Patent Description:
The present subject matter relates generally to particle sensors, and more particularly, to electrostatic dust sensors.

Many types of engines often require a large supply of clean air to ensure maximum engine performance and engine life and to reduce maintenance requirements. Air cleaning systems have been developed for some types of engines which will remove <NUM>% of the particulate matter drawn into the air intake system. Such high efficiency air cleaning systems are multi-stage units which include barrier type air filters. However, a simple dust leak in the air cleaning system (caused by, for example, accidental perforation of one of the air filters) can negate the effectiveness of the system. In addition, problems with excessively dusty air may be encountered in other types of applications where barrier filters cannot be employed, such as gas turbine engines.

A typical gas turbine engine generally includes, in serial flow order, a compressor section, a combustion section, a turbine section and an exhaust section. In operation, air enters an inlet of the compressor section where one or more axial or centrifugal compressors progressively compress the air until it reaches the combustion section. Fuel is mixed with the compressed air and burned within the combustion section to provide combustion gases. The combustion gases are routed from the combustion section through a hot gas path defined within the turbine section and then exhausted from the turbine section via the exhaust section.

Such gas turbine engines are commonly employed in an aircraft. During operation of the aircraft, the engine environmental particulate and dust ingestion level is a key input to the analytics process, resulting in specific engine-by-engine action. Current environmental dust/particulate level data is provided by ground-based and remote sensing systems separate from the aircraft. Such data has temporal and special variations as well as error, thereby making accurate assessment of engine conditions at takeoff and climb of the aircraft particularly difficult. On the other hand, if sensors are mounted on the engine, the electronics of such sensor systems are typically connected to the individual sensors via a plurality of long cables and connectors. In this case, any motion or vibration of the cabling can produce more signal than the dust particles passing the sensor face, thereby resulting in a poor signal-to-noise ratio. These spurious signals are due to triboelectric and piezoelectric effects of the cables and connectors. An example of such a sensor is disclosed in <CIT> wherein the concentration of particles in a gas is measured using an electrode disposed within a conduit. The electrode has the shape of an elongate, cylindrical rod and extends radially in the conduit. The free end of the electrode lies approximately on the axis of the conduit. The flow of gas containing charged particles along the electrode induces a current passing from the electrode through the current measuring device. <CIT> is directed to designing the shape of the electrode such that it does not seriously interfere with the airflow to the engine. It is an elongated electrode that protrudes into the flow, the electronics are not included in the housing.

Accordingly, the present disclosure is directed to an improved sensor system that addresses the aforementioned issues. More specifically, the present disclosure is directed to a sensor assembly that includes one or more improved electrostatic sensors having integrated electronics and/or shorter cable connections that more accurately detects dust particles and/or particulates.

Claim <NUM> defines a sensor assembly. In the following, apparatus and/or methods referred to as embodiments that nevertheless do not fall within the scope of the claims should be understood as examples useful for understanding the invention.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate aspects of the invention and, together with the description, serve to explain the principles of the invention.

In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention as defined by the appended claims.

Generally, the present disclosure is directed to a sensor assembly having at least one electrostatic sensor electrically coupled to a circuit board. In certain embodiments, the sensor assembly is designed as a function of the temperature of the application environment. For example, in one embodiment, the location of the electrostatic sensor may be cool enough such that the sensor circuit can be implemented with low temperature discrete electronic parts on a circuit board. Alternatively, in further embodiments, where the temperatures are higher, the sensor assembly may include an integrated MCM sensor assembly. As such, the MCM sensor assembly of the present disclosure may be used in a plurality of applications, such as an aircraft gas turbine engine, as well as any other suitable engine types. For example, it should be understood that the MCM sensor assembly and related methods are also suitable for any other type of engine, including but not limited to an industrial engine, a power generation engine, a land-based engine, a marine engine, or similar. More specifically, the electrostatic sensor includes an outer housing containing an electrode and an amplifier configured at least partially therein. Further, the electrode includes a first end and a second end separated by a predetermined length. The first end may be secured within the outer housing, whereas the second end may include a sensing face that is either flush with an edge of the outer housing or may extend within or past the edge of the outer housing. Further, as the electrode is a conductor, it contains a plurality of electrons configured to respond to one or more charged particles that flow past the sensing face by moving either towards or away from the second end. Thus, the amplifier is electrically coupled to the electrode so as to detect a particle level flowing past the sensing face as a function of the electron movement. Moreover, the circuit board is electrically coupled to the sensor either by being housed within the outer housing or connected to the sensor via a shortened cable.

