Abstract:
The pump includes a first rotatable member including a radially inward facing groove having an edge. The first rotatable member configured to receive a plurality of flows of fluid over the edge. The first rotatable member configured to rotate at a first angular velocity. The pump also includes a second rotatable member including a collector configured to rotate at a second angular velocity. The second rotatable member also includes a plurality of scoop tubes extending radially outwardly from the collector. Each scoop tube of the plurality of scoop tubes includes a first end coupled in flow communication to the collector and a second end including an inlet opening extending into the groove. The second end curved such that the inlet opening is open in a direction of rotation of the second rotatable member. The inlet opening configured to scoop a fluid collected in the groove.

Description:
BACKGROUND 
       [0001]    The field of the disclosure relates generally to pumping systems in a gas turbine engines and, more particularly, to a method and system for pumping oil in a gas turbine engine using a centrifugal pump. 
         [0002]    Scavenge oil, i.e., oil drained to an oil sump after lubricating bearings in gas turbine engines, is typically sent to a scavenge oil tank after lubricating the bearings. At least some known methods of transporting scavenge oil to a scavenge oil tank include a gravitational drain through a hot frame. As gas turbine engines become more powerful, the temperatures the hot frame is exposed to also increase. Transporting scavenge oil in the hot frame can cause the scavenge oil to coke because of the high temperatures the hot frame is exposed to. To reduce scavenge oil coking, cooling air is supplied to the hot frame to cool the scavenge oil as it is transported through the hot frame. Additionally, the hot frame strut thickness is increased to protect the scavenge oil drain piping. An additional cooling air system and a thicker hot frame strut adds weight to the gas turbine engine. 
       BRIEF DESCRIPTION 
       [0003]    In one aspect, a pump is provided. The pump includes a first rotatable member including a radially inward facing groove having an edge. The first rotatable member configured to receive a plurality of flows of fluid over the edge. The first rotatable member configured to rotate at a first angular velocity. The pump also includes a second rotatable member including a collector configured to rotate at a second angular velocity. The second rotatable member also includes a plurality of scoop tubes extending radially outwardly from the collector. Each scoop tube of the plurality of scoop tubes includes a first end coupled in flow communication to the collector and a second end including an inlet opening extending into the groove. The second end is curved such that the inlet opening is open in a direction of rotation of the second rotatable member. The inlet opening is configured to scoop a fluid collected in the groove. 
         [0004]    In another aspect, a method of pumping a fluid using a pump that includes a first rotatable member including a circumferential groove on a radially inner surface and a second rotatable member including one or more scoop tubes extending into the groove. The method includes receiving a flow of fluid at the first rotatable member. The first rotatable member circumscribes the second rotatable member. The method also includes centrifugally collecting the flow of fluid in a radially outer portion of the groove. The method further includes scooping a portion of the centrifugally collected fluid into the one or more scoop tubes. The method also includes channeling the scooped fluid to a fluid scavenge system. 
         [0005]    In yet another aspect, a gas turbine engine is provided. The gas turbine engine includes a high pressure power shaft rotationally coupled to a high pressure compressor and a high pressure turbine. The gas turbine engine also includes a low pressure power shaft rotationally coupled to a low pressure compressor and a low pressure turbine. The gas turbine engine further includes a pump including a first rotatable member including a radially inward facing groove having an edge. The first rotatable member configured to receive a plurality of flows of fluid over the edge. The low pressure power shaft configured to rotate the first rotatable member at a first angular velocity. The pump also includes a second rotatable member including a collector rotationally coupled to the high pressure power shaft and configured to rotate at a second angular velocity. The second rotatable member also includes a plurality of scoop tubes extending radially outwardly from the collector. Each scoop tube of the plurality of scoop tubes includes a first end coupled in flow communication to the collector and a second end including an inlet opening extending into the groove. The second end curved such that the inlet opening is open in a direction of rotation of the second rotatable member. The inlet opening is configured to scoop a fluid collected in the groove. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
           [0007]      FIGS. 1-4  show example embodiments of the method and apparatus described herein. 
           [0008]      FIG. 1  is a schematic view of a gas turbine engine. 
           [0009]      FIG. 2  is a schematic view of a low pressure turbine within a gas turbine engine. 
           [0010]      FIG. 3  is a schematic diagram of a scavenge oil pump. 
           [0011]      FIG. 4  is a schematic diagram of rotating oil groove or plenum. 
       
    
    
       [0012]    Although specific features of various embodiments may be shown in some drawings and not in others, this is for convenience only. Any feature of any drawing may be referenced and/or claimed in combination with any feature of any other drawing. 
