Optical turbine engine blade damage detector
A damage detection system includes one or more emitters, one or more receivers, and a controller. Emitters are arranged to transmit continuous beam or intermittent light pulses toward rotor blades during operation of a turbomachine. Light returns collected at the receivers define a light return amplitude profile. The controller analyzes the light return amplitude profile to identify light amplitude changes indicative of one or more damaged blades. When the light return profile satisfies one or more damage criteria, the controller outputs an indication of blade damage to another turbomachine controller, system, or display.
1 . A turbomachine comprising:
a plurality of blades rotatable about an axis of the turbomachine; and
a system for detecting damage of the plurality of blades, the system comprising:
an emitter mounted to the turbomachine and orientated to emit a plurality of light pulses along an emission axis intersecting the plurality of blades;
a first receiver mounted to the turbomachine that has a first field of view intersecting the emission axis to define a first interrogation volume through which the plurality of blades rotates during operation of the turbomachine, wherein the emitter and the first receiver are mounted to the turbomachine upstream from the plurality of blades relative to a direction of air flow through the plurality of blades during operation of the turbomachine; and
a controller in communication with the emitter and the first receiver, the controller comprising a processor and computer-readable memory encoded with instructions that, when executed by the processor, cause the system to:
emit the plurality of light pulses from the emitter toward the plurality of blades as the blades rotate within the turbomachine;
receive, at the first receiver, a plurality of first light returns scattered by the plurality of blades within the first interrogation volume;
receive, at the first receiver, an ambient light level;
determine, by the controller, a plurality of first times of flight of the plurality of first light returns;
identify, by the controller, a subset of the plurality of first light returns associated with the plurality of blades based on a time-of-flight range and the plurality of first times of flight;
determine, by the controller, a first amplitude change of the subset of the first light returns based on an amplitude of the first light returns and the ambient light level; and
output, by the controller, an indication of topographical damage to the blades based on a comparison between the first light amplitude change of the light returns and a threshold light amplitude change.
2 . The turbomachine of claim 1 , wherein the first receiver is collocated with the emitter to receive back scatter light returns, and wherein the controller outputs the indication of damage based on a change in backscatter light return amplitude and the threshold light amplitude change.
3 . The turbomachine of claim 1 , wherein the first receiver is spaced from the emitter to receive forward light scatter, and wherein the controller outputs the indication of damage based on a change in forward scatter light return amplitude and the threshold light amplitude change.
4 . The turbomachine of claim 1 , wherein the first receiver is spaced from the emitter to receive side scatter light returns, and wherein the controller outputs the indication of damage based on a change of side scatter light amplitude and the threshold light amplitude change.
5 . The turbomachine of claim 1 , wherein the computer-readable memory is encoded with instructions that, when executed by the processor, cause the system to:
determine, by the controller, a first subset of light returns corresponding to a plurality of first rotations of the plurality of blades; and
determine, by the controller, a second subset of light returns corresponding to a plurality of second rotations of the plurality of blades;
wherein the indication of damage is output by the controller based on a change in light return amplitude between the plurality of first rotations and the plurality of second rotations.
6 . The turbomachine of claim 1 , wherein the computer-readable memory is encoded with instructions that, when executed by the processor, cause the system to:
determine a rotational speed of the plurality of blades based on the plurality of first light returns.
7 . The turbomachine of claim 1 , wherein the first emitter includes a lens, the lens comprising a rounded inlet surface that diverges outward along the emission axis and terminates at an outlet surface normal to the emission axis, and wherein each light pulse of the plurality of light pulses refracts to form a light line upon passing through the lens.
8 . The turbomachine of claim 1 , wherein a frequency of the plurality of first light pulses is greater than a rotational frequency of the plurality of blades times a number of blades.