Thus, the outer housing of the sensor and the electronics configuration minimizes the distance between the sensor input and the electrode, thereby increasing sensitivity of the sensor. As such, the present disclosure provides various advantages not present in the prior art. For example, the electrostatic sensors of the present disclosure provide more accurate particle detection that is robust and reliable. Further, since the electronics are integrated within the sensor or closely coupled thereto, the present design requires less maintenance and suffers from fewer operational issues over prior art designs. Moreover, the amplifier low leakage current facilitates direct current (DC) coupling of the amplifier, which allows low frequency changes in particle levels to be captured. In addition, the high input impedance of the electrode improves the sensor's sensitivity to small changes in charge in the sensing face. Further, the high input impedance of the electrode also improves the low frequency response of the sensor by preventing the charge redistribution within the electrode caused by the sensed particles from leaking away such that an output signal cannot be produced. Thus, the electrostatic sensor of the present disclosure is capable of detecting from about one (<NUM>) part in seven (<NUM>) million by mass of particles. As such, the electrostatic sensor of the present disclosure is configured to detect dust, debris, airborne particulates, ice (i.e. very fine ice crystals), sand, volcanic ash, and/or any other particles within a fluid medium such as air, water, oil, fuel, and/or similar. In addition, the electrostatic sensor, when located in an engine exhaust nozzle, can also detect internally generated particles from rubs of internal engine parts and/or deterioration of engine parts which results in the release of debris. For example, such detection is accomplished by sensing the "natural charge" accumulation on the particles as they pass thru the engine. Thus, the integrated electronics / integral cable connections increase sensor sensitivity to the very small "natural charges" of the particles over prior art.

Referring now to the drawings, <FIG> and <FIG> illustrate various embodiments of a MCM sensor assembly <NUM> according to the present disclosure. As used herein, a MCM generally refers to an electronic assembly (such as a package with a number of conductor terminals or "pins") where multiple integrated circuits (ICs), semiconductor dies, and/or other discrete die components are integrated, usually onto a unifying substrate, so that in use it is treated as if it were a single component. More specifically, as shown in <FIG>, one embodiment of an integrated MCM assembly <NUM> is illustrated. For example, <FIG> illustrates a perspective view of integrated MCM assembly <NUM>; <FIG> illustrates a cross-sectional view of the integrated MCM assembly <NUM>; and <FIG> illustrates a top view of integrated MCM assembly <NUM>. <FIG> illustrate another embodiment of an MCM sensor assembly <NUM>, wherein the electronics are closely coupled together via a shortened cable <NUM> but not integrated.

Referring particularly to <FIG>, the integrated MCM assembly <NUM> includes at least one electrostatic sensor <NUM> having an outer housing <NUM> or casing. More specifically, as shown, the outer housing <NUM> may include a base or mounting portion <NUM> configured for mounting or otherwise securing the sensor <NUM> into a desired location. For example, as shown in <FIG> and <FIG>, the mounting portion <NUM> of the sensor <NUM> may include one or more through holes <NUM> configured for mounting the electrostatic sensor(s) <NUM> at the desired location(s). More specifically, in certain embodiments, each of the through holes <NUM> may be configured to receive a fastener (e.g. a threaded bolt) so as to secure the sensors <NUM> at the desired location(s). Alternatively, the electrostatic sensor(s) <NUM> may be secured or mounted via any other suitable methods, including but not limited to metal clips, clamps, welded nichrome foil, welding, or similar.

Further, as shown, the electrostatic sensor <NUM> contains an electrode <NUM> configured within the outer housing <NUM>. The electrode <NUM> includes a first end <NUM> and a second end <NUM> separated by a predetermined length L. In certain embodiments, the predetermined length L may be set by geometry constraints of the engine installation.

For example, in one embodiment, the predetermined length L may be from about <NUM> (<NUM> inch) to about <NUM> (<NUM> inches) to allow the electrons <NUM> to migrate in the electrode <NUM> and therefore be detectable by the amplifier <NUM> (which is discussed below). In addition, as shown, the electrode <NUM> includes a plurality of electrons <NUM> configured to move as charged particles flow past the sensing face <NUM> as indicated by arrow <NUM>. As such, the predetermined length L allows the electrons <NUM> to easily flow towards and/or away from the sensing face <NUM> depending on the charge of the particles flowing thereby. Further, the first end <NUM> of the electrode <NUM> is generally secured within the outer housing <NUM>, whereas the second end <NUM>, which includes the sensing face <NUM>, may be flush with an edge <NUM> of the outer housing <NUM>. Moreover, as shown in <FIG>, the sensing face <NUM> of the electrode <NUM> may include a curved surface having a predetermined radius.

