Patent Description:
In certain types of gas turbine engines, the fan includes a fan rotor having fan blades with integral platforms located near the roots of the fan blades. In other types of gas turbine engines with more complex fan blade designs, non-integral platforms radially extend from a fan rotor between adjacent fan blades. Because these platforms are non-integral with the fan blades, spaces may be formed between the platforms and the blades. As a result, aerodynamic efficiency may be lost due to these spaces between the platforms and the fan blades. In order to improve aerodynamic efficiency and secondary air flow, these spaces may be sealed.

One option for sealing the space between adjacent fan blades may be the inclusion of a fan blade platform seal mounted to the fan rotor between the adjacent fan blades. The fan blade platform seal may include a platform portion and seal portions mounted to the sides of the platform portion to form seals with the respective adjacent fan blades. However, conventional fan blade platform seals are not robust and may suffer from disbonding or inversion (e.g., rotation of the seal into the engine flow path) of the seal portions during certain conditions of gas turbine engine operation. Damage or loss of the seal portions during gas turbine engine operation may, in turn, lead to reduced performance of the gas turbine engine. Accordingly, what is needed is an improved fan blade platform seal which addresses one or more of the above-noted concerns without adding substantial weight or presenting additional foreign object damage risk.

<CIT> discloses a rotor seal in accordance with the preamble of claim <NUM>.

According to an aspect of the present invention, a fan blade platform seal is provided in accordance with claim <NUM>.

Optionally, the first sealing flap extends from the first bonding segment to a sealing end. The first sealing flap projects away from the platform portion. The first sealing flap includes a first seal inner surface extending from the first inner surface of the first bonding segment.

Optionally, the stiffening portion is additionally mounted to the first seal inner surface.

Optionally, the stiffening portion is additionally mounted to the bonding surface of the platform portion.

Optionally, the stiffening portion further includes a second bonding layer bonded to a second layer side of the stiffening layer opposite the first layer side.

Optionally, the first seal portion includes a seal body and a fabric layer covering at least a portion of the seal body.

Optionally, the platform portion further includes a forward end and an aft end and each of the first seal portion and the second seal portion extend from the forward end to the aft end.

Optionally, the stiffening layer extends from the forward end to the aft end.

According to another aspect of the present invention, a method for forming a fan blade platform seal is provided in accordance with claim <NUM>.

Optionally, the first seal portion further includes a first sealing flap extending from the first bonding segment to a sealing end. The method further includes applying the stiffening portion to a first seal inner surface of the first sealing flap by bonding the stiffening layer to the first seal inner surface with the bonding layer.

Optionally, the method further includes applying the stiffening portion to the bonding surface of the platform portion by bonding the stiffening layer to the bonding surface with the bonding layer.

Optionally, the bonding layer includes an adhesive.

Optionally, the stiffening portion extends from the first seal portion to the second seal portion.

Optionally, a gas turbine engine includes a fan configured to rotate about a longitudinal centerline of the gas turbine engine. The fan includes a plurality of fan blades extending radially outward from and circumferentially spaced about a fan rotor. The gas turbine engine further includes the fan blade platform seal circumferentially disposed between circumferentially adjacent fan blades of the plurality of fan blades.

The present invention, and all its aspects, embodiments and advantages associated therewith will become more readily apparent in view of the detailed description provided below, including the accompanying drawings.

It is noted that various connections are set forth between elements in the following description and in the drawings. It is noted that these connections are general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. A coupling between two or more entities may refer to a direct connection or an indirect connection. An indirect connection may incorporate one or more intervening entities. It is further noted that various method or process steps for embodiments of the present disclosure are described in the following description and drawings. The description may present the method and/or process steps as a particular sequence. However, to the extent that the method or process does not rely on the particular order of steps set forth herein, the method or process should not be limited to the particular sequence of steps described. As one of ordinary skill in the art would appreciate, other sequences of steps may be possible. Therefore, the particular order of the steps set forth in the description should not be construed as a limitation.