         [0013]    Unless otherwise indicated, the drawings provided herein are meant to illustrate features of embodiments of the disclosure. These features are believed to be applicable in a wide variety of systems comprising one or more embodiments of the disclosure. As such, the drawings are not meant to include all conventional features known by those of ordinary skill in the art to be required for the practice of the embodiments disclosed herein. 
       DETAILED DESCRIPTION 
       [0014]    In the following specification and the claims, reference will be made to a number of terms, which shall be defined to have the following meanings. 
         [0015]    The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. 
         [0016]    “Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not. 
         [0017]    Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about”, “approximately”, and “substantially”, are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and/or interchanged; such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. 
         [0018]    The following detailed description illustrates embodiments of the disclosure by way of example and not by way of limitation. It is contemplated that the disclosure has general application to a method and system for circulating oil in an aircraft engine. 
         [0019]    Embodiments of the pump described herein pump scavenge oil to an turbine rear frame (TRF). The pump includes a rotating oil plenum circumscribing a rotating tube assembly. Scavenge oil drains into the rotating oil plenum which rotates to form a uniform pool of oil. Rotating tube assembly includes a plurality of scoop tubes extending into the uniform pool of oil. Rotation of rotating tube assembly channels scavenge oil into the scoop tubes. The scoop tubes channel scavenge oil axially aft to an TRF. Scavenge oil drains through the TRF to a scavenge oil system. In an exemplary embodiment, the rotating oil plenum and the rotating tube assembly rotate in opposite directions. In an alternative embodiment, the rotating oil plenum and the rotating tube assembly rotate in the same direction. In an alternative embodiment, the rotating oil plenum is configured to rotate and the rotating tube assembly is configured to remain stationary. 
         [0020]    The pumps and scavenge oil transport systems described herein offer advantages over known methods of transporting scavenge oil in a gas turbine engine. More specifically, some known methods and systems of transporting scavenge oil include transporting scavenge oil through a turbine center frame (TCF). TCFs typically operate at higher temperatures, requiring cooling air and TCF struts to prevent scavenge oil coking in the scavenge oil drain line. Draining scavenge oil through a cooler TRF removes the need for cooling air in the TCF and allows the TCF to use thinner struts. A thinner TCF strut reduces the weight of the engine and improves the performance of the engine. 
         [0021]      FIG. 1  is a schematic cross-sectional view of a gas turbine engine  110  in accordance with an exemplary embodiment of the present disclosure.  FIG. 2  is a schematic cross-sectional view of a (LP) low pressure turbine  130  within gas turbine engine  110  in accordance with an exemplary embodiment of the present disclosure. In the example embodiment, gas turbine engine  110  is a high-bypass turbofan jet engine  110 , referred to herein as “turbofan engine  110 .” As shown in  FIG. 1 , turbofan engine  110  defines an axial direction A (extending parallel to a longitudinal centerline  112  provided for reference) and a radial direction R. In general, turbofan  110  includes a fan section  114  and a core turbine engine  116  disposed downstream from fan section  114 . 
         [0022]    Exemplary core turbine engine  116  depicted generally in  FIG. 1  includes a substantially tubular outer casing  118  that defines an annular inlet  120 . Outer casing  118  and a substantially tubular inner casing  119  encases, in serial flow relationship, a compressor section including a booster or low pressure (LP) compressor  122  and a high pressure (HP) compressor  124 ; a turbine center frame (TCF)  139  and an turbine rear frame (TRF)  141 ; a combustion section  126 ; a turbine section including a high pressure (HP) turbine  128  and LP turbine  130 ; and a jet exhaust nozzle section  132 . The volume between outer casing  118  and inner casing  119  forms a plurality of cavities  121 . A high pressure (HP) shaft or spool  134  drivingly connects HP turbine  128  to HP compressor  124 . A low pressure (LP) shaft or spool  136  drivingly connects LP turbine  130  to LP compressor  122 . The compressor section, combustion section  126 , turbine section, and nozzle section  132  together define a core air flowpath  137 . 
         [0023]    Referring to  FIG. 2 , a scavenge oil pump  143  is coupled to HP shaft or spool  134  and LP shaft or spool  136 . A scavenge oil system  145  is disposed within cavity  121 . Scavenge oil pump  143  and scavenge oil system  145  are coupled in flow communication by a scavenge oil drain pipe  147 . Scavenge oil drain pipe  147  extends generally along axial direction A aft of scavenge oil pump  143  to TRF  141 . Scavenge oil drain pipe  147  extends generally along radial direction R through TRF  141  to scavenge oil system  145 . 
