Patent Description:
Compressor and turbine sections of an aircraft include multiple rotors and stators. Gas turbine engines maintain an optimal clearance (distance) between the tips of the rotors and an outside diameter of a gas path within the turbine engine. Blade measurement systems are therefore used to obtain accurate measurements of blade parameters such as tip clearance and tip timing to maintain efficient engine operation and blade health monitoring. <CIT> discloses a device that uses a microwave radar system to determine the position of a blade relative to a housing. <CIT> discloses a multimode waveguide used in a monopulse radar.

As control and health monitoring systems become more complex, the interconnect count between system components increases, which also increases failure probabilities. With the increase in interconnects, large amounts of cabling may be used to connect sensors and actuators to controllers and/or diagnostic units of a machine. Long cable runs, including multiple wires, can add substantial weight and may increase susceptibility to noise effects and/or other forms of signal degradation. Increased wire connections can also result in a larger number of wire harnesses to remove and attach when servicing machine components. A larger number of wires and wire harnesses can increase the possibility of damage at pin/socket interconnects, particularly when the wire harnesses are attached and detached from components.

To achieve desired control, health monitoring and/or component measurement, sensing systems such as a blade measurement system, for example, may need information from locations that can be difficult to access due to moving parts, internal operating environment or machine configuration. The access limitations can make wire routing bulky, expensive, and potentially vulnerable to interconnect failures. Sensor and interconnect operating environments for desired sensor locations may exceed the capability of interconnect systems. In some cases, cable cost, volume, and weight may exceed desired limits for practical applications. Placement options and total number of sensors and actuators that may be installed in a machine can be limited by wiring and connector impacts on weight, reliability, physical sizing, and operating temperature limitations.

According to a first aspect, a multi-mode microwave waveguide blade sensing system includes a transceiver, a waveguide, a probe sensor, and a controller. The transceiver is configured to generate at least one microwave energy signal having a first waveguide mode and a second waveguide mode different from the first waveguide mode. The waveguide includes a first end is configured to receive the at least one microwave energy signal from the transceiver. The probe sensor includes a proximate end in signal communication with a second end of the waveguide to receive the at least one microwave energy signal and a distal end including an aperture configured to output the at least one microwave energy signal. The controller is configured to monitor rotation of a plurality of blades formed on a rotor of a machine, to determine a rotational position of a given blade among the plurality of blades with respect to the probe sensor, and to control the transceiver to vary characteristics of the at least one microwave energy signal to invoke the first and second waveguide modes. The probe sensor directs the microwave energy signal toward a machine at a first direction based on the first waveguide mode and a second direction different from the first direction based on the second waveguide mode, and receives different levels of reflected microwave energy based at least in part on a location at which the at least one microwave energy signal that is directed at the first direction is reflected from the machine compared to a location at which the at least one microwave energy signal that is directed at the second direction is reflected from the machine. The controller selectively invokes the first and second waveguide modes based on the rotational position of the given blade with respect to a field of view of the probe sensor.

A technical effect of the apparatus, systems and methods is achieved by a multi-mode microwave waveguide blade sensing system as described herein.

Turning first to an overview of technical details that are relevant to the disclosure, waveguides are devices capable of directing microwave energy signal (e.g., wave) from a signal source to one or more target destinations. The microwave energy signal can be propagated according to different waveguide modes. A waveguide mode is a particular electromagnetic field pattern of waves in a plane perpendicular to the radiation's propagation direction, e.g., the cross section of the waveguide. This pattern can take infinitely many different shapes in a waveguide. In addition, different waveguide modes can be selectively excited, and different waveguide modes can co-exist in the waveguide. Because the pattern of fields are different on the waveguide cross section, each mode has a different field pattern when they are output from the aperture of the waveguide.

Various non-limiting embodiments of the disclosure provide a multi-mode microwave waveguide blade sensing system configured to generate a blade signature of a given blade in a gas engine turbine. The multi-mode microwave waveguide blade sensing system utilizes a waveguide capable delivering at least one microwave energy signal having a first waveguide mode and a second waveguide mode different from the first waveguide mode. The different waveguide modes allow for targeting specific locations of the blade, which in turn maximize the level of energy reflected from the blade, thereby resulting in an improved resolution and accuracy of a blade signature of the blade.

Various embodiments of the present disclosure are related to electromagnetic communication through and to components of a machine. <FIG> schematically illustrates a gas turbine engine <NUM> as one example of a machine as further described herein. The gas turbine engine <NUM> is depicted as a two-spool turbofan that generally incorporates a fan section <NUM>, a compressor section <NUM>, a combustor section <NUM> and a turbine section <NUM>. Alternative engines may include an augmentor section (not shown) among other systems or features.