Referring to <FIG>, an exemplary gas turbine engine <NUM> is schematically illustrated. The gas turbine engine <NUM> is disclosed herein as a two-spool turbofan engine that generally includes a fan section <NUM>, a compressor section <NUM>, a combustor section <NUM>, and a turbine section <NUM>. The fan section <NUM> drives air along a bypass flow path <NUM> while the compressor section <NUM> drives air along a core flow path <NUM> for compression and communication into the combustor section <NUM> and then expansion through the turbine section <NUM>. Although depicted as a turbofan gas turbine engine in the disclosed non-limiting embodiments, 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 those with three-spool architectures.

The gas turbine engine <NUM> generally includes a low-pressure spool <NUM> and a high-pressure spool <NUM> mounted for rotation about a longitudinal centerline <NUM> of the gas turbine engine <NUM> relative to an engine static structure <NUM> via one or more bearing systems <NUM>. It should be understood that various bearing systems <NUM> at various locations may alternatively or additionally be provided.

The low-pressure spool <NUM> generally includes a first shaft <NUM> that interconnects a fan <NUM>, a low-pressure compressor <NUM>, and a low-pressure turbine <NUM>. The first shaft <NUM> is connected to the fan <NUM> through a gear assembly of a fan drive gear system <NUM> to drive the fan <NUM> at a lower speed than the low-pressure spool <NUM>. The high-pressure spool <NUM> generally includes a second shaft <NUM> that interconnects a high-pressure compressor <NUM> and a high-pressure turbine <NUM>. It is to be understood that "low pressure" and "high pressure" or variations thereof as used herein are relative terms indicating that the high pressure is greater than the low pressure. An annular combustor <NUM> is disposed between the high-pressure compressor <NUM> and the high-pressure turbine <NUM> along the longitudinal centerline <NUM>. The first shaft <NUM> and the second shaft <NUM> are concentric and rotate via the one or more bearing systems <NUM> about the longitudinal centerline <NUM> which is collinear with respective longitudinal centerlines of the first and second shafts <NUM>, <NUM>.

Airflow along the core flow path <NUM> is compressed by the low-pressure compressor <NUM>, then the high-pressure compressor <NUM>, mixed and burned with fuel in the combustor <NUM>, and then expanded over the high-pressure turbine <NUM> and the low-pressure turbine <NUM>. The low-pressure turbine <NUM> and the high-pressure turbine <NUM> rotationally drive the low-pressure spool <NUM> and the high-pressure spool <NUM>, respectively, in response to the expansion.

Referring to <FIG> and <FIG>, the fan <NUM> includes a plurality of fan blades <NUM> extending radially outward from and circumferentially spaced about a fan rotor <NUM>. A plurality of fan blade platform seals <NUM> extend from the fan rotor <NUM> with each fan blade platform seal <NUM> disposed between circumferentially adjacent fan blades of the plurality of fan blades <NUM>. The fan blade platform seal <NUM> includes a platform portion <NUM> having a first side <NUM> and a second side <NUM> opposite the first side <NUM>. The fan blade platform seal <NUM> further includes a first seal portion <NUM> mounted to the first side <NUM> of the platform portion <NUM> and a second seal portion <NUM> mounted to the second side <NUM> of the platform portion <NUM>. The first seal portion <NUM> is in sealing communication with a first fan blade of the plurality of fan blades <NUM> while the second seal portion <NUM> is in sealing communication with a second adjacent fan blade of the plurality of fan blades <NUM>.

Referring to <FIG>, the platform portion <NUM> further includes a flow path surface <NUM>, which is a radially outer surface of the platform portion <NUM>, and a bonding surface <NUM> opposite the flow path surface <NUM>. Each of the flow path surface <NUM> and the bonding surface <NUM> extend between the first side <NUM> and the second side <NUM> of the platform portion <NUM>. The flow path surface <NUM> and the bonding surface <NUM> further extend between a forward end <NUM> and an aft end <NUM> of the platform portion <NUM>.

