FEATURE FOR SAFELY INDICATING ROTOR TO STATOR CLASHING

Description

BACKGROUND

The present disclosure is directed to the improved system and method for indicating rotor to stator clash.

In engine operation in the field, some parts will wear and allow working gaps between rotors and stators, such as variable vanes, to decrease and eventually go to zero with parts clashing. This clashing presents a safety issue if not detected. In this instance, in the high pressure compressor of a gas turbine engine, a row of variable vanes are located in between rotors. The variable vanes are supported as a cantilever from the outer case. A bushing supports the variable vane and enables rotation of the variable vane. When the bushing is worn, the variable vane can tilt and deflect toward the rotors. Once the wear is severe enough, the vanes will tilt enough to rub against the adjacent rotor. If that rubbing continues undetected the rotor material properties will degrade and potentially lead to a failure of the rotor.

SUMMARY

In accordance with the present disclosure, there is provided a system for indicating rotor to stator clash comprising a rotor including a forward section and an aft section opposite the forward section; a stator located near the rotor; and a clash indication feature attached to the rotor, the clash indication feature configured to contact the stator responsive to a predetermined deflection dimension of the stator.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the clash indication feature is attached to the rotor on a rim portion of the rotor.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include clash indication feature is attached to the rotor proximate the aft section of the rotor.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the clash indication feature comprises a deposit of material on a surface of the rotor.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the clash indication feature is configured to contact an air seal of the stator.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the clash indication feature can be attached in opposing pairs in order to maintain rotor balance.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the system for indicating rotor to stator clash further comprising a visual indicator integral with the clash indication feature, the visual indicator configured detectable by visual inspection.

In accordance with the present disclosure, there is provided a system for indicating rotor to vane clash in a gas turbine engine comprising a gas turbine engine case; a variable vane attached to the gas turbine engine case; a rotor proximate the variable vane, the rotor comprising a rim portion having a surface; and a clash indication feature attached to the surface, the clash indication feature configured to contact the variable vane responsive to a predetermined deflection dimension of the variable vane.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the clash indication feature comprises a step change along the surface.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the clash indication feature is configured to contact an air seal of the variable vane.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the clash indication feature can be attached in balanced groups in order to maintain rotor balance.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the system for indicating rotor to vane clash in a gas turbine engine further comprising a visual indicator integral with the clash indication feature, the visual indicator configured detectable by visual inspection.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the clash indication feature is configured as a sacrificial element, capable of being worn away responsive to rubbing between the variable vane and the rotor.

In accordance with the present disclosure, there is provided a process for indicating rotor to vane clash in a gas turbine engine comprising providing a gas turbine engine case; attaching a variable vane to the gas turbine engine case; locating a rotor proximate the variable vane, the rotor comprising a rim portion having a surface; and attaching a clash indication feature to the surface; and configuring the clash indication feature to contact the variable vane responsive to a predetermined deflection dimension of the variable vane.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising creating a vibration by contacting the clash indication feature with the variable vane.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising detecting the vibration with an engine vibration sensor.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising configuring the clash indication feature as a sacrificial element worn away responsive to rubbing between the variable vane and the rotor.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising forming the clash indication feature as a step change along the surface.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising forming a visual indicator integral with the clash indication feature; and configuring the visual indicator detectable by visual inspection.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising attaching the clash indication feature in balanced groups; and maintaining rotor balance.

Other details of the system and method for indicating rotor to stator clash are set forth in the following detailed description and the accompanying drawings wherein like reference numerals depict like elements.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross section view of an exemplary gas turbine engine.

FIG. 2 is a schematic representation of an exemplary stator and rotor of a high pressure compressor.

FIG. 3 is a schematic representation of an exemplary stator and rotor of a high pressure compressor.

