Patent Publication Number: US-2019170009-A1

Title: Turbine engine with clearance control system

Description:
BACKGROUND OF THE INVENTION 
     Turbine engines are driven by a flow of combustion gases passing through the engine onto a multitude of rotating turbine blades. In some turbine engines, such as those used to propel aircraft, some aspects of engine performance depend upon clearances between turbine rotating blade tips and static shields or shrouds surrounding the blade tips. 
     A clearance control system can be configured to direct a cooling flow or a heating flow onto turbine casings to cause the casings to thermally expand or contract in order to increase or decrease a tip clearance. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In one aspect, the disclosure relates to a turbine engine comprising an annular casing having an exterior wall, a distribution manifold having at least one portion extending at least partially, circumferentially about the exterior wall, and at least one flow conduit extending at least partially, circumferentially within the exterior wall, and at least one connecting conduit fluidly connecting the distribution manifold to the flow conduit. 
     In another aspect, the disclosure relates to a clearance control system for a turbine engine, the clearance control system comprising an annular casing having an exterior wall, a distribution manifold having at least one portion extending at least partially, circumferentially about the exterior wall, and at least one flow conduit extending at least partially, circumferentially within the exterior wall, at least one connecting conduit fluidly connecting the distribution manifold to the flow conduit. 
     In yet another aspect, the disclosure relates to a method of distributing fluid within an annular casing for a turbine engine, the method comprising flowing the fluid through a distribution manifold at least partially circumscribing the annular casing, passing the fluid from the distribution manifold to a flow conduit within an exterior wall of the annular casing, and at least partially circumscribing the fluid about the annular casing to exchange heat between the annular casing and the fluid. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a schematic view of a turbine engine assembly including a distribution manifold for a clearance control system. 
         FIG. 2  is partially cutaway perspective view of the distribution manifold according to an aspect of the disclosure discussed herein. 
         FIG. 3  is a schematic cross-section view of the distribution manifold from  FIG. 2 . 
         FIG. 4  is a partially cutaway enlarged view of the distribution manifold from  FIG. 2 . 
         FIG. 5  is an enlarged view of  FIG. 4  only illustrating a method for using the distribution manifold from  FIG. 2 . 
         FIG. 6  is a flow chart diagram for the clearance control system of  FIG. 1 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
     Aspects of the disclosure described herein are directed to a clearance control system having a distribution manifold in a turbine engine. Specifically, the clearance control system includes flow conduits within a casing for the turbine engine that are fluidly coupled to the distribution manifold for cooling and/or heating the casing. For purposes of illustration, the present disclosure will be described with respect to a turbine engine. It will be understood, however, that aspects of the disclosure described herein are not so limited and that a combustor as described herein can be implemented in engines, including but not limited to turbojet, turboprop, turboshaft, and turbofan engines. Aspects of the disclosure discussed herein can have general applicability within non-aircraft engines having a combustor, such as other mobile applications and non-mobile industrial, commercial, and residential applications. 
     As used herein, the term “forward” or “upstream” refers to moving in a direction toward the engine inlet, or a component being relatively closer to the engine inlet as compared to another component. The term “aft” or “downstream” used in conjunction with “forward” or “upstream” refers to a direction toward the outlet of the engine or being relatively closer to the engine outlet as compared to another component. Additionally, as used herein, the terms “radial” or “radially” refer to a dimension extending between a center longitudinal axis of the engine and an outer engine circumference. Furthermore, as used herein, the term “set” or a “set” of elements can be any number of elements, including only one. 
     All directional references (e.g., radial, axial, proximal, distal, upper, lower, upward, downward, left, right, lateral, front, back, top, bottom, above, below, vertical, horizontal, clockwise, counterclockwise, upstream, downstream, forward, aft, etc.) are only used for identification purposes to aid the reader&#39;s understanding of the present disclosure, and do not create limitations, particularly as to the position, orientation, or use of aspects of the disclosure described herein. Connection references (e.g., attached, coupled, connected, and joined) are to be construed broadly and can include intermediate members between a collection of elements and relative movement between elements unless otherwise indicated. As such, connection references do not necessarily infer that two elements are directly connected and in fixed relation to one another. The exemplary drawings are for purposes of illustration only and the dimensions, positions, order and relative sizes reflected in the drawings attached hereto can vary. 
