System and method for optical measurement in a rotating machine

Abstract

The invention is entitled "System and method for optical measurement in a rotating machine." The invention provides a system having a measurement system (27) with a sensor mount (82), a light source (16), a light sensor (18), and a controller (14) coupled to the light source (16) and the light sensor (18). The controller (14) is configured to determine a clearance between a rotor (46) and a housing (48) based at least in part on an interruption of light (120) emitted from the light source (16) to the light sensor (18).

Description

BACKGROUND

[0001] The subject matter disclosed herein relates to gap measurement, and more specifically, to gap measurement between rotating and stationary components in a rotating machine, such as a compressor of a gas turbine engine.

[0002] Compressors are used in a variety of industries and systems to compress gases, such as air. For example, gas turbine engines often include a compressor to provide compressed air for combustion and cooling. The compressor includes a rotor assembly and a stator assembly. In a multi-stage compressor, the rotor assembly can include multiple rows (e.g., rotor stages) each having a plurality of rotor blades attached to one or more rotor wheels defining a shaft. Likewise, the stator assembly can include multiple rows (e.g., stator stages) each having a plurality of stator vanes attached to a casing that circumscribes the rotor blades. The rotor assembly is designed to rotate relative to the stator assembly, thereby compressing the intake fluid as it passes through the compressor. The gap between the rotor assembly and the stator assembly can be associated with the efficiency of the compressor. However, sensors for measuring the gap require radial holes for installation, which can create potential leak paths. SUMMARY

[0003] The following summary outlines certain embodiments comparable in scope to the originally claimed subject matter. These embodiments are not intended to limit the scope of the claimed invention, but rather these embodiments are merely intended to provide a brief overview of possible forms of the subject matter. In fact, the system of the invention can include various forms that can be similar or different from the embodiments set forth below.

[0004] In a first embodiment, a system includes a measurement system having a light source, a light sensor, and a controller coupled to the light source and the light sensor. The controller is configured to determine a gap between a rotor and a stator based at least in part on an interruption of light emitted from the light source to the light sensor.

[0005] In a second embodiment, a system includes a measurement system having a sensor mount having a curved top surface, a light source disposed in a first position in the sensor mount, and a light sensor disposed in a second position in the sensor mount, wherein the first position and the second position are circumferentially spaced apart from one another. The measurement system is configured to emit light from the light source to the light sensor as a chord across the curved top surface of the sensor mount, into a path of a rotor.

[0006] In a third embodiment, a method includes emitting light from a light source to a light sensor across a chord of a curved surface between a rotor and a stator. The method further includes determining a gap between the rotor and the stator based on a duration that the rotor interrupts the light and a rotational speed of the rotor. BRIEF DESCRIPTION OF DRAWINGS

[0007] These and other features, aspects, and advantages of the present subject matter will become better understood with reference to the following detailed description and appended claims, read in light of the accompanying drawings, wherein:

[0008] Figure 1 is a block diagram of an embodiment of a gas turbine system having a multi-stage axial compressor having a sensor assembly coupled to a controller;

[0009] Figure 2 is Figure 1 a cross-sectional side view of an embodiment of a gas turbine engine showing blade stages of a rotor assembly and vane stages of a stator assembly of a multi-stage axial compressor;

[0010] Figure 3 is Figure 1 a perspective view of an embodiment of a portion of a housing of a compressor showing a plurality of sensor mounts coupled to an inner surface of the housing;

[0011] Figure 4 is a partial perspective view of an embodiment of a housing of Figure 3 showing a circumferential end of one of the sensor mounts of Figure 3 coupled to the housing;

[0012] Figure 5 is a schematic cross-sectional view of an embodiment of a sensor assembly having a light source and a light sensor coupled to one of the sensor mounts in the housing of Figure 3 showing a blade of a rotor assembly moving along an inner circumference of the housing through a light path between the light source and the light sensor;

[0013] Figure 6 is a graph representing an embodiment of data obtained from the sensor assembly of Figure 5 showing a duration of blockage of a light path used to determine a gap between the housing and the blade of the rotor assembly;

[0014] Figure 7 is a flowchart of an embodiment of a method of measuring a gap between the housing and the blade of the rotor assembly of Figure 5 ;

[0015] Figure 8 is a schematic cross-sectional view of an embodiment of a sensor assembly having a plurality of light sources and a plurality of light sensors coupled to one of the sensor mounts in the housing of Figure 3 showing a blade of a rotor assembly moving along an inner circumference of the housing through one or more light paths between the light sources and the light sensors;

[0016] Figure 9is an embodiment of a lookup table that can be used to measure the gap between the housing and the paddle based on data obtained from Figure 8 a sensor assembly of

[0017] Figure 10 is an embodiment of a schematic cross-sectional view of a sensor assembly having a plurality of light sources and a plurality of light sensors coupled to one of the sensor mounts in the housing of Figure 3 illustrating the paddle of the rotor assembly moving along the inner circumference of the housing, passing through one or more light paths between the light sources and the light sensors;

[0018] Figure 11 is an embodiment of a flowchart of a method of measuring the gap between the housing and the paddle as well as the roundness of the housing as illustrated in Figure 10 ;

[0019] Figure 12 is an embodiment of a schematic cross-sectional view of a sensor assembly having a common light source and a plurality of light sensors coupled to one of the sensor mounts in the housing of Figure 3 illustrating the paddle of the rotor assembly moving along the inner circumference of the housing, passing through at least a portion of the light path between the common light source and the light sensors;

[0020] Figure 13 is an embodiment of a schematic cross-sectional view of a sensor assembly having a common light source and a plurality of light sensors coupled to one of the sensor mounts in the housing of Figure 3 illustrating the paddle of the rotor assembly moving along the inner circumference of the housing, passing through at least a portion of the light path between the common light source and the light sensors;

[0021] Figure 14 is an embodiment of a plot representing data obtained from Figure 12 and Figure 13 a sensor assembly of ;

[0022] Figure 15 is an embodiment of a schematic of a plurality of light sensors of a sensor assembly of Figure 12 and / or Figure 13 illustrating the light sensors arranged in a close-packed column or array;

[0023] Figure 16 is an embodiment of a schematic of a plurality of light sensors of a sensor assembly of Figure 12 and / or Figure 13 illustrating the light sensors arranged in a close-packed cluster or two-dimensional beam;

[0024] Figure 17 is an embodiment of a method of measuring Figure 12 andFigure 13 a flowchart of an embodiment of a method of measuring a gap between a rotor assembly and a shell of a turbomachinery system; and

[0025] Figure 18 is a schematic diagram of an embodiment of a measurement system that can be used to measure a gap between a rotor assembly (e.g., a rotor, a blade, or both) and a shell that surrounds the rotor assembly. DETAILED DESCRIPTION

[0026] One or more specific embodiments of the present subject matter will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation can not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers’ specific goals, such as compliance with system-related and business-related constraints, which can vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0027] When introducing elements of various embodiments of the present subject matter, the articles “a,” “an,” “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there can be additional elements other than the listed elements.

[0028] The disclosed embodiments relate to measuring a gap between a rotor assembly (e.g., a rotor, a blade, or both) and a stator assembly (e.g., a shell, a vane, or both) of a machine, such as a compressor, a pump, a turbomachinery, or another rotating machine. For example, the disclosed embodiments include optical or light-based measurements of a gap between a rotor blade and a shell of a compressor.

[0029] In certain embodiments, a compressor of a turbomachinery system can include multiple stages or rows of rotor blades that are configured to rotate to compress a gas (e.g., air) and then deliver the gas to a fuel nozzle and / or a combustor for a combustion process. During rotation, a tip of a rotor blade (e.g., a compressor blade) is spaced apart from an inner surface of a shell of the compressor by a relatively small distance. In particular, a spacing or a gap between the compressor blade tip and the shell can be minimal such that the rotor blade effectively compresses the air while not contacting the shell.

[0030] In some cases, the gap between the rotor blades and the casing can change over time. For example, during normal operation, the gap can change due to thermal expansion and contraction of the rotating and stationary portions of the machine (e.g., the casing, blades, etc.). The gap can also vary with each rotation of the rotor if the geometry of the rotor or casing becomes less circular, i.e., out-of-round conditions. More severe out-of-round conditions will result in greater variation in the gap with each rotation of the rotor. Other causes of gap variation can include degradation of the rotor blades, vibrations or oscillations in the compressor, cracks or fracture tips of the rotor blades, and friction conditions that result in the tips of the rotor blades being partially removed.

[0031] In some cases, to detect the gap between the rotor blades and the casing, an operator can drill a hole that is angled radially toward the longitudinal axis of the compressor. The operator can then insert a sensor (e.g., a proximity sensor) into the hole to detect the blade tip gap in the radial direction. However, this gap measurement method can be inaccurate and inefficient. That is, it can be difficult to ensure the radial orientation of the hole and sensor, as well as the circumferential location of the hole and sensor. Accordingly, inconsistencies between the orientation and location of the sensor can present difficulties in calibrating the collected measurement data. Furthermore, the radial hole creates a potential leak path in the casing, which can create additional maintenance issues. Too many radial holes in the casing can also impact the structural integrity of the casing.

[0032] Accordingly, as discussed in further detail below, the disclosed embodiments include systems and methods for determining blade tip gaps of a compressor using a chordal orientation sensor and a light source disposed within an internal track of the compressor casing. For example, in certain embodiments, the system can utilize a track (e.g., channel) disposed circumferentially along an inner surface of the casing. The track can be configured to receive arcuate mounts that can hold a sensor assembly configured for determining blade tip gaps. The sensor assembly can include one or more light sources and one or more light sensors, and can be communicatively coupled to a controller. That is, the sensor assembly and the controller can collectively form a measurement system configured to determine blade tip gaps. The light sources and light sensors are configured to collect data indicative of the blade tip gaps, and the controller is configured to determine the blade tip gaps and other measurements based on the collected data.

[0033] To illustrate, the light source is configured to direct light from a first location (e.g., a first circumferential location or region) on the inner surface of the casing to a second location (e.g., a second circumferential location or region) on the inner surface of the casing. In practice, the light sensor can be located at the second location to detect the light. In other words, the one or more light sources can emit one or more beams of light as a chordal line across the inner surface (e.g., curved surface or inner circumference) of the casing toward the one or more light sensors.

[0034] In certain embodiments, the light sources can emit collimated light toward corresponding light sensors. The collimated light can be disrupted (e.g., blocked) by the respective rotor blades through which the collimated light passes. Thus, the blade tip to inner housing surface gap can be based on the duration for which the collimated light is disrupted or interrupted. Moreover, in certain embodiments, the plurality of light sources can emit a plurality of beams of collimated light that are radially stacked parallel to one another (e.g., parallel beams of light at different radial heights) across the inner surface of the housing toward a plurality of similarly stacked light sensors. The stacked collimated light can be disrupted by the rotor blades through which the collimated light passes. Thus, the blade tip to inner housing surface gap can be based on the respective locations of the collimated light that is disrupted by the rotor blades.

[0035] Moreover, in certain embodiments, the light sources can emit light toward a sensor group (e.g., array). The light can be diverging light, such as a cone-shaped beam of light. A portion of the light can be disrupted by the rotor blades through which the light passes. Thus, the blade tip gap can be based on the number of sensors in the sensor group that do not detect light when the rotor blades pass through the light.