The fan section <NUM> drives air along a bypass flow path B in a bypass duct to provide a majority of the thrust, while the compressor section <NUM> drives air along a core flow path C for compression and communication into the combustor section <NUM> then expansion through the turbine section <NUM>. Although depicted as a two-spool turbofan gas turbine engine in the disclosed non-limiting embodiment, it should be understood that the concepts described herein including for example the non-limiting embodiments of the multi-mode microwave waveguide blade sensing system and the probe sensor described herein, are not limited to use with two-spool turbofans as the teachings may be applied to other types of turbine engines including three-spool architectures or any other machine that requires sensors to operate with similar environmental challenges or constraints. Additionally, the concepts described herein may be applied to any machine or system comprised of control and / or health monitoring systems. Examples can include various moderate to high temperature environments, such as glass and metal forming systems, petroleum-oil-and-gas (POG) systems, ground-based turbine for energy generation, nuclear power systems, and transportation systems.

With continued reference to <FIG>, the exemplary engine <NUM> generally includes a low speed spool <NUM> and a high speed spool <NUM> mounted for rotation about an engine central longitudinal axis A relative to an engine static structure <NUM> via several bearing systems <NUM>.

A combustor <NUM> is arranged in exemplary gas turbine engine <NUM> between the high pressure compressor <NUM> and the high pressure turbine <NUM>.

It will be appreciated that the positions of the fan section <NUM>, compressor section <NUM>, combustor section <NUM>, turbine section <NUM>, and fan drive gear system <NUM> may be varied. In direct drive configurations, the gear system <NUM> can be omitted.

A significant amount of thrust can be provided by the bypass flow B due to the high bypass ratio. The example low pressure turbine <NUM> can provide the driving power to rotate the fan section <NUM> and therefore the relationship between the number of turbine rotors <NUM> in the low pressure turbine <NUM> and the number of blades in the fan section <NUM> can establish increased power transfer efficiency.

The disclosed example gas turbine engine <NUM> includes a control and health monitoring system <NUM> (generally referred to as system <NUM>) utilized to monitor component performance and function. The system <NUM> includes a network <NUM>, which is an example of a waveguide electromagnetic transmission network. The network <NUM> includes a controller <NUM> operable to communicate with nodes 68a, 68b through electromagnetic signals. The controller <NUM> can be in signal communication with a microwave transceiver to generate and transmit the electromagnetic signals. The nodes 68a, 68b can be distributed throughout the gas turbine engine <NUM> or other such machine. Node 68a is an example of an actuator node that can drive one or more actuators/effectors of the gas turbine engine <NUM>. Node 68b is an example of a sensor node that can interface with one or more sensors of the gas turbine engine <NUM>. Nodes 68a, 68b can include processing support circuitry to transmit/receive electromagnetic signals between sensors or actuators and the controller <NUM>. A coupler <NUM> can be configured as a splitter between a waveguide <NUM> coupled to the controller <NUM> and waveguides <NUM> and <NUM> configured to establish wireless communication with nodes 68a and 68b respectively. The coupler <NUM> can be a simple splitter or may include a repeater function to condition electromagnetic signals sent between the controller <NUM> and nodes 68a, 68b.

In the example of <FIG>, a radio frequency-based repeater <NUM> is interposed between the coupler <NUM> and node 68b, where waveguide <NUM> is a first waveguide coupled to the coupler <NUM> and radio frequency-based repeater <NUM>, and waveguide <NUM> is a second waveguide coupled to the radio frequency-based repeater <NUM> and node 68b. Collectively, waveguides <NUM>, <NUM>, <NUM>, <NUM> are configured to direct transmission of the radio frequencies (e.g., electromagnetic signals) between the controller <NUM> and one or more of the nodes 68a, 68b. The transmission media within waveguides <NUM>-<NUM> may include dielectric or gaseous material. In embodiments, the waveguides <NUM>-<NUM> can be hollow metal tubes. The waveguides <NUM>-<NUM> may be ridged or may include flexible material. The disclosed system <NUM> may be utilized to control and/or monitor any component function or characteristic of a turbomachine, aircraft component operation, and/or other machines.

