Patent Description:
A gas turbine engine includes a plurality of turbine blades and compressor blades each received in a slot of a disk. The blades are exposed to aerodynamic forces that can result in vibratory stresses. A seal damper or damper can be located under platforms of adjacent blades to reduce the vibratory response and provide frictional damping between the blades. The seal damper slides on an underside of the platforms. The seal damper is made of a material that is dissimilar from the material of the blades. When the vibratory motions of adjacent blades oppose each other (that is, occur out of phase), the seal damper slides to absorb the energy of vibration.

Seal dampers work by conforming to the underside of blade platforms to seal the mate-face gap between blades and provide frictional damping to suppress the vibratory response of the blades to excitations in the engine. These dampers are typically made of sheet metal and have been shown to readily conform to the underside of the platform when subjected to centrifugal loads in a high temperature environment due to their lack of stiffness out-of-plane.

Sometimes seal dampers will experience unintentional bulk tangential movement relative to the damper pocket due to the dynamic forces imposed on it by the rotation of the blades and the lack of sufficient restraint devices. To maximize damper efficiency, damper configurations are sought which minimize weight and maximize damper stiffness. Thus it is desirable to limit the number of weight increasing restraint devices on the damper (i.e. features which interlock with "damper tabs", "damper nubs", or some other feature of the under-platform geometry, or "bathtub" type designs that pre-conform to under-platform filleting).

<CIT> discloses a blade rotor feather seal.

<CIT> discloses a turbine wheel for a turbine engine with sealing and damping sheets housed in a cavity connecting the platforms.

<CIT> discloses a fan blade platform seal for reducing fluid flow through the gap between adjacent blade platforms.

Accordingly, it is desirable to provide a method and apparatus for restraining movement of a damper with respect to a blade platform.

Viewed from one aspect the invention provides a disk for a gas turbine engine, the disk having a plurality of blades secured thereto, each blade comprising: a root; an airfoil; a platform located between the root and the airfoil of the blade, and a damper restraint located at a peripheral edge of the platform, wherein the damper restraint comprises at least one raised feature extending along at least a portion of the peripheral edge of the platform; wherein adjacent platforms of adjacent blades of the plurality of blades of the disk define a cavity and a seam, and a damper seal is received in the cavity and covers the seam; wherein a concave surface formed in a top surface portion of the damper seal contacts and engages the raised feature and bends round the raised feature; and wherein the raised feature has a cross-section with a smooth profile, and extends along an entire length of the damper seal.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the damper restraint may be a pair of raised features extending along at least a portion of opposing peripheral edges of the platforms of the adjacent blades.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the damper restraint may extend along a suction side of the platform.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the damper restraint may extend along a pressure side of the platform.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the blades may be turbine blades.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the blades may be compressor blades.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the damper seal may be formed from stamped sheet metal.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the raised feature may be added to each blade via an additive technique such as welding.

In another aspect of the invention, there is provided a method of damping vibrations between adjacent blades secured to a disk of a gas turbine engine, each blade comprising: a root, an airfoil, and a platform located between the root and the airfoil of each blade, wherein adjacent platforms of adjacent blades define a cavity and a seam, the method comprising steps of: locating a damper seal in the cavity adjacent to a seam defined by adjacent platforms of the adjacent blades of the gas turbine engine; and restraining the movement of the damper seal in a direction away from the seam by retaining the damper seal with at least one protrusion extending along a peripheral edge of at least one of the adjacent platforms, where a concave surface in a top surface portion of the damper seal contacts and engages the at least one protrusion, and bends around the at least one protrusion, wherein the raised feature has a cross-section with a smooth profile, and extends along an entire length of the damper seal.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the damper seal may be formed from stamped sheet metal and the blades may be either compressor blades or turbine blades.

The at least one protrusion may be added to each blade via an additive technique such as welding.

The following descriptions are by way of example only, and should not be considered limiting in any way. With reference to the exemplary accompanying drawings, like elements are numbered alike:.

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.

The turbine section <NUM> includes turbine disks <NUM> that each rotate about the axis A. As is known in the related arts, the turbine section may include a plurality of stages each having a plurality of turbine blades mounted to a respective turbine disk of each stage.

<FIG> illustrates a non-limiting perspective view of a damper seal or damper seal <NUM> for installation under platforms of adjacent turbine blades to reduce the vibratory response and provide frictional damping between the turbine blades as well as sealing the mate-face gap between blades. These dampers may be made of sheet metal and conform to the underside of the platform when subjected to centrifugal loads in a high temperature environment due to their lack of stiffness out-of-plane. Although the present disclosure is described with reference to turbine blades it is understood that anyone of the various embodiments disclosed herein may be applied to platforms of adjacent compressor blades of a compressor disk or rotor to reduce the vibratory response and provide frictional damping between the compressor blades as well as sealing the mate-face gap between blades. Therefore and when referring to <FIG> these may alternatively be referred to as compressor blades. Moreover, various embodiments of the present disclosure may be applied in any other application where there is a desire to reduce the vibratory response and provide frictional damping between two adjacent items that are rotated about an axis as sealing the mate-face gap between the two adjacent items. <FIG> is a side view of the damper seal or damper seal <NUM> illustrated in <FIG>.