[0036] Moreover, in some embodiments, in addition to the blade tip gap, the measurement system can detect the roundness or curvature of the housing, e.g., out-of-round conditions (e.g., deviations from a circular shape) and the severity of such conditions. For example, in some embodiments, the curvature of the housing can change (e.g., deform) over time due to stresses experienced during normal operation. As discussed in further detail below, the measurement system is configured to detect such changes in roundness. In some embodiments, the measurement system can monitor the blade tip gap and the housing curvature over time and can identify changes in the blade tip gap and the curvature over time. These changes in the blade tip gap and the housing curvature can be evaluated to detect oscillations and / or vibrations in the compressor.

[0037] Figure 1 is a block diagram of an embodiment of a turbine system 10 including a gas turbine engine 12 and a controller 14 (e.g., an electronic and / or processor-based controller). The illustrated gas turbine engine 12 includes a compressor 20 (e.g., a multi-stage axial compressor or compressor portion), a turbine 22 (e.g., a multi-stage turbine or turbine portion), and a fuel nozzle 24 coupled to one or more combustors 26 (e.g., combustor portions). The compressor 20 and turbine 22 can each have any number of stages (e.g., rows) of rotor blades and stator vanes (e.g., 1 to 20). The controller 14 can be communicatively coupled to a plurality of groups of light sources 16 (e.g., lasers) and light sensors 18 (e.g., fiber optic sensors / detectors) disposed in a housing of the compressor 20.

[0038] For example, data collected by the light sensor 18 can be used to determine a gap between a rotor blade and a casing of the compressor 20. As discussed in detail below, the controller 14 can receive data from the light sensor 18 and can determine (e.g., calculate or measure) a blade tip gap and other operating parameters of the compressor 20 based on the collected data. As discussed herein, the light sensor 18, the light source 16, and the controller 14 collectively form a measurement system 27. While the following discussion presents embodiments of the measurement system 27 in the context of the compressor 20, the measurement system 27 (e.g., the light source 16, the light sensor 18, and the controller 14) can be coupled to any rotating machine, such as a turbomachine 22, a pump, a steam turbine, a hydro turbine, or any combination thereof. Prior to presenting details of the measurement system 27, the following discussion provides a brief description of the gas turbine engine 12 and its operation.

[0039] In operation, the compressor 20 is configured to compress a compressible fluid (e.g., a gas such as air, oxygen, and / or exhaust gas) and deliver the compressed fluid to the fuel nozzles 24 and / or the combustors 26. While the compressible fluid can include any suitable gas, as one non-limiting example, the following discussion can generally refer to the compressible fluid as an oxidant (e.g., air). The fuel nozzles 24 are configured to supply fuel (e.g., from one or more fuel supplies) to one or more combustors 26 (e.g., in a combustion chamber) that combust the fuel with the oxidant (e.g., air) to generate hot combustion gases to drive the turbomachine 22. The fuel nozzles 24 can be designed as premix fuel nozzles 24 and / or diffusion fuel nozzles 24. Premix fuel nozzles 24 mix the fuel with the oxidant (e.g., air) to produce a premixed type flame. Diffusion fuel nozzles 24 do not premix the fuel with the oxidant, thus producing a diffusion type flame. Regardless of the type of flame, the hot combustion gases flow from the combustors 26 into the turbomachine 22, driving rotation of one or more stages of turbine blades coupled to a turbine rotor and shaft 30 along an axis 32. Ultimately, the hot combustion gases exit the turbomachine 22 through an exhaust outlet 28 (e.g., an exhaust stack, an exhaust end).

[0040] In the illustrated embodiment, the shaft 30 is coupled to the compressor 20 and a load 36 such that rotation of the shaft 30 also drives rotation of the compressor 20 and the load 36. The compressor 20 can draw in the oxidant (e.g., air) through an intake 34, which can include a filter, a thermal control system, or any other pre-processing system. The load 36 can include an electrical generator, a rotating machine, a propulsion system of a vehicle, or any other suitable device.

[0041] Compressor 20 can include alternating rows of rotating blades and stationary vanes (e.g., airfoils) that can be provided in multiple stages, described in greater detail below. As air moves downstream in compressor 20, oxidant (e.g., air) can be progressively compressed in stages or rows of rotating blades and corresponding stator vanes. In the illustrated embodiment, compressor 20 is a multi-stage axial compressor 20 having at least two rows or stages of blades and vanes. For example, in certain embodiments, multi-stage axial compressor 20 can have any number (e.g., 2 to 14 or any number more) of rows or stages of compressor blades and vanes.

[0042] It can be beneficial to illustrate more detailed views of certain components of gas turbine engine 12. Accordingly, Figure 2 is Figure 1 a cross-sectional side view of an embodiment of compressor 20 of gas turbine engine 12. In Figure 2 Throughout the discussion of the present disclosure, reference will be made to a set of axes. These axes are based on a cylindrical coordinate system and refer to an axial direction 38 (e.g., downstream), a radial direction 40, and a circumferential direction 42. For example, axial direction 38 extends generally parallel to axis 32 downstream through compressor 20, extends away from axis 32 along radial direction 40, and extends around axis 32 along circumferential direction 42.

[0043] In operation, air enters compressor 20 along axial direction 38 through intake 34 and can be pressurized in multi-stage axial compressor 20. The compressed air can then be mixed with fuel for combustion within combustor 26 to drive turbine 22 to rotate shaft 30 along circumferential direction 42, thereby rotating multi-stage axial compressor 20 and load 36. Rotation of shaft 30 also causes one or more blades 44 (e.g., compressor rotor blades) within multi-stage axial compressor 20 to draw in and pressurize air received by intake 34.

[0044] Multi-stage axial compressor 20 can include a rotor assembly 46 having a plurality of rotor blades 44 surrounded by a static housing 48 (e.g., a stator, housing, or outer wall) having a plurality of stator vanes 50. In some embodiments, static housing 48 or intake 34 of compressor 20 can have one or more sets of inlet guide vanes 52 (IGVs) (e.g., variable IGV stator vanes) that can control the flow into compressor 20. Compressor 20 can include a plurality of rows or stages 54, such as 2 to 30, 2 to 25, 2 to 20, 2 to 14, or 2 to 10 rows or stages, or any particular number or range therein. In each stage, multi-stage axial compressor 20 can include 2 to 1000, 5 to 500, or 10 to 100 rotor blades 44, and a corresponding adjacent set of 2 to 1000, 5 to 500, or 10 to 100 stator vanes 50.

[0045] In particular, the illustrated embodiment of the multi-stage axial compressor 20 includes 14 stages (denoted as 54a-54n), although more or fewer stages 54 can be used. It will be appreciated that each stage 54 has a set of rotor blades 44 disposed at a first axial location and a set of stator vanes 50 disposed adjacent the set of rotor blades 44 at a second axial location along the length of the compressor 20. In other words, each stage 54 has rotor blades 44 and stator vanes 50 axially offset from one another such that the compressor 20 has an alternating arrangement of rotor blades 44 and stator vanes 50 disposed one after another along the length of the compressor 20. Each set of rotor blades 44 extends (e.g., in a spaced apart arrangement) in the circumferential direction 42 about the shaft 30, and each set of stator vanes 50 extends (e.g., in a spaced apart arrangement) in the circumferential direction 42 within the static casing 48.

[0046] In use, the rotor blades 44 can rotate about the axis 32 and relative to the static casing 48 and stator vanes 50. Rotation of the rotor blades 44 can cause air to enter the inlet 34. The air is then compressed as it passes through the various stages 54 of the compressor 20 and moves in the axial direction 38 downstream of the multi-stage axial compressor 20. The compressed air can then exit through an outlet 56 of the multi-stage axial compressor 20. The outlet 56 can have a set of outlet guide vanes 58 (EGVs). The compressed air exiting the compressor 20 can be mixed with fuel, directed to the combustor 26, directed to the turbine 22, or used elsewhere in the turbine system 10.

[0047] As the air flows through the compressor 20, compression of the air can be based at least in part on the gaps between the rotors (e.g., the rotor blades 44) and the stators (e.g., the casing 48 and the stator vanes 50) of the compressor 20. Minimization of these gaps can result in increased compression of the air. More particularly, the gap between the rotor blades 44 and the inner surface 70 of the casing 48 can be directly related to the efficiency of air compression of the compressor 20. In fact, the smaller the gap between the rotor blades 44 and the inner surface 70, the more efficient the compressor 20 is at compressing air. Thus, the gap between the rotor blades 44 and the inner surface 70 of the casing 48 (e.g., the blade tip gap) can be monitored. In some embodiments, operation of the compressor 20 can be based on the blade tip gap to improve the efficiency of the compressor 20. For example, in some embodiments, based on the blade tip gap, the position of the rotor blades 44 can be adjusted or maintenance can be performed on the compressor 20.

[0048] As discussed herein, the casing 48 of the compressor 20 is configured to house the light sensor 18 and the light source 16, which are used to collect data indicative of the gap between the rotor blades 44 and the inner surface 70 of the casing 48. With this in mind, Figure 3 is a perspective view of an embodiment of the casing 48 of the compressor 20. In particular, Figure 3This is a perspective view of the housing portion 80 of the housing 48 of the compressor 20. In some embodiments, the housing 48 may be composed of multiple housing portions 80 that can be joined together to form the housing 48. For example, the housing 48 may include two, three, four, or more housing portions 80 circumferentially spaced 42 around axis 32 to form the entire circumference of the housing 48. The housing 48 extends circumferentially 42 around the rotor assembly 46 of the compressor 20.

[0049] like Figure 3 As shown, the housing 48 may include one or more mounting brackets 82 (e.g., bow-shaped mounting brackets, inserts) coupled to the inner surface 70 of the housing 48. Additionally, the housing 48 may include a rotor blade region 83 and a stator blade region 84, which extend around the inner surface 70 in a circumferential direction 42 and alternate in an axial direction 38. The rotor blade region 83 may be a rotor blade 44 (…). Figure 2 The tip of the rotor blade is configured to pass through the region therethrough. In other words, when the housing 48 is coupled to the rotor assembly 46, the rotor blade region 83 can be aligned axially 38 and radially 40 with the rotor blade 44. Although not explicitly shown, the stator blade region 84 may include stator blades 50 extending from the inner surface 70 of the housing 48. Figure 2 In fact, it should be noted that the illustrations have been deliberately simplified to focus attention on certain aspects, as discussed herein. That is, housing 48 may include additional elements (e.g., stator blades 50) not explicitly shown in the exemplary illustrations.

[0050] Mounting bracket 82 may be coupled to the inner surface 70 of housing 48 at rotor blade region 83. In some embodiments, the location of mounting bracket 82 may define rotor blade region 83. Mounting bracket 82 may also include housing structure 86 configured to provide a housing for sensor assembly 88 (e.g., light sensor 18 and / or light source 16). Housing structure 86 may be embedded within mounting bracket 82 such that sensor assembly 88 may be disposed below the inner surface 70 of housing 48. In other words, sensor assembly 88 may be radially 40 disposed between the inner surface 70 of housing and the outer surface 90 of housing 48. Therefore, it should be understood that sensor assembly 88 is configured to detect the presence and clearance of rotor blade 44 as rotor blade 44 passes along mounting bracket 82.

[0051] The curvature of the mounting racks 82 can substantially match the curvature of the inner surface 70 of the housing 48. As such, when the mounting racks 82 are coupled to the housing 48 (as shown), the top surface 100 of the mounting racks 82 can be substantially flush with the inner surface 70 of the housing 48. In particular, the inner surface 70 of the housing 48 can include tracks 102 (e.g., channels) configured to receive the mounting racks 82. In particular, each track 102 can be disposed along the inner surface 70 of the housing 48 in the circumferential direction 42, such as within the rotor blade region 83.

