Bladed rotor disk including anti-vibratory feature

A rotor disk includes a ring shaped rotor body defining a radially inward opening, rims protrude radially outward from the rotor body, and outwardly facing rotor blade retention slots are defined between circumferentially adjacent rims. Each slot is operable to receive and retain a corresponding rotor blade, and each rim of the rims includes an anti-vibratory feature. The anti-vibratory feature includes a structure defining an isogrid pattern intruding into a surface of the rim.

TECHNICAL FIELD

The present disclosure relates generally to bladed rotor disk assemblies for a gas powered turbine, and more specifically to an anti-vibratory feature for the same.

BACKGROUND

Gas powered turbines, such as those used in commercial and military aircraft, include a compressor that compresses air, a combustor that mixes the compressed air with a fuel and ignites the mixture, and a turbine section through which the resultant combustion gasses are expanded. The expansion of the combustion gasses across the turbine section drives the turbine section to rotate. The turbine section is connected to the combustor section via one or more shafts, and the rotation of the turbine section drives the compressor section to rotate.

Multiple compressor and turbine stages are included in each of the corresponding sections, with each stage including a rotor and a corresponding stator or a corresponding vane. Rotor based systems, such as a gas turbine engine, often display coupled vibratory modes during engine operation. A coupled vibratory modes place high vibratory stresses on the rotor disk, the rotor blade, or both the rotor disk and the rotor blade when the engine is operating at or near a certain frequency.

Further, any given rotor blade or rotor disk can include multiple distinct vibratory modes, with each distinct vibratory mode corresponding to a particular engine rotational speed. In an ideal engine, every vibratory mode of a given rotor assembly is tuned to fall significantly higher than the frequency range of the typical engine operation. However, tuning rotor disks and rotor blades such that the vibratory modes fall significantly higher than the frequency range of typical engine operation significantly increases the weight of the corresponding rotor, and is not practical in all cases due to engine component size constraints.

SUMMARY OF THE INVENTION

In one exemplary embodiment, a rotor disk includes a ring shaped rotor body defining a radially inward opening, rims protruding radially outward from the rotor body, and outwardly facing rotor blade retention slots defined between circumferentially adjacent rims. Each slot is operable to receive and retain a corresponding rotor blade, and each rim of the rims includes an anti-vibratory feature. The anti-vibratory feature includes a structure defining an isogrid pattern intruding into a surface of the rim.

In another exemplary embodiment of the above described rotor disk, the isogrid pattern comprises a plurality of geometric intrusions into the surface, and wherein the geometric intrusions are separated by, and define, a plurality of stiffening ribs.

In another exemplary embodiment of any of the above described rotor disks, each of the geometric intrusions is a uniform shape.

In another exemplary embodiment of any of the above described rotor disks, the geometric intrusions vary in at least one of a depth, a corner angle, a cross sectional area.

In another exemplary embodiment of any of the above described rotor disks, the geometric intrusions include at least two distinct geometric shapes.

In another exemplary embodiment of any of the above described rotor disks, each of the geometric intrusions intrudes a uniform radial depth into the surface.

In another exemplary embodiment of any of the above described rotor disks, the anti-vibratory feature includes localized tuning features local to subsections of the surface.

In another exemplary embodiment of any of the above described rotor disks, the plurality of geometric intrusions comprises at least one of triangular intrusions, rectangular intrusions, and circular intrusions.

In another exemplary embodiment of any of the above described rotor disks, the surface is a radially outward facing surface of the rim.

In another exemplary embodiment of any of the above described rotor disks, the surface extends a full axial length of the rim.

An exemplary method for reducing vibrational bending in a bladed rotor disk includes tuning a rotor rim for at least one vibrational mode using an anti-vibratory feature. The anti-vibratory feature comprises an isogrid pattern.

In a further example of the above exemplary method, the anti-vibratory feature is disposed on a radially outward facing surface of a rotor rim.

In a further example of any of the above exemplary methods tuning a rotor rim for at least one vibrational mode comprises providing localized vibrational tuning in distinct subsections of the rotor rim.

In a further example of any of the above exemplary methods the localized vibration tuning is achieved utilizing an isogrid pattern having geometric intrusions where at least one of a radial depth of the geometric intrusion, a cross sectional area of the geometric intrusion, and a corner angle of the geometric intrusion is varied across the isogrid pattern.

In one exemplary embodiment, a rotor disk for utilization in a gas turbine engine includes a ring shaped rotor body defining an axis, rim features protruding radially outward from the ring shaped body, and outwardly facing rotor blade retention slots defined between circumferentially adjacent rims. Each rim of the rims includes an anti-vibratory feature. The anti-vibratory feature includes a structure defining an isogrid pattern intrudes into a surface of the rim.

In another exemplary embodiment of the above described rotor disk, the isogrid pattern comprises a plurality of geometric shaped intrusions into the radially outward facing surface, and a plurality of ribs defined by the geometric intrusions.

In another exemplary embodiment of any of the above described rotor disks, the geometric intrusions are a uniform geometric shape.

