Patent Publication Number: US-10323539-B2

Title: System and method for cleaning gas turbine engine components

Description:
FIELD OF THE INVENTION 
     The present subject matter relates generally to gas turbine engines, and more particularly, to systems and methods for in-situ cleaning of gas turbine engine components using abrasive particles. 
     BACKGROUND OF THE INVENTION 
     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 10), 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. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention. 
     In one aspect, the present disclosure is directed to a method 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. 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 dry cleaning medium containing a plurality of abrasive microparticles. Each of the abrasive microparticles has a particle diameter size range of from about 10 microns to about 100 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. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. 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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: 
         FIG. 1  illustrates a schematic cross-sectional view of one embodiment of a gas turbine engine according to the present disclosure; 
         FIG. 2  illustrates a flow diagram of one embodiment of a method for in-situ cleaning of one or more components of a gas turbine engine according to the present disclosure; 
         FIG. 3  illustrates a partial, cross-sectional view of one embodiment of a gas turbine engine, particularly illustrating a cleaning medium being injected into the engine at a plurality of locations according to the present disclosure; and 
         FIG. 4  illustrates a schematic diagram of one embodiment of a cleaning system for cleaning gas turbine engine components according to the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation 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 or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
     As used herein, the terms “first”, “second”, and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. 
     The terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows. 
     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. 1  illustrates a schematic cross-sectional view of one embodiment of a gas turbine engine  10  (high-bypass type) according to the present disclosure. As shown, the gas turbine engine  10  has an axial longitudinal centerline axis  12  therethrough for reference purposes. Further, as shown, the gas turbine engine  10  preferably includes a core gas turbine engine generally identified by numeral  14  and a fan section  16  positioned upstream thereof. The core engine  14  typically includes a generally tubular outer casing  18  that defines an annular inlet  20 . The outer casing  18  further encloses and supports a booster  22  for raising the pressure of the air that enters core engine  14  to a first pressure level. A high pressure, multi-stage, axial-flow compressor  24  receives pressurized air from the booster  22  and further increases the pressure of the air. The pressurized air flows to a combustor  26 , 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  26  to a first (high pressure) turbine  28  for driving the high pressure compressor  24  through a first (high pressure) drive shaft  30 , and then to a second (low pressure) turbine  32  for driving the booster  22  and the fan section  16  through a second (low pressure) drive shaft  34  that is coaxial with the first drive shaft  30 . After driving each of the turbines  28  and  32 , the combustion products leave the core engine  14  through an exhaust nozzle  36  to provide at least a portion of the jet propulsive thrust of the engine  10 . 
     The fan section  16  includes a rotatable, axial-flow fan rotor  38  that is surrounded by an annular fan casing  40 . It will be appreciated that fan casing  40  is supported from the core engine  14  by a plurality of substantially radially-extending, circumferentially-spaced outlet guide vanes  42 . In this way, the fan casing  40  encloses the fan rotor  38  and the fan rotor blades  44 . The downstream section  46  of the fan casing  40  extends over an outer portion of the core engine  14  to define a secondary, or bypass, airflow conduit  48  that provides additional jet propulsive thrust. 
     From a flow standpoint, it will be appreciated that an initial airflow, represented by arrow  50 , enters the gas turbine engine  10  through an inlet  52  to the fan casing  40 . The airflow passes through the fan blades  44  and splits into a first air flow (represented by arrow  54 ) that moves through the conduit  48  and a second air flow (represented by arrow  56 ) which enters the booster  22 . 
     The pressure of the second compressed airflow  56  is increased and enters the high pressure compressor  24 , as represented by arrow  58 . After mixing with fuel and being combusted in the combustor  26 , the combustion products  60  exit the combustor  26  and flow through the first turbine  28 . The combustion products  60  then flow through the second turbine  32  and exit the exhaust nozzle  36  to provide at least a portion of the thrust for the gas turbine engine  10 . 
     Still referring to  FIG. 1 , the combustor  26  includes an annular combustion chamber  62  that is coaxial with the longitudinal centerline axis  12 , as well as an inlet  64  and an outlet  66 . As noted above, the combustor  26  receives an annular stream of pressurized air from a high pressure compressor discharge outlet  69 . A portion of this compressor discharge air flows into a mixer (not shown). Fuel is injected from a fuel nozzle  80  to mix with the air and form a fuel-air mixture that is provided to the combustion chamber  62  for combustion. Ignition of the fuel-air mixture is accomplished by a suitable igniter, and the resulting combustion gases  60  flow in an axial direction toward and into an annular, first stage turbine nozzle  72 . The nozzle  72  is defined by an annular flow channel that includes a plurality of radially-extending, circumferentially-spaced nozzle vanes  74  that turn the gases so that they flow angularly and impinge upon the first stage turbine blades of the first turbine  28 . As shown in  FIG. 1 , the first turbine  28  preferably rotates the high-pressure compressor  24  via the first drive shaft  30 , whereas the low-pressure turbine  32  preferably drives the booster  22  and the fan rotor  38  via the second drive shaft  34 . 
     The combustion chamber  62  is housed within the engine outer casing  18  and fuel is supplied into the combustion chamber  62  by one or more fuel nozzles  80 . More specifically, liquid fuel is transported through one or more passageways or conduits within a stem of the fuel nozzle  80 . 
     Referring now to  FIG. 2 , a flow diagram of one embodiment of a method  100  for in-situ cleaning one or more components of a gas turbine engine (e.g. such as the gas turbine engine  10  illustrated in  FIG. 1 ) is illustrated. For example, in certain embodiments, the component(s) of the gas turbine engine  10  may include any of the components of the engine  10  as described herein, including but not limited to the compressor  24 , the high-pressure turbine  28 , the low-pressure turbine  32 , the combustor  26 , the combustion chamber  62 , one or more nozzles  72 ,  80 , one or more blades  44  or vanes  42 , the booster  22 , a casing  18  of the gas turbine engine  10 , cooling passageways of the engine  10 , turbine shrouds, or similar. 