[0052] In some embodiments, each track 102 can be configured to receive a plurality of mounting racks 82. That is, each mounting rack 82 can include opposing circumferential ends 104. In some embodiments, when the mounting racks 82 are inserted into the tracks 102, the circumferential ends 104 of adjacent mounting racks 82 can contact or can be coupled together. Indeed, as shown, each mounting rack 82 can include any suitable respective arcuate length extending between the circumferential ends 104. As such, any suitable number of mounting racks 82 can be inserted into each track 102. For example, each housing portion 80 can include a single mounting rack 82 in each track 102, e.g., sized to substantially match the circumferential 42 length of the housing portion 80. Alternatively, each housing portion 80 can include 2, 3, 4, 5, 6, or more mounting racks 82 of the same or different circumferential 42 lengths sized to collectively fit within each track 102 in the housing portion 80. Moreover, the disclosed embodiments can include a plurality of different series of mounting racks 82, each designed for a particular configuration of sensor assemblies 88, as discussed in further detail below.

[0053] Moreover, in some embodiments, the mounting racks 82 can include circumferential slots disposed opposite the top surface 100 (e.g., within a bottom surface 110) configured to organize and guide electrical wires (e.g., conductors) coupled to the sensor assemblies 88. As such, electrical wires from multiple locations of the housing 86 of a mounting rack 82 within one of the tracks 102 can be grouped together. Thus, electrical wires from sensor assemblies 88 disposed within one of the tracks 102 can be guided through a single or common hole in the housing 48 to, for example, the controller 14. In contrast to sensors requiring a radial hole for each individual sensor, the disclosed embodiments are capable of significantly reducing the number of holes, and thus the number of potential leak paths in the housing 48. To further illustrate, Figure 4 is a partial cutaway perspective view of the housing 48 taken within the dashed line 4-4 Figure 3 showing the circumferential ends 104 of one of the mounting racks 82.

[0054] As shown, the mount 82 can be coupled to the rail 102 such that the top surface 100 of the mount 82 is substantially flush with and contoured to match the inner surface 70 of the housing 48 (e.g., having substantially the same inner curvature). To couple with the rail 102, the mount 82 can include opposing flanges 112 configured to engage opposing recesses 114 of the rail 102. In the illustrated embodiment, the opposing flanges 112 and the opposing recesses 114 extend in both the upstream and downstream directions of the axial direction 38 while also extending circumferentially 42 along the length of the mount 82 and the rail 102.

[0055] Additionally, as shown, the bottom surface 110 of the mount 82 can include a circumferential slot 116. As described above, the slot 116 can be configured to guide electrical wires 118 from the sensor assembly 88 disposed within the outer housing 86. In some embodiments, the slot 116 can be defined by the space disposed between the bottom surface 110 of the mount 82 and the rail 102 and between the opposing flanges 112. In some embodiments, the slot 116 can be disposed entirely within the interior of the mount 82 such that the walls of the mount 82 enclose the slot 116. In this way, a portion or all of the electrical wires 118 from the sensor assembly 88 disposed within the corresponding rail 102 can be grouped together and guided through a single exit through the housing 80 to communicatively couple to an external device such as the controller 114.

[0056] It will be appreciated that the outer housing 86 of the mount 82 can allow the light sensor 18 and the light source 16 to be oriented across the secant (e.g., geometric chord) of the circumference of the inner surface 70. In other words, the sensor assembly 88 can send and receive light across the entire inner surface 70 such that the light is not oriented radially 40 toward the axis 32 of the compressor 20. In certain embodiments, a portion or all of each mount 82 can be constructed of a transparent material configured to transmit light between the light source 16 and the light sensor 18 while also conforming to the inner curvature of the housing 48.

[0057] Generally, the sensor assembly 88 is configured to emit and receive light substantially linearly across the entire inner surface 70 of the housing 48. A portion of the light can pass through the transparent material of the mount 82, while the remaining portion (e.g., the majority) of the light can pass directly through the interior volume of the housing 48 in a tangential direction to facilitate gap measurements. The rotor blade 44 can pass through (e.g., interrupt, block) the light. The light sensor 18 can collect various data as an effect of the rotor blade 44 passing through the light. The controller 14 can then receive the data and calculate blade tip gap, out-of-roundness, vibration, and other parameters based on the various data received from the light sensor 18. For example, the received data can include a light blockage duration of each light beam between the light source 16 and the light sensor 18, a number and location of blocked light beams between the one or more light sources 16 and the plurality of light sensors 18, or a combination thereof. The controller 14 can also acquire other operational data, such as a rotational speed of the rotor and / or rotor blade 44.

[0058] Figure 5 is a schematic cross-sectional view of an embodiment of the sensor assembly 88 of the measurement system 27 having a light source 16 and a light sensor 18 coupled to Figure 3 of the housing 48, showing the blade 44 of the rotor assembly 46 moving along the inner circumference 70 of the housing 48, passing through a light path 120 between the light source 16 and the light sensor 18 (e.g., along a secant of the inner circumference 70). The sensor assembly 88 is configured to detect a blade tip gap 119 of the rotor blade 44 of the rotor assembly 46. For simplicity, Figure 5 shows one rotor blade 44 of the rotor assembly 46. However, the rotor assembly 46 includes a plurality of rotor blades 44 coupled to a central rotor, hub, or shaft, where the rotor blades 44 are spaced apart circumferentially 42 about the axis 32. The blade tip gap 119 can be defined as a distance measured in a radial direction 40 from a distal end 121 of the rotor blade 44 to the inner surface 70 of the housing 48 and / or the top surface 100 of the mount 82.

[0059] As shown in the current embodiment, the sensor assembly 88 can include at least one light source 16 (e.g., a single light source 16) and at least one light sensor 18 (e.g., a single light sensor 18). Specifically, the sensor assembly 88 can be disposed in an enclosure 86 provided via the mount 82. In some embodiments, the light source 16 and the light sensor 18 can be disposed in respective different enclosures 86. In some embodiments, the light source 16 and the light sensor 18 can be disposed in a common enclosure 86. The light source 16 and the light sensor 18 can be substantially flush or recessed relative to the inner surface 70 (e.g., inner circumference) of the housing 48 and / or the mount 82.

[0060] Further, the mount 82 can include a transparent portion 123 extending along the optical path between the light source 16 and the light sensor 18. For example, in the illustrated embodiment and each embodiment disclosed herein, the entire mount 82 can be formed of a transparent material, or the mount 82 can include a transparent portion 123 (e.g., a transparent insert or an injected transparent material) in a recess or slot 125 extending between the light source 16 and the light sensor 18. The profile of the outer surface of the transparent portion 123 can be formed to substantially match the curvature of the inner surface 70 (e.g., inner circumference) of the housing 48 and / or the mount 82.

[0061] As shown, the light source 16 is configured to direct light 120 (e.g., a beam of light, collimated light, laser light) along an optical path toward the light sensor 18. As provided in context herein, reference number 120 will refer to the light produced by the light source 16 or the optical path between the light source 16 and the light sensor 18. As discussed herein, the light 120 can be collimated light, such as light that is substantially free of divergence and substantially parallel light rays. The light sensor 18 is configured to detect whether the light sensor 18 is receiving the light 120. That is, the rotor blade 44 can pass through the light 120, thereby preventing the light sensor 18 from receiving the light 120 when the rotor blade 44 is disposed within the path of the light 120 (i.e., blocks, impedes, or interrupts the light).

[0062] For illustration, the rotor blade 44 can be configured to travel along a rotor path 122. The rotor path 122 can be substantially concentric with the inner surface 70 of the housing 48. However, as discussed below, in some embodiments, the rotor assembly 46 can oscillate or vibrate, which can similarly cause fluctuations in the rotor path 122. The rotor blade 44 is configured to continuously travel along the rotor path 122 from a first position 124 through a second position 126, a third position 128, a fourth position 130, a fifth position 132, a sixth position 134, and a seventh position 136. In practice, although shown as distinct positions, it should be understood that the rotor blade 44 can continuously travel from the first position 124 through the seventh position 136 at a substantially constant rotational speed during a gap measurement. Additionally, it should be noted that the rotor path 122 can extend in the circumferential direction 42 along the entire housing 48.

[0063] As shown, the rotor blade 44 can be disposed outside of the light 120 (e.g., not impeding or blocking the light 120) when in the first position 124. The rotor blade 44 can then be disposed within the light 120 (e.g., impeding or blocking the light 120) when in the second position 126 through the sixth position 134. The light sensor 18 does not receive (e.g., detect) the light 120 when the rotor blade 44 is disposed within (e.g., blocks or interrupts) the optical path of the light 120. The rotor blade 44 can then be disposed outside of the light 120 when in the seventh position 136.

[0064] The light sensor 18 can send (e.g., transmit, emit) a signal to the controller 14, where the signal indicates the duration of time that the light sensor 18 receives light and / or does not receive light. For example, the light sensor 18 can send a signal to the controller 14 indicating the presence or absence of light, which in turn can correlate the signal (e.g., the presence or absence of light) with a clock indicating the duration of time that the light is present and the duration of time that the light is not present. The controller 14 can also receive sensor data from one or more additional sensors that measure parameters of the turbomachinery system 10, such as the rotational speed of the compressor 20. The controller 14 can then compare the duration of time that the light is not present, as acquired from the light sensor 18, with the rotational speed of the rotor blade 44 to calculate the blade tip clearance 119. In effect, the duration of time that the rotor blade 44 obstructs the light 120 can be directly related to the blade tip clearance 119.

[0065] That is, a longer duration of time that the light 120 is obstructed by the rotor blade 44 indicates a smaller blade tip clearance 119, while a shorter duration of time that the light 120 is obstructed by the rotor blade 44 indicates a larger blade tip clearance 119. For example, when considering the rotational speed of the rotor blade 44, if the light sensor 18 detects the absence of light for the duration of time corresponding to the entire distance from the light source 16 to the light sensor 18, the controller 14 will calculate a minimum value for the blade tip clearance 119 (e.g., approximately zero or substantially close to zero). In contrast, when considering the rotational speed of the rotor blade 44, if the light sensor 18 detects the absence of light for the duration of time corresponding to a negligible distance (e.g., 0.01% of the entire distance) from the light source 16 to the light sensor 18, the controller 14 will calculate a maximum value for the blade tip clearance 119 (e.g., the radial 40 distance between the inner surface 70 and the light path of the light 120) that can be detected by the measurement system 27. In a similar manner, the controller 14 is configured to calculate the blade tip clearance 119 between the minimum and maximum values when the duration of time that the light is not present falls somewhere between the above-described embodiments.

[0066] In certain embodiments, the controller 14 can store data correlating the light beam height 127 with the circumferential distance between the light source 16 and the light sensor 18 for each position along the light path of the light 120 from the light source 16 to the light sensor 18, as well as the correlation between a particular light beam height 127 and the circumferential distance between the start 129 and end 131 of the interruption in the light path of the light 120. Based on this correlation, the rotational speed, and the measured duration of time that the light is not present, the controller 14 can be programmed to calculate the blade tip clearance 119. In some embodiments, the controller 14 can include a lookup table, a formula, a computer model, or other computational technique configured to determine the blade tip clearance 119 based on the rotational speed, the measured duration of time that the light is not present, and various known parameters.

