embodiments of the invention is shown. A core flow path C flows through the turbine section <NUM>. The core flow path C is defined with an outer gas path surface <NUM> and an inner gas path surface <NUM> that is defined along several adjacent components. In the illustrative example, the turbine section <NUM> and the gas path surfaces <NUM>, <NUM> are defined by fixed turbine vanes <NUM> that are interspersed with turbine rotors <NUM> having blades that rotate about an engine central longitudinal axis A. A blade outer air seal (BOAS) <NUM> is disposed radially outward of each of the rotating airfoils (blades) of the turbine rotors <NUM> to define a portion of the outer gas path surface <NUM> of the core flow path C. Further, one or more seals <NUM> are provided between the fixed turbine vanes <NUM> and the BOAS <NUM>.

As shown, the turbine vanes <NUM> include an outer diameter platform <NUM> and an inner diameter platform <NUM>. An airfoil <NUM> extends between the platforms <NUM>, <NUM> within the core flow path C. The outer diameter platform <NUM> includes a forward rail <NUM> and an aft rail <NUM>. The forward rail <NUM> includes a hook <NUM> that engages a portion of a turbine case <NUM> to support the turbine vane <NUM>. The rails <NUM>, <NUM> may be subject to deflections, as described herein.

For example, referring to <FIG>, a schematic illustration of a vane assembly <NUM> is shown. <FIG> illustrates a conventional high pressure turbine vane outer diameter section of the vane assembly <NUM>. The vane assembly <NUM> includes a platform <NUM> with a forward rail <NUM> and an aft rail <NUM>. The forward rail <NUM> includes a forward hook <NUM> for engaging with a portion of a turbine case. An airfoil <NUM> extends radially inward from the platform <NUM>. The vane assembly <NUM> is constrained in a radial direction via interfacing hardware that exposes the forward hook <NUM> to a forward distributed reaction force <NUM>. The vane assembly <NUM> is constrained in the axial direction via interfacing hardware that exposes the aft rail <NUM> to an aft distributed reaction force <NUM>. The forward distributed reaction force <NUM> causes the forward rail <NUM> to deflect in an aftward direction <NUM> and the aft distributed reaction force <NUM> causes the aft rail <NUM> to deflect in a forward direction <NUM>. Generally speaking, directions <NUM>, <NUM> are parallel to an engine axis. Without additional support, the deflection of the forward rail <NUM> in the aftward direction <NUM> and the aft rail <NUM> in the forward direction <NUM> may be of a magnitude that can cause high stresses in the vane assembly <NUM>, may limit overall structural capability, and may negatively impact part life.

Referring now to <FIG>, a schematic illustration of a vane assembly <NUM> in accordance with an embodiment of the invention is shown. <FIG> illustrates a high pressure turbine vane outer diameter section of the vane assembly <NUM>. The vane assembly <NUM> includes a platform <NUM> with a forward rail <NUM> and an aft rail <NUM>. The forward rail <NUM> includes a forward hook <NUM> for engaging with a portion of a turbine case. An airfoil <NUM> extends radially inward from the platform <NUM>. The vane assembly <NUM> is constrained in a radial direction via interfacing hardware that exposes the forward hook <NUM> to a forward distributed reaction force <NUM>. The vane assembly <NUM> is constrained in the axial direction via interfacing hardware that exposes the aft rail <NUM> to an aft distributed reaction force <NUM>. The forward distributed reaction force <NUM> tends to cause the forward rail <NUM> to deflect in an aftward direction <NUM> and the aft distributed reaction force <NUM> tends to cause the aft rail <NUM> to deflect in a forward direction <NUM>.

As shown, the vane assembly <NUM> includes support beams <NUM>. The support beams <NUM> are structural elements that extend between the forward rail <NUM> and the aft rail <NUM> at an outer diameter or end opposite the platform of the vane assembly. That is, the support beams <NUM> are arranged at the maximal end or extent of the rails <NUM>, <NUM> and away from the platform <NUM>. The support beams <NUM>, which connect the forward rail <NUM> and the aft rail <NUM>, are arranged generally extending in a forward/aftward direction (<NUM>, <NUM>), but are skewed or angled relative to the forward/aftward directions (<NUM>, <NUM>) which are parallel to an engine axis. The support beams <NUM> are configured to reduce the deflections of the forward rail <NUM> and the aft rail <NUM> in the aftward direction <NUM> and the forward direction <NUM>, respectively. This reduction in deflections can reduce peak stresses in the part, increase overall structural capability, and positively impact part life.