       FIG. 1  is a schematic cross sectional view of a turbine engine  10  for an aircraft. The turbine engine  10  includes a clearance control system  100 , according aspects of the disclosure discussed herein. Turbine engine  10  can include in a downstream serial flow relationship, a fan assembly  12  with a fan  14 , a low pressure compressor  16 , a high pressure compressor  18 , a combustion section  20 , a high pressure turbine  22 , and a low pressure turbine  24 . A high pressure shaft  26  can be disposed about an engine axis  8  and can drivingly connect the high pressure turbine  22  with the high pressure compressor  18 . A low pressure shaft  28  can drivingly connect low pressure turbine  24  to low pressure compressor  16  and, in some cases also to the fan  14 . High pressure turbine  22  can include a high pressure rotor  30 , which can comprise a plurality of first stage turbine blades  34  and second stage turbine blades  35  mounted at a periphery of rotor  30 . An annular casing  32  can circumscribe the turbine blades  34 ,  35 . 
     An engine core  36  collectively includes the compressors  16 , 18 , the combustion section  20 , and the turbines  22 ,  24  and terminates in an exhaust  37 . A nacelle  38  can circumscribe the engine core  36  to define a bypass duct  39  therebetween. 
     In operation, an airflow  40  flows through the fan assembly  12  and a core airflow (Ac) is channeled through compressors  16 ,  18  wherein the core airflow (Ac) is further compressed and delivered to the combustion section  20 . Hot products of combustion (not shown) from the combustion section  20  are utilized to drive turbines  22 ,  24  and thus produce engine thrust. A bypass airflow (Ab) is discharged from fan assembly  12  and can flow through the bypass duct  39 . 
     A supply conduit  42  can be disposed proximate the bypass duct  39  and can be coupled to a valve  44  for controlling an amount of thermal control fluid  46  within the supply conduit  42 . The valve  44  can be controlled by a controller  48 , such as a digital electronic engine control system often referred to as a full authority digital engine control (FADEC). Thermal control fluid  46  can be controllably flowed through the supply conduit  42  and supplied to the clearance control system  100  via a distribution manifold  50 . The distribution manifold  50  can be used to cool or heat the annular casing  32 . 
     By way of non-limiting example, the thermal control fluid  46  can be compressed core airflow (Ac) supplied via an air supply inlet  52  to the supply conduit  42 . The air supply inlet  52  can be located downstream of exit guide vanes  54  disposed in the bypass duct  39  downstream of the fan  14 . It should be appreciated that the term “fluid” as used herein includes any material or medium that flows, including, but not limited to, liquid, gas and air. 
       FIG. 2  is a partial cutaway perspective view of the distribution manifold  50  disposed circumferentially around the annular casing  32 , according to at least some aspects of the disclosure described herein. The annular casing  32  can be formed from semicircular segments  56 , by way of non-limiting example four semicircular segments  56   a,    56   b,    56   c,    56   d  defining an exterior wall  58 . It should be understood that the rounded segments can be shroud segments, or the like, and can form an annular casing for any portion of the engine, which by way of non-limiting example is the annular casing  32  for the high pressure turbine  22  as illustrated in  FIG. 1 . 
     The distribution manifold  50  can include at least one portion, illustrated as multiple discrete circumferential segmented portions  60 , extending at least partially, circumferentially about the exterior wall  58 . By way of non-limiting example the circumferential segmented portions  60  include a supply tube  62 , illustrated as a first supply tube  62   a  and a second supply tube  62 b. The circumferential segmented portions  60  further include a collection tube  64 , illustrated as a first collection tube  64   a  and a second collection tube  64   b  are illustrated as disposed generally circumferentially around the annular casing  32 . The supply tube  62  can be axially spaced from and next to the collection tube  64  as illustrated. The orientation and number of tubes is depicted for illustrative purposes only and not meant to be limiting. 
