Patent Application
20190170009
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.
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.
In the drawings:
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'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.
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.
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 62a and a second supply tube 62b. The circumferential segmented portions 60 further include a collection tube 64, illustrated as a first collection tube 64a and a second collection tube 64b 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 62a and second supply tube 62b, 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 68a fluidly coupled to supply conduit 42, and a lateral, generally circumferentially oriented outlet 70 fluidly coupled to second supply tube 62b. The supply tube 62 can receive thermal control fluid 46 from supply conduit 42 via inlet 68b 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 74a fluidly coupled to the exhaust 37 and a lateral, generally circumferentially oriented inlet 76 fluidly coupled to second collection tube 64b. The collection tube 64 can exhaust thermal control fluid 46 into the exhaust 37 via outlet 74b 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
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 80a can be fluidly connected to the supply tube 62 and an outlet conduit 80b can be fluidly connected to the collection tube 64.
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 80a. The connecting conduit 80 can fluidly connect the flow conduit 78 to the collection tube 64 to define the outlet conduit 80b. The flow conduit 78 is fluidly connected to both the supply tube 62 via the inlet conduit 80a and the collection tube 64 via the outlet conduit 80b 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
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 80b, 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.
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
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.
