This disclosure relates to a stator assembly for a gas turbine engine. More particularly, the disclosure relates to a damping configuration for stator vanes in the stator assembly.
Typically, gas turbine engines include a stator assembly arranged at one or more stages in the compressor section of the gas turbine engine. The stator assembly includes an array of circumferentially arranged discrete stator segments. The stator segments include an outer shroud that provides opposing hooks supported relative to an outer case. The stator segments move relative to the outer case during engine operation. Some stator assemblies have attachment liners mounted between the hooks and their supporting structure to provide a wearable structure that can be replaced.
One type of stator assembly includes an inner shroud supported at the radial innermost portion of the stator segment. The inner shrouds stabilize the stator assembly and minimize vibration. In one stator assembly configuration, an abradable seal is supported by each inner shroud to seal the compressor rotor relative to the stator assembly. A spring is arranged between the inner shroud and the seal.
Another type of stator assembly includes stator segments without an inner shroud. Individual springs are provided between the outer shroud of each stator segment and the outer case. The springs are configured to bias the stator segments radially inward. No liners may be used.
An embodiment addresses a stator assembly that may include: an outer case; a stator subassembly including an array of circumferentially stator vanes; and a spring damper that may be provided between the array and the outer case. The spring damper may be configured to bias the array radially inward from the outer case.
In a further embodiment of the foregoing stator assembly, at least one of the stator vanes may include first and second hooks. The first and second attachment liners may be respectively secured to the first and second hooks to provide the stator subassembly. The damper may be discrete from the first and second attachment liners.
In a further embodiment of the foregoing stator assembly, at least one of the stator vanes may include a recess having lateral walls and an adjoining bottom wall. The damper spring may engage the outer case, and the lateral walls and bottom wall.
In a further embodiment of the foregoing stator assembly, the damper spring may include first and second symmetrically shaped sides. The first and second sides may have asymmetrically oriented notches respectively providing first and second fingers. The first and second fingers may be circumferentially offset relative to one another and may engage first and second hooks that are circumferentially offset from one another.
In a further embodiment of the foregoing stator assembly, the damper spring may be generally W-shaped, wherein each of the first and second fingers includes a lateral bend and a foot. The lateral bends may engage the lateral walls, and the feet may engage the bottom wall. The damper spring may include a valley provided between the peaks, and the peaks may engage the outer case.
In a further embodiment of the foregoing stator assembly embodiment, the damper spring may be generally V-shaped and may include first and second legs adjoined by a bend. The first leg may engage the stator vanes, and the second leg may engage the outer case.
In a further embodiment of the foregoing stator assembly embodiment, adhesive may secure the damper spring to the subassembly.
In a further embodiment of the foregoing stator assembly embodiments, a blade outer air seal may be secured to the outer case. First and second channels may be provided by at least one of the blade outer air seal and the outer case. The first and second attachment liners may be respectively received in the first and second channels.
In a further embodiment of the foregoing stator assembly embodiment, the stator vanes may include radially inwardly extending airfoils that may provide a tip at an inner diameter that may be structurally unsupported relative to the adjacent tips.
Another embodiment addresses a method of manufacturing a stator assembly that may include the steps of: positioning stator vanes relative to one another to provide a circumferential array of stator vanes; installing an attachment liner onto stator vane hooks to provide a subassembly of stator vanes; and arranging a damper spring between the subassembly and an outer case. The method may also include mounting the subassembly onto the outer case and biasing the subassembly radially inward with the damper spring.
In a further embodiment of the foregoing method embodiment, the positioning step may include lining the hooks relative to one another, and the installing step may include sliding the attachment liner over the hooks.
In a further embodiment of the foregoing method embodiment, the mounting step may include sliding the hooks into a channel of at least one of a blade outer air seal and the outer case.
In a further embodiment of the foregoing method embodiment, the mounting step may include securing a blade outer air seal to an outer case to provide a channel. The subassembly may be positioned within the channel and held between the blade outer air seal and the outer case.
In another embodiment that addresses a spring damper for a stator assembly, first and second symmetrically shaped sides providing a generally W-shaped arcuate structure may be provided. The first and second sides may have asymmetrically oriented notches respectively providing first and second fingers. The first and second fingers may be circumferentially offset relative to one another. Each of the first and second fingers may include a lateral bend and a foot. A valley may be provided between the peaks opposite the feet, the peaks at an outer circumference and the feet at an inner radius.