FIG. 4 is a schematic representation of an exemplary stator and rotor of a high pressure compressor.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates a gas turbine engine 20. The gas turbine engine 20 is disclosed herein as a two-spool turbofan that generally incorporates a fan section 22, a compressor section 24, a combustor section 26 and a turbine section 28. The fan section 22 may include a single-stage fan 42 having a plurality of fan blades 43. The fan blades 43 may have a fixed stagger angle or may have a variable pitch to direct incoming airflow from an engine inlet. The fan 42 drives air along a bypass flow path B in a bypass duct 13 defined within a housing 15 such as a fan case or nacelle, and also drives air along a core flow path C for compression and communication into the combustor section 26 then expansion through the turbine section 28. A splitter 29 aft of the fan 42 divides the air between the bypass flow path B and the core flow path C. The housing 15 may surround the fan 42 to establish an outer diameter of the bypass duct 13. The splitter 29 may establish an inner diameter of the bypass duct 13. Although depicted as a two-spool turbofan gas turbine engine in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to use with two-spool turbofans as the teachings may be applied to other types of turbine engines including three-spool architectures.

The exemplary engine 20 generally includes a low speed spool 30 and a high speed spool 32 mounted for rotation about an engine central longitudinal axis A relative to an engine static structure 36 via several bearing systems 38. It should be understood that various bearing systems 38 at various locations may alternatively or additionally be provided, and the location of bearing systems 38 may be varied as appropriate to the application.

The low speed spool 30 generally includes an inner shaft 40 that interconnects, a first (or low) pressure compressor 44 and a first (or low) pressure turbine 46. The inner shaft 40 is connected to the fan 42 through a speed change mechanism, which in the exemplary gas turbine engine 20 is illustrated as a geared architecture 48 to drive the fan 42 at a lower speed than the low speed spool 30. The inner shaft 40 may interconnect the low pressure compressor 44 and low pressure turbine 46 such that the low pressure compressor 44 and low pressure turbine 46 are rotatable at a common speed and in a common direction. In other embodiments, the low pressure turbine 46 drives both the fan 42 and low pressure compressor 44 through the geared architecture 48 such that the fan 42 and low pressure compressor 44 are rotatable at a common speed. Although this application discloses geared architecture 48, its teaching may benefit direct drive engines having no geared architecture. The high speed spool 32 includes an outer shaft 50 that interconnects a second (or high) pressure compressor 52 and a second (or high) pressure turbine 54. A combustor 56 is arranged in the exemplary gas turbine 20 between the high pressure compressor 52 and the high pressure turbine 54. A mid-turbine frame 57 of the engine static structure 36 may be arranged generally between the high pressure turbine 54 and the low pressure turbine 46. The mid-turbine frame 57 further supports bearing systems 38 in the turbine section 28. The inner shaft 40 and the outer shaft 50 are concentric and rotate via bearing systems 38 about the engine central longitudinal axis A which is collinear with their longitudinal axes.

Airflow in the core flow path C is compressed by the low pressure compressor 44 then the high pressure compressor 52, mixed and burned with fuel in the combustor 56, then expanded through the high pressure turbine 54 and low pressure turbine 46. The mid-turbine frame 57 includes airfoils 59 which are in the core flow path C. The turbines 46, 54 rotationally drive the respective low speed spool 30 and high speed spool 32 in response to the expansion. It will be appreciated that each of the positions of the fan section 22, compressor section 24, combustor section 26, turbine section 28, and fan drive gear system 48 may be varied. For example, gear system 48 may be located aft of the low pressure compressor, or aft of the combustor section 26 or even aft of turbine section 28, and fan 42 may be positioned forward or aft of the location of gear system 48.

The low pressure compressor 44, high pressure compressor 52, high pressure turbine 54 and low pressure turbine 46 each include one or more stages having a row of rotatable airfoils. Each stage may include a row of static vanes adjacent to the rotatable airfoils. The rotatable airfoils and vanes are schematically indicated at 47 and 49.

Referring also to FIG. 2, FIG. 3 and FIG. 4, an exemplary system for rotor and stator clash 60 is shown. An engine case 62 supports a stator such as a variable vane 64. The variable vane 64 can be located in the high pressure compressor 52. The variable vane 64 can be supported in a cantilever style. The variable vane 64 can be supported by a shaft section 66 in operative communication with a bushing 68. The bushing 68 is configured to support the shaft section 66 and allow for rotary motion of the variable vane 64. The bushing 68 can wear and degrade allowing for the variable vane 64 to deflect from the as built dimensions. The deflection of the variable vane 64 can cause the variable vane 64 to clash or otherwise contact with a rotor 70 proximate the variable vane 64. The rotor 70 can also be located in the high pressure compressor 52.