In addition, as shown in the illustrated embodiment, the electrostatic sensor <NUM> may include at least one amplifier <NUM> configured within the outer housing <NUM> that is electrically coupled to the electrode <NUM>. In such embodiments, the amplifier <NUM> may have an operating temperature range of from about -<NUM> degrees Celsius (°C) to about <NUM>, more preferably from about <NUM> to about <NUM>. More specifically, the amplifier <NUM> may include a silicone on insulator (SOI) operational amplifier. For example, in certain embodiments, the amplifier <NUM> of the present disclosure may include the wideband SOI operational amplifier manufactured by Honeywell, Inc. of Plymouth, Minnesota, USA. Such amplifiers have extremely low leakage current and are capable of operating at high temperatures. As such, the amplifier <NUM> of the present disclosure is configured to detect or measure a particle level passing by the sensing face <NUM> as a function of the electron movement.

Further, the MCM assembly <NUM> may include an integrated circuit board <NUM> configured within the outer housing <NUM> and electrically coupled to the sensor <NUM>, e.g. via the amplifier <NUM>. More specifically, as shown, the circuit board <NUM> may be configured adjacent to the electrode <NUM> and opposite the sensing face <NUM>. In additional embodiments, the circuit board <NUM> may be located at any suitable location within the outer housing <NUM> of the sensor <NUM>. Further, the circuit board <NUM> as described herein may include any suitable circuit board that mechanically supports and electrically connects the electronic components within the outer housing <NUM> of the sensor(s) <NUM>. More specifically, certain circuit boards of the present disclosure may include conductive tracks, pads, and/or other features etched from sheets of metal, such as copper, that are laminated onto a non-conductive substrate. Further, the circuit board <NUM> of the present disclosure may be single-sided, double-sided, or multi-layered. Thus, the circuit board <NUM> as described herein may be configured to send one or more signals to a controller <NUM> that are indicative of the particle level passing the sensing face <NUM>, which is described in more detail below.

Referring particularly to <FIG>, the electrostatic sensor(s) <NUM> may also include one or more insulators or insulation layers <NUM>. For example, as shown, the electrostatic sensor(s) <NUM> may include one or more insulation layers <NUM> configured between the electrode <NUM> and the outer housing <NUM>. In addition, the electrostatic sensor(s) <NUM> may include one or more insulation layers <NUM> within the mounting portion <NUM> thereof so as to insulate the sensor components from an operating environment. It should further be understood that any number of insulation layers may be employed at any suitable location within the sensor <NUM>.

Referring now to <FIG>, another embodiment of an MCM sensor assembly <NUM> of the present disclosure is illustrated. More specifically, as shown in <FIG>, the MCM assembly <NUM> includes at least one electrostatic sensor <NUM> coupled to an electronics housing <NUM> via a cable <NUM>. Further, as shown in <FIG>, the electrostatic sensor <NUM> has an outer housing <NUM> or casing. More specifically, as shown, the outer housing <NUM> may include a mounting portion <NUM> configured for mounting or otherwise securing the sensor <NUM> into a desired location. For example, as shown in <FIG>, the mounting portion <NUM> of the sensor <NUM> may include a threaded outer surface or a B-nut configured for securing or installing the electrostatic sensor(s) <NUM> in a desired location. Further, as shown in <FIG> and <FIG>, the outer housing <NUM> of the sensor <NUM> may also include one or more wrenching flats <NUM> configured to aid in sensor assembly and/or disassembly as well as installation. In addition, as shown in <FIG>, the various components of the sensor <NUM> may be easily secured together via one or more threaded joints <NUM>.