Each seal portion <NUM>, <NUM> includes a seal body <NUM> including a sealing flap <NUM>, a bumper rib <NUM>, and a bonding segment <NUM>. The sealing flap <NUM>, bumper rib <NUM>, and bonding segment <NUM> of the seal portions <NUM>, <NUM> may extend along the respective sides <NUM>, <NUM> of the platform portion for all or a portion of a distance between the forward end <NUM> and the aft end <NUM> of the platform portion. The bonding segment <NUM> may be mounted to the platform portion <NUM> by any suitable means such as, for example, an adhesive. The bonding segment <NUM> may include an outer surface <NUM> mounted to the bonding surface <NUM> of the platform portion <NUM> and an inner surface <NUM> opposite the outer surface <NUM>. The outer surface <NUM> and the inner surface <NUM> may extend between the sealing flap <NUM> and a bonding segment end <NUM> of the bonding segment <NUM>.

The sealing flap <NUM> may extend from the bonding segment <NUM> to a sealing end <NUM> and may converge with the bonding segment <NUM> at a crook <NUM> so that the sealing flap <NUM> is bendable with respect to the bonding segment <NUM>. The sealing flap <NUM> may project away from the platform portion <NUM> so as to contact an adjacent fan blade of the plurality of fan blades <NUM>. The sealing flap <NUM> may include a seal outer surface <NUM> extending from the bumper rib <NUM> to the sealing end <NUM> and a seal inner surface <NUM>, opposite the seal outer surface <NUM>, and extending from the inner surface <NUM> of the bonding segment <NUM>.

The bumper rib <NUM> may extend from the seal portion <NUM>, <NUM> in a substantially radial direction proximate the location of the seal portion <NUM>, <NUM> where the sealing flap <NUM> converges with the bonding segment <NUM>. Similar to the bonding portion <NUM>, in various embodiments, the bumper rib <NUM> may be mounted to the respective side <NUM>, <NUM> of the platform portion <NUM> by any suitable means such as, for example, an adhesive. The bumper rib <NUM> may be configured to provide a locating feature for mounting the seal portion <NUM>, <NUM> to the platform portion <NUM>. In various embodiments the bumper rib <NUM> may include an end <NUM> which may be substantially rounded or squared. In various embodiments, the end <NUM> of the bumper rib <NUM> may be flush with the flow path surface <NUM> of the platform portion <NUM>. While <FIG> illustrates the first seal portion <NUM>, it should be understood that the illustrated features of the first seal portion <NUM> may also be illustrative of the features of the second seal portion <NUM> as described above.

Referring to <FIG>, the fan blade platform seal <NUM> further includes a stiffening portion <NUM>. As will be described in greater detail, the stiffening portion <NUM> may be mounted to one or more surfaces on the radially interior side of the fan blade platform seal <NUM>. The stiffening portion <NUM> includes a stiffening layer <NUM> bonded to one or more of the platform portion <NUM> and the seal portions <NUM>, <NUM> by a first bonding layer <NUM> on a first layer side <NUM> of the stiffening layer <NUM>. In various embodiments, the stiffening portion <NUM> may further include a second bonding layer <NUM> bonded to all or a portion of a second layer side <NUM> of the stiffening layer <NUM> opposite the first layer side <NUM>.

The stiffening layer <NUM> may be formed from any suitable material having sufficient stiffness and lightweight properties. The stiffening layer <NUM> is formed from or includes a reinforcement fabric, for example, a fiberglass material such as a fiberglass cloth. In various other embodiments, the stiffening layer <NUM> may be formed from or include other reinforcement fabrics, for example, carbon fiber, aramid fiber, polyester fabric, KEVLAR, etc. The bonding layers <NUM>, <NUM> may be formed from or may include an adhesive such as, for example, a resin epoxy, a silicon adhesive, or any other suitable bonding agent. One or both of the bonding layers <NUM>, <NUM> may saturate, at least in part, the stiffening layer <NUM>, thereby further stiffening the stiffening layer <NUM> once the bonding layer <NUM>, <NUM> has cured. The material of the bonding layers <NUM>, <NUM> may have a sufficiently low viscosity, in an uncured state, to saturate the stiffening layer <NUM>, while providing suitable stiffness to the stiffening layer <NUM> and one or more portions of the fan blade platform seal <NUM>, in a cured state. In various embodiments, a material of the bonding layer <NUM> may be different than a material of the bonding layer <NUM>.