     Thus, as shown at  102 , the method  100  may include injecting a dry cleaning medium  84  into the gas turbine engine  10  at one or more locations. More specifically, the step of injecting the cleaning medium into the gas turbine engine  10  may include injecting the cleaning medium  84  into an inlet (e.g. inlet  20 ,  52  or  64 ) of the engine  10 . Alternatively or in addition, as shown, the step of injecting the cleaning medium  84  into the gas turbine engine  10  may include injecting the cleaning medium  84  into one or more ports  82  of the engine  10 . Further, the step of injecting the cleaning medium  84  into the gas turbine engine  10  may include injecting the cleaning medium  84  into an existing baffle plate system (not shown) of the gas turbine engine  10 . Further, the cleaning medium  84  may be injected into the engine  10  using any suitable means. More specifically, in certain embodiments, the cleaning medium  84  may be injected into the engine  10  using automatic and/or manual devices configured to pour, funnel, or channel substances into the engine  10 . 
     For example, referring now to  FIG. 3 , a partial, cross-sectional view of one embodiment of the gas turbine engine  10  according to the present disclosure is illustrated. As shown, the cleaning medium (as indicated by arrow  84 ) may be injected into the engine  10  at a plurality of locations. More specifically, as shown, the cleaning medium is injected to the inlet  20  of the engine  10 . Further, as shown, the cleaning medium  84  may be injected into one or more ports  82  of the engine  10 . For example, as shown, the cleaning medium  84  may be injected into a port  82  of the compressor  24  and/or a port  82  of the combustion chamber  62 . Further, the cleaning medium  84  contains a plurality of abrasive microparticles. Thus, the cleaning medium particles are configured to flow through the engine  10  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  84  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 0.1 microns or micrometers to about 100 microns. In certain embodiments, the plurality of microparticles may have particle diameter of from about 10 microns to about 100 microns. Below 10 microns, the particle momentum may not be sufficient to effectively remove dust in the engine  10  and could potentially accumulate within particular cooling circuits. Further, above 100 microns, the particles may not have sufficient velocity and therefore will not be able to effectively remove dust in the engine  10  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 10 microns and to about 100 microns. 
     In addition, the cleaning medium  84  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  84  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  10  after cleaning. In additional embodiments, the cleaning medium  84  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  84  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 100 microns. For example, in certain embodiments, the first set of microparticles may have a median particle diameter equal to or less than 20 microns, whereas the second set of microparticles may have a median particle diameter equal to or greater than 20 microns. More specifically, the first micron range may be equal to or less than 10 microns, whereas the second micron range may be equal to or greater than 30 microns, or more preferably equal to or greater than 40 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  104  of  FIG. 2 , the method  100  may also include circulating the cleaning medium  84  through at least a portion of the gas turbine engine  10  such that the plurality of abrasive microparticles clean the one or more components thereof. More specifically, the abrasive microparticles of the cleaning medium  84  can be carried into smaller areas of the engine  10 , e.g. into the smaller cooling passageways, which are inaccessible to larger particles. 
     In additional embodiments, the step of circulating the cleaning medium  84  through at least a portion of the gas turbine engine  10  may include motoring or running the engine  10  during injection of the cleaning medium  84  so as to circulate the particles through the gas turbine engine  10  via airflow. Alternatively, the step of circulating the cleaning medium  84  through at least a portion of the gas turbine engine  10  may include utilizing one or more external pressure sources to provide airflow that circulates the particles through the gas turbine engine  10 . For example, in certain embodiments, the external pressure sources  96  ( FIG. 4 ) may include a fan, a blower, or similar. 
     Referring now to  FIG. 4 , a schematic diagram of one embodiment of a cleaning system  90  for in-situ cleaning of one or more components of a gas turbine engine  10  is illustrated. As shown, the cleaning system  90  includes a cleaning medium  84  containing a plurality of microparticles  92  as described herein. Further, as shown, the cleaning system  90  includes a delivery system  94  configured to deliver the cleaning medium  84  at one or more locations of the gas turbine engine  10  so as to clean the one or more components thereof. More specifically, the delivery system  94  may include any suitable delivery device for delivering the cleaning medium  84 , including but not limited to the one or more external pressure sources  96  in fluid communication with the various components of the engine  10  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  10 , one or more cooling passageways of the gas turbine engine  10 , and/or an existing baffle plate. The abrasive cleaning system  90  can also be employed in cooling passages that operate at air pressures of up to 1000 pounds per square inch (psi) in the turbine engine during service. Further, the abrasive medium and delivery system  90  can be employed at pressures from about five (5) psi to about 1000 psi to clean passages. Thus, it is intended that the cleaning medium  84  and delivery system  94  can be employed such that it can be transmitted into the cooling structure of the turbine engine  10  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  94  may include one or more external pressure sources  96  configured to provide airflow to the engine  10  so as to circulate the abrasive microparticles  92  therethrough. For example, in certain embodiments, the external pressure source(s)  96  may include a fan, a blower, a pump, or any other suitable device. 
     Thus, as shown, in certain embodiments, the method  100  may also include creating a cleaning mixture  99  by mixing the plurality of abrasive microparticles and a liquid  98 , e.g. such as water or water-based detergent. In such embodiments, the step of circulating the cleaning medium  84  through at least a portion of the gas turbine engine  10  may include circulating the cleaning mixture  99  through the gas turbine engine  10  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  10  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. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.