Further, as generally shown in <FIG>, the electrostatic sensor <NUM> has an electrode <NUM> configured at least partially within the outer housing <NUM>. More specifically, as shown in <FIG>, the electrode <NUM> includes a first end <NUM> and a second end <NUM> separated by a predetermined length L. As such, the electrode <NUM> is configured to act as an "electron lake" on which the passing charged particles move electrons "in the lake" either towards or away from the electrode second end <NUM> based on their charge. This shift of electron distribution within the electrode <NUM> is detected by the amplifier <NUM>. Such a feature therefore is configured to extend the low frequency bandwidth of the sensor <NUM> below one (<NUM>) Hertz (Hz). More specifically, the first end <NUM> is secured within the outer housing <NUM>, whereas the second end <NUM> includes a sensing face <NUM> that extends beyond an edge <NUM> of the outer housing <NUM>. For example, as shown, the first end <NUM> is secured within the outer housing <NUM> via at least one fastener, e.g. nut <NUM>. It should be understood that the first end <NUM> of the electrode <NUM> may be further secured using any other suitable means. In addition, as shown in <FIG> and <FIG>, the cable <NUM> may extend into the sensor <NUM> through an open cavity <NUM> and secured and/or electrically coupled to the sensor <NUM> via fastener <NUM>. More specifically, the outer sheath of the cable <NUM> may be grounded to the body of the sensor <NUM> via welded nichrome strips, whereas the inner conductor of the cable <NUM> may be attached to the sensor <NUM> via the fastener <NUM>.

Moreover, as shown in <FIG>, the sensing face <NUM> of the electrode <NUM> may include a curved surface having a predetermined radius. In certain embodiments, the predetermined radius is introduced to increase the surface area of the sensing face <NUM> and/or to increase the sensors gain. Thus, in particular embodiments, the radius may depend on the room available where the sensor assembly <NUM> is to be installed. In one embodiment, for example, it may be desirable to introduce a radius that increases the surface area of the sensing face <NUM> by about <NUM>% if possible over a flat sensing face. Such a sensor requires more installation volume, but will be able to detect particles at lower concentration levels.

Further, as shown, the curved surface of the sensing face <NUM> may have a sculpted profile having one or more protrusions <NUM>. For example, as shown, the protrusions <NUM> correspond to arcuate ridges that increase the surface area of the sensing face <NUM> by about <NUM>%. In further embodiments, it should be understood that the curved surface and/or the protrusions <NUM> may be configured to increase the surface area of the sensing face <NUM> by less than <NUM>% or more than <NUM>%. As such, the curved surface and/or the protrusions <NUM> are configured to maximize the area presented to the flow stream of the sensor <NUM> so as to increase the sensitivity of the sensor <NUM>. It should be understood that the protrusions <NUM> of the sensing face <NUM> described herein may further have any suitable shape and/or size so as to increase the sensitivity of the sensor <NUM>.

In addition, as shown in <FIG> and <FIG>, the electrode <NUM> of the sensor <NUM> includes a plurality of electrons <NUM> configured to move as charged particles flow past the sensing face <NUM>. Thus, the electrons <NUM> are configured to move or flow as charged dust particles flow past the sensing face <NUM>. More specifically, the electrons <NUM> move within the electrode <NUM> either towards or away from the sensing face <NUM> based on the charge of the passing particles.

Referring particularly to <FIG> and <FIG>, the electronics housing <NUM> of the MCM sensor assembly <NUM> is separate from the electrostatic sensor <NUM> but still closely coupled thereto via the cable <NUM>. More specifically, in certain embodiments, the cable <NUM> length may range from about <NUM> (<NUM> inches) to about <NUM> (<NUM> inches), more preferably from about <NUM> (<NUM> inches) to about <NUM> (<NUM> inches). As such, even when the electronics are not integrated within the outer housing <NUM>, they are still closely coupled to the sensor components so as to provide increased sensitivity to the sensor <NUM>. Further, the cable <NUM> may be any suitable electrical cable configured for electrically coupling the sensor <NUM> to the suitable electronics within the electronics housing <NUM>. For example, in certain embodiments, the cable <NUM> is a coaxial cable. More specifically, in certain embodiments, the cable <NUM> may include an integral mineral insulated hardline cable. In such embodiments, the electronics housing <NUM> can be routed to a cooler location away from the sensor <NUM>, which will be discussed in more detail below.

Further, the electronics housing <NUM> may have any suitable shape. For example, as shown, the electronics housing <NUM> has a generally cylindrical shape. Moreover, as shown, the electronics housing <NUM> may be formed from two halves <NUM> secured together via a plurality of fasteners <NUM>. As such, the cable <NUM> can be electrically coupled to the circuit board <NUM> by placing the cable <NUM> between the halves <NUM> and securing the halves <NUM> together. In addition, as shown in <FIG>, the electronics housing <NUM> may also include a pin connector <NUM> electrically coupled to the circuit board <NUM>, e.g. opposite the cable connection.