Prior control and diagnostic system architectures utilized in various applications include a centralized system architecture in which the processing functions reside in an electronic control module. Actuator and sensor communications were accomplished through analog wiring for power, command, position feedback, sensor excitation and sensor signals. Cables and connections include shielding to minimize effects caused by electromagnetic interference (EMI). The use of analog wiring and the required connections can limit application and capability of such systems due to the ability to locate wires, connectors and electronics in harsh environments that experience extremes in temperature, pressure, and/or vibration. Exemplary embodiments can use electromagnetic radiation having radio frequencies transmitted through waveguides <NUM>-<NUM> in a wireless architecture to provide both electromagnetic communication signals and power to the individual elements of the network <NUM>.

The use of electromagnetic radiation in the form of radio waves (MHz to GHz) to communicate and power the sensors and actuators using a traditionally complex wired system provides substantial architectural simplification, especially as it pertains to size, weight, and power (SWaP). Embodiments of the invention provide extension of a network where reduced SNR may compromise network performance by trading off data rates for an expansion of the number of nodes and distribution lines; thereby providing for more nodes / sensors, with greater interconnectivity.

Referring to <FIG>, a waveguide electromagnetic transmission network <NUM> is depicted as an example expansion of the network <NUM> of <FIG>. The waveguide electromagnetic transmission network <NUM> can include the controller <NUM> coupled to coupler <NUM> through waveguide <NUM>. The coupler <NUM> is further coupled to coupler 67a through waveguide <NUM> and to coupler 67b through waveguide <NUM>. Coupler 67a is further coupled to three nodes 68a through waveguides 173a, 173b, 173c in parallel. The nodes 68a can respectively interface or be combined with multiple actuators <NUM>.

Coupler 67b is coupled to waveguides 174a and 174b in parallel. Waveguide 174a establishes signal communication with node 68b, which can interface or be combined with multiple sensors <NUM>. Waveguide 174b includes a portion referred to herein as a probe sensor <NUM>, which is configured to perform blade measurements of a gas turbine engine <NUM>. A first end of the waveguide <NUM> is coupled to the coupler 67b so as to establish signal communication with the controller <NUM>. The probe sensor <NUM> includes a proximate probe end 178a and a distal probe end 178b. The proximate probe end 178a is coupled to the second end of the waveguide 174a, thereby establishing signal communication between the controller <NUM> and the probe sensor <NUM>. The distal probe end 178b is arranged adjacent, or in some cases coupled, to an engine case <NUM> of the gas turbine engine <NUM>.

The engine case <NUM> houses a plurality of blades <NUM> (also referred to as airfoils) formed on a rotor <NUM>. The blades <NUM> are arranged circumferentially on the rotor <NUM> and are spaced apart from one another to define voids <NUM> therebetween. The engine case <NUM> can include an opening that exposes the internal area of the engine case to the distal end 178b of the probe sensor <NUM>. As the rotor <NUM> rotates, the blades <NUM> pass by the opening in the engine case <NUM>, thereby allowing the probe sensor <NUM> to perform blade measurements as described in greater detail below.

Nodes 68a, 68b can be associated with particular engine components, actuators or any other machine part from which information and communication is performed for monitoring and/or control purposes. The nodes 68a, 68b may contain a single or multiple electronic circuits or sensors configured to communicate over the waveguide electromagnetic transmission network <NUM>. Although the example of <FIG> depicts connections to actuators <NUM> and sensors <NUM> isolated to different branches, it will be understood that actuators <NUM> and sensors <NUM> can be interspersed with each other and need not be isolated on dedicated branches of the waveguide electromagnetic transmission network <NUM>. Couplers <NUM>, 67a, 67b can be splitters and/or can incorporate instances of the radio frequency-based repeater <NUM> of <FIG>. Further, one or more instances of the radio frequency-based repeater <NUM> can be installed at any of the waveguides <NUM>, <NUM>, <NUM>, 173a-c, and/or 174a-b depending on the signal requirements of the waveguide electromagnetic transmission network <NUM>.

The controller <NUM> can send and receive power and data to and from the nodes 68a, 68b. The controller <NUM> may be located on equipment near other system components or located remotely as desired to meet application requirements. The controller <NUM> can be constructed as an electronic hardware controller that includes memory and a processor configured to execute algorithms and computer-readable program instructions stored in the memory. In one or more non-limiting embodiments, the controller <NUM> is a full authority digital engine controller (FADEC) configured to control and monitor one or more processes of the machine. Accordingly, the controller <NUM> can determine a rotational speed and/or position of the rotor, and therefore can calculate a rotational speed and/or rotational position of a blade <NUM> in relation to the location of the probe sensor <NUM>. The controller <NUM> is also configured to perform signal generation, one or more signal processing operations and/or data analysis operation.

