Abstract:
A fluid delivery assembly for delivering fluid to a component in a gas turbine engine includes a rotating shaft having a central bore and at least one fluid exhaust in communication with the central bore for centrifugally expelling fluid, and a delivery scoop disposed around the rotating shaft and spaced apart from the rotating shaft by an annular gap. The delivery scoop includes an annular body having at least one impingement surface facing the at least one fluid exhaust and configured to scoop the fluid expelled by the at least one fluid exhaust. The impingement surface has at least one outlet for delivering the scooped fluid to the component. A method of delivering pressurised fluid in a fluid system is also presented.

Description:
TECHNICAL FIELD 
     The application relates generally to gas turbine engines and, more particularly, to fluid delivery systems. 
     BACKGROUND 
     Various parts of gas turbine engines are lubricated using a stream of lubricant fluid. The fluid has to be routed up to the very location where the lubrication or feeding is needed. For example, when feeding bearing gaps, also known as bearing dampers, a complex routing of dedicated oil feed line through the gaspath may be needed to reach the delivery point. Besides the complexity of the routing, and its associated weight, the oil feed line is disposed in the gaspath, which may bring the oil at relatively high temperatures and which may in turn cause coking. 
     SUMMARY 
     In one aspect, there is provided an oil scoop to be disposed around a rotating shaft of a gas turbine engine and adapted to receive centrifugally expelled fluid from the rotating shaft, the delivery scoop comprising: an annular body having a generally U-shape cross-section, an inner surface of the annular body including a plurality of circumferentially disposed impingement surfaces circumferentially separated by a plurality of vanes extending radially inwardly from the annular body, a plurality of independent fluid channels being defined by adjacent vanes and the impingement surfaces disposed between the adjacent vanes, the independent fluid channels having corresponding slot outlets defined in an axial end wall of the annular body, the axial end wall closing otherwise the independent fluid channels. 
     In another aspect, there is provided a fluid delivery assembly for delivering fluid to a component in a gas turbine engine, the fluid delivery assembly comprising: a rotating shaft having a central bore and at least one fluid exhaust in communication with the central bore for centrifugally expelling fluid; and a delivery scoop disposed around the rotating shaft and spaced apart from the rotating shaft by an annular gap, the delivery scoop including an annular body having at least one impingement surface facing the at least one fluid exhaust and configured to scoop the fluid expelled by the at least one fluid exhaust, the impingement surface having at least one outlet for delivering the scooped fluid to the component. 
     In yet another aspect, there is provided a method of delivering pressurised fluid in a fluid system, the method comprising: centrifugally expelling fluid from a central bore of a rotating shaft; scooping the fluid with a delivery scoop located about the rotating shaft such that the fluid conserves at least partially its kinetic energy; and directing the fluid with its kinetic energy to a component adjacent to an outlet of the delivery scoop. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       Reference is now made to the accompanying figures in which: 
         FIG. 1  is a schematic cross-sectional view of a gas turbine engine; 
         FIG. 2  is a schematic cross-sectional view of a shaft, bearing and associated bearing damper fluid delivery system; 
         FIG. 3  is a schematic cross-sectional view of the shaft, bearing and associated bearing damper fluid delivery system taken along line  3 - 3  in  FIG. 2 ; and 
         FIG. 4  is a schematic perspective view of a scoop for the damper fluid delivery system. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a gas turbine engine  10  of a type preferably provided for use in subsonic flight, generally comprising in serial flow communication a fan  12  through which ambient air is propelled, a compressor section  14  for pressurizing the air, a combustor  16  in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, and a turbine section  18  for extracting energy from the combustion gases. The engine  10  includes at least one bearing  20  disposed around a shaft  22 . The bearing  20  is here shown around the power shaft  22  of the engine  10  for illustration purposes, but it is contemplated that the bearing  20  could be disposed around any other rotating shaft of the engine  10 . 