As shown in <FIG>, in various embodiments, the stiffening portion <NUM> may be configured as a joining member 96A with the stiffening layer <NUM> bonded to one or more of the inner surface <NUM> of the bonding segments <NUM> of the seal portions <NUM>, <NUM> as well as the bonding surface <NUM> of the platform portion <NUM> by the first bonding layer <NUM>. For example, the stiffening layer <NUM> may extend across the fan blade platform seal <NUM> from the inner surface <NUM> of the bonding segment <NUM> of the first seal portion <NUM> to the inner surface <NUM> of the bonding segment <NUM> of the second seal portion <NUM> along the bonding surface <NUM> of the platform portion <NUM>. In this configuration, the stiffening portion <NUM> of the fan blade platform seal <NUM> may provide additional stiffness and strength to the fan blade platform seal <NUM> while also supporting and/or retaining the seal portions <NUM>, <NUM> to prevent disbonding of the seal portions <NUM>, <NUM> from the platform portion <NUM>. In various embodiments, the stiffening portion <NUM> may contact the seal inner surface <NUM> of the sealing flap <NUM> while in other various embodiments the stiffening portion <NUM> may not contact the seal inner surface <NUM> of the sealing flap <NUM>. In various embodiments, the stiffening portion <NUM> may be disposed at the aft end <NUM> of the fan blade platform seal <NUM>, for example, along the Line A-A shown in <FIG>. However, in various other embodiments, the stiffening portion <NUM> may be disposed along other portions of the fan blade platform seal <NUM> between the forward end <NUM> and the aft end <NUM> or may extend an entire length of the fan blade platform seal <NUM> between the forward end <NUM> and the aft end <NUM>. Further, in various embodiments, the stiffening portion <NUM> shown in <FIG> may be used in combination with one or more additional embodiments of the stiffening portion <NUM>, which will be discussed in further detail.

As shown in <FIG>, in various embodiments, the stiffening portion <NUM> may be configured as a stiffening member 96B with the stiffening layer <NUM> bonded to the inner surface <NUM> of the bonding segment <NUM> as well as the seal inner surface <NUM> of the sealing flap <NUM> for one or both of the seal portions <NUM>, <NUM>. For example, the stiffening layer <NUM> may extend across the inner surface <NUM> and the seal inner surface <NUM> from the sealing end <NUM> to the bonding segment end <NUM>. In this configuration, the stiffening portion <NUM> of the fan blade platform seal <NUM> may provide additional stiffness and strength to the sealing flap <NUM> so as to prevent or reduce the likelihood of an inversion of the sealing flap <NUM>. In various embodiments, the stiffening portion <NUM> may be disposed in a central portion of the fan blade platform seal <NUM> between the forward end <NUM> and the aft end <NUM>, for example, along the Line B-B shown in <FIG>. However, in various other embodiments, the stiffening portion <NUM> may be disposed along other portions of the fan blade platform seal <NUM> between the forward end <NUM> and the aft end <NUM> or may extend an entire length of the fan blade platform seal <NUM> between the forward end <NUM> and the aft end <NUM>. Further, as discussed above with respect to the stiffening portion <NUM> shown in <FIG>, in various embodiments, the stiffening portion <NUM> shown in <FIG> may be used in combination with one or more additional embodiments of the stiffening portion <NUM>.