In one or more non-limiting embodiments, the controller <NUM> generates an electromagnetic microwave energy signal, which is output to the waveguide network <NUM>. In one or more non-limiting embodiments, the microwave energy signal includes a continuous series of individual multiple radio frequency (RF) pluses. In other non-limiting embodiments, the microwave energy signal includes an RF continuous wave (CW). The RF pulses or CW can have a frequency, for example, of about <NUM> gigahertz (GHz). It should be appreciated, however, that RF pulses having different frequencies can be utilized without departing from the scope of the invention. In either embodiment, the controller <NUM> can vary the frequency, energy level, shape and/or phase of the output RF pulses and/or CW, thereby invoking different waveguide modes of a microwave energy signal as described in greater detail below. Going forward, the microwave energy signal will be described in terms of RF pulses. However, it should be appreciated that the inventive teachings described herein can be applied to a CW without departing from the scope of the invention.

A transmission path (TP) between the controller <NUM> and nodes 68a, 68b can be used to send and receive data routed through the controller <NUM> from a control module or other components. The TP may utilize electrical wire, optic fiber, waveguide or any other electromagnetic communication including radio frequency/microwave electromagnetic energy, visible or non-visible light. The interface between the controller <NUM> and nodes 68a, 68b can transmit power and signals.

In one or more embodiments, RF pulses output by the controller <NUM> can be guided via the waveguides (e.g., <NUM>, <NUM>, and 174b) to the probe sensor <NUM>, which directs them into the engine case <NUM> via the opening and toward the blades <NUM>. RF energy reflected by a given blade <NUM> is detected by the probe sensor <NUM>, which in turn generates an output signal indicative of a corresponding reflection magnitude. The output signals can be guided back to the controller <NUM> via the waveguides (e.g., <NUM>, <NUM>, and 174b) such that controller <NUM> can generate a blade signature of a given blade <NUM> based on its corresponding reflection magnitude.

The example nodes 68a, 68b can include processing circuitry, controllers, memory and/or the interfaces to connect to conventional sensors or actuators, such as solenoids or electro-hydraulic servo valves. The waveguides <NUM>, <NUM>, <NUM>, 173a-c, and/or 174a-b can be shielded paths that support electromagnetic communication, including, for instance, radio frequency, microwaves, magnetic or optic waveguide transmission. Shielding can be provided such that electromagnetic energy or light interference <NUM> with electromagnetic signals <NUM> (shown schematically as arrows) are mitigated in the waveguide electromagnetic transmission network <NUM>. Moreover, the shielding provides that the electromagnetic signals <NUM> are less likely to propagate into the environment outside the waveguide electromagnetic transmission network <NUM> and provide unauthorized access to information. In some embodiments, confined electromagnetic radiation is in the range <NUM>-<NUM>. Electromagnetic radiation can be more tightly controlled around specific carrier frequencies, such as <NUM>-<NUM>, <NUM>, <NUM>, or <NUM>-<NUM> as examples in the microwave spectrum. A carrier frequency can transmit electric power, as well as communicate information, to multiple nodes 68a, 68b using various modulation and signaling techniques.

The nodes 68a with actuators <NUM> may include control devices, such as a solenoid, switch or other physical actuation devices. RF, electromagnetic or optical devices implemented as node 68b, along with sensors <NUM> can provide information indicative of a physical parameter, such as pressure, temperature, speed, proximity, vibration, identification, and/or other parameters used for identifying, monitoring or controlling component operation. Signals communicated in the waveguide electromagnetic transmission network <NUM> may employ techniques such as checksums, hash algorithms, error control algorithms and/or encryption to mitigate cyber security threats and interference.