Referring particularly to <FIG> and <FIG>, the electronics housing <NUM> is configured to house at least one amplifier <NUM> that is electrically coupled to the electrode <NUM>. Since the amplifier <NUM> (and remaining electronics) of <FIG> is separate from the sensor <NUM>, the MCM sensor assembly <NUM> may have a higher operating temperature range of from about <NUM> degrees Celsius (°C) to about <NUM>, more preferably from about <NUM> to about <NUM> than the integrated sensor assembly of <FIG>. Further, it should be understood that the amplifier <NUM> may include any of the amplifiers as described herein such that the amplifier <NUM> is configured to detect or measure a particle level passing by the sensing face <NUM> of the sensor <NUM> as a function of the electron movement. In addition, as shown, the electronics housing <NUM> also houses the circuit board <NUM> that is electrically coupled to the sensor <NUM> via the cable <NUM>. As mentioned, the circuit board <NUM> as described herein may include any suitable circuit board that mechanically supports and electrically connects the electronic components (such as the amplifier <NUM>) to the sensor(s) <NUM>. More specifically, certain circuit boards of the present disclosure may include conductive tracks, pads, and/or other features etched from sheets of metal, such as copper, that are laminated onto a non-conductive substrate.

The amplifiers <NUM> of the present disclosure are extremely sensitive and capable of more accurately detecting particle levels. More specifically, in certain embodiments, the amplifier <NUM> may include a leakage current of from about <NUM> femtoampere to about <NUM> femtoamperes, more preferably about <NUM> femtoamperes. Thus, the low leakage current facilitates DC coupling of the amplifier <NUM>, which allows low frequency changes in particle levels to be captured. Further, the electrode <NUM> of the present disclosure may have an impedance of greater than about <NUM>-Ohm, for example about <NUM>-Ohm. As such, the high input impedance of the electrode <NUM> is configured to improve the sensor sensitivity to small changes in charge in the sensing face <NUM>. Further, the high input impedance is also configured to improve the low frequency response of the electrostatic sensor <NUM> by preventing sensed charge from leaking away such that an output voltage cannot be produced. Thus, the electrostatic sensor(s) <NUM> of the present disclosure is capable of detecting from about one (<NUM>) part in seven (<NUM>) million by mass of particles.

Referring particularly to <FIG> and <FIG>, the electrostatic sensor(s) <NUM> may also include one or more insulators or insulation layers <NUM>. For example, as shown in <FIG> and <FIG>, the electrostatic sensor(s) <NUM> may include a ceramic insulator <NUM> (such as alumina) between the electrode <NUM> and the outer housing <NUM>. It should further be understood that any number of insulation layers may be employed at any suitable location within the sensor <NUM>.

In addition, as shown, the electrostatic sensor <NUM> may further include one or more mechanical fasteners configured within the outer housing <NUM> between the ceramic insulator <NUM> and the cable <NUM>. The mechanical fastener(s) may include flat washers, beveled washers, nuts, screws, or threads. More specifically, as shown in <FIG>, the sensor <NUM> includes two inner flat washers <NUM> with an inner beveled washer <NUM> configured therebetween. Further, as shown, the sensor <NUM> also includes two outer flat washers with an outer beveled washer <NUM> configured therebetween. As such, the beveled washers <NUM>, <NUM> are configured to act as a spring within the sensor <NUM> to relieve thermal stresses and/or to allow for expansion of the various components of the sensor <NUM> when operating at high temperatures. In addition, the inner and outer washer stacks may be separated or isolated from each other via gap <NUM> to allow movement at high temperatures without cracking the ceramic insulator <NUM>. Similarly, another gap <NUM> may exist between the ceramic insulator <NUM> and the electrode <NUM> to further relieve thermal stresses therebetween. Still referring to <FIG>, as mentioned, the mechanical fastener(s) may also include nut <NUM> adjacent to the inner washers <NUM>, <NUM> that is configured for securing the electrode <NUM> within the outer housing <NUM>.