[0067] Each sensor assembly 88 in the sensor assembly 88 can be configured to collect data indicative of the blade tip clearance 119 at a respective clearance location 144 along the inner surface 70 of the casing 48 (e.g., a region with circumferentially 42 spaced apart light sources 16 and light sensors 18). In the presently illustrated embodiment, the clearance location 144 can be defined by a circumferential distance (e.g., an angular distance or an arc length) along the inner surface 70 of the casing 48 and between the light source 16 and the light sensor 18. Accordingly, the controller 14 can determine the blade tip clearance 119 relative to an approximation (e.g., an average) of the circumferential distance included in the clearance location 144 of the casing 48.

[0068] For example, in certain embodiments, the angular distance of each clearance location 144 can be 1 to 15 degrees, 1 to 10 degrees, or 1 to 5 degrees. In certain embodiments, the arc length of each clearance location 144 can be greater than zero and less than 1%, 2%, 3%, 4%, or 5% of the circumference of the inner surface 70 of the casing 48. The measurement system 27 can include sensor assemblies 88 having equal or different circumferential distances (e.g., angular distances or arc lengths) between the light source 16 and the light sensor 18, which can be located at different circumferential locations spaced apart around the circumference of the inner surface 70 of the casing 48. In some embodiments, the clearance locations 144 can be provided at 2, 3, 4, 5, 6, 7, 8, 9, 10, or more equidistant circumferential locations of the casing 48. For example, the clearance locations 144 can be provided at four circumferentially spaced apart locations of the casing 48, such as 3 o’clock, 6 o’clock, 9 o’clock, and 12 o’clock locations.

[0069] The controller 14 is configured to monitor the sensor data and measure the blade tip clearance 119 of the rotor blades 44 over time to: determine trends in the clearance 119, compare the clearance 119 of multiple or all rotor blades 44 of each stage at each rotation, identify oscillations or vibrations in the rotor blades 44 and / or the casing 48, identify sudden changes indicative of catastrophic events (e.g., blade tip breakage), compare the clearance 119 between different stages of the compressor 20, predict future clearances 119 and effects on compressor 20 efficiency, schedule maintenance or repairs to correct any issues with unacceptable clearances 119, and control the system 10 based on the measured clearances 119.

[0070] Figure 6 is indicative of the difference between the measured tip clearance 119 and the average tip clearance 119 of the compressor 20. Figure 5A graph 150 of an embodiment of data acquired by sensor assembly 88 and received by controller 14 shows the duration of obstruction of the optical path 120 used to determine the gap 119 between housing 48 and blades 44 of rotor assembly 46; graph 150 may include a light detection axis 152 indicating whether light sensor 18 is receiving light. Graph 150 may also include a time axis 154 indicating time. As shown, light detection axis 152 may be binary. That is, light sensor 18 may receive light, indicated by "1", or may not receive light, indicated by "0". As shown, light sensor 18 may not receive light from "t1" to "t2" on time axis 154. Specifically, rotor blades 44 may block light from "t1" to "t2". The controller 14 can determine the blade tip gap 119 based on the duration during which the light sensor 18 does not receive light 120, the rotational speed of the rotor blade 44 measured by the speed sensor, and known parameters of the sensor assembly 88 (e.g., the circumferential distance between the light source 16 and the light sensor 18, the radius of the inner circumference of the housing 48, and / or the beam height 127 along the light path of the light 120).

[0071] Figure 7 Is using Figure 5 A flowchart of an embodiment of a method 158 for measuring the gap 119 between housing 48 and rotor assembly 46 blades 44 using a measurement system 27 (e.g., light sensor 18, light source 16, and controller 14). At block 160, a light beam (e.g., light 120) may be emitted from a light source (e.g., light source 16) along the housing (e.g., housing 48) surrounding the rotor (e.g., rotor blades 44 of rotor assembly 46) to a light sensor (e.g., light sensor 18). As discussed herein, the rotor may be any suitable rotor, such as shaft 30 or other rotating object. In fact, it should be understood that the embodiments discussed herein are broadly applicable to determining the gap 119 between any suitable rotor and the corresponding housing (e.g., outer shell).

[0072] At block 162, method 158 detects the duration of the interruption of the light beam 120. Specifically, method 158 measures the duration for which the rotor (e.g., rotor blades 44) obstructs the light sensor 18 from receiving the light beam 120. In some embodiments, the duration may be measured by the light sensor 18 and / or the controller 14. At block 164, method 158 calculates the gap 119 based at least in part on the duration of the interruption and the rotational speed of the rotor. In some embodiments, the rotational speed may be a directly measurable parameter (e.g., via a rotational speed sensor) or may be predetermined. That is, the rotor may rotate at a predetermined rotational speed.

[0073] Further, in some embodiments, the gap 119 can be used to further calculate oscillations or vibrations in the rotor. For example, at block 166, the gap of the rotor can be monitored over time. Specifically, in some embodiments, the gap 119 between the rotor and the housing 48 can be monitored relative to one or more gap locations in the housing (e.g., respective gap locations 144). More specifically, the gap 119 of a particular point on the rotor can be monitored relative to several gap locations of the housing 48. Additionally, in some embodiments, multiple points of the rotor (e.g., multiple rotor blades 44) can be monitored relative to multiple gap locations of the housing 48. It should be understood that the gap 119 of a particular rotor point can change with successive rotations through the gap locations 144 and / or can change relative to individual gap locations 144. In other words, the rotor can oscillate and / or vibrate relative to the housing 48 such that the gap 119 can change over time.

[0074] At block 168, the method 158 can identify changes in the gap 119 over time. For example, as discussed above, instances of the gap 119 of the rotor can be monitored relative to the gap locations 144 along the housing 48. Accordingly, changes (e.g., differences, gap trends) between each monitored (e.g., monitored, measured) instance of the gap 119 can be monitored relative to time. At block 170, the changes identified at block 168 can be evaluated to determine oscillations of the gap 119 over the time period. Specifically, changes in the gap 119 of the rotor over time can be indicative of the rotor oscillating at one or more frequencies. Accordingly, in some embodiments, the frequency of the oscillations can be determined.

[0075] At block 172, the gap, changes, and oscillations of the rotor can be output to an output device. For example, in some embodiments, the output device can be a computer (e.g., the controller 14) having a user interface. Data indicative of the gap, changes, and / or oscillations can be displayed via the user interface (e.g., an electronic display or monitor). In some embodiments, the data can be depicted in the form of a graph (e.g., gap, changes, and / or oscillations versus time), a graphical representation of the rotor (e.g., a 2D or 3D image), or any other suitable manner.

[0076] At block 174, operation of the system 10 can be controlled (e.g., adjusted) based on the output of block 172. For example, in some embodiments, a controller (e.g., the controller 14) can control operation of the system 10 (e.g., the compressor 20) to correct or compensate for any undesirable gap, changes, and / or oscillations of the rotor. In some embodiments, control of the operation can be implemented via maintenance or service requests for maintenance of the rotor.

[0077] Figure 8is a schematic cross-sectional view of an embodiment of a sensor assembly 88 of the measurement system 27 having a plurality of light sources 16 and a plurality of light sensors 18 coupled to Figure 3 of the housing 48, showing the blade 44 of the rotor assembly 46 moving along the inner circumference 70 of the housing 48, through one or more light paths 120 (e.g., along a secant of the inner circumference 70) between the light sources 16 and the light sensors 18. The sensor assembly 88 is configured to detect a blade tip clearance 119 of the rotor blade 44 of the rotor assembly 46. For simplicity, Figure 8 shows one rotor blade 44 of the rotor assembly 46. However, the rotor assembly 46 includes a plurality of rotor blades 44 coupled to a central rotor, hub, or shaft, where the rotor blades 44 are spaced apart circumferentially 42 about the axis 32.

[0078] As shown in the current embodiment, the sensor assembly 88 can include a plurality of light sources 16 and at least a corresponding number of light sensors 18 (e.g., a 1 : 1 ratio of light sources 16 and light sensors 18). The sensor assembly 88 arranges the light sources 16 and the light sensors 18 into a plurality of pairs, each pair having a light source 16 aligned with a light sensor 18 to define a light path of light 120. The light paths of light 120 in the plurality of pairs can be substantially parallel to one another and offset from one another by a small radial distance (e.g., in a radially stacked beam 120), where the light paths of light 120 can be perpendicular to the radius 178 of the housing 48 and substantially tangent to the inner circumference along the inner surface 70 of the housing 48. The illustrated embodiment includes five pairs of five light sources 16 aligned with five light sensors 18 defining light paths 120a-120e. However, embodiments of the sensor assembly 88 can include at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 20, 25, 30, or more light sources 16 and light sensors 18 arranged in pairs.

[0079] The sensor assembly 88 can be disposed in an enclosure 86 provided via the mounting bracket 82. In some embodiments, each of the light sources 16 and the light sensors 18 can be disposed in a respective different enclosure 86. In some embodiments, more than one of the light sources 16 and / or the light sensors 18 can be disposed in a common enclosure 86.

[0080] The light sources 16 and the light sensors 18 can be substantially flush or recessed relative to the inner surface 70 (e.g., inner circumference) of the housing 48 and / or the mounting bracket 82. Further, the mounting bracket 82 can include a transparent material 123 (e.g., a continuous or segmented piece of transparent material) that extends along the optical path between the light sources 16 and the light sensors 18. For example, in the illustrated embodiment and each embodiment disclosed herein, the entire mounting bracket 82 can be formed of a transparent material, or the mounting bracket 82 can include a transparent portion 123 (e.g., a transparent insert or an injected transparent material) in a recess or slot 125 that extends between the light sources 16 and the light sensors 18. The profile of the outer surface of the transparent portion 123 can be formed to substantially match the curvature of the inner surface 70 (e.g., inner circumference) of the housing 48 and / or the mounting bracket 82.

[0081] As shown, each of the light sources 16 is configured to direct a respective light 120 along an optical path toward a respective light sensor 18. As described above, each of the lights 120 can be a substantially collimated light, such as a light that is substantially free of divergence and substantially parallel light rays. Each of the light sensors 18 is configured to detect (e.g., receive) the respective light 120. Indeed, in some embodiments, each light source 16 can be equal in radial height 180 to the corresponding light sensor 18 (e.g., when measured from a midpoint along the optical path of the light 120 between the light source 16 and the light sensor 18). The radial height 180 can be measured in the gap location 144 from the inner surface 70 of the housing 48 in the radial direction 40.

[0082] In the presently illustrated embodiment, the gap location 144 can be defined by a circumferential distance (e.g., angular distance or arc length) along the inner surface 70 of the housing 48 and between the light source 16 and the light sensor 18 in a particular pair (e.g., the outermost pair of light sources 16 and light sensors 18). The radial height 180 for each pair of light source 16 and light sensor 18 can be defined as the maximum radial height between the optical path of the light 120 and the inner surface 70, which can correspond to the radial height at the midpoint between the light source 16 and the light sensor 18 of the particular pair. In a series of paired light sources 16 and light sensors 18, the radial height 180 can gradually increase from one pair to the next, and the incremental change (e.g., increase) in radial height can be relatively small to provide a more fine measurement (or greater precision) of the blade tip gap 119.