The waveguide electromagnetic transmission network <NUM> may be installed in a mixed temperature environment, such as a machine having a hotter portion and a cooler portion. In reference to the example of <FIG>, the fan section <NUM> and compressor section <NUM> of the gas turbine engine <NUM> can be designated as cooler portions relative to hotter portions of the gas turbine engine <NUM>, such as the combustor section <NUM> and turbine section <NUM>. To further accommodate the temperature variations within the gas turbine engine <NUM>, a variety of approaches can be used. As one example, electronics devices within the nodes 68a, 68b, actuators <NUM>, and/or sensors <NUM> can include wide band gap semiconductor devices, such as silicon carbide or gallium nitride devices supporting higher operating temperatures than typical semiconductor devices. Further, the controller <NUM> operable to communicate with the network of nodes 68a, 68b through the two or more radio frequencies using a higher frequency to communicate with one or more of the nodes 68a, 68b in the cooler portion of the machine and a lower frequency to communicate with one or more of the nodes 68a, 68b in the hotter portion of the machine. As an example, communication between the controller <NUM> and nodes 68a, 68b at the fan section <NUM> or compressor section <NUM> of the gas turbine engine <NUM> may use radio frequencies at or above <NUM>, while communication to nodes 68a, 68b at the combustor section <NUM> or turbine section <NUM> may use frequencies at or below <NUM>. The radio frequency threshold selected can depend on resultant heating effects that can occur at higher frequencies. Placement of the nodes 68a, 68b can also impact performance capabilities in the hotter portion of the machine. Where actuators <NUM> or sensors <NUM> are needed at locations that would potentially exceed the desired operating temperature of the nodes 68a, 68b that directly interface with the actuators <NUM> or sensors <NUM>, relatively short wired connections, referred to as "pigtails" can be used between the nodes 68a, 68b and the actuators <NUM> or sensors <NUM>. The pigtail wiring can provide thermal separation and may support the use of legacy wired actuators <NUM> and sensors <NUM> to connect with nodes 68a, 68b. Further temperature accommodations may include cooling systems, heat sinks, and the like.

In some embodiments, shielding in the waveguide electromagnetic transmission network <NUM> can be provided such that power and communication signals are shielded from outside interference, which may be caused by environmental electromagnetic or optic interference. Moreover, the shielding reduces or prevents intentional interference <NUM> with communication at the components. Intentional interference <NUM> may take the form of unauthorized data capture, data insertion, general disruption and/or any other action that degrades system communication. Environmental sources of interference <NUM> may originate from noise generated from proximate electrical systems in other components or machinery along with electrostatic and magnetic fields, and/or any broadcast signals from transmitters or receivers. Additionally, pure environmental phenomena, such as cosmic radio frequency radiation, lightning or other atmospheric effects, could interfere with local electromagnetic communications.

It should be appreciated that while the system <NUM> is explained by way of example with regard to a gas turbine engine <NUM>, other machines and machine designs can be modified to incorporate built-in shielding for monitored or controlled components to use of a waveguide electromagnetic transmission network. For example, the system <NUM> can be incorporated in a variety of harsh environment machines, such as manufacturing and processing equipment, a vehicle system, an environmental control system, and all the like. As a further example, the system <NUM> can be incorporated in an aerospace system, such as an aircraft, rotorcraft, spacecraft, satellite, or the like. The disclosed system <NUM> includes the network <NUM>, <NUM> that provides consistent communication with electromagnetic devices, such as the example nodes 68a, 68b, and removes variables encountered with electromagnetic communications such as distance between transmitters and receiving devices, physical geometry in the field of transmission, control over transmission media such as air or fluids, control over air or fluid contamination through the use of filtering or isolation and knowledge of temperature and pressure.

The system <NUM> provides for a reduction in cable and interconnecting systems to reduce cost and increases reliability by reducing the number of physical interconnections. Reductions in cable and connecting systems further provides for a reduction in weight while enabling additional redundancy. Moreover, additional sensors can be added without the need for additional wiring and physical connections to the controller <NUM>, which may provide for increased system accuracy and response. Embodiments can provide a "plug-n-play" approach to add a new node, potentially without a requalification of the entire system but only the new component; thereby greatly reducing qualification burdens.

With reference now to <FIG> and <FIG>, a probe sensor <NUM> configured to perform blade measurements of a gas turbine engine <NUM> is illustrated according to non-limiting embodiments of the disclosure. Turning first to <FIG>, the probe sensor includes a hollow probe body <NUM> having a proximate end 178a (see <FIG>) and a distal end 178b. The probe body <NUM> extends from the proximate end 178a to the distal end 178b to define a probe channel. As described above, the proximate end 178a is configured to establish signal communication with a waveguide (e.g., waveguide 174b included in the waveguide electromagnetic transmission network <NUM> (see <FIG>). In one or more embodiments, the proximate end 178a can be in signal communication with a microwave transceiver (not shown) that provides an RF signal source independently from the controller <NUM>.

The distal end 178b includes an aperture and is configured to mate with an opening <NUM> formed in the engine case <NUM> (see <FIG>). For example, the distal end <NUM> can extend into the opening <NUM> so as to deliver a series of RF signal pulses having an energy level, a shape and a phase into the engine case <NUM>. The probe sensor <NUM> further includes a lens <NUM> disposed in the probe channel of the distal end <NUM> to focus the RF pulses into the engine case <NUM>. The lens <NUM> can also adjust the field of view (FOV) of the probe aperture to increase detectability of the turbine blades <NUM> contained in the engine case <NUM>. Although the probe sensor <NUM> is shown as having a single lens <NUM> corresponding to a single probe channel, the present inventive teachings are not limited thereto.