Referring now to <FIG> a schematic diagram of one embodiment of circuit topology <NUM> that is suitable for the electrostatic sensor <NUM> according to the present disclosure is illustrated. As shown, the circuit <NUM> receives one or more sensor inputs from the electrostatic sensor <NUM>. For example, the sensor inputs may be received from the electrode <NUM> of the sensor <NUM>. The inputs are then transferred to a first amplifier <NUM>. More specifically, the sensor input may first pass through a resistor R<NUM> so as to prevent and/or reduce electrostatic discharge (ESD) in the signal. Further, as shown, a large resistance resistor R<NUM> (e.g. about <NUM>-ohms) is provided on the input path (designated as Pin <NUM>) to bypass amplifier leakage current to ground. From Pin <NUM>, a copy of the input signal is transferred to a second amplifier <NUM> at Pin <NUM>. As shown, the signal travels through resistors R<NUM> and R<NUM>, which set the gain of the signal. R<NUM> isolates the input capacitance of Pin <NUM> of amplifier <NUM> from the input signal. At least one of the resistors (i.e. R<NUM>) may also include a capacitor Ci configured in parallel therewith to limit the bandwidth of the amplifier <NUM>. Capacitors C<NUM>, C<NUM>, C<NUM>, and C<NUM> act as decoupling capacitors for the amplifiers <NUM> and <NUM>. Resistors R<NUM> and R<NUM> protect amplifier outputs from ESD and also isolate the circuit from long external cables. A purpose of the second amplifier <NUM> is to guard the tiny sensor signal. For example, the second amplifier <NUM> may be configured with the same voltage and amplitude as the input to the first amplifier <NUM> but provides a low impedance source current. As such, as shown at Pin <NUM>, the second amplifier <NUM> guards the sensor signal by tracking the sensor input voltage and diverting extraneous charges away from the sensor input. Thus, the amplifier configuration of the present invention includes a voltage follower with gain that is guarded by the second amplifier <NUM> tracking the sensor input voltage so as to guard it and produce a better signal to noise ratio.

The electrostatic sensors <NUM> described herein may have any suitable application. For example, in certain embodiments, the electrostatic sensors <NUM> of the present disclosure may be utilized in the aviation industry, such as an in aircraft gas turbine engine, as well as any other suitable engine types. More specifically, <FIG> illustrates a schematic cross-sectional view of one embodiment of a gas turbine engine <NUM> (high-bypass type) that may benefit from the electrostatic sensors <NUM> as described herein. As shown, the gas turbine engine <NUM> has an axial longitudinal centerline axis <NUM> therethrough for reference purposes. Further, as shown, the gas turbine engine <NUM> preferably includes a core gas turbine engine section generally identified by numeral <NUM> and a fan section <NUM> positioned upstream thereof. The core engine <NUM> typically includes a generally tubular outer casing <NUM> that defines an annular inlet <NUM>. The outer casing <NUM> further encloses and supports a booster <NUM> for raising the pressure of the air that enters core engine <NUM> to a first pressure level. A high pressure, multi-stage, axial-flow compressor <NUM> receives pressurized air from the booster <NUM> and further increases the pressure of the air. The compressor <NUM> includes rotating blades and stationary vanes that have the function of directing and compressing air within the turbine engine <NUM>. The pressurized air flows to a combustor <NUM>, where fuel is injected into the pressurized air stream and ignited to raise the temperature and energy level of the pressurized air. The high energy combustion products flow from the combustor <NUM> to a first (high pressure) turbine <NUM> for driving the high pressure compressor <NUM> through a first (high pressure) drive shaft <NUM>, and then to a second (low pressure) turbine <NUM> for driving the booster <NUM> and the fan section <NUM> through a second (low pressure) drive shaft <NUM> that is coaxial with the first drive shaft <NUM>. After driving each of the turbines <NUM> and <NUM>, the combustion products leave the core engine <NUM> through an exhaust nozzle <NUM> to provide at least a portion of the jet propulsive thrust of the engine <NUM>.

The fan section <NUM> includes a rotatable, axial-flow fan rotor <NUM> that is surrounded by an annular fan casing <NUM>. It will be appreciated that fan casing <NUM> is supported from the core engine <NUM> by a plurality of substantially radially-extending, circumferentially-spaced outlet guide vanes <NUM>. In this way, the fan casing <NUM> encloses the fan rotor <NUM> and the fan rotor blades <NUM>. The downstream section <NUM> of the fan casing <NUM> extends over an outer portion of the core engine <NUM> to define a secondary, or bypass, airflow conduit <NUM> that provides additional jet propulsive thrust.

From a flow standpoint, it will be appreciated that an initial airflow, represented by arrow <NUM>, enters the gas turbine engine <NUM> through an inlet <NUM> to the fan casing <NUM>. The airflow passes through the fan blades <NUM> and splits into a first air flow (represented by arrow <NUM>) that moves through the conduit <NUM> and a second air flow (represented by arrow <NUM>) which enters the booster <NUM>.