[0083] Accordingly, the plurality of optical paths of the light 120 directed from the plurality of light sources 16 to the plurality of light sensors 18 can be radially spaced apart (e.g., creating a radially stacked parallel beam) from the curved surface (e.g., inner circumference 70 or top surface 100) at a plurality of radial heights 180. These radial heights 180 can be accurately measured and stored in the memory of the controller 14 for use in calculating the blade tip gap 119 during operation of the system 10.

[0084] In some embodiments, each respective light source 16 can emit respective light 120 at a different and respective wavelength (e.g., color of light). Thus, in some embodiments, each respective light sensor 18 can be configured to only detect the respective wavelength of light 120 emitted from the corresponding light source 16 (e.g., the light source 16 at the same radial height 180 as the light sensor 18). However, embodiments of the measurement system 27 can also enable each light sensor 18 to detect light from any light source 16, such that an unintended detection of the wavelength of light 120 at a particular light sensor 18 (or light 120 at an unintended light sensor 18) can indicate a misround condition (e.g., the inner circumference of the housing 48 is not circular), a vibration condition, a misalignment condition, or some other issue.

[0085] For example, the sensor assembly 88 includes light sources 16 and light sensors 18 in a first pair at a first radial height, a second pair at a second radial height greater than the first radial height, a third pair at a third radial height greater than the second radial height, a fourth pair at a fourth radial height greater than the third radial height, and a fifth pair at a fifth radial height greater than the fourth radial height. If a light sensor 18 in the third group receives light from a light source 16 in the first group, the second group, the fourth group, or the fifth group, the light sensor 18 or the controller 14 can identify the unintended reception of light 120 (e.g., due to an unintended wavelength) and identify a misalignment or misround condition and its severity according to the wavelength of light received by the light sensor 18. For example, if the received wavelength (e.g., at the light sensor 18 in the third group) corresponds to the fifth group instead of the fourth group, or even further apart in the sixth group, the seventh group, or the eighth group of light sources 16 and light sensors 18, the controller 14 can be configured to estimate an increasing severity of the misalignment or misround condition.

[0086] The rotor blades 44 are configured to rotate along the rotor path 122. As the rotor blades 44 move along the rotor path 122, the rotor blades 44 move through the gap location 144 and can obstruct one or more of the light paths of the light 120 emitted from the light sources 16 toward the light sensors 18. Thus, as the rotor blades 44 move along the rotor path 122 and obstruct one or more of the light paths of the light 120 (e.g., parallel light paths radially offset from one another), one or more of the light sensors 18 can not detect (e.g., receive) the light 120 due to the obstruction. The position and detection state (e.g., detecting light or not detecting light) of each light sensor 18 in the sensor assembly 88 is indicative of the blade tip gap 119, as the light paths of the light 120 between each pair of light sources 16 and light sensors 18 are disposed at different radial heights 180 (e.g., the maximum radial height between each pair of light sources 16 and light sensors 18).

[0087] In the illustrated embodiment, the sensor assembly 88 includes five pairs of light sources 16 and light sensors 18 to emit and receive light 120 along five different light paths (e.g., a first light path of light 120a, a second light path of light 120b, a third light path of light 120c, a fourth light path of light 120d, and a fifth light path of light 120e). However, embodiments of the sensor assembly 88 can include any number (e.g., any number from 2 to 1000 or more) of pairs of light sources 16 and light sensors 18 arranged to have light paths of light 120 at successively greater radial heights 180 away from the inner surface 70 of the housing 48 such that the blade tip gap 119 can be measured with greater accuracy over greater radial heights 180 and / or with light paths of light 120 spaced closer together. Rotor blades 44 having larger blade tip gaps 119 can only pass through light paths of light 120 associated with larger radial heights 180 (e.g., pairs of light sources 16 and light sensors 18 disposed further away from the inner surface 70). In contrast, rotor blades 44 having smaller blade tip gaps 119 can pass through light associated with smaller radial heights 180 as well as light 120 associated with larger radial heights 180.

[0088] In Figure 8 In the illustrated gap position 144, the illustrated rotor blade 44 obstructs the light paths 120a, 120b, 120c, and 120d of light sensed by the light sensors 18, but does not obstruct the light path 120e of light sensed by the light sensors 18. Thus, four radially innermost light sensors 18 (i.e., closest to the rotational axis 32 and farthest from the inner surface 70) indicate light obstruction, and one radially outermost light sensor 18 (i.e., farthest from the rotational axis 32 and closest to the inner surface 70) indicates no light obstruction. Accordingly, the controller 14 receives and processes signals from the light sensors 18 to identify light obstructions and their corresponding positions (e.g., radial heights 180) and light passages and their corresponding positions (e.g., radial heights 180) to measure or estimate the blade tip gap 119. For example, the controller 14 can calculate or estimate the blade tip gap 119 to be equal to the radial height 180 corresponding to the light path of light 120e, which is the only light path of light that is not obstructed by the rotor blade 44.

[0089] However, if multiple light sensors 18 receive light 120 from light source 16, controller 14 can receive and process signals from light sensors 18 to calculate or estimate the blade tip gap 119 as equal to the maximum radial height 180 of the unobstructed light path of light 120. Similarly, if light sensors 18 detect that rotor blades 44 interrupt the first path 120a and the second path 120b of light, while simultaneously detecting that rotor blades 44 do not interrupt the third path 120c, the fourth path 120d, and the fifth path 120e of light, controller 14 can receive and process signals from light sensors 18 to calculate or estimate the blade tip gap 119 of rotor blades 44 as equal to the radial height 180 corresponding to the light path 120c (i.e., the maximum radial height 180 of the three unobstructed paths 120c, 120d, and 120e of light).

[0090] The measurement accuracy of the blade tip gap 119 depends at least in part on the radial spacing between the optical paths of the light 120 between different pairs of light sources 16 and light sensors 18. Therefore, the closer the radial spacing, the greater the measurement accuracy of the blade tip gap 119. In some embodiments, the controller 14 may also measure the duration of optical path obstruction of the light 120, similar to the description above. Figure 5 to Figure 7 The method described, and combined with the approach to Figure 8 The aforementioned measurement technique is used to improve the measurement accuracy of the blade tip clearance 119 and / or provide redundancy in the measurement.

[0091] Figure 9 This is an implementation of lookup table 159, which the controller 14 can use to base its decisions on the lookup table from... Figure 8 The sensor assembly 88 obtains data to determine the blade tip gap 119 between the housing 48 and the blade 44. The controller 14 can store a lookup table 159 in memory and execute measurement code stored in memory and executable on the processor to determine the blade tip gap 119 based on the lookup table and sensor data. As discussed above, each pair of light sources 16 and light sensors 18 has an optical path (e.g., radial height 180) of light 120 associated with the blade tip gaps 119, 182. For example, a first light 120a may be associated with a first gap 182a, a second light 120b may be associated with a second gap 182b, a third light 120c may be associated with a third gap 182c, a fourth light 120d may be associated with a fourth gap 182d, and a fifth light 120e may be associated with a fifth gap 182e. As shown, the gaps 182 may be arranged in descending order, such that the first gap 182a is greater than the second gap 182b, and so on.

[0092] The controller 14 can receive data from the light sensors 18 indicating whether the respective light sensor 18 is receiving (e.g., detecting) or not receiving the respective light 120. The controller 14 can then utilize a lookup table 159 to determine the gap 182 based on the data. For example, the data received from the light sensors 18 can indicate that the light sensors 18 are not at least temporarily detecting the first, second, and third lights 120a, 120b, 120c, while the light sensors 18 are indeed detecting the fourth and fifth lights 120d, 120e. Accordingly, the controller 14 can determine that the blade tip gap 119 is less than the third gap 182c and at least equal to the fourth gap 182d, and possibly between the third and fourth gaps 182c, 182d.

[0093] Figure 10 is a schematic cross-sectional view of an embodiment of the sensor assembly 88 of the measurement system 27 having a plurality of light sources 16 and a plurality of light sensors 18 coupled to Figure 3 of the housing 48, showing the blade 44 of the rotor assembly 46 moving along the inner circumference 70 of the housing 48, passing through one or more light paths 120 (e.g., along a secant of the inner circumference 70) between the light sources 16 and the light sensors 18. As discussed below, the illustrated embodiment of the sensor assembly 88 can be configured to measure the blade tip gap 119 in substantially the same manner as described above with reference to Figure 8 and Figure 9 The illustrated embodiment of the sensor assembly 88 can be configured to measure the blade tip gap 119 in substantially the same manner as described above with reference to Figure 10 shows one rotor blade 44 of the rotor assembly 46. However, the rotor assembly 46 includes a plurality of rotor blades 44 coupled to a central rotor, hub, or shaft, where the rotor blades 44 are spaced apart circumferentially 42 about the axis 32.

[0094] As illustrated in the current embodiment, the sensor assembly 88 includes a plurality of pairs of light sources 16 and light sensors 18, each pair having a light source 16 aligned with a light sensor 18 to define a light path of light 120. The alignment of each pair of light sources 16 and light sensors 18 and the corresponding light path of light 120 can define a secant relative to the curvature (e.g., annular surface) of the inner surface 70 (e.g., inner circumference) of the housing 48 and the top surface 100 of the mount 82. That is, the light path 120 can intersect the curvature of the inner surface 70 at two points.

[0095] Further, the plurality of pairs of light sources 16 and light sensors 18 and their corresponding light paths of light 120 can be substantially parallel and radially spaced apart from one another by an intermediate gap (e.g., radial gap), thereby defining radially stacked beams 120 at a plurality of radial heights relative to the inner surface 70. The intermediate gap can be uniform (or variable) among the plurality of light paths of light 120.

[0096] As discussed above, the light source 16 and the light sensor 18 (e.g., the sensor assembly 88) can be coupled to the mount 82, which engages with the track 102 in the housing 48. In some embodiments, the sensor assembly 88 can be coupled to an insert 190 (e.g., a recess) of the mount 82. The insert 190 of the mount 82 can be defined by a space of the mount 82 extending below a top surface 100 of the mount 82, where a profile of the top surface 100 is formed to match a curvature of an inner circumference of the housing 48. In some embodiments, the insert 190 of the mount 82 can include a transparent material 192, such as the transparent portion 123 in the recess or slot 125 as discussed above (e.g., a transparent insert or an injected transparent material). The transparent material 192 can be a solid medium through which the light 120 can be transmitted. The light source 16 can be positioned in the insert 190 to emit a light path of the light 120 at least partially through the insert 190 (e.g., through the transparent material 192) toward the light sensor 18.

[0097] For example, in the illustrated embodiment, the light source 16 is disposed on a first side 193 of the insert 190 and the light sensor 18 is disposed on a second side 195 thereof, where the first and second sides 193, 195 can be parallel to one another such that a spacing between the light source 16 and the light sensor 18 is uniform in the radial direction 40. However, in certain embodiments, the first and second sides 193, 195 can be angled relative to one another (e.g., diverging or converging in the radial inward direction) such that the spacing between the light source 16 and the light sensor 18 varies in the radial direction 40.