As shown in <FIG>, in various embodiments, the stiffening portion <NUM> may extend across a width of the fan blade platform seal <NUM>. For example, in various embodiments, the stiffening portion <NUM> may extend from the sealing end <NUM> of the first seal portion <NUM> to the sealing end <NUM> of the second seal portion <NUM>. The stiffening layer <NUM> may be bonded to one or more of the inner surfaces <NUM> and seal inner surfaces <NUM> of the seal portions <NUM>, <NUM> as well as the bonding surface <NUM> of the platform portion <NUM> by the first bonding layer <NUM>. In various embodiments, the stiffening portion <NUM> may extend continuously across the width of the fan blade platform seal <NUM>, while in various other embodiments, the stiffening portion <NUM> may be segmented along the width of the fan blade platform seal <NUM>. In various embodiments, the stiffening portion <NUM> may be disposed in a portion of the fan blade platform seal <NUM> between the forward end <NUM> and the aft end <NUM>, for example, along the Lines A-A and/or B-B shown in <FIG>. However, in various other embodiments, the stiffening portion <NUM> may be disposed along other portions of the fan blade platform seal <NUM> between the forward end <NUM> and the aft end <NUM> or may extend an entire length of the fan blade platform seal <NUM> between the forward end <NUM> and the aft end <NUM>. Further, as discussed above with respect to the stiffening portion <NUM> shown in <FIG> and <FIG>, in various embodiments, the stiffening portion <NUM> shown in <FIG> may be used in combination with one or more additional embodiments of the stiffening portion <NUM>.

In various embodiments, one or both of the seal portions <NUM>, <NUM> may include a fabric layer <NUM> covering at least a portion of the seal body <NUM>, as exemplified by the dashed lines in <FIG>. The fabric layer <NUM> may be formed from, but is not limited to, a polyester weave or an aramid. The fabric layer <NUM> may aid in protecting the seal portions <NUM>, <NUM> from wear and may facilitate improved bonding of the seal portions <NUM>, <NUM> to one or both of the platform portion <NUM> and the stiffening portion <NUM>.

Claim 1:
A fan blade platform seal (<NUM>) for a gas turbine engine (<NUM>), the fan blade platform seal (<NUM>) comprising:
a platform portion (<NUM>) comprising a first side (<NUM>) and a second side (<NUM>) opposite the first side (<NUM>), the platform portion (<NUM>) further comprising a flow path surface (<NUM>) extending between the first side (<NUM>) and the second side (<NUM>) and a bonding surface (<NUM>) opposite the flow path surface (<NUM>);
a first seal portion (<NUM>) comprising a first seal body (<NUM>), the first seal body (<NUM>) comprising a first sealing flap (<NUM>), a first bumper rub (<NUM>), and a first bonding segment (<NUM>), the first bonding segment (<NUM>) comprising a first outer surface (<NUM>), mounted to the platform portion (<NUM>) on the first side (<NUM>) of the platform portion (<NUM>), and a first inner surface (<NUM>) opposite the first outer surface (<NUM>);
a second seal portion (<NUM>) comprising a second seal body (<NUM>), the second seal body (<NUM>) comprising a second sealing flap (<NUM>), a second bumper rib (<NUM>), and a second bonding segment (<NUM>), the second bonding segment (<NUM>) comprising a second outer surface (<NUM>), mounted to the platform portion (<NUM>) on the second side (<NUM>) of the platform portion (<NUM>), and a second inner surface (<NUM>) opposite the second outer surface (<NUM>); and
a stiffening portion (<NUM>) mounted to the first inner surface (<NUM>) and the second inner surface (<NUM>),
wherein
the stiffening portion (<NUM>) comprises a first bonding layer (<NUM>) bonded to the first inner surface (<NUM>) and the second inner surface (<NUM>), and characterized in that, the stiffening portion (<NUM>) further comprises a stiffening layer (<NUM>) bonded to the first bonding layer (<NUM>) on a first layer side (<NUM>) of the stiffening layer (<NUM>), wherein the stiffening layer (<NUM>) comprises a reinforcement fabric.