Patent Description:
Gas turbine engine rotors typically have a row of stator vanes upstream or downstream thereof. Vanes may be provided in segments, but may also be provided as individually insertable vanes. The vanes are usually individually manufactured from a molding and/or machining process and are radially inserted inside the engine case through the annular gas flow passage. To minimize leakage between the vane and the case, a grommet may be disposed between the external surface of the case and the vane head. However, the grommet may be subjected to air leaks which may affect the engine's performance.

<CIT> discloses an assembly according to the preamble of claim <NUM>, and a method according to the preamble of claim <NUM>. <CIT> discloses vane assemblies for gas turbine engines, <CIT> discloses a shroud for a gas turbine engine, and <CIT> discloses a stator vane seal arrangement for a gas turbine engine.

In one aspect, the invention describes an assembly as set forth in claim <NUM>.

According to another aspect, the invention describes a method as set forth in claim <NUM>.

Embodiments of the invention are set forth in the dependent claims.

The following invention relates to stator vanes for gas turbine engines, and associated installation methods. A vane as disclosed herein includes a vane body configured to extend in a gas path of the gas turbine engine and a vane head disposed at an axial end of the vane body. The vane head is configured to be sealed with a case defining par of the gas path. The seal between the vane head and the case is achieved using a compressible sealing member that is retained on the vane head. Retaining the sealing member on the vane head may facilitate installation of the vane in the engine by preventing the sealing member from becoming displaced from the vane head during handling and positioning of the vane in the engine.

In some embodiments, the design of the vane head disclosed herein may accommodate a standard (e.g., off the shelf) sealing member such as an o-ring to be used instead of a more expensive custom-molded grommet.

Aspects of various embodiments are described in relation to the figures. The term "substantially" as used herein may be applied to modify any quantitative representation which could permissibly vary without resulting in a change in the basic function to which it is related.

<FIG> illustrates a gas turbine engine <NUM> of a type preferably provided for use in subsonic flight, generally comprising in serial flow communication, a multistage compressor <NUM> for pressurizing air received through an inlet <NUM> of the gas turbine engine <NUM>, 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. Engine <NUM> may include a conventional or other type of gas turbine engine suitable for use in aircraft applications. For example, engine <NUM> may include a turbofan or a turboprop type of engine. In the case of a turbofan engine, ambient air is propelled through a fan <NUM> upstream of the multistage compressor <NUM>.

The flow of air/gas through the gas turbine engine <NUM> between the inlet <NUM> and an outlet <NUM> of the gas turbine engine <NUM> defines a gas path <NUM>. An outer circumference of the gas path <NUM> is defined by a case <NUM> of the gas turbine engine <NUM>. The case <NUM> may include one or a plurality of separate components. The separated components may be assembled to form an internal surface for substantially directing the flow of gas through the gas turbine engine <NUM> and thereby forming the gas path <NUM> which may be substantially annular. For example, the case <NUM> may include a plurality of cylindrical components of varying diameters and means for inter-connecting the plurality of cylindrical components.

In some embodiments, the gas path <NUM> may be a bypass flow path <NUM> (bypass duct) lying between an outer surface of an engine core <NUM> and an inner surface of an outer case <NUM> of the gas turbine engine <NUM>. The outer case <NUM> may be surrounded by additional components (e.g., nacelle) of the gas turbine engine <NUM>. The engine core <NUM> includes the multistage compressor <NUM>, combustor <NUM>, and turbine section <NUM>. In some embodiments, the gas path <NUM> maybe be a substantially annular gas path <NUM> (hereafter referred to as gas path <NUM>) passing through the engine core <NUM>, i.e. a flow path through the multistage compressor <NUM>, combustor <NUM>, and the turbine section <NUM>, and lying between a case <NUM> of the engine core <NUM> and radially-inner surface of the engine core <NUM>.

The gas turbine engine <NUM> may include a plurality of rotors rotating about a central axis <NUM> of the gas turbine engine <NUM>, e.g. fan <NUM>, impellers of the multistage compressor <NUM>, or turbine rotors of the turbine section <NUM>. The gas turbine engine <NUM> may further include one or more stators. In some embodiments, stators may be present upstream of an impeller or other bladed rotor of the multistage compressor <NUM> in the gas path <NUM>. In some embodiments, stators may be present downstream of the fan <NUM> in the bypass flow path <NUM> (fan exit stators). A stator may comprise one or more vanes as described herein circumferentially distributed around the central axis <NUM> and disposed in the gas path <NUM>.