Turning to <FIG>, for example, the probe sensor <NUM> is shown as having a plurality of probe channels 175a and 175b. The probe channels 175a and 175b extend from the proximate end 178a to the distal end 178b. Accordingly, the probe channel 175a and 175b can respectively deliver an independent series of RF pulses to the opening <NUM> formed in the engine case <NUM>. Although two probe channels 175a and 175b are shown in <FIG>, it should be appreciated that the probe sensor <NUM> can include additional probe channels without departing from the scope of the invention.

Although the probe channels 175a and 175b are shown being arranged horizontally, one next to the other the arrangement of the probe channels 175a and 175b is not limited thereto. In other non-limiting embodiments, for example, the plurality of probe channels 175a and 175b can be a stacked vertically atop one another. In yet other non-limiting embodiments, the probe sensor <NUM> can include a first probe channel and a second probe channel disposed against the first channel, where the second channel is partitioned to define a plurality of sub-channels. Accordingly, a sub-channel can be configured to deliver an individual series of RF pulses.

With continued reference to <FIG>, the probe sensor <NUM> further includes a plurality of lenses 179a and 179b. The lenses 179a and 179b are disposed in or at a respective probe channel 175a and 175b of the distal end 178b. The lenses 179a and 179b are configured to focus the RF pulses traveling through the respective probe channels 175a and 175b into the opening <NUM> of the engine case <NUM>. In one or more embodiments, each lens 179a and 179b can have a different lens index with respect to one another to focus the RF pulses to target locations of the turbine blades <NUM>. The lenses 179a and 179b are also configured to refine the field of view (FOV) of the probe aperture, thereby improving the precision at which the turbine blades <NUM> are detected.

In one or more non-limiting embodiments, a first probe channel (e.g., probe channel 175a) among the plurality of probe channels can deliver a first series of RF pulses having a first energy level, first shape and first phase to the first lens 179a, while a second channel (e.g., 175b) among the plurality of probe channels delivers a second series of RF pulses having a different second energy level, different second shape and/or a different second phase to the second lens 179b. The varying the energy level, shape and/or phase can control the direction at which the RF pulses exit the probe sensor <NUM>. In this manner, the energy level, shape and/or phase can be varied so as to focus the RF pulses toward the tip of a given blade <NUM> or toward the leading and trailing edges of given blade <NUM>. In one or more non-limiting embodiments, the first and second series of RF pulses can be delivered simultaneously with respect to one another regardless as to rotational position of the blades <NUM>. In other non-limiting embodiments, the first and second RF pulses can be delivered at different times with respect to one another.

In such an embodiment, the timing at which the first and second RF pulses are generated and output can be based on a rotational position of the blades <NUM>. For example, the first series of RF pulses can be generated when a tip of a given blade <NUM> is expected centered with respect to the FOV of the probe sensor <NUM>. The second series of RF pulses can be generated when a leading edge or trailing edge of a given blade <NUM> is expected to enter or leave the FOV, respectively. In some embodiments, the probe sensor <NUM> can be configured to deliver the first and second RF pulses along a single probe channel. In other embodiments, the probe sensor <NUM> can be configured to deliver the first RF pulses along a first probe channel and deliver the second RF pulses along a second probe channel different from the first probe channel.

With reference now to <FIG>, a multi-mode microwave waveguide blade sensing system <NUM> is illustrated according to a non-limiting embodiment. The multi-mode microwave waveguide blade sensing system <NUM> includes a controller <NUM>, a waveguide 174b, and a probe sensor <NUM>. Although a single waveguide 174b is shown, it should be appreciated that additional waveguides can be employed without departing from the scope of the invention.

The controller <NUM> is configured to output one or more microwave energy signals. As described herein a microwave energy signal can include one or more series of RF pulses or a RF CW, either signal having an energy level, a shape and phase. The RF pulses can have a frequency, for example, of about <NUM>.

The controller <NUM> is further configured to determine a rotational position of a gas turbine engine rotor <NUM> and thus the rotational position of a turbine blade formed on the rotor <NUM>. The rotational position of the blades <NUM> include the rotational position of a tip of a given blade <NUM> and one or both of a leading edge <NUM> and trailing edge <NUM> of the given blade <NUM>. The rotational speed and/or position of the rotor <NUM> and blades <NUM> can be determined by calculation and/or based on an output from a speed sensor and/or blade detection sensor.