[0098] Additionally, in some embodiments, the insert 190 of the mount 82 can include a raised portion 194 that extends radially inward away from the base 191 of the transparent material 192 and the recess 125 without extending beyond the top surface 100 (e.g., is flush with the top surface 100). The raised portion 194 can be configured to block one or more of the light paths of the light 120 emitted from the light sources 16 toward the light sensors 18. That is, in the round condition of the inner perimeter circle of the housing 48, the raised portion 194 can be configured to block one or more light sensors 18 from receiving the light 120 emitted from one or more light sources 16. Further, as shown, in some embodiments, the sensor assembly 88 can include one or more auxiliary light sensors 196 that are not directly paired with a corresponding light source 16. In some embodiments, the light sensors 18 that correspond to the light paths of the light 120 blocked by the raised portion 194 can similarly be considered auxiliary light sensors 196. However, the number of auxiliary light sensors 18, 196 can be greater than the corresponding number of light sources 16 that are directed toward the raised portion 194. The auxiliary light sensors 196, alone or in combination with the light sensors 18, can be used to detect changes in the roundness of the housing 48. Further, although the presently shown embodiment includes three auxiliary light sensors 196, it should be noted that the embodiments discussed herein can include any suitable number of auxiliary light sensors 196.

[0099] In some embodiments, the roundness of the housing 48 can change over time. The roundness of the housing 48 can be defined as a measure of how close the shape of the housing 48 (e.g., the inner perimeter 70) is to the shape of a mathematically perfect circle. The roundness of the housing 48 can change as the housing 48 experiences thermal expansion and contraction, thermal stress, or other issues during operation of the compressor 20. In some embodiments, as the roundness of the housing 48 changes, the angle at which the light 120 is emitted (e.g., relative to the housing 48) can similarly change. Specifically, in such embodiments, the angle of the light 120 can change such that one or more of the auxiliary light sensors 196 or unintended light sensors 18 can detect one or more of the light 120. Indeed, detection of the light 120 at the auxiliary light sensors 196 can be indicative of a change in the roundness of the housing 48. Further, in some embodiments, as the roundness of the housing 48 changes, a light sensor 18 that is positioned to detect light from a particular light source 16 can instead detect light from a different light source 16, which can further be indicative of a change in the roundness of the housing 48.

[0100] For example, as described above, in some embodiments, each beam of light 120 may be associated with a corresponding wavelength, and the light sensor 18 may be correspondingly configured to detect the corresponding wavelength. Therefore, in some embodiments, when the roundness of the housing 48 changes and the angle of the light 120 changes, the wavelength that the corresponding light sensor 18 can receive may similarly change (e.g., the light sensor 18 may receive an unintended wavelength of the light 120). Thus, the change in the roundness of the housing 48 may be determined by the auxiliary light sensor 196 that detects the light 120 and / or the light sensor 18 that detects the light 120 from the unintended light source 16, due to the change in the emission angle of the light 120.

[0101] The controller 14 can be configured to determine the non-roundness condition and its severity by processing sensing signals from various light sensors 16 and 196, identifying the light source 16 and the expected position based on the wavelength of the sensed light 120, and calculating the amount of roundness deviation based on deviations in the optical path of the light 120. For example, if light 120 of a specific wavelength is expected at a specific light sensor 18 in a roundness condition of the housing 48, then if light 120 of the specific wavelength is received at multiple positions (or distances) of the light sensor 18 or 196 away from the expected sensor position, the controller 14 can use the number of positions (or radial distances) to determine the severity of the non-roundness condition. A larger number of positions (or radial distances) may mean a larger deviation in roundness (i.e., a more severe non-roundness condition), while a smaller number of positions (or shorter radial distances) may mean a smaller deviation in roundness (i.e., a less severe non-roundness condition).

[0102] Figure 11 Is it used as Figure 10 The flowchart illustrates an embodiment of a method 198 for measuring the gap 119 between housing 48 and blade 44 and the roundness of housing 48 using a measurement system 27 (e.g., light sensor 18, light source 16, and controller 14). At block 200, multiple light beams (e.g., the optical path of light 120) may be emitted from multiple light sources (e.g., light source 16) along the housing (e.g., housing 48) surrounding the rotor (e.g., rotor blade 44 of rotor assembly 46) toward multiple light sensors (e.g., light sensor 18). As discussed herein, the rotor can be any suitable rotor, such as shaft 30 or other rotating object. In fact, it should be understood that the embodiments discussed herein are broadly applicable to determining the gap between any suitable rotor and the corresponding housing (e.g., outer shell).

[0103] At block 202, the method 198 detects an interruption in the plurality of light beams 120. Specifically, the method 198 detects whether the light sensors 18 are receiving the plurality of light beams 120 or whether the light beams 120 are being interrupted (e.g., blocked) before reaching the plurality of sensors 18. At block 204, the method 198 calculates or estimates the gap based on the identification and location of the light beams 120 that successfully reached the sensors 18 and based on the signals from the light sensors 18 and the known locations (e.g., the known radial height of the light path of each pair of light source 16 and light sensor 18, the known blade tip clearance of each light sensor 18, etc.) of the light beams 120 that were blocked from reaching the sensors 18. For example, the method 198 can use a lookup table 159 of Figure 9 .

[0104] The method 198 can determine that the gap 119 of the rotor is less than the radial height associated with the light beams 120 that were interrupted and thus not detected by the expected light sensors 18, and the method can determine that the gap 119 of the rotor is at least equal to the radial height associated with the light beams 120 that were successfully transmitted and received by the expected light sensors 18. If the method 198 identifies multiple light sensors 18 that successfully received the expected light beams, the method 198 can calculate or estimate the blade tip clearance 119 to be equal to the maximum of the radial heights associated with these light sensors 18.

[0105] At block 206, the method 198 assesses the roundness of the housing 48 based on the interruption and location of the light beams 120, and more specifically based on the location of the light sources 16 that transmitted the light beams 120 and the location of the light sensors 18 that received the light beams 120. As discussed above, the roundness of the housing 48 can affect the angle of transmission of the light beams 120. Thus, the light sensors 18 that receive the light beams 120 can change based on the adjusted angle of transmission of the light beams 120. The roundness can then be determined based on which of the light sensors 18 are receiving which of the light beams 120. In some embodiments, each light beam 120 can include a respective and different wavelength (e.g., color of light). As the angle of transmission of the light beams 120 and the angle of transmission of the sensors 18 that receive the light beams 120 changes, the respective wavelengths that the sensors 18 can detect can similarly change. Thus, in some embodiments, the roundness can be based on the location of the sensors 18 that receive the light and the wavelengths that the sensors 18 receive, which can indicate the location of the light sources 16 of the respective wavelengths.

[0106] At block 208, the method 198 monitors the clearance 119 of the rotor and the roundness of the casing 48 over a period of time. Specifically, in some embodiments, the clearance 119 between the rotor and the casing 48 can be monitored relative to one or more clearance positions in the casing 48 (e.g., respective clearance positions 144). More specifically, the clearance 119 of a particular point on the rotor can be monitored relative to several clearance positions of the casing 48. Additionally, in some embodiments, multiple points of the rotor (e.g., multiple rotor blades 44) can be monitored relative to multiple clearance positions of the casing 48. It should be appreciated that the clearance 119 of a particular rotor point can vary with successive passes through the clearance positions and / or can vary relative to individual clearance positions. In other words, the rotor can oscillate and / or vibrate relative to the casing 48 such that the clearance 119 can vary over time. Similarly, in some embodiments, the roundness of the casing 48 can be monitored at multiple points along the casing 48, which can correspond to the clearance positions discussed above.

[0107] At block 210, the method 198 can identify changes in the clearance 119 of the rotor and / or changes in the roundness of the casing 48 over time. For example, as discussed above, instances of the clearance 119 of the rotor and the roundness of the casing 48 can be monitored relative to the clearance positions along the casing 48. Accordingly, changes (e.g., differences, clearance trends, and / or roundness) between each monitored (e.g., measured) instance of the clearance 119 and / or the roundness can be monitored relative to time. At block 212, the changes identified at block 210 can be evaluated to determine oscillations of the clearance and / or the roundness over the period of time. Specifically, changes in the clearance 119 of the rotor over time can indicate that the rotor is oscillating at one or more frequencies. Similarly, changes in the roundness of the casing 48 over time can indicate that the roundness of the casing 48 is oscillating. Accordingly, in some embodiments, the frequency of the oscillations can be determined.

[0108] At block 214, the clearance 119, roundness, changes, and oscillations of the rotor and / or the casing 48 can be output to an output device. For example, in some embodiments, the output device can be a computer (e.g., the controller 14) having a user interface. Data indicative of the clearance 119, roundness, changes, and / or oscillations can be displayed via the user interface (e.g., an electronic display or monitor). In some embodiments, the data can be depicted in the form of a graph (e.g., clearance, roundness, changes, and / or oscillations versus time), a graphical representation (e.g., a 2D or 3D image) of the rotor and / or the casing 48, or any other suitable manner.

[0109] At block 216, operation can be controlled (e.g., adjusted) based on the output of block 214. For example, in some embodiments, a controller (e.g., controller 14) can control operation of system 10 (e.g., compressor 20) to correct or compensate for any undesirable clearances, roundness, variations, and / or oscillations of the rotor and / or housing. In some embodiments, control of operation can be achieved via maintenance or service requests for maintenance of the rotor.

[0110] Figure 12 is a schematic cross-sectional view of an embodiment of sensor assembly 88 having common light source 16 and multiple light sensors 18 coupled to Figure 3 is a schematic cross-sectional view of an embodiment of sensor assembly 88 having common light source 16 and multiple light sensors 18 coupled to

[0111] In operation, rotor blade 44 can move along rotor path 122 near clearance location 144 of housing 48. Indeed, as described above, sensor assembly 88 can be positioned in mount 82 to detect blade tip clearance 119 at clearance location 144 of housing 48. In particular, clearance location 144 can be defined by the arc length of inner surface 70 of housing 48 between light source 16 and light sensors 18. In some embodiments, clearance location 144 can be disposed at the midpoint of the arc length between light source 16 and light sensors 18. As rotor blade 44 moves along rotor path 122, rotor blade 44 can interrupt a portion of light 120, as shown, such that one or more of light sensors 18 do not detect (e.g., receive) light 120.

[0112] For example, all (or a predetermined amount) of the light sensors 18 can detect light 120 before the rotor blade 44 moves through the gap location 144. As the rotor blade 44 moves through the gap location 144, some of the light sensors 18 can be blocked from receiving light 120. In other words, as the rotor blade 44 moves through the scattered light 120 from the light source 16, the rotor blade 44 casts a shadow on one or more of the light sensors 18. As the rotor blade 44 continues to move through the gap location 144 and out of the gap location 144, all of the light sensors 18 can again receive light 120. The blade tip gap 119 is a function of the height of the shadow cast by the passing rotor blade 44 and / or the height of the light 120 that is bypassed by the rotor blade 44. Thus, as the rotor blade 44 moves through the gap location 144, the blade tip gap 119 can be determined based on the number, location, and / or identity of the light sensors 18 that receive light 120 (i.e., successful transmission of light 120) or do not receive light 120 (i.e., interruption of light 120).

[0113] In fact, the number of light sensors 18 that detect light 120 and / or the number of light sensors 18 that do not detect light 120 as the rotor blade 44 moves through the gap location 144 can be directly related to the blade tip gap 119 at the gap location 144. For example, the smaller the blade tip gap 119, the fewer the number of light sensors 18 that can detect light 120 and the greater the number of light sensors 18 that cannot detect light 120. Similarly, the greater the blade tip gap 119, the greater the number of light sensors 18 that can detect light 120 and the fewer the number of light sensors 18 that cannot detect light 120. The light sensors 18 can transmit data to the controller 14 indicating whether or not they detected light 120. The controller 14 can then determine the blade tip gap 119 based on the data received from the light sensors 18 (e.g., the number of light sensors 18 that received and / or did not receive light 120).