<FIG> is a cross-section of a vane <NUM>. <FIG> is a cross-section of the vane <NUM> of <FIG> installed in a gas turbine engine <NUM>. In reference to both <FIG> and <FIG>, the vane <NUM> is at least partially disposed in a gas path <NUM>. The vane <NUM> passes through a vane-receiving aperture <NUM> formed in a case <NUM> of the gas turbine engine <NUM>. The vane <NUM> may extend from the case <NUM> towards the central axis <NUM>. In some embodiments, the vane <NUM> is a fan exit vane disposed in the bypass flow path <NUM>, <NUM>. In other embodiments, the vane <NUM> is a compressor vane disposed in a portion of the gas path <NUM> within the multistage compressor <NUM>.

The vane <NUM> includes a vane body <NUM> at least partially disposed in the gas path <NUM>. In some embodiments, the vane body <NUM> is substantially completely disposed in the gas path <NUM>. Depending on its configuration, the vane body <NUM> may, in some embodiments, be substantially aligned with an aperture axis <NUM> of the vane-receiving aperture <NUM>. In some embodiments, the aperture axis <NUM> may extend between two ends of the vane body <NUM>. The aperture axis <NUM> may be substantially parallel to an airfoil stacking line of the vane <NUM> in some embodiments. In some embodiments, the aperture axis <NUM> may be substantially aligned with a radial direction of the gas turbine engine <NUM>. For example, the aperture axis <NUM> may be substantially perpendicular to the central axis <NUM>. In some embodiments, when the vane <NUM> is installed in the gas turbine engine <NUM>, the aperture axis <NUM> may extend between a point of the vane body <NUM> closest to the central axis <NUM> of the gas turbine engine <NUM> and another point closest to the case <NUM>.

The vane <NUM> includes a vane head <NUM> disposed at one end of the vane <NUM>, wherein the end is with respect to the aperture axis <NUM>. The vane head <NUM> is disposed outside the gas path <NUM> on outer side <NUM> opposite the gas path <NUM>. The vane head <NUM> includes an abutting surface <NUM> in contact with a portion of a surface <NUM> of the case <NUM> when the vane body <NUM> extends through the vane-receiving aperture <NUM>.

The vane head <NUM> includes a groove <NUM> extending completely around the aperture axis <NUM>. The groove <NUM> defines a circumferential path around the aperture axis <NUM> at a peripheral end of the vane head <NUM>. A sealing member <NUM> is retained in the groove <NUM>. The sealing member <NUM> may be a gasket. The sealing member <NUM> may be made of an elastomeric or other material suitable for withstanding the applicable operating conditions depending on which region of the engine <NUM> the vane <NUM> is installed. The sealing member <NUM> may be an o-ring. The sealing member <NUM> may have a substantially circular overall shape and a circular cross-sectional profile when not deformed. Alternatively, the sealing member <NUM> may have a noncircular overall shape and/or a noncircular cross-sectional profile when not deformed.

The sealing member <NUM> is retained in the groove <NUM> prior to installation of the vane <NUM> in the gas turbine engine <NUM>. The sealing member <NUM> may be so retained without excessive deformation/stretching of the sealing member <NUM>. Upon installation in the gas turbine engine <NUM>, the sealing member <NUM> is compressed. A compression of the sealing member <NUM> facilitates creation of a sealing engagement between the case <NUM> and the vane <NUM>. The sealing may be achieved by way of a compressive force applied to the sealing member <NUM> between the abutting surface <NUM> and the surface <NUM> of the case <NUM>.

A strap <NUM> extending around an outer circumference of the case <NUM> may secure the vane <NUM> in-place by applying a radially-inward force on the vane head <NUM> thereby compressing the sealing member <NUM>. The strap <NUM> may apply a radially inward compressive force on the vane head <NUM> against the case <NUM>, relative to the central axis <NUM>. The strap <NUM> may apply a compressive force on the vane head <NUM> (on an outer surface 36A thereof) along a direction parallel to the aperture axis <NUM>.

The vane head <NUM> may have an outer surface 36A that defines a strap holder for receiving a corresponding fastening strap <NUM> or other member used to fasten and retain the vane <NUM> in place with the case <NUM>. In one embodiment, the strap <NUM> extends circumferentially over the strap holder of all by-pass stator vanes that may be part of a vane ring in order to retain a circular array of vanes <NUM>. The strap holder may include two elongated and axially spaced-apart fingers extending outwardly from the outer surface 36A of the vane head <NUM>. In an alternate embodiment, the strap holder is in the form of a circumferential groove defined in the outer surface 36A. Any other suitable means may be used to maintain the vanes <NUM> in position, such as, but not limited to clamps, fasteners, passages, channels, and the like. In an embodiment, the outer surface 36A is smooth and without a strap holder, the strap holder relying on friction or on other components on the case <NUM> to remain in position.