The waveguide 174b includes a first end configured to a microwave energy signal from a signal source (e.g., transceiver) and a second end in signal communication with the probe sensor. The probe sensor <NUM> is configured to direct the microwave energy signal toward the blades <NUM> and to detect or receive reflected microwave energy signals produced when the directed microwave energy signal is reflected from a passing blade <NUM>. Accordingly, the probe sensor <NUM> effectively generates an output sensor signal indicating a magnitude of the reflected portion of microwave energy signal reflected by a given passing blade <NUM>. The output sensor signal is passed to the waveguide 174b, which in turn guides it back to the controller <NUM>. Accordingly, the controller <NUM> can generate a blade signature of a given blade <NUM> based on the sensor output signal, e.g., the magnitude of the reflected portion of microwave energy signal reflected by a given blade <NUM> passing in front of the probe sensor <NUM>.

As described herein, each mode of the directed microwave energy signal has a different field pattern when they are output from the probe sensor <NUM> such that the pattern of fields are different on the waveguide cross section. Accordingly, the amount of reflected microwave energy signal received by the sensor by probe is low when the leading edge <NUM> and trailing edge of the blade <NUM> enters and exits the FOV of the probe sensor <NUM>. The low reflection can cause the controller <NUM> to produce inaccurate measurements of the leading edge <NUM> and trailing edge <NUM>, thereby producing an inaccurate resolution or blade signature of a given blade <NUM>. In one or more non-limiting embodiments, the controller <NUM> is configured to invoke different waveguide modes that vary the characteristics of generated microwave energy signal (e.g., the generated RF pulses and/or RF CW), which in turn significantly increases the resolution and accuracy of the blade signatures. For instance, a first waveguide mode generates a first microwave energy signal type configured to achieve a high or maximum reflection from the center tip <NUM> of a given blade <NUM>. A second waveguide mode generates a second microwave energy signal type configured to achieve maximum reflection from the leading edge and trailing edge of a given blade <NUM>. Accordingly, the probe sensor <NUM> can receive high or maximum reflected microwave energy from the entire blade <NUM>, thereby improving the resolution and blade signature generated by the controller <NUM>.

In some non-limiting embodiments, the first and second waveguide modes can be selectively invoked. For instance, the second waveguide mode for generating an initial type of microwave energy signal can be invoked at a time when the leading edge of a given blade <NUM> enters the FOV of the probe sensor <NUM>. The first waveguide mode can then be sequentially invoked to generate a different type of microwave energy signal at a time when the blade tip of the given blade <NUM> enters the FOV. The second waveguide mode can then again be sequentially invoked to generate the initial type of microwave energy signal at a time when the trailing edge of the given blade <NUM> enters the FOV.

In other non-limiting embodiments, the first and second waveguide modes can operate simultaneously such that the two different types of waveguide modes are generated at the same time and co-exist in the waveguide. The controller <NUM> is configured to receive what appears as a single reflected energy signal, but can decompose the reflected energy to identify both independent reflected microwave energy signals corresponding to the two different types of microwave energy signal. Accordingly, the controller <NUM> can determine the energy levels corresponding to an individual reflected microwave energy signal and generate a blade profile of a given blade based on the individual energy levels.

With reference to <FIG>, the controller <NUM> is illustrated operating in a plurality of different waveguide modes to generate different types of microwave energy signals. The different types of microwave energy signals can be defined by their respective energy level, shape and/or phase. <FIG>, for example, shows the controller <NUM> generating a microwave energy signal having a first mode, which is and output from the aperture (e.g., lens <NUM>) of the waveguide <NUM>. The first waveguide mode can define a first microwave energy signal type having an energy level, a shape, and a phase. <FIG> shows the controller <NUM> generating a microwave energy signal having a second mode, which is and output from the aperture (e.g., lens <NUM>) of the waveguide 176a. The second waveguide mode can define a second microwave energy signal type having a different energy level, different shape and different phase.

In one or more non-limiting embodiments, the controller <NUM> can simultaneously invoke both the first and second waveguide modes (e.g., control a transceiver to generate a microwave signal having the first and second waveguide modes), which in turn simultaneously generates the first and second series of RF pulses. In other non-limiting embodiments, the controller <NUM> can selectively invoke the first and second waveguide modes at different times based on the based on the rotational position of the blades <NUM> relative to the location of the probe sensor <NUM>. For example, the timing at which the first RF pulses are output is based on a rotational position of a tip of a given blade <NUM> in relation to the aperture of the probe sensor <NUM>, while the timing at which the second RF pulses are output is based on the rotational position of one or both of a leading edge and trailing edge of the given blade <NUM> in in relation to the aperture of the probe sensor <NUM>.