     The supply tube  62  and collection tube  64  can be constructed in the form of generally cylindrical tubing, which can form a generally toroidal shape about engine axis  8 . In some aspects, the generally toroidal shape can be interrupted, such as by a gap  65  between downstream ends of first supply tube  62   a  and second supply tube  62   b,  which can be closed. The supply tube  62  and the collection tube  64  can comprise a generally tubular arc which forms part of the generally toroidal shape. 
     In aspects of the disclosure discussed herein the supply tube  62  can receive thermal control fluid  46  from supply conduit  42  via a tee  66 . For example, tee  66  can comprise an inlet  68   a  fluidly coupled to supply conduit  42 , and a lateral, generally circumferentially oriented outlet  70  fluidly coupled to second supply tube  62   b.  The supply tube  62  can receive thermal control fluid  46  from supply conduit  42  via inlet  68   b  as well. The manner in which the thermal control fluid  46  is received within the supply tube  62  can be in any suitable configuration. 
     In aspects of the disclosure discussed herein the collection tube  64  can exhaust thermal control fluid  46  via a tee  72 . For example, tee  72  can comprise an outlet  74   a  fluidly coupled to the exhaust  37  and a lateral, generally circumferentially oriented inlet  76  fluidly coupled to second collection tube  64   b.  The collection tube  64  can exhaust thermal control fluid  46  into the exhaust  37  via outlet  74   b  as well. The manner in which the thermal control fluid  46  is exhausted can be in any suitable configuration. 
     It is further contemplated that the thermal fluid  46  is recycled. By way of non-limiting example the collection tube  64  and the supply tube  62  can be fluidly connected such that the thermal control fluid  46  can pass from one to the other. 
     Turning to  FIG. 3  a schematic cross-section of the distribution manifold  50  and annular casing  32  as described herein. The supply tube  62  is shown in circumferential segmented portions  60  for purposes of description only. While it is contemplated that the supply tube  62  can be in circumferential segmented portions  60 , it is also contemplated that the supply tube  62  can extend circumferentially all the way around the annular casing  32 . Collection tube  64  is illustrated as extending circumferentially all the way around the annular casing  32 . It should be understood that collection tube  64  can be segmented as well. 
     At least one flow conduit  78  is disposed within the exterior wall  58  of the annular casing  32  and can also extend circumferentially all the way around the annular casing  32 . It should be further understood that the flow conduit  78 , like the supply and collection tubes  62 ,  64 , can also extend partially circumferentially around the annular casing  32 . A connecting conduit  80  can fluidly connect the distribution manifold  50  to the flow conduit  78  at any location along the exterior wall  58 . More specifically, by way of non-limiting example, an inlet conduit  80   a  can be fluidly connected to the supply tube  62  and an outlet conduit  80   b  can be fluidly connected to the collection tube  64 . 
       FIG. 4  illustrates an enlarged view of distribution manifold  50  according to at least some aspects of the disclosure discussed herein. It can more clearly be seen that the annular casing  32  can be formed from multiple segments  82   a,    82   b,    82   c  defining the exterior wall  58 . Each multiple segment can terminate in a flange  84 . The flange  84  can extend radially from the exterior wall  58  to define an annular confronting face  86 . Each segment  82   a  can be coupled to the next consecutive segment  82   b  at opposing annular confronting faces  86  to further define an axial length (L) of the annular casing  32 . While two confronting flanges  84  are illustrated for coupling two segments  82   a,    82   b,  it should be appreciated that the segments  82   a,    82   b  as illustrated can include multiple circumferentially distributed segments  82   c.  It should be further appreciated that the annular casing  32  can extend axially to varying lengths (L) such that multiple axially consecutive flanges define the annular casing  32 . 