9 . A turbomachine comprising:
a plurality of blades rotatable about an axis of the turbomachine; and
a system for detecting damage of the plurality of blades, the system comprising:
an emitter mounted to the turbomachine and orientated to emit a plurality of light pulses along an emission axis intersecting the plurality of blades;
a first receiver mounted to the turbomachine that has a first field of view intersecting the emission axis to define a first interrogation volume through which the plurality of blades rotates during operation of the turbomachine;
a second receiver mounted to the turbomachine that has a second field of view intersecting the emission axis to define a second interrogation volume through which the plurality of blades rotates during operation of the turbomachine, wherein the emitter, the first receiver, and the second receiver are mounted to the turbomachine upstream from the plurality of blades relative to a direction of air flow through the plurality of blades during operation of the turbomachine; and
a controller in communication with the emitter, the first receiver, and the second receiver, the controller comprising a processor and computer-readable memory encoded with instructions that, when executed by the processor, cause the system to:
emit the plurality of light pulses from the emitter toward the plurality of blades as the blades rotate within the turbomachine;
receive, at the first receiver, a plurality of first light returns scattered by the plurality of blades within the first interrogation volume;
receive, at the second receiver, a plurality of second light returns scattered by the plurality of blades within the second interrogation volume;
receive, at the first receiver, an ambient light level;
determine, by the controller, a plurality of first times of flight of the plurality of first light returns;
identify, by the controller, a subset of the plurality of first light returns associated with the plurality of blades based on a time-of-flight range and the plurality of first times of flight;
determine, by the controller, a first amplitude change of the first light returns based on an amplitude of the subset of first light returns and the ambient light level;
determine, by the controller, a plurality of second times of flight of the plurality of second light returns;
identify, by the controller, a subset of the plurality of second light returns associated with the plurality of blades based on the time-of-flight range and the plurality of second times of flight;
determine, by the controller, a second amplitude change of the second light returns based on an amplitude of the subset of second light returns and the ambient light level; and
output, by the controller, an indication of topographical damage to the blades based on a comparison of the first light amplitude change of the light returns and a first threshold light amplitude change and a second comparison between the second amplitude change of light returns and a second threshold light amplitude change.
10 . The turbomachine of claim 9 , wherein the first receiver is collocated with the emitter to receive back scatter light returns, and wherein the second receiver is spaced from the emitter to receive forward scatter light returns or side scatter light returns.
11 . The turbomachine of claim 10 , wherein the first amplitude change exceeds the first threshold light amplitude change of the plurality of first light returns and the second amplitude exceeds the second threshold light amplitude change of the plurality of second light returns.
12 . The turbomachine of claim 11 , wherein the first amplitude change is indicative of an increase in backscatter light returns, and wherein the second amplitude change is indicative of a decrease in forward scatter light returns or side scatter light returns.
13 . The turbomachine of claim 9 , wherein the emitter, the first receiver, and the second receiver are mounted to a surface of the turbomachine surrounding and facing the plurality of blades, and wherein the emitter, the first receive, and the second receiver are circumferentially spaced about a rotational axis of the plurality of blades along the surface.
14 . A method of detecting damage of a plurality of blades rotatable within a turbomachine, the method comprising:
emitting a plurality of light pulses from an emitter toward the plurality of blades as the blades rotate within the turbomachine;
receiving, at a first receiver, a plurality of first light returns scattered by the plurality of blades, wherein the emitter and the first receiver are mounted to the turbomachine upstream from the plurality of blades relative to a direction of air flow through the plurality of blades during operation of the turbomachine;
receiving, at the first receiver, an ambient light level;
determining, by the controller, a plurality of first times of flight of the plurality of first light returns;
identifying, by the controller, a subset of the plurality of first light returns associated with the plurality of blades based on a time-of-flight range and the plurality of first times of flight;
determining, by the controller, a first amplitude change of the first light returns based on an amplitude of the subset of first light returns and the ambient light level; and
outputting, by a controller, an indication of topographical damage based on a comparison between the first amplitude change of the light returns and a first threshold light amplitude change.
15 . The method of claim 14 , further comprising:
determining, by the controller, the first subset of light returns corresponding to a plurality of first rotations of the plurality of blades; and
determining, by the controller, a second subset of light returns corresponding to a plurality of second rotations of the plurality of blades;
wherein the indication of topographical damage is output by the controller based on a change in light return amplitude between the plurality of first rotations and the plurality of second rotations.
16 . The method of claim 14 , further comprising:
receiving, at the second receiver, a plurality of second light returns scattered by the plurality of blades; and
determining, by the controller, a second amplitude change of the second light returns;
wherein the indication of topographical damage is output based on the comparison between the first amplitude change and the first threshold light amplitude change and a second comparison between the second amplitude change and a second threshold light amplitude change.
17 . The method of claim 16 , wherein the first light returns are back scatter light returns and wherein the second light returns are forward scatter light returns.
18 . The method of claim 17 , wherein the first amplitude change is indicative of an increase in back scatter light returns that exceed a first threshold light amplitude change of the plurality of first light returns and the second amplitude change is indicative of a decrease in forward light scatter returns that exceed a second threshold light amplitude change of the plurality of second light returns.