The pressure of the second compressed airflow <NUM> is increased and enters the high pressure compressor <NUM>, as represented by arrow <NUM>. After mixing with fuel and being combusted in the combustor <NUM>, the combustion products <NUM> exit the combustor <NUM> and flow through the first turbine <NUM>. The combustion products <NUM> then flow through the second turbine <NUM> and exit the exhaust nozzle <NUM> to provide at least a portion of the thrust for the gas turbine engine <NUM>.

Still referring to <FIG>, the combustor <NUM> includes an annular combustion chamber <NUM> that is coaxial with the longitudinal centerline axis <NUM>, as well as an inlet <NUM> and an outlet <NUM>. As noted above, the combustor <NUM> receives an annular stream of pressurized air from a high pressure compressor discharge outlet <NUM>. A portion of this compressor discharge air flows into a mixer (not shown). Fuel is injected from a fuel nozzle <NUM> to mix with the air and form a fuel-air mixture that is provided to the combustion chamber <NUM> for combustion. Ignition of the fuel-air mixture is accomplished by a suitable igniter, and the resulting combustion gases <NUM> flow in an axial direction toward and into an annular, first stage turbine nozzle <NUM>. The nozzle <NUM> is defined by an annular flow channel that includes a plurality of radially-extending, circumferentially-spaced nozzle vanes <NUM> that turn the gases so that they flow angularly and impinge upon the first stage turbine blades of the first turbine <NUM>. The first turbine <NUM> preferably rotates the high-pressure compressor <NUM> via the first drive shaft <NUM>, whereas the low-pressure turbine <NUM> preferably drives the booster <NUM> and the fan rotor <NUM> via the second drive shaft <NUM>.

The combustion chamber <NUM> is housed within the engine outer casing <NUM> and fuel is supplied into the combustion chamber <NUM> by one or more fuel nozzles <NUM>. More specifically, liquid fuel is transported through one or more passageways or conduits within a stem of the fuel nozzle <NUM>.

During operation, dust and other types of particles can be ingested by the gas turbine engine <NUM>, e.g. from air entering the inlet <NUM>. Dust and particle accumulation is a key input for engine analytics as these levels are important in evaluating engine service time, wear and tear, and/or other maintenance schedules. Thus, as mentioned, the electrostatic sensors <NUM> of the present disclosure are particularly useful for detecting dust and/or debris in such engines <NUM>. As such, the electrostatic sensors <NUM> of the present disclosure may be located at any suitable location of the gas turbine engine <NUM>. For example, the electrostatic sensors <NUM> of the present disclosure may be located within a borescope port, a compressor inlet <NUM> (<FIG>), a compressor bleed pipe <NUM> (<FIG>), a booster inlet <NUM> (<FIG>), or a turbine or afterburner exit of the engine of the engine <NUM>. More specifically, the electrostatic sensor <NUM> is capable of detecting very fine ice crystals, as can be encountered by a passenger aircraft at high altitude near the earth's equator. For such ice detection, the sensor <NUM> can be mounted at the booster inlet <NUM> or the compressor inlet <NUM>. Further, the sensing face <NUM> can be sealed with a non-conductive epoxy coating to prevent water or melting ice from shorting out the electrode <NUM> to the body of the sensor <NUM>.

More specifically, it should be understood that the electrostatic sensor <NUM> of the present disclosure may have any suitable shape to correspond with a desired mounting location. For example, in certain embodiments, the electrostatic sensor <NUM> may have a predetermined shape configured to fit in an existing location, a hole, or inlet of the gas turbine engine <NUM> such that the sensing face <NUM> is flush with an internal surface thereof. Particularly, as shown in <FIG> and <FIG>, the electrostatic sensor <NUM> may have a generally oblong or oval shape. Such a shape generally corresponds to an existing inlet location of the engine <NUM>, such as but not limited to the compressor inlet <NUM> and/or the booster inlet <NUM>. Alternatively, as shown in <FIG> and <FIG>, the electrostatic sensor <NUM> may have a generally cylindrical shape that corresponds to an inlet of the compressor bleed pipe <NUM> of the engine <NUM>. Further, as particularly illustrated in <FIG>, the sensor <NUM> may be mounted adjacent to the compressor bleed pipe <NUM> such that the sensing face <NUM> does not penetrate or intersect the flow path therein.