As illustrated in <FIG>, the support beams <NUM> are discrete structures that extend in the forward-aft direction between the rails <NUM>, <NUM>. In directions normal to the forward-aft direction (e.g., radially inward toward the platform <NUM> ("D<NUM>") and/or in a direction between the support beams <NUM> ("D<NUM>")) are voids or empty space. This allows for reduced weight of the vane assembly <NUM> while improving structural integrity and part life. The support beams <NUM> may include filleted or chamfered surfaces <NUM> at the points where the support beams <NUM> connect to or attach to the respective rails <NUM>, <NUM>.

In some embodiments, such as shown in <FIG>, the support beams <NUM> may be integrally formed with the vane assembly <NUM>. That is, the support beams <NUM> may be formed during a casting or machining process such that the support beams <NUM> are formed from the same material as the rest of the vane assembly <NUM>. In other embodiments, the support beams <NUM> may be secured to the rails <NUM>, <NUM> by bonding, welding, brazing, adhesives, and the like. In still other embodiments, fasteners may be used, such that a fastener passes through a respective rail <NUM>, <NUM> to engage with and secure the support beams <NUM> in place. In some embodiments, the support beams <NUM> may be formed from materials different from the vane assembly <NUM>. For example, because the support beams <NUM> are arranged away from the platform <NUM>, the support beams <NUM> may not be subject to the high temperatures present along the platform <NUM>. As such, the material of the support beams <NUM> may be selected for weight or strength purposes but may not require high temperature materials to be selected, in some embodiments.

The support beams are arranged to reduce deflections of the rails and thus reduce mechanical fatigue caused by such deflections. By arranging the support beams at a position or end of the rails away from the platform, maximal support may be provided, in contrast to a configuration that includes support at the end/location of the platform. Moreover, such arrangement can minimize the size and dimensions of the support beams by reducing the amount of material at the location of the platform itself.

Although shown in <FIG> with only two support beams, those of skill in the art will appreciate that other configurations are possible without departing from the scope of the invention. For example, referring to <FIG>, a schematic illustration of a vane assembly <NUM> in accordance with an embodiment of the invention is shown. <FIG> illustrates a high pressure turbine vane outer diameter section of the vane assembly <NUM>. The vane assembly <NUM> includes a platform <NUM> with a forward rail <NUM> and an aft rail <NUM>. The forward rail <NUM> includes a forward hook <NUM> for engaging with a portion of a turbine case. An airfoil <NUM> extends radially inward from the platform <NUM>. The vane assembly <NUM>, in this embodiment, includes a single support beam <NUM>. The support beam <NUM> is a structural element that extends between the forward rail <NUM> and the aft rail <NUM> at an outer diameter of the vane assembly. The support beam <NUM> extends between the forward rail <NUM> and the aft rail <NUM>. The support beam <NUM> is configured to reduce deflections of the forward rail <NUM> and the aft rail <NUM>, as described above. This reduction in deflection can reduce peak stresses in the part, increase overall structural capability, and positively impact part life.

In <FIG>, the support beam <NUM> does not include the filleted or chamfered surfaces where the support beam <NUM> joins with the rails <NUM>, <NUM>. In contrast, in this embodiment, fasteners <NUM> are used which pass through the rails <NUM>, <NUM> and fixedly attach to and retain the support beam <NUM> in place between the rails <NUM>, <NUM>. It will be appreciated that other types of joining/fastening mechanisms may be employed without departing from the scope of the invention. For example, a support beam may be attached by welding, brazing, adhesives, bonding, integral casting or molding, additive manufacturing, or the like.

It will be appreciated that a greater number of support beams may be employed in various configurations in accordance with the invention. For example, three or more support beams may be incorporated into vane assemblies without departing from the scope of the invention. Further, the support beams disclosed herein may be applied to both inner diameter platforms/vane assemblies (e.g., inner diameter platform <NUM> of <FIG>) and outer diameter platforms/vane assemblies (e.g., outer diameter platform <NUM> of <FIG>).

Turning now to <FIG>, schematic illustrations of a vane assembly <NUM> are shown. <FIG> is a side view illustration of the vane assembly <NUM> as installed within a gas turbine engine and <FIG> is a top down (or radially inward) view of the vane assembly <NUM>. As shown in <FIG>, the vane assembly <NUM> includes a platform <NUM> with a forward rail <NUM> and an aft rail <NUM>. The forward rail <NUM> includes a forward hook <NUM> for engaging with a portion of a turbine case <NUM>. An airfoil <NUM> extends radially inward from the platform <NUM>.