In embodiments where the first and second series of RF pulses are generated at different times, the probe sensor <NUM> can deliver the different RF pulses along individual respective probe channels. For example, the probe sensor <NUM> can deliver the first series of RF pulses along a first probe channel and deliver the second series of RF pulses along a second probe channel different from the first probe channel.

In any case, the type of RF pulses generated according to a respective waveguide mode can control the direction at which the RF pulses are output from the probe sensor <NUM>. As shown in <FIG>, for example, the first series of RF pulses exit the probe sensor <NUM> in a first direction (e.g., in a substantially center direction) based on at least one of the first energy level, the first shape and first phase. In this manner, the first RF pulses can be focused toward the tip of a given blade <NUM>. As shown in <FIG>, however, the second series of RF pulses are exit the probe sensor <NUM> in a second different direction (e.g., a laterally) based on at least one of the second energy level, second shape and second phase. In this manner, the second RF pulses can be focused toward the leading edge <NUM> and trailing edge <NUM> of a given blade <NUM>.

With reference to <FIG>, a probe sensor <NUM> is illustrated performing multi-mode blade measurements of a targeted turbine blade <NUM> at different rotational angles according to a non-limiting embodiment of the disclosure. <FIG> depicts a graph illustrating a reflection magnitude vs. a rotational angle of the targeted blade <NUM> shown in <FIG> measured according to the first waveguide mode, e.g., where a first type of RF pulses are focused toward a center tip <NUM> of the targeted blade <NUM>. Similarly, <FIG> depicts a graph illustrating a reflection magnitude vs. a rotational angle of the targeted blade <NUM> shown in <FIG> measured according to the second waveguide mode, e.g., where a second type of RF pulses are focused toward the leading edge <NUM> and trailing edge of the targeted blade <NUM>.

Referring first to <FIG>, as the targeted blade moves through the FOV (e.g., - <NUM>° to +<NUM>°) of the probe sensor <NUM>, the measured microwave energy <NUM> generated in response to the first waveguide mode and reflected from the blade tip <NUM> increases as the blade tip <NUM> moves toward the center of the FOV. However, the measured microwave energy <NUM> from the energy reflected by the leading edge <NUM> and trailing edge <NUM> according to the second waveguide mode decreases as the blade tip <NUM> moves toward the center of the FOV and the leading and trailing edges exit and enter the FOV, respectively.

Referring to <FIG>, however, as the targeted blade moves through the FOV (e.g., -<NUM>° to +<NUM>°) of the probe sensor <NUM>, the measured microwave energy <NUM> generated in response to the second waveguide mode and reflected from the leading edge <NUM> and trailing edge <NUM> increases as the leading and trailing edges enter an exit the FOV, while the measured microwave energy <NUM> generated by the blade tip decreases as it moves away from the center of the FOV.

Accordingly, by combining the microwave energy reflection provided by the blade tip <NUM> obtained according to the first waveguide mode and the microwave energy reflection provided by the leading and trailing edges <NUM>, <NUM> obtained according to the second waveguide mode, the controller <NUM> can obtain a maximum amount of reflected microwave energy from a given passing blade <NUM>. In this manner, the controller <NUM> can generate a blade signature having improved resolution and accuracy.

Claim 1:
A multi-mode microwave waveguide blade sensing system (<NUM>), comprising:
a transceiver configured to generate at least one microwave energy signal having a first waveguide mode and a second waveguide mode different from the first waveguide mode;
a waveguide (174b) including a first end configured to receive the at least one microwave energy signal from the transceiver;
a probe sensor (<NUM>) including a proximate end (178a) in signal communication with a second end of the waveguide to receive the at least one microwave energy signal and a distal end (178b) including an aperture configured to output the at least one microwave energy signal; and
a controller configured to monitor rotation of a plurality of blades formed on a rotor of a machine, to determine a rotational position of a given blade among the plurality of blades with respect to the probe sensor, and to control the transceiver to vary characteristics of the at least one microwave energy signal to invoke the first and second waveguide modes,
wherein the probe sensor (<NUM>) directs the microwave energy signal toward a machine at a first direction based on the first waveguide mode and a second direction different from the first direction based on the second waveguide mode, and receives different levels of reflected microwave energy based at least in part on a location at which the at least one microwave energy signal that is directed at the first direction is reflected from the machine compared to a location at which the at least one microwave energy signal that is directed at the second direction is reflected from the machine, and
wherein the controller selectively invokes the first and second waveguide modes based on the rotational position of the given blade with respect to a field of view of the probe sensor.