Referring now to <FIG>, <FIG>, and <FIG>, the MCM sensor assembly <NUM> is communicatively coupled to a controller <NUM> that is configured to receive the sensor signals generated by the electrode <NUM> of the sensor <NUM>. More specifically, as shown in <FIG>, there is illustrated a block diagram of one embodiment of suitable components that may be included in the controller <NUM> according to the present disclosure. As shown, the controller <NUM> includes one or more processor(s) <NUM> and associated memory device(s) <NUM> configured to perform a variety of computer-implemented functions (e.g., performing the methods, steps, calculations and the like and storing relevant data as disclosed herein). Additionally, the controller <NUM> may also include a communications module <NUM> to facilitate communications between the controller <NUM> and the electrostatic sensor(s) <NUM>. Further, the communications module <NUM> may include a sensor interface <NUM> (e.g., one or more analog-to-digital converters) to permit signals transmitted from the sensor(s) <NUM> to be converted into signals that can be understood and processed by the processor(s) <NUM>. It should be appreciated that the sensor(s) <NUM> may be communicatively coupled to the communications module <NUM> using any suitable means. For example, as shown in <FIG>, the sensors <NUM> are coupled to the sensor interface <NUM> via a wired connection. However, in other embodiments, the sensors <NUM> may be coupled to the sensor interface <NUM> via a wireless connection, such as by using any suitable wireless communications protocol known in the art. As such, the processor(s) <NUM> may be configured to receive one or more signals from the sensors <NUM>.

As used herein, the term "processor" refers not only to integrated circuits referred to in the art as being included in a computer, but also refers to a controller, a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific integrated circuit, and other programmable circuits. Additionally, the memory device(s) <NUM> may generally include memory element(s) including, but not limited to, computer readable medium (e.g., random access memory (RAM)), computer readable non-volatile medium (e.g., a flash memory), cloud storage, a floppy disk, a compact disc-read only memory (CD-ROM), a magneto-optical disk (MOD), a digital versatile disc (DVD) and/or other suitable memory elements. Such memory device(s) <NUM> may generally be configured to store suitable computer-readable instructions that, when implemented by the processor(s) <NUM>, configure the controller <NUM> to perform various functions of the gas turbine engine <NUM>.

Referring now to <FIG>, a flow diagram of one embodiment of a method <NUM> for detecting particles in a gas turbine engine <NUM>, e.g. an aircraft engine, is illustrated. As shown at <NUM>, the method <NUM> includes providing at least one of the electrostatic sensors <NUM> as described herein in one or more locations in the gas turbine engine <NUM>. Further, as shown at <NUM>, the method <NUM> includes arranging the sensing face <NUM> of each sensor <NUM> in a particle flow path at the one or more locations. Thus, as shown at <NUM>, the method <NUM> also includes determining, via the amplifier <NUM> of each sensor <NUM>, a particle level within the gas turbine engine <NUM> as a function of electron movement in the electrode <NUM>. As shown at <NUM>, the method <NUM> includes generating, via a circuit board <NUM> closely coupled to the sensor <NUM>, one or more signals indicative of the particle level in response to detecting charged particles.

In one embodiment, the method <NUM> may also include sending, via the circuit board <NUM> of the each of the electrostatic sensors <NUM>, the signal(s) to the controller <NUM> of the gas turbine engine <NUM>. As such, the sensors <NUM> described herein provide real-time, accurate particulate level data to a user.

Claim 1:
A sensor assembly (<NUM>), comprising:
an electrostatic sensor (<NUM>) comprising:
an outer housing (<NUM>),
an electrode (<NUM>) configured within the outer housing, wherein the electrode comprising a first end (<NUM>) and an opposing second end (<NUM>) separated by a predetermined length, the first end being secured within the outer housing, the second end comprising a sensing face (<NUM>) that is substantially flush with an edge (<NUM>) of the outer housing, the electrode comprising a plurality of electrons (<NUM>) that respond to one or more charged particles that flow past the sensing face, said electrons moving either towards or away from the second end,
an amplifier (<NUM>) configured within the outer housing and electrically coupled to the electrode, wherein a particle level flowing past the sensing face as a function of electron movement is detected via said amplifier;
a circuit board (<NUM>) configured within the outer housing and electrically coupled to the electrostatic sensor; and
a controller (<NUM>) configured to receive one or more signals from the circuit board (<NUM>) indicative of the particle level, wherein the controller comprises one or more processors (<NUM>) and one or more memory devices (<NUM>).