The vane assembly <NUM>, in this embodiment, includes two support beam 614a, 614b. The support beams 614a, 614b are structural elements that extend between the forward rail <NUM> and the aft rail <NUM> at an outer diameter of the vane assembly <NUM>. The support beams 614a, 614b are sized and shaped to maximize structural support while minimizing impact to cooling and weight. As such, as shown in <FIG>, the support beam 614a has a thickness T<NUM> in a radial direction that is a percentage of a total radial extent T<NUM> of the vane assembly <NUM>. For example, in some embodiments, the thickness T<NUM> of the support beam 614a may be <NUM>% or less of the total radial extent T<NUM> of the vane assembly <NUM>. This configuration enables a cooling flow to flow through and along the vane assembly <NUM> to provide cooling to the platform <NUM> and the rails <NUM>, <NUM>. The cooling flow may be in a circumferential direction (e.g., into/out of the page of <FIG>). The circumferential cooling flow area is indicated by area A<NUM> in <FIG> (e.g., a void or unobstructed area/space). Accordingly, or stated another way, the support beams 614a, 614b may only block <NUM>% or less of the circumferential direction, allowing for cooling flow in the circumferential direction to be substantially unimpeded. Although described as covering <NUM>% or less of the total radial extent T<NUM>, in some embodiments, the support beams 614a, 614b may cover <NUM>% or less, <NUM>% or less, <NUM>% or less, <NUM>% or less, or other percentage of the total radial extent T<NUM> of the vane assembly <NUM>.

As shown in <FIG>, the support beams 614a, 614b have a thickness D1a, D1b in a circumferential direction that is a percentage of a total circumferential extent D<NUM> of the vane assembly <NUM>. For example, in some embodiments, the combined thickness D1a+D1b of the support beams 614a, 614b may be <NUM>% or less of the total circumferential extent D<NUM> of the vane assembly <NUM>, with each support beam 614a, 614b being substantially the same and thus occupying half of the combined thickness D1a+D1b of the support beams 614a, 614b. This configuration enables a cooling flow to flow into the vane assembly <NUM> in a radial direction to provide cooling to the platform <NUM> and the rails <NUM>, <NUM>. A cooling flow supply may be in a radial direction (e.g., into/out of the page of <FIG>). The radial cooling flow area is indicated by area A<NUM> in <FIG> (e.g., a void or unobstructed area/space). Accordingly, or stated another way, the support beams 614a, 614b may only block <NUM>% or less of the radial direction, allowing for cooling flow in the radial direction to be substantially unimpeded. Although described as covering <NUM>% or less of the total circumferential extent D<NUM>, in some embodiments, the support beams 614a, 614b may cover <NUM>% or less, <NUM>% or less, <NUM>% or less, <NUM>% or less, or other percentage of the total circumferential extent D<NUM> of the vane assembly <NUM>. Furthermore, even with additional support beams added (e.g., between the illustrated support beams 614a, 614b), the total combined circumferential blockage of the support beams may be <NUM>% or less in combination.

As illustratively shown in <FIG>, the support beams 614a, 614b may have substantially square or rectangular cross-section geometry. In other embodiments, the support beams may have circular cross-sectional geometries, or other geometric shape. It will be appreciated from the illustrative embodiments, that the support beams may have substantially uniform cross-section geometry along the axial (forward-aft) direction, except where the support beams join or are attached to the forward and aft rails. Further, although referred to as support beams, it will be appreciated that the support beams may not be exactly at the outer diameter extent, but rather may be set slightly radially inward from the maximum outer diameter point of the respective rails (e.g., as shown in <FIG>). Similarly, in the circumferential direction, the support beams may not be exactly at the outer edge extent (e.g., as shown in <FIG>).

The terms "substantially" and "about" are intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. Similarly, "substantially" can include deviations of a measurement or value within known errors and variation.

Claim 1:
A vane assembly (<NUM>; <NUM>; <NUM>) comprising:
a platform (<NUM>; <NUM>; <NUM>);
an airfoil (<NUM>; <NUM>; <NUM>) extending from a first side of the platform;
a forward rail (<NUM>; <NUM>; <NUM>) extending from a second side of the platform and arranged along a forward side of the platform;
an aft rail (<NUM>; <NUM>; <NUM>) extending from the second side of the platform and arranged along an aft side of the platform;
at least one support beam (<NUM>; <NUM>; 614a, 614b) extending in a forward-aft direction between the forward rail and the aft rail and separated from the platform by a first distance,
wherein the at least one support beam has a thickness (T<NUM>) in a radial direction of <NUM>% or less of a total radial extent (T<NUM>) from the platform to an outer diameter edge of at least one of the forward rail and the aft rail, and
characterized in that
the at least one support beam has a thickness (D<NUM>a, D1b) in a circumferential direction of <NUM>% or less of a total circumferential extent (D<NUM>) of the vane assembly, to define an unobstructed space (A<NUM>) to permit a cooling flow to flow into the vane assembly in a radial direction to provide cooling to the platform (<NUM>; <NUM>; <NUM>), the forward rail (<NUM>; <NUM>; <NUM>) and the aft rail (<NUM>; <NUM>; <NUM>).