Patent Description:
A 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.

In particular configurations, the turbine section includes, in serial flow order, a high pressure (HP) turbine and a low pressure (LP) turbine. The HP turbine and the LP turbine each include various rotatable turbine components such as turbine rotor blades, rotor disks and retainers, and various stationary turbine components such as stator vanes or nozzles, turbine shrouds, and engine frames. The rotatable and stationary turbine components at least partially define the hot gas path through the turbine section. As the combustion gases flow through the hot gas path, thermal energy is transferred from the combustion gases to the rotatable and stationary turbine components.

A typical gas turbine engine includes very fine cooling passages that allow for higher gas temperatures in the combustor and/or the HP or LP turbines. During operation, particularly in environments that contain fine-scale dust (e.g. PM <NUM>), environmental particulate accumulates on engine components and within the cooling passages of the engine. For example, dust (reacted or non-reacted), sand, or similar can build up on the flow path components and on the impingement cooled surfaces during turbine engine operation. In addition, particulate matter entrained in the air that enters the turbine engine and the cooling passages can contain sulphur-containing species that can corrode the components. Such accumulation can lead to reduced cooling effectiveness of the components and/or corrosive reaction with the metals and/or coatings of the engine components. Thus, particulate build-up can lead to premature distress and/or reduced engine life. Additionally, accumulations of environmental contaminants (e.g. dust-reacted and unreacted, sand, etc.) such as these can degrade aerodynamic performance of the high-pressure components and lower fuel efficiency of the engine through changes in airfoil morphology.

Accordingly, the present disclosure is directed to a system and method for cleaning engine components using abrasive particles that addresses the aforementioned issues. More specifically, the present disclosure is directed to a system and method for in-situ cleaning of engine components that utilizes abrasive microparticles that are particularly useful for cleaning internal cooling passages of the gas turbine engine.

<CIT> relates to coke compositions for in-line gas turbine cleaning and discloses injecting a dry cleaning medium into the gas turbine engine at one or more locations, the dry cleaning medium comprising a plurality of abrasive microparticles; and circulating the cleaning medium through at least a portion of the gas turbine engine such that the abrasive microparticles abrade a surface of the one or more components such as to clean the surface.

<CIT> relates to improvements in or relating to gas turbine plants and methods of operating the same. <CIT> relates to turbine engine cleaning. <CIT> relates to a water soluble blast media containing a surfactant.

In one aspect, the present disclosure is directed to a method for in-situ, on-wing cleaning one or more components of a gas turbine engine. The method includes injecting a dry cleaning medium into the gas turbine engine at one or more locations. The dry cleaning medium includes a plurality of abrasive microparticles. Thus, the method also includes circulating the dry cleaning medium through at least a portion of the gas turbine engine such that the abrasive microparticles abrade a surface of the one or more components so as to clean the surface. Further, the abrasive microparticles may be subsequently removed from the engine either through standard engine operation cooling airflow and/or via incineration such that the residual ash content meets the requirements for application to a fully assembled gas turbine on-wing.

In another aspect, the present disclosure is directed to a cleaning system for in-situ cleaning of one or more components of a gas turbine engine. The cleaning system includes a gas turbine engine; and a dry cleaning medium containing a plurality of abrasive microparticles. Each of the abrasive microparticles has a particle diameter size range of from about <NUM> microns to about <NUM> microns. Further, the cleaning system includes a delivery system configured to deliver the cleaning medium at one or more locations of the gas turbine engine so as to clean the one or more components thereof. The gas turbine engine is in-situ on-wing.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention, which is defined by the method in accordance with claim <NUM> and the system in accordance with claim <NUM>.

Generally, the present disclosure is directed to cleaning systems and methods for in-situ (e.g. on-wing) cleaning one or more components of a gas turbine engine. The method includes injecting a dry cleaning medium into the gas turbine engine at one or more locations, wherein the dry cleaning medium includes a plurality of abrasive microparticles. Further, the abrasive microparticles may be suspended in air, water, and/or water-based detergent. Thus, the method also includes circulating the cleaning medium through at least a portion of the gas turbine engine such that the abrasive microparticles abrade a surface of the one or more components so as to clean the surface.

The present disclosure provides various advantages not present in the prior art. For example, gas turbine engines according to present disclosure can be cleaned on-wing, in-situ, and/or off-site with the engine maintained in the fully assembled condition. Further, the cleaning methods of the present disclosure provide simultaneous mechanical and chemical removal of particulate deposits in cooling passageways of gas turbine engines. In addition, the system and method of the present disclosure improves cleaning effectiveness and has significant implications for engine time on-wing durability. Moreover, the present invention provides an abrasive media cleaning and delivery system and a method for uniform circumferential cleaning of a turbine engine that does not necessarily require a subsequent rinse cycle.