In another exemplary embodiment of any of the above described rotor disks, the geometric intrusions are a plurality of varied geometric shapes.

In another exemplary embodiment of any of the above described rotor disks, at least one of a radial depth of the geometric intrusion, a cross sectional area of the geometric intrusion, and a corner angle of the geometric intrusion is varied across the radially outward facing surface such that the anti-vibratory feature includes localized tuning for a plurality of vibratory modes.

In another exemplary embodiment of any of the above described rotor disks, the isogrid pattern is cast with the rim.

DETAILED DESCRIPTION OF AN EMBODIMENT

Each stage within the compressor section24and the turbine section28is defined by a rotor and a corresponding stator or a corresponding vane. Each rotor includes a rotor disk section with multiple rotor blades protruding radially outward from the rotor disk section. This arrangement is also referred to as a bladed rotor disk. Due to the specific sizes and shapes of the rotor blades and the rotor disks, bladed rotor disks are subject to unwanted vibratory modes while the engine is operating at certain frequencies. Unwanted vibratory modes are instances of the rotor blade, the rotor disk, or both exhibiting undesirable vibrations while rotating at or near a specific frequency.

The vibrations caused by the vibratory modes can be bending vibrations, torsional vibrations, or both. A bending vibration occurs when a rotor blade root and a rotor disk rim vibrate causing the blade to bend. A torsional vibration occurs when vibration of the rotor blade and a rotor disk rim causes the blade to twist about the spanwise direction. Depending on the coupled vibratory mode, the disk lug will deflect differently. For one case the disc lug may tend to twist from front to back at max blade deflection, while in another the disc lug may simply bend uniformly from front to back.

By way of example, if the foremost portion of the rotor rim is bending clockwise, and the aftmost portion of the rim is bending counterclockwise, the bending is a torsional bending. In further examples, the torsional or bending vibrations can be localized to a specific portion of the rotor rim. In yet further examples, the torsional or bending vibrations can be spread across the rotor rim, but have a particularly strong effect in a localized portion of the rotor rim.

With continued reference toFIG. 1,FIG. 2Aschematically illustrates an isometric view of a bladed rotor assembly100including a rotor disk102and a single exemplary rotor blade110interconnected with the rotor disk102. In an installed configuration, multiple rotor blades110are connected to the rotor disk102, however only a single rotor blade110is illustrated for explanatory purposes.

The rotor disk102has a generally ring shaped rotor body140that defines an axis B. Multiple rotor rims120protrude radially outward from the ring shaped rotor body140. The rotor rims120are alternatively referred to as dead rims. Each rotor rim120has a stem portion124and a body portion126, with the stem portion124connecting the body portion126to the ring shaped rotor body140. Each rotor rim120further includes a radially outward facing surface122that extends the axial length of the rotor disk102.

Defined between each rotor rim120and each adjacent rotor rim120is a slot114. In an assembled configuration, a root portion112of a rotor blade110is received and retained in the slot114. The root portion112can be retained using any known rotor blade retention configuration including a fir tree connection or any similar root portion112and rotor disk102interfacing.

A radially inward facing surface130of the bladed rotor disk100includes an interfacing feature132for interfacing the rotor disk102with a corresponding shaft. In one example, the interfacing feature132can be a spline. In alternative examples, any suitable interfacing feature can be used in place of a spline.

With continued reference toFIGS. 1 and 2A,FIG. 2Billustrates a cross sectional view of the rotor disk102ofFIG. 2Acut along view line150. The ring shaped rotor body140includes a ring shaped plate element142connecting a radially outward body segment144to a radially inward body segment146. The interfacing feature132and the radially inward facing surface130of the rotor body are included on the radially inward body segment146. Similarly, each of the rotor rims120protrudes radially outward from the radially outward body segment144.

During operation of the gas turbine engine20(illustrated inFIG. 1), certain engine rotational speeds can cause the bladed rotor assembly100to vibrate in either a torsional vibration or a bending vibration. Existing design paradigms attempt to address the vibrational bending by adding material to the rotor rim120. Adding material to the rotor rim120increases the engine rotational speeds that cause the vibrational bending, but also carries an associated increase in weight of the bladed rotor disk assembly. The adjustment to the rotational speeds that causes the vibrational bending is referred to as vibrational tuning. Further, bladed rotor disks frequently have multiple vibratory modes (multiple engine operation frequencies that cause vibrations), and tuning the rotor rim to move one vibratory mode outside of the expected engine rotational speeds can unintentionally shift another vibratory mode into the expected engine rotational speeds.

With continued reference toFIGS. 1, 2A and 2B,FIG. 3Aillustrates an example rotor disk200including an anti-vibratory feature260in a rotor rim220. The general rotor disk200structure is the same as the bladed rotor disk100illustrated inFIGS. 2A and 2B, with a ring shaped rotor disk body240, and multiple rotor rims220protruding radially outward from the rotor disk200. Each of the rotor rims220includes a stem224and a rim body portion226having a radially outward facing surface222.