The damper seal <NUM> may also be formed by direct metal laser sintering. Other manufacturing methods are possible. The damper seal <NUM> may be ductile enough to conform to a lower surface of the platform of the turbine blade. In one example, the damper seal <NUM> is substantially c-shaped.

Referring now to <FIG>, a top perspective view of the damper seal <NUM> installed in adjacent turbine blades <NUM> is provided. The damper seal <NUM> is located in a neck cavity <NUM> of the turbine blades <NUM>. As illustrated in at least <FIG>, the neck cavity <NUM> is defined as being located below the platform <NUM> of the turbine blade <NUM> and above the turbine disk the blades <NUM> are secured to.

As illustrated, the damper seal <NUM> spans a space <NUM> between adjacent platforms <NUM> of adjacent turbine blades <NUM> to provide both damping and sealing and prevent the leakage of the cooling air from the cavity <NUM>. The damper seal <NUM> imposes a normal load on the adjacent turbine blades <NUM> due to centrifugal force. The resulting frictional force created by the normal load produces damping to reduce a vibratory response. The damper seal <NUM> prevents the cooling air in the neck cavity <NUM> from leaking into the hot flow gas path between airfoils <NUM> of the turbine blades <NUM>.

In accordance with an embodiment of the present disclosure, a damper restraint <NUM> for retaining a damper seal <NUM> received in the cavity <NUM> is provided. In one embodiment, the damper restraint <NUM> is a raised portion of material, rib, bump or feature located at a lateral or peripheral edge <NUM> of the platform <NUM>.

The damper restraint <NUM> is configured to engage a top portion or top surface portion <NUM> of the damper seal <NUM> that extends between a first end portion <NUM> and an opposing second end portion <NUM> of the damper seal <NUM>. As illustrated, the first end portion <NUM> and the second end portion <NUM> extend towards a root <NUM> of the turbine blade <NUM> when the damper seal <NUM> is located in the cavity <NUM>.

In one embodiment and as illustrated in the attached FIGS. , the damper restraint <NUM> may be the combination of a raised feature, or rail or "bump" <NUM> located at the peripheral edge <NUM> under a suction side <NUM> of the platform <NUM> that runs along the peripheral or lateral edge <NUM> of the platform <NUM> of one blade or a first blade <NUM> and a raised feature, or rail or "bump" <NUM> located at the peripheral edge <NUM> under a pressure side <NUM> of the platform <NUM> of another blade or second blade <NUM> that is adjacent to the first blade <NUM>. As such, the pair of side by side raised features, rails or "bumps" <NUM>, <NUM> provide the damper restraint <NUM> when they are side by side, which corresponds to the blades <NUM> being secured to the disk <NUM>. One non-limiting configuration is illustrated in <FIG>.

In one embodiment and as illustrated in <FIG>, the raised feature(s), or rail(s) or "bump(s)" <NUM>, <NUM>, may run along the entire length of edge <NUM>. Alternatively, the raised feature(s), or rail(s) or "bump(s)" <NUM>, <NUM>, may run along a majority (e.g. greater than <NUM> %) of the entire length of edge <NUM>. Of course, other variations less than <NUM>% are also considered to be within the scope of various embodiments of the present disclosure. In yet another embodiment and referring now to <FIG> the raised feature(s), or rail(s) or "bump(s)" <NUM>, <NUM>, may run intermittently and comprise an interrupted pattern or plurality of raised feature(s), or rail(s) or "bump(s)" <NUM>, <NUM> that run along the entire length of edge <NUM> or any portion thereof (e.g., greater or less than <NUM>%).

In yet another embodiment the raised feature(s), or rail(s) or "bump(s)" <NUM>, <NUM> may be located on only one side of the platform <NUM> (e.g., either the suction side <NUM> or the pressure side <NUM>.

By locating the damper restraint <NUM> on an interior surface <NUM> of the platform <NUM>, a device is created that restrains the damper <NUM> from sliding toward the suction side of the pocket <NUM> when it is subject to tangential dynamic forces or rotational forces (e.g. induced by the orientation of the pocket (or broach angle) relative to the axis of rotation). Thus, undesired tangential movement of the damper seal <NUM> is prevented.

The dashed lines <NUM> in <FIG> illustrate the nominal position of the edges <NUM> (illustrated in <FIG>) of the damper seal <NUM>.