         [0024]    Referring back to  FIG. 1 , for the embodiment depicted, fan section  114  includes a variable pitch fan  138  having a plurality of fan blades  140  coupled to a disk  142  in a spaced apart manner. As depicted, fan blades  140  extend outwardly from disk  142  generally along radial direction R. Each fan blade  140  is rotatable relative to disk  142  about a pitch axis P by virtue of fan blades  140  being operatively coupled to a suitable pitch change mechanism  144  configured to collectively vary the pitch of fan blades  140  in unison. Fan blades  140 , disk  142 , and pitch change mechanism  144  are together rotatable about longitudinal axis  112  by LP shaft  136  across a power gear box  146 . Power gear box  146  includes a plurality of gears for adjusting the rotational speed of fan  138  relative to LP shaft  136  to a more efficient rotational fan speed. 
         [0025]    Referring still to the exemplary embodiment of  FIG. 1 , disk  142  is covered by rotatable front hub  148  aerodynamically contoured to promote an airflow through plurality of fan blades  140 . Additionally, exemplary fan section  114  includes an annular fan casing or outer nacelle  150  that circumferentially surrounds fan  138  and/or at least a portion of core turbine engine  116 . It should be appreciated that nacelle  150  may be configured to be supported relative to core turbine engine  116  by a plurality of circumferentially-spaced outlet guide vanes  152 . In the exemplary embodiment, outlet guide vanes  152  include engine oil heat exchangers. Moreover, a downstream section  154  of nacelle  150  may extend over an outer portion of core turbine engine  116  so as to define a bypass airflow passage  156  therebetween. 
         [0026]    During operation of turbofan engine  110 , a volume of air  158  enters turbofan  110  through an associated inlet  160  of nacelle  150  and/or fan section  114 . As volume of air  158  passes across fan blades  140 , a first portion of air  158  as indicated by arrows  162  is directed or routed into bypass airflow passage  156  and a second portion of air  158  as indicated by arrow  164  is directed or routed into core air flowpath  137 , or more specifically into LP compressor  122 . The ratio between first portion of air  162  and second portion of air  164  is commonly known as a bypass ratio. The pressure of second portion of air  164  is then increased as it is routed through HP compressor  124  and into combustion section  126 , where it is mixed with fuel and burned to provide combustion gases  166 . 
         [0027]    Combustion gases  166  are routed through HP turbine  128  where a portion of thermal and/or kinetic energy from combustion gases  166  is extracted via sequential stages of HP turbine stator vanes  168  and HP turbine rotor blades  170 . HP turbine stator vanes  168  are coupled to outer casing  118 . HP turbine rotor blades  170  are coupled to HP shaft or spool  134 . Rotation of HP turbine rotor blades  170  causes HP shaft or spool  134  to rotate, thereby supporting operation of HP compressor  124 . Combustion gases  166  are then routed through LP turbine  130  where a second portion of thermal and kinetic energy is extracted from combustion gases  166  via sequential stages of LP turbine stator vanes  172  and LP turbine rotor blades  174 . LP turbine stator vanes  172  are coupled to outer casing  118 . LP turbine rotor blades  174  are coupled to LP shaft or spool  136 . Rotation of LP turbine rotor blades  174  causes LP shaft or spool  136  to rotate, thereby supporting operation of LP compressor  122  and/or rotation of fan  138 . 
         [0028]    Referring to  FIG. 2 , Oil lubricates components of gas turbine engine  110 . Scavenge oil collects in sumps and drains to scavenge oil pump  143 . Scavenge oil pump  143  channels a plurality of flows of scavenge oil to scavenge oil drain pipe  147  which channels scavenge oil to scavenge oil system  145 . 
         [0029]    Referring back to  FIG. 1 , Combustion gases  166  are subsequently routed through jet exhaust nozzle section  132  of core turbine engine  116  to provide propulsive thrust. Simultaneously, the pressure of first portion of air  162  is substantially increased as first portion of air  162  is routed through bypass airflow passage  156  before it is exhausted from a fan nozzle exhaust section  176  of turbofan  110 , also providing propulsive thrust. HP turbine  128 , LP turbine  130 , and jet exhaust nozzle section  132  at least partially define a hot gas path  178  for routing combustion gases  166  through core turbine engine  116 . 