Incorporated into each of the body portions226of the rims220is an anti-vibratory feature260including an isogrid pattern protruding radially into the outward facing surface220. The isogrid pattern is, in some examples, machined into the radially outward facing surface222. One of skill in the art having the benefit of this disclosure will understand that, in general, an isogrid pattern is a partially hollowed out structure including integral stiffening ribs. In some examples, the isogrid structure utilizes a triangular stiffening rib structure. In other examples, alternative shaped stiffening ribs can be utilized to similar effect.

With continued reference toFIGS. 1, 2A, 2B and 3A,FIG. 3Bschematically illustrates a zoomed in view of the rotor rims220ofFIG. 3B, illustrating the anti-vibratory feature260. The anti-vibratory feature260is an isogrid pattern that is machined into the exterior facing surface222of the rotor rim220. Isogrid patterns as anti-vibratory features260are generally created using a set of geometric shapes intruding into the rotor rim to create the stiffening ribs, while adding a minimal amount of weight to the rotor rim. While the example illustrated inFIGS. 3A and 3Butilizes triangular geometric shapes, alternative shaped intrusions can be utilized to provide the same, or a similar, effect. The illustrated isogrid pattern utilizes varied sized and dimensioned triangular intrusions262machined into the exterior facing surface222to create stiffening ribs264that circumferentially span the radially outward facing surface222of the rim220.

With regards to the shapes and depths of the triangular intrusions262, one of skill in the art, having the benefit of this disclosure, will understand that the specific radial depth of the triangular intrusions26and size of the triangular intrusions26can be adjusted to compensate for expected bending due to vibration. In this way, the rotor rims220can be tuned for specific vibratory modes while minimally affecting other vibratory modes, thereby decreasing the risk of exciting a damaging mode during operation. By way of example, the triangular intrusions26at an upstream edge270of the rotor rim220have a smaller cross-sectional area and are tuned to a type of vibration that is localized at the upstream edge270. Similarly, the triangular intrusions26at a downstream edge of the rotor rim220have a larger cross-sectional area, and are tuned to vibrations that are localized at the downstream edge272. In alternative examples, the radial depth of the triangular intrusions262can be varied further to provide further tuning.

The particular cross sectional area, corner angles, and radial depth of the isogrid pattern for a given rotor rim220can be determined by one of skill in the art based on the parameters and needs of a given engine. In this way, the isogrid pattern can be specifically designed to tune multiple vibratory modes, and to tune specific locations for vibratory modes that have an increased localized effect.

With specific regard to the anti-vibratory feature260illustrated inFIG. 3A, the smaller triangular intrusions262located at the upstream edge270stiffen the rotor rim220against a first vibratory mode, while the larger triangular intrusions262located near the downstream edge272stiffen the rotor rim against a second vibratory mode. Each of the first vibratory mode and the second vibratory modes have different frequencies. By adjusting, or altering, the depth of each triangular intrusions262, the angles of the ribs264, and the cross sectional area of the triangular intrusions262, the stiffening of the rotor rim220is targeted toward specific vibrational frequencies, and bladed rotor assembly100is stiffened with minimal additional weight.

In some examples, the anti-vibration feature260is created in the rotor disk102either by creating a conventional bladed rotor assembly100(illustrated inFIG. 1) and milling the isogrid pattern into the radially outward facing surface. In alternative examples, the isogrid pattern can be cast in the rotor rim. In the alternative examples, the isogrid pattern can be further milled out to specific tolerances, when the tolerances on the isogrid pattern are tighter than the casting process can meet.

With continued reference toFIGS. 1, 2A, 2B, 3A, and 3B,FIGS. 4, 5 and 6illustrate alternative geometric shaped intrusions362,462,562that can be utilized to create an isogrid anti-vibratory feature360,460,560for a bladed rotor assembly. As with the example anti-vibratory feature260ofFIGS. 3A and 3B, the alternative geometric shaped intrusions362,462,562create ribs364,464,564that function similarly to the ribs264defined by the anti-vibratory feature260ofFIGS. 3A and 3B. The ribs364,464,564in the alternative examples function in a similar manner.

The utilization of different shaped intrusions to form the isogrid pattern creates ribs364,464,564having varying strengths and varying abilities to tune vibratory modes. In the illustrated examples, the various geometric shaped intrusions protruding into the rotor rim320,420,520are uniform with a single shape intrusion being utilized to form all of the geometric shaped intrusions362,462,562in a single rotor rim320,420,520. One of skill in the art, having the benefit of this disclosure, will understand that, in some examples, a combination of varied geometric shaped intrusions362,462,562can be utilized on a single rotor rim320,420,520to achieve a desired tuning effect.

While illustrated and described above with reference to a geared turbofan engine, one of skill in the art having the benefit of this disclosure will recognize that the described rotor disk assemblies including anti-vibratory features can be beneficially utilized in any gas powered turbine, including, but not limited to, direct drive gas turbine engines, land based turbines, and marine turbines.