[0114] Alternatively or additionally, the specific identification of the light sensor 18 that detects the light 120 when the rotor blade 44 moves through the gap position 144 can be directly correlated to the blade tip gap 119 at the gap position 144. For example, when the controller 14 is programmed using other measurement techniques, mathematical calculations, computer models, etc., the blade tip gap 119 can be calculated for each light sensor 18 that receives the light 120 and stored in the memory of the controller 14. Thus, during later operation, if a particular light sensor 18 receives the light 120, the controller 14 can determine the corresponding blade tip gap 119 based on the identification of the particular light sensor 18 and the gap data stored in the memory of the controller 14. If multiple light sensors 18 receive the light 120, the controller 14 can determine the blade tip gap to be the largest blade tip gap 119 associated with those light sensors 18.

[0115] Additionally or alternatively, if multiple light sensors 18 do not receive the light 120, the controller 14 can determine the blade tip gap to be the smallest blade tip gap 119 associated with those light sensors 18. In certain embodiments, the data received from the light sensors 18 can provide the identification of that particular light sensor 18 to the controller 14 based on the color or wavelength of the light (e.g., by filtering the light received by the light sensor 18), an identifier or location data embedded in the sensor data, or some other type of identifying information.

[0116] In the illustrated embodiment, the light sensors 18 can be stacked in a direction that intersects the direction of projection of the light 120 within the housing 86 (e.g., the centerline of the light 120). For example, the light sensors 18 can be stacked along a side 195 that can be parallel, diverging, or converging relative to the side 193 having the light source 16. The side 195 having the light sensors 18 can be directly aligned with the radius of the housing 48, or the side 195 can be slightly angled (e.g., 0 to 30 degrees) relative to the radius. In either case, the light sensors 18 can be described as being positioned at a single circumferential location along the inner circumference 70 of the housing 48 (e.g., one aligned stack of sensors 18 or a radial stack of sensors 18).

[0117] In the illustrated embodiment, the radial stack of light sensors 18 is recessed below a top surface 100 of the sensor mount 82, such that the light sensors 18 are disposed at a plurality of depths (e.g., radial depths) below the top surface 100. Additionally, as illustrated, the light sensors 18 and / or the light source 16 can be disposed within an insert 190 of the mount 82. As discussed above, the insert 190 can comprise a transparent material 192. The transparent material 192 can be a solid medium through which the light 120 can be transmitted. In some embodiments, the top surface 100 of the mount 82 can be at least partially defined by an upper surface of the transparent material 192, both of which can be contoured to match a curvature of the inner surface 70 (e.g., inner circumference) of the housing 48.

[0118] Figure 13 is a schematic cross-sectional view of an embodiment of the sensor assembly 88 having a common light source 16 and a plurality of light sensors 18 coupled to Figure 3 one of the sensor mounts 82 in the housing 48 of Figure 12 is illustrated moving along the inner circumference 70 of the housing 48, through at least a portion of the light path 120 between the common light source 16 and the light sensors 18 (e.g., along a chord of the inner circumference 70). The illustrated embodiment of the sensor assembly 88 can be configured to measure the blade tip clearance 119 in substantially the same manner as discussed above with reference to Figure 12 However, unlike the stack of light sensors 18 as Figure 13 illustrated, the illustrated embodiment of has a plurality of light sensors 18 spaced apart from one another in the circumferential direction 42 along the inner circumference 70 of the housing 48 (i.e., at a plurality of circumferential locations over a circumferential distance).

[0119] Figure 13 In some embodiments, as Figure 12 illustrated, the light sensors 18 can be positioned in the housing 86 of the mount 82 such that the light sensors 18 are spaced apart in the circumferential direction 42 along the top surface 100 of the mount 82. As discussed above with reference to illustrated, the light sensors 18 can be positioned in the housing 86 of the mount 82 such that the light sensors 18 are spaced apart in the circumferential direction 42 along the top surface 100 of the mount 82. As discussed above with reference to

[0120] As the rotor blade 44 moves through the clearance location 144, the blade tip clearance 119 can be determined based on the number, location, and / or identity of the light sensors 18 that receive the light 120 (i.e., successful transmission of the light 120) or do not receive the light 120 (i.e., interruption of the light 120). The controller 14 receives and processes the sensor data from the light sensors 18 and determines the clearance 119 from the amount of light 120 that is blocked and / or bypassed by the rotor blade 44. Figure 12 Figure 13 Some embodiments discussed with reference to Figure 10One or more of the features discussed and illustrated. For example, in some embodiments, the sensor assembly 88 can include one or more of an auxiliary light sensor 196 and / or a raised portion 194. The auxiliary light sensor 196 and the raised portion 194 can function similarly as described above. That is, the auxiliary light sensor 196 can be configured to detect the light 120 when the angle of emission of the light 120 changes due to a change in the roundness of the housing 48. Further, as described above, the raised portion 194 of the mounting bracket 82 can be configured to block a portion of the light 120. As such, as the roundness of the housing 48 changes, the portion of the light 120 blocked by the raised portion 194 can similarly change, which can be detected by the light sensor 18. In operation, the controller 14 can be configured to determine the roundness of the inner circumference 70 based at least in part on the interruption or emission of the light 120 relative to the raised portion 194. Additionally, the controller 14 can be configured to determine the roundness of the inner circumference 70 based at least in part on the emission of the light 120 to one or more unintended light sensors 18 of the plurality of light sensors 18.

[0121] Figure 14 is representative of data obtained from the sensor assembly 88 of Figure 12 and Figure 13 The graph 220 of an embodiment representing data obtained from the sensor assembly 88 of The graph 220 can include a light detection axis 222 indicating the number of light sensors 18 that detected the light 120. The graph 220 also includes a time axis 224 indicating time. As discussed above, the blade tip clearance 119 can be based on the number (e.g., a minimum number) of light sensors 18 that detected the light 120 during the time period (e.g., a blade sensing duration) that the rotor blade 44 passes between the light source 16 and the light sensors 18, where the number of light sensors 18 that detected the light 120 decreases, reaches a local minimum 226, and then increases. The blade tip clearance 119 corresponds to the local minimum 226 shown in the graph 220. At this local minimum 226, the controller 14 is configured to determine the blade tip clearance 119 based on a correlation between the number of light sensors 18 that detected the light 120 and the known blade tip clearance 119 (e.g., based on prior testing, measurements, mathematical calculations, computer models, etc.).

[0122] As Figure 12 and Figure 13As shown, the axes of the optical sensors 18 can be arranged parallel to one another within the mounting rack 82, such that the optical paths of the light 120 are also parallel to one another. In some embodiments, the lateral distance or spacing between the axes of the optical sensors 18 (or the distance between the optical paths of the light 120) can depend on the configuration of the optical sensors 18. For example, the optical sensors 18 can be arranged in direct contact with one another to minimize the spacing between the axes of the optical sensors 18, and / or the optical sensors 18 can be spaced apart from one another (e.g., with a gap between the sidewalls of the optical sensors 18). The optical sensors 18 can be arranged in an ordered manner and / or in clusters.

[0123] Figure 15 is Figure 12 and / or Figure 13 FIG. 18 is a schematic cross-sectional view of an embodiment of an arrangement of the optical sensors 18 of the sensor assembly 88 showing the optical sensors arranged in a tightly packed array 228 (e.g., a one-dimensional arrangement in a column or row 230). In the embodiment shown, the opposing sides 227 of the optical sensors 18 abut one another directly without any intervening spacing, and the optical sensors 18 are arranged in a single column or row 230. However, the optical sensors 18 can have intervening spacing between the sides 227 of the optical sensors 18, and / or the optical sensors 18 can be arranged in multiple rows and columns 230 such as a grid to provide additional optical sensors 18 at each radial 40 position. In a grid embodiment, the optical sensors 18 can be aligned directly with one another in both the rows and columns of the grid. The resolution of the sensor assembly 88 can depend on the spacing between the axes of the optical sensors 18, which can also depend on the diameter 229 of the optical sensors 18 and / or the optical fibers within the optical sensors 18. In certain embodiments, the diameter of each optical sensor 18 (e.g., fiber optic sensor) can be less than or equal to about 3, 4, 5, 6, 7, 8, 9, or 10 thousandths of an inch.

[0124] Figure 16 is Figure 12 and / or Figure 13FIG. 6 is a schematic cross-sectional view of an embodiment of the plurality of light sensors 18 of the sensor assembly 88, showing the light sensors 18 arranged in a tightly packed array 228 (e.g., a two-dimensional bundle or cluster 232). In the illustrated embodiment, the light sensors 18 are generally staggered relative to one another in two dimensions (e.g., in the radial direction 40 and the axial direction 38). This staggered arrangement of the light sensors 18 in the cluster 232 can improve the resolution of the sensor assembly 88 by placing sensors 18 in intermediate positions between other adjacent sensors 18 in the radial direction 40 and the axial direction 38 (e.g., midway between the axes of sensors 18 that are directly adjacent to one another). Thus, the staggered arrangement of the light sensors 18 in the radial direction 38 can significantly improve the measurement accuracy of the blade tip clearance 119. For example, the greater the amount of the sensors 18 that are staggered in the radial direction 40, the higher the resolution of the sensor assembly 88, and thus the higher the measurement accuracy of the blade tip clearance 119.

[0125] In some embodiments, in addition to monitoring the blade tip clearance 119, the clusters 232 of light sensors 18 can also be used to monitor the shape of the rotor blade 44. For example, as the rotor blade 44 passes through the light 120, the shadow cast by the rotor blade 44 on the light sensors 18 can form a profile of the rotor blade 44 in the radial direction 40 and the axial direction 38. Thus, the detection of the light 120 by the light sensors 18 can be based on the shape of the shadow of the rotor blade 44, and data indicative of the shape of the rotor blade 44 can be output to the controller 14. In some embodiments, the controller 14 can utilize the data to create an image (e.g., a profile) of the rotor blade 44. For example, the controller 14 can display the image of the rotor blade 44 via an electronic display or computer monitor. In certain embodiments, the controller 14 can compare the measured shape of the rotor blade 44 to a baseline shape (e.g., an original shape) of the rotor blade 44, and identify deviations between the measured shape and the baseline shape. For example, based on the comparison between the measured shape and the baseline shape, the controller 14 can identify areas of the rotor blade 44 (e.g., tips, sides, etc.) that have experienced wear, abrasion, cracking, surface defects, or other structural issues.

[0126] Figure 17 is used to Figure 12 and Figure 13FIG. 24 is a flowchart of an embodiment of a method 238 of measuring a gap 119 between a housing 48 and a paddle 44 and a roundness of the housing 48 of a rotor assembly 46 with a measurement system 27 (e.g., light sensors 18, a light source 16, and a controller 14). At block 240, diverging light (e.g., light 120) can be emitted from a light source (e.g., light source 16) along a housing (e.g., housing 48) around a rotor (e.g., rotor paddle 44 of rotor assembly 46) toward a plurality of light sensors (e.g., light sensors 18, detector array). As discussed herein, the rotor can be any suitable rotor, such as shaft 30 or other rotating object. Indeed, it should be understood that the embodiments discussed herein can be widely applicable to determining a gap between any suitable rotor and a corresponding housing (e.g., enclosure).