Another embodiment addresses a spring damper for a stator assembly that includes: first and second legs adjoined by a bend providing a generally V-shaped arcuate structure. The first leg may be provided at an inner circumference and may include a second bend opposite the first bend. A bow may be provided in the first leg between the first and second bends.
The disclosure can be further understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
An example gas turbine engine 10 is schematically illustrated in
The gas turbine engine 10 includes a compressor section 12, a combustor section 14 and a turbine section 16, which are arranged within a housing 24. In the example illustrated, high pressure stages of the compressor section 12 and the turbine section 16 are mounted on a first shaft 20, which is rotatable about an axis A. Low pressure stages of the compressor section 12 and turbine section 16 are mounted on a second shaft 22 which is coaxial with the first shaft 20 and rotatable about the axis A. In the example illustrated, the first shaft 20 rotationally drives a fan 18 that provides flow through a bypass flow path 19. The gas turbine engine 10 may include a geartrain (not shown) for controlling the speed of the rotating fan 18. More specifically, the geartrain may enable (e.g., using a gear reduction ratio of greater than about 2.4) a reduction of the speed of the fan 18 relative to the low compressor. The geartrain can be any known gear system, such as a planetary gear system with orbiting planet gears, a planetary system with non-orbiting planet gears or other type of gear system. The low speed second shaft 22 may drive the geartrain and the low pressure compressor. It should be understood that the configuration illustrated in
The first and second shafts 20, 22 are supported for rotation within the housing 24. The housing 24 is typically constructed of multiple components to facilitate assembly.
An example stator assembly 26 is illustrated in
Each stator 29 includes first and second hooks 34, 36 that are received in corresponding first and second channels 35, 37. The channels 35, 37 may be provided in at least one of a blade outer air seal 86, the outer case 28, or both. Locating features 38 (
In one example, first and second attachment liners 40, 42 are respectively secured to the first and second hooks 34, 36. The attachment liners 40, 42 join groups of stators 29 into subassemblies and provide a wearable structure between the outer shroud 30 and the outer case 28.
The stators 29 include a recess 46 that receives an arcuate damper spring 44. In the embodiments shown in
Referring to
A portion of the damper spring 44 arranged at an outer circumference includes peaks 62 providing a centrally located valley 64. Each of first and second sides 52, 54 includes a lateral bend 66 and a foot 68 extending to a terminal end 70. The feet 68 are arranged at an inner circumference of the damper spring 44. The peaks 62 engage the outer case 28 and the lateral bends 66 engage the lateral walls 48 to stabilize the stators 29. The damper spring 44 is shown in an uncompressed state in
Referring to
One or more blade outer air seals 86 may be secured to the outer case 28 by fasteners 88, as shown in
In one example, a method of manufacturing the stator assembly 26 includes positioning stator vanes 29 relative to one another to provide a circumferential array of stator vanes 29. In one example, the positioning step includes aligning the hooks 34, 36 relative to one another. One or more attachment liners 40, 42 are installed onto stator vane hooks 34, 36 to provide a subassembly of stator vanes 29. In one example, the installing step includes sliding the attachment liners 40, 42 over the hooks 34, 36. A damper spring 44/72 is arranged between the subassembly and the outer case 28. The subassembly is mounted onto the outer case 28 and biases the subassembly radially inward with the damper spring 44/72.
In the example arrangement shown in
Referring to
The first attachment liner 100 is generally arcuate and S-shaped and includes a first wall 108. A first leg 110 extends from the first wall 108 at a bend 109 to provide the first damper spring 104. The first leg 110 engages the bottom wall 50 of the recess 46 and is spaced from the outer case. The first leg 110 terminates in a hook 112, which may be used during assembly to position the stator vanes 29 relative to the first damper spring 104.
The second attachment liner 102 is generally arcuate and S-shaped and includes an axial biasing portion 114 arranged between the stator 29 and the integrated outer case and blade outer air seal 90. The second attachment liner 102 also includes a leg 116 providing a bow 118 extending to a terminal end 120. The leg 116 engages the outer case and is spaced from the bottom wall 50 of the recess 46.
Several stators 29 are circumferentially arranged to provide a subassembly 121, as shown in
Although an example embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of the claims. For that reason, the following claims should be studied to determine their true scope and content.
This application relates to U.S. patent application Ser. No. 13/343,784 concurrently filed herewith entitled “STATOR VANE INTEGRATED ATTACHMENT LINER AND SPRING DAMPER.”