The groove <NUM> is open to the abutting surface <NUM> and hence to the surface <NUM> of the case <NUM> when installed. The groove <NUM> is also outwardly open relative to an inner region <NUM> surrounded by the groove <NUM> including the (vane-receiving) aperture <NUM>. The groove <NUM> is outwardly open relative to the aperture axis <NUM>. The groove <NUM> defines an inner seating surface <NUM>, wherein the inner seating surface <NUM> is inner relative to the aperture axis <NUM> and the inner region <NUM>. The inner seating surface <NUM> hinders movement of the sealing member <NUM> in the groove <NUM>, thereby retaining the sealing member <NUM> in the groove <NUM>. The inner seating surface <NUM> hinders movement of the sealing member <NUM> towards the abutting surface <NUM>. The inner seating surface <NUM> may hinder movement of the sealing member <NUM> along the aperture axis <NUM>. The inner seating surface <NUM> may be shaped to obstruct movement of the sealing member <NUM>. The inner seating surface <NUM> is a C-shaped inner seating surface <NUM> having a C-shaped cross-section in a plane transvers to a path <NUM> (shown in <FIG>) of the groove <NUM>. In some embodiments, the inner seating surface <NUM> may be C-shaped inner seating surface <NUM> having a C-shaped cross-section in a plane containing the aperture axis <NUM> , e.g. the cross-section shown in <FIG> and <FIG>. The shape of the inner seating surface <NUM> may conform to a shape of the sealing member <NUM> so as to form a complementary fit between the two. In some embodiments, the inner seating surface <NUM> may have a non-linear cross-sectional profile in a plane transvers to the path <NUM> (shown in <FIG>) of the groove <NUM>. In some embodiments, the inner seating surface <NUM> may have a non-linear cross-sectional profile in the plane containing the aperture axis <NUM>. In some embodiments, the inner seating surface <NUM> may have a non-linear cross-sectional profile in the plane containing the aperture axis <NUM>. The two-sided open shape of the groove <NUM> may define an overhanging portion <NUM>. The overhanging portion <NUM> may overhang the surface <NUM> when the vane <NUM> is installed in the gas turbine engine <NUM>.

The groove <NUM> and the inner seating surface <NUM> may be shaped to facilitate manufacturability, e.g. by molding. Aspects of this disclosure may facilitate vanes made of fiber-reinforced composite materials (e.g., carbon fiber reinforced polymer composites). For example, the outwardly open configuration of the groove <NUM> may facilitate a molding process (e.g., opening of a mold) used to manufacturing the vane <NUM>. For example, the configuration of the groove <NUM> may permit the groove <NUM> to be formed by the molding process as opposed to be formed by a subsequent machining or other material removal operation(s).

<FIG> is a transverse cross-section of the vane <NUM>. The cross-section is taken along a section P-P' shown in <FIG> and <FIG>, and the associated cross-sectional plane may be substantially perpendicular to the aperture axis <NUM>. The cross-sectional plane may be substantially perpendicular to a radial direction of the gas turbine engine <NUM>. In this cross-sectional plane, the groove <NUM> (and inner seating surface <NUM>) may follow a circumferential path <NUM> around the inner region <NUM>. The groove <NUM> (and inner seating surface <NUM>) may follow the circumferential path <NUM> around the aperture axis <NUM>. The groove <NUM> may be shaped such that the circumferential path <NUM> is entirely convex, wherein a straight line joining any two points of the circumferential path <NUM> lies completely within the vane head <NUM>. As an example, two points, a and b, are shown on the seating surface <NUM> in <FIG>, along with a line a-b joining a and b. The line a-b lies completely within the vane head <NUM>. In other words, any tangent line on seating surface <NUM> when viewed in the orientation of <FIG> would only intersect the seating surface once. In other words, the circumferential path <NUM> of the groove <NUM> around the inner region <NUM> may be devoid of any concave portions when viewed along the aperture axis <NUM>. The circumferential path <NUM> of the groove <NUM> around the aperture axis <NUM> may be devoid of any concave portions when viewed along a direction along which the inner seating surface <NUM> is configured to hinder movement. Such a shaped groove <NUM> may facilitate the use of a standard o-ring as the sealing member <NUM> and promote uninterrupted contact between the sealing member <NUM> and the inner seating surface <NUM> around the aperture axis <NUM>. The circumferential path <NUM> of the groove <NUM> may be non-circular when viewed along a direction along which the inner seating surface <NUM> is configured to hinder movement. The circumferential path <NUM> of the groove <NUM> may be non-circular when viewed along the aperture axis <NUM>. It is understood that the sealing member <NUM> may be slightly stretched outwardly relative to the inner region <NUM> when retained in the groove <NUM>.