[0127] At block 242, interruptions in the diverging light 120 can be identified by the light sensors 18 and the controller 14. Specifically, the light sensors 18 can detect whether the light sensors 18 are receiving the diverging light 120 or whether portions of the diverging light 120 are interrupted (e.g., blocked) before reaching the plurality of sensors 18. At block 244, the gap 119 can be determined by the controller 14 based on the number of light sensors 18 that do not detect light 120. Indeed, the larger the paddle tip gap 119, the more light sensors 18 can detect light 120. In some embodiments, the paddle tip gap 119 can be determined based on the location of the light sensors 18 and whether they detect light 120. In other words, the paddle tip gap 119 can be directly related to the location of the light sensors 18 that are blocked from receiving light 120.

[0128] At block 246, the roundness of the housing 48 can be assessed by the controller 14 based on the interruptions in the light 120. As discussed above, the roundness of the housing 48 can affect the angle of emission of the diverging light 120. Thus, the sensors 18 that receive the diverging light 120 can change based on the adjusted angle of emission of the diverging light 120. The roundness can then be determined by the controller 14 based on which of the sensors 18 receive light 120.

[0129] Further, in some embodiments, the clearances 119 and roundness can be used to further calculate oscillations / vibrations in the rotor and / or the housing 48. For example, at block 248, the clearances 119 of the rotor and the roundness of the housing 48 can be monitored over time. Specifically, in some embodiments, the clearances 119 between the rotor and the housing 48 can be monitored relative to one or more clearance locations in the housing 48 (e.g., respective clearance locations 144). More specifically, the clearances 119 of a particular point on the rotor can be monitored relative to several clearance locations of the housing 48. Additionally, in some embodiments, multiple points of the rotor (e.g., multiple rotor blades 44) can be monitored relative to multiple clearance locations of the housing 48. It should be understood that the clearances 119 of a particular rotor point can change with successive passes through the clearance locations and / or can change relative to individual clearance locations. In other words, the rotor can oscillate and / or vibrate relative to the housing 48 such that the clearances 119 can change over time. Similarly, in some embodiments, the roundness of the housing 48 can be monitored at multiple points along the housing 48, which can correspond to the clearance locations discussed above.

[0130] At block 250, the changes in the clearances 119 and the roundness over time can be identified by the controller 14. For example, as discussed above, instances of the clearances 119 of the rotor and the roundness of the housing 48 can be monitored relative to the clearance locations along the housing 48. Accordingly, the changes (e.g., differences, trends in the clearances 119 and / or the roundness) between each monitored (e.g., measured) instance of the clearances 119 and / or the roundness relative to time can be monitored by the controller 14. At block 252, the changes identified at block 250 can be evaluated by the controller 14 to determine oscillations of the clearances 119 and / or the roundness over the time period. Specifically, changes in the clearances 119 of the rotor over time can indicate that the rotor is oscillating at one or more frequencies. Similarly, changes in the roundness of the housing 48 over time can indicate that the roundness of the housing 48 is oscillating. Accordingly, in some embodiments, the frequencies of the oscillations can be determined.

[0131] At block 254, the clearances 119, roundness, changes, and oscillations of the rotor and / or the housing 48 can be output to an output device. For example, in some embodiments, the output device can be a computer (e.g., the controller 14) having a user interface (e.g., an electronic display or computer monitor). Data indicative of the clearances 119, roundness, changes, and / or oscillations can be displayed via the user interface. In some embodiments, the data can be depicted in the form of a graph (e.g., clearances 119, roundness, changes, and / or oscillations versus time), a graphical representation (e.g., a 2D or 3D image) of the rotor and / or the housing 48, or any other suitable manner.

[0132] At block 256, operation of the system 10 can be controlled (e.g., adjusted) by the controller 14 based on the output of block 254. For example, in some embodiments, the controller (e.g., the controller 14) can control operation of the compressor 20 to correct for any undesirable gaps, roundness, variations, and / or oscillations of the rotor and / or the housing 48. In some embodiments, the control of operation can be implemented via a maintenance or service request for maintenance of the rotor and / or the housing 48 of the compressor 20.

[0133] Figure 18 is a schematic illustration of an embodiment of a measurement system 27 that can be used to measure a gap 260 (e.g., a blade tip gap 119) between a rotor assembly 46 (e.g., a rotor 262, a blade 44, a shaft 30, etc.) and a housing 48 that surrounds the rotor assembly 46. The measurement system 27 can include one or more light sources 16, one or more light sensors 18, and a controller 14, as discussed above with reference to Figure 5 to Figure 17 The light source 16 is configured to emit light 120 toward the light sensor 18. In some embodiments, the light source 16 can include a broadband light source 270 that is configured to emit broadband light (e.g., white light) toward the light sensor 18. The broadband light source 270 can be configured to emit collimated light and / or divergent light. In some embodiments, the light source 16 can include a monochromatic or single-wavelength light source 272. The single-wavelength light source 272 can be configured to direct collimated light of a single wavelength, such as a specific color of light, toward the light sensor 18.

[0134] The light 120 (e.g., one or more beams of collimated light, one or more light beams, divergent light) can be emitted from the light source 16 toward the light sensor 18. At the same time, the rotor 262 (e.g., the blade 44) can travel along the rotor path 122 to block (e.g., interrupt) the light 120 or a portion of the light 120. Thus, as discussed in detail above with reference to Figure 5 to Figure 17 The rotor gap 260 can be determined by the controller 14 based on the interruption of the light 120 by the rotor 262 (e.g., the blade 44) and known information (e.g., prior measurements) relating the interruption of the light 120 to various gap 260 values, as discussed in detail above with reference to

[0135] The light sensor 18 is configured to detect the light 120 emitted from the light source 16. In some embodiments, the light sensor 18 can include a fiber optic sensor. In some embodiments, the light sensor 18 can include one or more optical spectrometers 280. The optical spectrometer 280 is configured to detect the light 120, and more specifically, can detect the color or wavelength of the light 120. In some embodiments, the light sensor 18 can include one or more optical filters 282. The optical filter 282 is configured to filter the light received by the light sensor 18. Specifically, in some embodiments, such as embodiments including multiple light sensors 18, each light sensor 18 can include a respective optical filter 282. The light 120 received by the respective light sensor 18 can be filtered through the optical filter 282 to the optical spectrometer 280. That is, the optical filter 282 can be configured to filter out one or more specific colors or wavelengths of light 120. The optical spectrometer 280 can then determine which of the light sensors 18 is receiving the light 120 based on the filtered light received by the optical spectrometer 280.

[0136] The light sensor 18 can be communicatively coupled to the controller 14. As such, the light sensor 18 can transmit data indicative of the detection of the light 120. Specifically, the data can be indicative of whether the light sensor 18 detected light, the color or wavelength of the detected light, the duration of the light detection, the location of the light sensor, or a combination thereof. As discussed herein, the controller 14 can then determine the rotor gap 260 based on the data received from the light sensor 18 using any of the techniques referenced above. Figure 5 to Figure 17

[0137] The technical effects of the present disclosure include systems and methods for determining a gap 119 between a rotor (e.g., the paddle 44) and a housing 48 surrounding the rotor. The system can include a light measurement system 27 having a light source 16 configured to emit light 120 toward a light sensor 18. The light 120 can be emitted as a chord relative to an arcuate surface of the housing 48. The rotor (e.g., the paddle 44) can rotate through the light 120 such that the light 120 is interrupted from reaching the light sensor 18. The light sensor 18 can output data indicative of the interruption to the controller 14. The controller 14 can then determine the gap 119 based on the data. As such, the gap 119 can be accurately determined. In some cases, the gap 119 can also be used to control the operation of the compressor 20.

[0138] ​This written description uses examples to disclose the subject matter, including the best mode, and also to enable any person skilled in the art to practice the subject matter, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the subject matter is defined by the claims, and can include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent Figure 1 to Figure 18 Features of the application can be combined in any suitable manner.

Claims

1. A system for optical measurement in a rotating machine, comprising: a measurement system (27), the measurement system comprising: a sensor mount (82) having a curved top surface (100); a light source (16) mounted to the sensor mount (82); a light sensor (18) mounted to the sensor mount (82) and circumferentially spaced from the light source (16) about an axis of rotation of a rotor (30, 46); and a controller (14) coupled to the light source (16) and the light sensor (18), wherein the controller (14) is configured to determine a gap (119) between the rotor (30, 46) and a housing (48) based at least in part on an interruption of light (120) emitted from the light source (16) to the light sensor (18) as a chord across a curved surface of the housing (48), wherein the controller (14) is configured to determine the gap (119) between the rotor (30, 46) and the housing (48) based at least in part on a duration of the interruption of light (120) emitted from the light source (16) to the light sensor (18).

2. The system of claim 1, comprising a gas turbine (12) having the rotor (30, 46) and the housing (48), a compressor (20), and a turbine (22); wherein the rotor (30, 46) extends through the compressor (20) and the turbine (22), and the housing (48) surrounds at least a portion of the compressor (20) or the turbine (22); and wherein the measurement system (27) is coupled to the gas turbine (12).

3. The system of claim 2, wherein the rotor (30, 46) comprises a rotor blade (44) in the compressor (20) or the turbine (22), and the gap (119) is located between a tip of the rotor blade (44) and the curved surface of the housing (48).

4. The system of claim 1, wherein the sensor mount (82) is configured to be mounted in a circumferential track (102) along the curved surface (70) of the housing (48).

5. The system of claim 1, wherein the sensor mount (82) of the measurement system (27) comprises a transparent material (123) disposed circumferentially between the light source (16) and the light sensor (18).

6. The system of claim 1, wherein the curved surface (70) extends along a circumference of the housing (48).

7. The system of claim 1, wherein the controller (14) is configured to determine the gap (119) between the rotor (30, 46) and the housing (48) based at least in part on a rotational speed of the rotor (30, 46).

8. The system of claim 1, wherein the light source (16) comprises a laser, the light (120) comprises collimated light, and the light sensor (18) comprises a fiber optic sensor.

9. The system of claim 1, wherein the measurement system (27) comprises a plurality of sensor assemblies (88) circumferentially spaced apart about the rotational axis of the rotor (30, 46) at different circumferential locations; and wherein each of the plurality of sensor assemblies (88) is coupled to the controller (14) and each of the plurality of sensor assemblies (88) has one of the light sources (16) and one of the light sensors (18).

10. The system of claim 9, wherein the controller (14) is configured to monitor and compare the gap (119) at the different circumferential locations.

11. The system of claim 1, wherein the controller (14) is configured to monitor the gap (119) over time and identify changes in the gap (119) over time, the changes comprising oscillations in the gap (119) over time, trends in the gap (119) over time, or a combination thereof.

12. A method for optical measurement in a rotating machine, comprising: emitting light (120) from a light source (16) along a chord of a curved surface (70) of a rotational path between a rotor (30, 46) and a housing (48) to a light sensor (18); and determining a gap (119) between the rotor (30, 46) and the housing (48) based on a duration that the light (120) is interrupted by the rotor (30, 46) and a rotational speed of the rotor (30, 46) using a controller (14) coupled to the light source (16) and the light sensor (18).

13. The method of claim 12, comprising monitoring and comparing the gap (119) at different circumferential locations using a plurality of sensor assemblies (88) coupled to the controller (14), each sensor assembly (88) having at least one of the light source (16) and the light sensor (18).

14. The method of claim 12, comprising monitoring the gap (119) over time and identifying changes in the gap (119) over time using the controller (14), the changes comprising oscillations in the gap (119) over time, trends in the gap (119) over time, or a combination thereof.

Images