This design feature (e.g., damper restraint <NUM>) allows the potential elimination of weight increasing damper restraint devices as it only requires features at the peripheral edges of the platform. It can make new and current damper designs more effective without modifying the damper itself, and with only a minimal change to the blade platform that can be readily cast in. The feature can also be formed through some additive technique such as welding so that is can be used as a potential aftermarket fix to reduce the amount of damper deformation seen in service.

Furthermore and in one embodiment, one or more rails, or regions of generally raised material, running along the damper edge are formed on the underside of the blade suction side or pressure side platform by casting, machining, or some additive method. The restraint extends according to the invention along the entire length of the damper seal. The cross section of the rail has a smooth profile according to the invention, or a circular profile.

By bending the top surface portion <NUM> about the protrusion formed by the bumps or features <NUM>, <NUM>, a radial component is added to the top surface portion <NUM> of the damper seal <NUM>. In other words, the concave surface formed in the top surface portion <NUM>, which is caused by the heat and centripetal forces applied thereto, is adjacent to the surfaces of the damper restraint <NUM> formed by bumps or features <NUM>, <NUM>. This radial component is illustrated by curved line <NUM>. This radial component improves dampening in the radial direction between the adjacent platforms <NUM> illustrated by arrows <NUM>.

In addition, the chamfers or bevels also restrain movement of the damper seal <NUM> in the directions of arrows <NUM>. Accordingly, the platforms <NUM> with rails, bumps or features <NUM>, <NUM> provide damping in a radial direction as well as preventing movement of the damper seal in a tangential direction(s) <NUM>.

In one embodiment, the rails, bumps or features <NUM>, <NUM> on the platform edge may be formed into existing or new designs. In other words, the rails, bumps or features <NUM>, <NUM> may be formed on the platform <NUM> through some additive technique such as welding, and can be used as a potential aftermarket fix to reduce the amount of damper deformation seen in service. Or for new designs, the rails, bumps or features <NUM>, <NUM> may be included into a cast used to form new platforms <NUM>. Moreover, by using rails, bumps or features <NUM>, <NUM> at peripheral edges <NUM> of the platform <NUM>, there is no need for a special damper seal design. In this way, the use of rails, bumps or features <NUM>, <NUM> at peripheral edges <NUM> of the platform <NUM> can be particularly useful in the aftermarket as a way of correcting unintended damper operation. For example an existing platform <NUM> can be worked on through any suitable process to add rails, bumps or features <NUM>, <NUM> at peripheral edges <NUM> of the platform <NUM>.

In accordance with one non-limiting embodiment, the rails, bumps or features <NUM>, <NUM> at peripheral edges <NUM> of the platform <NUM> extend over a portion or the entire length of both the pressure side and suction side of the platform edges or alternatively only along one of the pressure side and suction side of the platform edges. The damper seal <NUM> plastically deforms under centrifugal loading and high temperature. Alternatively, the damper seal <NUM> may be preformed with a concave top surface portion <NUM>. The rails, bumps or features <NUM>, <NUM> provide a contact surface between the underside of the platforms and the top surface portion <NUM> of the damper seal <NUM> such that a system is provided for suppressing both radial and tangential vibration.

Various embodiments of the present disclosure provide improved damper performance for blades that exhibit radial vibration. In addition, existing designs can be easily modified to incorporate the design. As such, a potential aftermarket fix to correct excessive damper deformation is provided. Still further, the overall weight of the platform <NUM> may be reduced by limiting the amount of material necessary for the rails, bumps or features <NUM>, <NUM>. Moreover, by locating the rails, bumps or features <NUM>, <NUM> on an interior surface of the platform <NUM>, a device is created that restrains the damper seal <NUM> from sliding toward the suction side of the pocket <NUM> or the pressure side of the pocket <NUM> when it is subject to tangential dynamic forces or rotational forces (e.g. induced by the orientation of the pocket (or broach angle) relative to the axis of rotation).

Claim 1:
A disk for a gas turbine engine (<NUM>), the disk having a plurality of blades (<NUM>) secured thereto, each blade comprising:
a root (<NUM>);
an airfoil (<NUM>);
a platform (<NUM>) located between the root and the airfoil of the blade, and
a damper restraint (<NUM>) located at a peripheral edge (<NUM>) of the platform, wherein the damper restraint comprises at least one raised feature (<NUM>; <NUM>) extending along at least a portion of the peripheral edge of the platform;
wherein adjacent platforms of adjacent blades of the plurality of blades of the disk define a cavity (<NUM>) and a seam (<NUM>), and a damper seal (<NUM>) is received in the cavity and covers the seam;
wherein a concave surface formed in a top surface portion (<NUM>) of the damper seal contacts and engages the raised feature and bends around the raised feature (<NUM>; <NUM>); and
wherein the raised feature has a cross-section with a smooth profile, and extends along an entire length of the damper seal.