Referring now to the drawings, <FIG> illustrates a schematic cross-sectional view of one embodiment of a gas turbine engine <NUM> (high-bypass type) according to the present disclosure. 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 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 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>. As shown in <FIG>, 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>.

Referring now to <FIG>, a flow diagram of one embodiment of a method <NUM> for in-situ cleaning one or more components of a gas turbine engine (e.g. such as the gas turbine engine <NUM> illustrated in <FIG>) is illustrated. For example, in certain embodiments, the component(s) of the gas turbine engine <NUM> may include any of the components of the engine <NUM> as described herein, including but not limited to the compressor <NUM>, the high-pressure turbine <NUM>, the low-pressure turbine <NUM>, the combustor <NUM>, the combustion chamber <NUM>, one or more nozzles <NUM>, <NUM>, one or more blades <NUM> or vanes <NUM>, the booster <NUM>, a casing <NUM> of the gas turbine engine <NUM>, cooling passageways of the engine <NUM>, turbine shrouds, or similar.

Thus, as shown at <NUM>, the method <NUM> may include injecting a dry cleaning medium <NUM> into the gas turbine engine <NUM> at one or more locations. More specifically, the step of injecting the cleaning medium into the gas turbine engine <NUM> may include injecting the cleaning medium <NUM> into an inlet (e.g. inlet <NUM>, <NUM> or <NUM>) of the engine <NUM>. Alternatively or in addition, as shown, the step of injecting the cleaning medium <NUM> into the gas turbine engine <NUM> may include injecting the cleaning medium <NUM> into one or more ports <NUM> of the engine <NUM>. Further, the step of injecting the cleaning medium <NUM> into the gas turbine engine <NUM> may include injecting the cleaning medium <NUM> into an existing baffle plate system (not shown) of the gas turbine engine <NUM>. Further, the cleaning medium <NUM> may be injected into the engine <NUM> using any suitable means. More specifically, in certain embodiments, the cleaning medium <NUM> may be injected into the engine <NUM> using automatic and/or manual devices configured to pour, funnel, or channel substances into the engine <NUM>.

For example, referring now to <FIG>, a partial, cross-sectional view of one embodiment of the gas turbine engine <NUM> according to the present disclosure is illustrated. As shown, the cleaning medium (as indicated by arrow <NUM>) may be injected into the engine <NUM> at a plurality of locations. More specifically, as shown, the cleaning medium is injected to the inlet <NUM> of the engine <NUM>. Further, as shown, the cleaning medium <NUM> may be injected into one or more ports <NUM> of the engine <NUM>. For example, as shown, the cleaning medium <NUM> may be injected into a port <NUM> of the compressor <NUM> and/or a port <NUM> of the combustion chamber <NUM>. Further, the cleaning medium <NUM> contains a plurality of abrasive microparticles. Thus, the cleaning medium particles are configured to flow through the engine <NUM> and abrade the surfaces of the engine components so as to clean said surfaces. In addition, in certain embodiments, where organic abrasive microparticles are used, the cleaning medium <NUM> does not necessarily require a subsequent rinse cycle after cleaning.

As used herein, "microparticles" generally refer to particles having a particle diameter of between about <NUM> microns or micrometers to about <NUM> microns. In certain embodiments, the plurality of microparticles may have particle diameter of from about <NUM> microns to about <NUM> microns. Below <NUM> microns, the particle momentum may not be sufficient to effectively remove dust in the engine <NUM> and could potentially accumulate within particular cooling circuits. Further, above <NUM> microns, the particles may not have sufficient velocity and therefore will not be able to effectively remove dust in the engine <NUM> and could potentially accumulate within particular cooling circuits. In other words, it is necessary for the particles to be larger than a sticking size and smaller than a critical size than can lead to plugging of the fine cooling circuits. Thus, the preferred particle size for cleaning both the flow path of the components and the cooling circuits of the turbine is typically from about <NUM> microns and to about <NUM> microns.

In addition, the cleaning medium <NUM> of the present disclosure may include any suitable abrasive particles now known or later developed in the art. For example, in one embodiment, the cleaning medium <NUM> may include organic particles such as nut shells (e.g. walnut shells), fruit pit stones (e.g. plum), and/or any other suitable organic material. The organic material has some cleaning advantages, including but not limited to ease of elimination from the engine <NUM> after cleaning. In additional embodiments, the cleaning medium <NUM> may also include non-organic particles such as e.g., alumina, silica (e.g. silicon carbide), diamond, or similar.