<FIG> is a perspective view of the vane <NUM> with a sealing member <NUM> retained therein, according to the embodiment of <FIG>. <FIG> is an enlarged perspective view of the vane <NUM> shown in <FIG>. The sealing member <NUM> is retained in the groove <NUM> by the movement-hindering effect of the inner seating surface <NUM>. Retaining the sealing member <NUM> in the groove <NUM> in such a manner, prior to installation in the gas turbine engine <NUM>, may facilitate installation by preventing inadvertent displacement of the sealing member <NUM> from the vane head <NUM> during manipulation of the vane <NUM>.

<FIG> is a cross-section of a vane <NUM> according to another embodiment. <FIG> is a cross-section of the vane <NUM> of <FIG> installed in a gas turbine engine <NUM>. In reference to both <FIG> and <FIG>, the groove <NUM> is defined by inner seating surface <NUM>, overhanging portion <NUM> and a fillet <NUM> (rounded intersection) disposed between the inner seating surface <NUM> and the overhanging portion <NUM>. The inner seating surface <NUM> and the overhanging portion <NUM> may define two non-parallel walls forming an acute angle <NUM>. The acute angle formed between the two non-parallel walls may provide retention of sealing member <NUM> within the groove <NUM> prior to and during installation of the vane <NUM> in the gas turbine engine <NUM>. In various embodiments, the acute angle <NUM> may be less than <NUM>°, less than <NUM>°, less than <NUM>°, less than <NUM>°, less than <NUM>°, less than <NUM>° or less than <NUM>° for example. The fillet <NUM> may extend along the entirety of the groove <NUM>. The fillet <NUM> may have a radius that is smaller, larger or substantially the same as a radius of the circular transverse cross-sectional profile of the sealing member <NUM>.

<FIG> is a flowchart illustrating an exemplary method <NUM> of installing a vane <NUM> in a gas turbine engine. The method <NUM> is performed using the vane <NUM> as described herein. The method <NUM> comprises:.

As explained above, the sealing member <NUM> may be an o-ring. The o-ring is retained in the groove <NUM> including the inner seating surface <NUM> configured to hinder movement of the o-ring towards the abutting surface <NUM>. In some embodiments, the inner seating surface <NUM> may be configured to hinder movement of the o-ring along the aperture axis <NUM> of the vane body <NUM>. As shown in <FIG>, the circumferential path <NUM> of the groove <NUM> around the aperture axis <NUM> may be devoid of any concave portions when viewed along the aperture axis <NUM>. The circumferential path <NUM> of the groove <NUM> around the aperture axis <NUM> may be devoid of any concave portions when viewed along a direction along which the inner seating surface <NUM> is configured to hinder movement.

Claim 1:
An assembly for a gas turbine engine (<NUM>) comprising:
a case (<NUM>, <NUM>) having an inner side defining a portion of a gas path (<NUM>, <NUM>) of the gas turbine engine (<NUM>) and an outer side opposite the inner side, the case (<NUM>, <NUM>) having an aperture (<NUM>) extending from the inner side to the outer side;
a sealing member (<NUM>); and
a vane disposed in the gas path (<NUM>, <NUM>) and comprising:
a vane body (<NUM>) extending through the aperture (<NUM>); and
a vane head (<NUM>) disposed at an end of the vane body (<NUM>) and disposed outside the gas path (<NUM>, <NUM>), the vane head (<NUM>) having:
an abutting surface (<NUM>) contacting an outer surface (<NUM>) of the case (<NUM>, <NUM>); and
a groove (<NUM>) receiving the sealing member (<NUM>), the groove (<NUM>) surrounding an inner region (<NUM>) including the aperture (<NUM>) when the vane body (<NUM>) extends through the aperture (<NUM>), the groove (<NUM>) extending completely around an axis (<NUM>) of the aperture (<NUM>) and opening to the abutting surface (<NUM>), characterised in that:
the groove (<NUM>) defines a circumferential path around the aperture axis (<NUM>) at a peripheral end of the vane head (<NUM>),
the groove (<NUM>) is outwardly open relative to the inner region (<NUM>) and the aperture axis (<NUM>), and the groove (<NUM>) has an inner seating surface (<NUM>) receiving the sealing member (<NUM>) and hindering movement of the sealing member (<NUM>) toward the abutting surface (<NUM>), wherein the inner seating surface (<NUM>) has a C-shaped cross-sectional profile in a plane transverse to a path of the groove (<NUM>).