     The flow conduit  78  as discussed herein can be disposed in the exterior wall  58  radially within the flange  84 . The flow conduit  78  can include at least one flow enhancer  85 . The flow enhancer  85  can be a dimple, pin fin, or turbulator, or any other suitable flow enhancer  85  for increasing the heat exchange between the exterior wall  58  and the thermal control fluid  46 . The flow conduit  78  can be separate segmented flow conduits  78  located parallel to each other as illustrated. It is further contemplated that the flow conduit  78  is staggered, a single flow conduit, segmented flow conduits, or the like. 
     The connecting conduits  80  as discussed herein can extend through the flange  84  and fluidly connect the flow conduit  78  to the supply tube  62  to define the inlet conduit  80   a.  The connecting conduit  80  can fluidly connect the flow conduit  78  to the collection tube  64  to define the outlet conduit  80   b.  The flow conduit  78  is fluidly connected to both the supply tube  62  via the inlet conduit  80   a  and the collection tube  64  via the outlet conduit  80   b  in any suitable configuration and is not limited to the description described herein. 
     The distribution manifold  50  can include multiple holes  88  disposed in one or both of the supply tube  62  and collection tube  64 . The multiple holes  88  face the annular casing  32 . In particular the multiple holes  88  are impingement holes facing the flange  84 . 
     In operation, the annular casing  32  surrounds the turbine blades  34  as discussed herein and can define a clearance depth (D) therebetween. During take-off the clearance depth (D) will decrease, due to an increase in overall engine temperature, causing parts of the engine, including the rotor  30 , turbine blades  34 , and annular casing  32  to expand. A minimum clearance depth (D) is desirable for decreasing leakage and increasing overall efficiency of the engine. 
     The rotor  30 , turbine blades  34 , and annular casing  32  can expand at different rates. In the event the rotor  30  and turbine blades  34  expand more quickly than the annular casing  32 , a blade out can occur, in which a part of the blade  34  hits the annular casing  32 , which can result in damage to the blade  34  and/or annular casing  32 . Actively heating the annular casing  32  during take-off can cause the annular casing  32  to expand at a faster rate than the rotor  30  and turbine blades  34  enabling control of the clearance depth (D). Maintaining the minimum clearance depth (D) provides maximum engine efficiency while minimizing or preventing blade out occurrences. 
     Once cruising, the overall engine temperature remains relatively constant. Once take-off is complete, any continued active heating of the annular casing would increase the clearance depth (D) too much causing inefficiencies. Actively cooling the annular casing  32  during cruising enables control of the clearance depth (D). Maintaining the minimum clearance depth (D) again maximizes engine efficiency while minimizing or preventing blade out occurrences. During operation, thermal control fluid  46  can be introduced to the supply tube  62  for heating or cooling the annular casing  32 . 
     Turning to  FIG. 5 , a method  200  of distributing fluid within the annular casing  32  is illustrated.  FIG. 5  is an enlarged version of  FIG. 4 , with some numbers from  FIG. 4  removed for clarity. The method  200  includes as indicated by arrow  202 , flowing fluid, by way of non-limiting example the thermal control fluid  46 , through the distribution manifold  50  at least partially circumscribing the annular casing  32 . The thermal control fluid  46  is then passed, as indicated by arrow  204 , from the distribution manifold  50  to the flow conduit  78  within the exterior wall  58  of the annular casing  32 . The thermal control fluid  46  can be passed through the connecting conduit  80 , by way of non-limiting example the inlet conduit  80   a,  located in the flange  84  to enter the flow conduit  78 . The thermal control fluid  46  can then at least partially circumscribe the annular casing  32 , as indicated by arrow  206 , to exchange heat between the annular casing  32  and the thermal control fluid  46 . 