In addition, the particles of the cleaning medium <NUM> may have varying particle sizes. For example, in certain embodiments, the abrasive microparticles may include a first set of microparticles having a median or average particle diameter within a first, smaller micron range and a second set of microparticles having a median particle diameter within a second, larger micron range. More specifically, as used herein, a "micron range" generally encompasses a particle diameter size range measured in micrometers and less than <NUM> microns. For example, in certain embodiments, the first set of microparticles may have a median particle diameter equal to or less than <NUM> microns, whereas the second set of microparticles may have a median particle diameter equal to or greater than <NUM> microns. More specifically, the first micron range may be equal to or less than <NUM> microns, whereas the second micron range may be equal to or greater than <NUM> microns, or more preferably equal to or greater than <NUM> microns. Thus, a median of the second micron range may be larger than a median or average of the first micron range.

Accordingly, as shown at <NUM> of <FIG>, the method <NUM> may also include circulating the cleaning medium <NUM> through at least a portion of the gas turbine engine <NUM> such that the plurality of abrasive microparticles clean the one or more components thereof. More specifically, the abrasive microparticles of the cleaning medium <NUM> can be carried into smaller areas of the engine <NUM>, e.g. into the smaller cooling passageways, which are inaccessible to larger particles.

The step of circulating the cleaning medium <NUM> through at least a portion of the gas turbine engine <NUM> includes motoring the engine <NUM> during injection of the cleaning medium <NUM> so as to circulate the particles through the gas turbine engine <NUM> via airflow.

Referring now to <FIG>, a schematic diagram of one embodiment of a cleaning system <NUM> for in-situ cleaning of one or more components of a gas turbine engine <NUM> is illustrated. As shown, the cleaning system <NUM> includes a cleaning medium <NUM> containing a plurality of microparticles <NUM> as described herein. Further, as shown, the cleaning system <NUM> includes a delivery system <NUM> configured to deliver the cleaning medium <NUM> at one or more locations of the gas turbine engine <NUM> so as to clean the one or more components thereof. More specifically, the delivery system <NUM> may include any suitable delivery device for delivering the cleaning medium <NUM>, including but not limited to the one or more external pressure sources <NUM> in fluid communication with the various components of the engine <NUM> to be cleaned via pipes, hose, conduits, tubing, or similar. Further, the location(s) may include a gas turbine inlet, one or more ports of the gas turbine engine <NUM>, one or more cooling passageways of the gas turbine engine <NUM>, and/or an existing baffle plate. The abrasive cleaning system <NUM> can also be employed in cooling passages that operate at air pressures of up to <NUM> MPa (<NUM> pounds per square inch (psi)) in the turbine engine during service. Further, the abrasive medium and delivery system <NUM> can be employed at pressures from about <NUM> kPa (five (<NUM>) psi) to about <NUM> MPa (<NUM> psi) to clean passages. Thus, it is intended that the cleaning medium <NUM> and delivery system <NUM> can be employed such that it can be transmitted into the cooling structure of the turbine engine <NUM> through the outer wall of the engine through ports such as bore scope access ports, fuel nozzle flanges, instrumentation access ports. Further, in certain embodiments, the delivery system <NUM> may include one or more external pressure sources <NUM> configured to provide airflow to the engine <NUM> so as to circulate the abrasive microparticles <NUM> therethrough. For example, in certain embodiments, the external pressure source(s) <NUM> may include a fan, a blower, a pump, or any other suitable device.

Thus, as shown, in certain embodiments, the method <NUM> may also include creating a cleaning mixture <NUM> by mixing the plurality of abrasive microparticles and a liquid <NUM>, e.g. such as water or water-based detergent. In such embodiments, the step of circulating the cleaning medium <NUM> through at least a portion of the gas turbine engine <NUM> may include circulating the cleaning mixture <NUM> through the gas turbine engine <NUM> via a pump. As such, for certain components, air can be used for injecting the abrasive particles, e.g. via fan, whereas in other components such as shrouds, combustors, and nozzles, water may be used as the medium for delivery of the abrasive particles.

More specifically, in certain embodiments, cleaning of the engine <NUM> may be performed by spraying the abrasive media at the component that has a dust layer on it. For example, the abrasive medium may be sprayed through the baffle plate system that is used in the engine for impingement cooling. In another example, the abrasive medium may be sprayed through a borescope injection port while rotating the core of the compressor, so as to impinge upon the compressor airfoils.

Claim 1:
A method for in-situ cleaning one or more components of a gas turbine engine (<NUM>), the method comprising:
injecting a dry cleaning medium (<NUM>) into the gas turbine engine (<NUM>) at one or more locations, the dry cleaning medium (<NUM>) comprising a plurality of abrasive microparticles (<NUM>); and
circulating, via motoring of the gas turbine engine during the injecting, the cleaning medium (<NUM>) through at least a portion of the gas turbine engine (<NUM>) in-situ on-wing such that the abrasive microparticles (<NUM>) abrade a surface of the one or more components so as to clean the surface.