     Turning to  FIG. 2 , the shaft  22  defines an axial direction A and a radial direction R. The shaft  22  is hollow and includes a central bore  24 . The central bore  24  is adapted to receive a flow of fluid, e.g. lubricant, illustrated by arrow  26 . An end  28  of the bore  24  may include a dam  30  to prevent or reduce back flow of the fluid. Another end  32  of the bore  24  may be closed. The shaft  22  includes a plurality of fluid exhaust or nozzles  34  distributed circumferentially (circumferential direction C shown in  FIG. 3 ) and in communication with the central bore  24 . In this example, the shaft  22  includes three nozzles  34 , but it is contemplated that the shaft  22  could include any number of nozzles  34  that is one or more. A number of nozzles  34  may be selected in accordance with a flow rate of fluid to carry. The nozzles  34  extend through the shaft  22 , bringing in fluid communication the bore  24  with an outside of the shaft  22 . The nozzles  34  may be simply shaped as cylindrical openings in the shaft  22 . The nozzles  34  deviate a portion of the fluid from the bore  24  to the outside of the shaft  22 . When the shaft  22  rotates, centrifugal forces tend to dispose the oil  26  towards walls of the bore  24 , and as a result to flow through the nozzles  34 , as illustrated by arrow  40 . Given the radial orientation of the nozzles  34 , the flow of oil exiting the nozzles  34  is, in the illustrated embodiment, radial. In this example, the nozzles  34  are equidistantly circumferentially disposed (as best shown in  FIG. 3 ), although the spacing between the nozzles  34  may be other than equidistant. In the embodiment shown in the figures, the nozzles  34  are radially oriented, meaning that they are perpendicular relative to the shaft  22 . It is however contemplated that the nozzles  34  could be at an angle in axial and/or circumferential direction other than 90 degrees relative to the shaft  22 . For example, the nozzles  34  could be at 110 degrees or 80 degrees relative to the shaft  22  depending on the desired fluid path. The nozzles  34  are shown herein to be straight, but it is contemplated that the nozzles  34  could be curved, and have varying diameter, so as to deliver oil in a desired trajectory based on the fluid delivery target. 
     A delivery scoop  50  (also known as an oil scoop) is disposed around the shaft  22  and in alignment with the nozzles  34 . The delivery scoop  50  is configured to recover oil jet momentum from the oil expelled from the nozzles  34 , and deliver the oil to a feature that need pressurized oil, such as a reservoir of a bearing damper. The delivery scoop  50  is designed to scoop or channel the fluid, thereby conserving at least partially a kinetic energy of the oil. In one embodiment, delivery scoop  50  also assists in converting the oil&#39;s kinetic energy into static pressure, by enabling the delivery of pressurized oil to a target having a closed cavity (e.g. bearing damper), in such a way that oil pressure builds up at the target. In one embodiment, the delivery scoop  50  redirects (i.e. changes a direction of) the jet of pressurised oil  40  to the target. In the particular embodiment shown in the figures, the delivery scoop  50  redirects the radial jet  40  of fluid to a generally axial direction (see arrow  41 ) toward an axially elongated bearing gap, or damper,  51  disposed between the bearing  20  and a bearing support  53 . It is contemplated that various orientations and fluid delivery targets could be associated with the delivery scoop  50 . To redirect the jet of oil  40 , the delivery scoop  50  includes one or more impingement surface(s)  52  whose shape determines a deviation of the jet of pressurised oil  40  from its trajectory. 
     In one embodiment, the delivery scoop  50  is connected to the bearing support  53  at support outer race  20   b  of the bearing  20 , the shaft  22  being connected to an inner race  20   a  of the bearing  20 . An annular radial gap  49  is defined by a free space between the shaft  22  and the delivery scoop  50  and spans at least a portion of the bearing  20 . A retaining ring  56  ensures a tight fit between the delivery scoop  50  and the outer race  20   b.  It is contemplated that the delivery scoop  50  could be secured to the outer race  20   b  and/or bearing support  53  by other ways than a tight fit or abutment. For example, it could be fastened to the outer race  20   b  and/or bearing support  53 . The delivery scoop  50  could also be connected to a static portion of the engine  10 , other than the bearing  20  and/or bearing support  53 . It is also contemplated that the delivery scoop  50  could be connected to a rotating portion of the gas turbine engine  10 . For example, should the outer race  20   b  of the bearing  20  be rotating (for example, an inter-shaft bearing which is not the case in the illustrated example), the delivery scoop  50  would be rotating. The delivery scoop  50  could be rotating in a direction of rotation of the shaft  22  or in a direction opposite to a rotation of the shaft  22 . 