     It is further contemplated that the thermal control fluid  46  can be impinged, as indicated by arrow  208 , onto a portion of the annular casing  32 , by way of non-limiting example the flange  84  through the multiple holes  88  located in the distribution manifold  50  to further exchange heat between the thermal control fluid  46  and the annular casing  32 . The thermal control fluid  46  can exit, as indicated by arrow  210 , via the connecting conduit  80 , by way of non-limiting example the outlet conduit  80   b,  to the collection tube  64 . The thermal control fluid  46  can be recycled back through the supply conduit  62  after being heated or cooled, depending on a stage of operation, for example take-off or cruise as described herein, in which the engine  10  is operating. In this manner, the distribution manifold  50 , the at least one flow conduit  78 , and the connecting conduit  80  are part of a closed system  89 . It is further contemplated that the thermal control fluid  46  is exhausted via the exhaust  37 . 
     The exchange of heat between the thermal control fluid  46  and the annular casing  32  can result in heating the annular casing  32 . By way of non-limiting example the heating of the annular casing  32  can occur during take-off as described herein. It is also contemplated that the exchange of heat between the fluid and the annular casing can result in cooling the annular casing  32 . By way of non-limiting example the cooling of the annular casing can occur during take-off as described herein. 
       FIG. 6  is a flow chart for the clearance control system  100  that utilizes the distribution manifold  50  as described herein. Bypass airflow (Ab) can pass through a heat exchanger  90 , which can be a fan stream heat exchanger or surface cooler, oil or fuel heat exchanger, or other dedicated bus fluid cooling system. By way of non-limiting example the heat exchanger  90  can be proximate the exit guide vane  54  downstream of the fan assembly  12  in  FIG. 1 . Thermal control fluid  46 , which can be by way of non-limiting example the bypass airflow (Ab) or a liquid fluid cooled by the bypass airflow (Ab), is then introduced to the distribution manifold  50  as a cooling fluid (C) to cool the annular casing  32  during a stage of operation where cooling is necessary as discussed herein. The cooling fluid (C) can be returned via a valve  44  to the heat exchanger  90 . It should be understood that cooling fluid (C) will be warmed within the distribution manifold  50  and is returned as heated fluid (H). 
     It is contemplated that the heated fluid (H) can pass through a second heat exchanger  92 , by way of non-limiting example a waste heat recovery, system air pre-cooler, oil or fuel heat exchanger, or other dedicated bus fluid heating system. By way of non-limiting example the heat exchanger  92  is located proximate the engine exhaust  37  downstream with respect to the core airflow (Ac) in the low pressure turbine  24  in  FIG. 1 . Thermal control fluid  46 , which can be by way of non-limiting example the core airflow (Ac) or a fluid heated by the core airflow (Ac), is then introduced to the distribution manifold  50  as a heating fluid (H) to heat the annular casing  32  during a stage of operation where heating is necessary as discussed herein. The heating fluid (H) can be returned via a valve  44  to the heat exchanger  92 . It should be understood that heating fluid (H) will be cooled within the distribution manifold  50  and is returned as cooled fluid (C). 
     Benefits associated with the disclosure as discussed herein include heating/cooling the annular casing from within an exterior wall of the annular casing. Specifically the thermal control fluid can flow directly through the casing all the way to the root of the flange resulting in better clearance control. Controlling the clearance gap between the casing and the blades is important for engine performance. Minimizing the clearance is the best for performance, and controlling for any rubbing between the blade and the annular casing is also important for optimal performance of the turbine engine. Controlling the clearance during take-off and cruise improves the specific fuel capacity of the engine. 
     To the extent not already described, the different features and structures of the various aspects of the disclosure as described herein can be used in combination with each other as desired. That one feature is not illustrated in all of the exemplary illustrations is not meant to be construed that it cannot be, but is done for brevity of description. Thus, the various features of the different aspects of the disclosure as discussed herein can be mixed and matched as desired to form new aspects, whether or not the new aspects are expressly described. All combinations or permutations of features described herein are covered by this disclosure. 
     It should be appreciated that application of the disclosed design is not limited to turbine engines with fan and booster sections, but is applicable to turbojets and turbo engines as well. 
     This written description uses examples to describe aspects of the disclosure described herein, including the best mode, and also to enable any person skilled in the art to practice aspects of the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of aspects of the disclosure 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 have 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.