         [0030]    It should be appreciated, however, that exemplary turbofan engine  110  depicted in  FIG. 1  and  FIG. 2  is by way of example only, and that in other exemplary embodiments, turbofan engine  110  may have any other suitable configuration. It should also be appreciated, that in still other exemplary embodiments, aspects of the present disclosure may be incorporated into any other suitable gas turbine engine. For example, in other exemplary embodiments, aspects of the present disclosure may be incorporated into, e.g., a turboprop engine. 
         [0031]      FIG. 3  is a schematic diagram of scavenge oil pump  143 . Scavenge oil pump  143  includes a rotating oil groove or plenum  302  circumscribing a rotating scoop tube assembly  304 .  FIG. 4  is a schematic diagram of rotating oil groove or plenum  302 . Rotating oil plenum  302  includes a cylinder  306  and two side walls  308  coupled to and extending generally along radial direction R inward from each end of cylinder  306  forming a U-shaped plenum  310  to contain a uniform pool of oil  312 . Rotating oil plenum  302  is rotationally coupled to LP shaft or spool  136 . Rotating scoop tube assembly  304  includes a plurality of scoop tubes  314  extending generally along radial direction R outward from centerline  112  into uniform pool of oil  312 . Scoop tubes  314  are coupled in flow communication with stationary scavenge oil drain pipe  147  at the bottom of the sump. Rotating scoop tube assembly  304  is rotationally coupled to HP shaft or spool  134 . 
         [0032]    During operation of scavenge oil pump  143 , scavenge oil collects in sumps and drains into rotating oil plenum  302 . LP shaft or spool  136  rotates rotating oil plenum  302  with a first angular velocity as indicated by arrow  316 . Centrifugal force from rotation of rotating oil plenum  302  forms drained scavenges oil into uniform pool of oil  312 . HP shaft or spool  134  rotates rotating scoop tube assembly  304  with a second angular velocity as indicated by arrow  318 . First angular velocity  316  rotates in an opposite direction from second angular velocity  318  because HP shaft or spool  134  rotates counter to LP shaft or spool  136 . Scavenge oil is channeled into scoop tubes  314  which channels scavenge oil into stationary scavenge oil drain pipe  147  as indicated by arrows  320 . Scavenge oil drain pipe  147  channels oil to scavenge oil system  145  located at the bottom of gas turbine engine  110  (shown in  FIG. 1 ). 
         [0033]    In an alternative embodiment, rotating oil plenum  302  and rotating scoop tube assembly  304  are configured to rotate in the same direction rather than opposite directions. Rotating oil plenum  302  rotates in the direction of a third angular velocity as indicated by arrow  322 . The rotational direction of second angular velocity  318  and third angular velocity  322  are equal. However, the magnitude of rotational speed of second angular velocity  318  and third angular velocity  322  are unequal to channel scavenge oil into scoop tubes  314 . 
         [0034]    In an alternative embodiment, rotating oil plenum  302  is configured to rotate and rotating scoop tube assembly  304  is configured to remain stationary. Rotating oil plenum  302  rotates in the direction of first angular velocity  316 . Rotation of rotating oil plenum  302  channels scavenge oil into scoop tubes  314 . 
         [0035]    The above-described pump provides an efficient method for transporting scavenge oil in a gas turbine engine. Specifically, the above-described pump pumps scavenge oil to an inner radius of a gas turbine engine. Scavenge oil is channeled aft to a TRF which experiences cooler operating temperatures than TCFs. Channeling scavenge oil through a TRF allows reduction of the thickness of the TFC. Reduced TFC strut thickness reduces the weight of the gas turbine engine. As such, channeling scavenge oil through a TRF improves the performance of the gas turbine engine. Additionally, channeling scavenge oil through a TRF eliminates the need for cooling air in the TFC to reduce scavenge oil coking. 
         [0036]    Exemplary embodiments of a pump for scavenge oil are described above in detail. The pump, and methods of operating such systems and devices are not limited to the specific embodiments described herein, but rather, components of systems and/or steps of the methods may be utilized independently and separately from other components and/or steps described herein. For example, the methods may also be used in combination with other systems requiring scavenge oil pumping, and are not limited to practice with only the systems and methods as described herein. Rather, the exemplary embodiment can be implemented and utilized in connection with many other machinery applications that are currently configured to receive and accept pumps. 
         [0037]    Example methods and apparatus for a pump in a gas turbine engine are described above in detail. The apparatus illustrated is not limited to the specific embodiments described herein, but rather, components of each may be utilized independently and separately from other components described herein. Each system component can also be used in combination with other system components. 
         [0038]    This written description uses examples to describe the disclosure, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope 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.