The rotor can include a rim portion 72. The rim portion 72 can include a forward section 74 and an aft section 76. A clash indication feature 78 can be attached to the rotor 70, such as near the rim portion 72. The clash indication feature 78 can be configured to rub against the variable vane 64 responsive to the variable vane 64 deflection. The clash indication feature 78 can be formed as a deposit of material 80 on a surface 82 of the rotor 70 as seen in FIG. 3. The clash indication feature 78 can be a coating material in an exemplary embodiment. The clash indication feature 78 can be attached as groups that balance the rotor 70, such as in opposing balanced pairs in order to maintain rotor 70 balance. There can be multiple balanced pairs of clash indication features 78 attached to the rotor 70. These multiple pairs can be symmetrically applied along the surface 82 of the rotor 70 in order to maintain proper rotor 70 balance.

The variable vane 64 can include an air seal 84, such as an inner air seal, distal from the shaft section 66. The air seal 84 can be configured to prevent air leakage between the variable vane 64 and rotor sections 70.

The clash indication feature 78 can be configured to contact the air seal 84 of the variable vane 64. During a clash condition when the variable vane 64 deflects enough to rub against the rotor 70, the clash indication feature 78 can rub intermittently on the air seal 84. The air seal 84 can be segmented. The clash indication feature 78 contacting the air seal 84 can create a vibration from rubbing the air seal 84. The vibration can be detectable by an engine vibration sensor 86. The vibration sensor 86 can be in operative communication with the case 62 proximate the high pressure compressor 52. Detection of the rub induced vibration can be accomplished before damage caused to the stator 64 or rotor 70, allowing for engine repair. A predetermined vibration threshold can be set for the vibration sensor 86 to indicate a particular acceleration (inch/sec./sec.).

The clash indication feature 78 can be configured with a visual indicator 88 integral with the clash indication feature 78. The visual indicator 88 can be configured to be detectable by visual inspection. The visual indicator 88 can reveal contact between the stator 64 and rotor 70. The visual indicators 88 can be a redundant feature of the clash detection feature 78 to allow for detection by either vibration detection or visual inspection. The clash indication feature 78 can be configured as a sacrificial element, capable of being worn away responsive to rubbing between the stator 64 and rotor 70. The clash indication feature 78 can be configured as a step change along the surface 82. The clash indication feature 78 can be applied by any coating technique, such as plasma spray techniques.

The clash indication feature 78 can be configured to last for multiple flight cycles, such as hundreds of cycles. The clash indication feature 78 can be dimensioned to be responsive to the wear in the bushing 68 and resultant deflection of the stator 64. In an exemplary embodiment, the bushing 68 can be known to wear as a given rate over a number of engine cycles. The wear of the bushing 68 can lead to a predetermined deflection dimension 90 of the stator 64. The clash indication feature 78 can be sized to create contact at a certain predetermined value of the stator predetermined deflection dimension 90. In an exemplary embodiment the predetermined deflection dimension can be 10 mils or a 0.15 inch gap.

A technical advantage of the disclosed system and method for indicating rotor to stator clash includes a system that creates a detectable vibration to initiate safe removal of an engine.

Another technical advantage of the disclosed system and method for indicating rotor to stator clash includes a detectable visual indicator to initiate safe removal of an engine.

Another technical advantage of the disclosed system and method for indicating rotor to stator clash includes a sacrificial rub indicator to prevent continued damaging rubbing between base metal parts of a rotor and a stator.

Another technical advantage of the disclosed system and method for indicating rotor to stator clash includes a coating patch with durability to withstand multiple flight cycles.

Another technical advantage of the disclosed system and method for indicating rotor to stator clash includes a detectable vibration signal initiator located on the closest points of contact between the rotor and stator.

There has been provided a system and method for indicating rotor to stator clash. While the system and method for indicating rotor to stator clash has been described in the context of specific embodiments thereof, other unforeseen alternatives, modifications, and variations may become apparent to those skilled in the art having read the foregoing description. Accordingly, it is intended to embrace those alternatives, modifications, and variations which fall within the broad scope of the appended claims.