     Referring additionally to  FIG. 4 , the delivery scoop  50  includes an annular or body  60  having a generally U-shaped cross-sectional shape. In one embodiment, the annular body  60  is made of metal or a composite. The annular body  60  has a general U-shaped cross-section formed by a generally L-shaped annular wall  61   a  at one axial end, and a facing annular end wall  61   b  at another axial end. A radial inner end  59  of the annular body  60  is open to reveal the impingement surface  52  of the generally L-shaped wall  61   a.  The impingement surface  52  extends circumferentially, and is shaped and oriented such that the jet  40  of oil impacting it is redirected axially (see arrow  41 ). In one embodiment, the impingement surface  52  is curved, or may have any other shape so as to direct oil to its desired destination, with other cross-sectional profiles being considered including a sloped cross-sectional profile, a parabolic profile, etc. Having a curved impingement surface  52  may minimize kinetic energy loss. The impingement surface  52  includes a first end  52   a  generally radially aligned and a second end  52   b  at an angle relative to the first end  52   a.  In one embodiment, the second end  52   b  is generally axially aligned. 
     The annular body  60  may include outlets in the shape of a plurality of arcuate slots  64  formed in the end wall  61   b  of the annular body  60 . The slots  64  are adjacent to the second end  52   b  of the impingement surface  52 , and are adjacent to the damper  51 . The redirected axial jet  41  exits the delivery scoop  50  via a plurality of slots  64  into the damper  51 . It is contemplated that the plurality of slots  64  and the end wall  61   b  could be omitted. It is also contemplated that the slots  64  could be flat, or be shaped as openings (e.g. round openings). It could also be one continuous circumferential slot. 
     The delivery scoop  50  may include a plurality of radially inwardly (i.e. toward the shaft  22 ) extending curved walls, or vanes  66  creating fluidly independent channels  67 . The vanes  66  fraction the impingement surface  52  into a plurality of impingement surfaces  53 , each associated with one of the slots  64 . The channels  67  are defined by the fractionned impingement surfaces  53  and their associated adjacent vanes  66 . The slots  64  are outlets of the channels  67 . The vanes  66  are axially aligned with the nozzles  34 . The vanes  66  may be angled to help redirect the radial jet  40  of oil toward the slots  64 , as the shaft  22  and the nozzles  34  rotate, and thereby keeping the jet  40  pressurized. In the example shown in the figures, the delivery scoop  50  includes six vanes  66 , but it is contemplated that the delivery scoop  50  could include more or less than six vanes  66 . The delivery scoop  50  could also have no vanes, in cases for example where pressurization of the oil may not be a constraint. The number of vanes  66  may vary as a function of a number of rotating nozzles  34  and targeted oil pressure. 
     The delivery scoop described above may allow delivering pressurized oil from a rotating shaft cavity to axially oriented elements, such as bearing dampers. Bearing dampers are conventionally dead-ended and form a receptacle for oil, whereby the delivery scoop may assist in building a static oil pressure in the damper bearing. A similar approach may be used with other components which are also dead-ended, or with throat portions limiting the exit of oil. The scoop may also be shaped to redirect to directions other than axially. The scoop may be configured to recover oil jet momentum and deliver oil axially into dampers or any other features that need pressurized oil. The above described scoop may avoid complex fluid paths to reach the delivery point, and may be retrofitted in existing shafts and bearing assemblies. In one embodiment, the scoop may take advantage of existing under race bearing oil feed system to also feed the bearing damper, thus eliminating the external oil feed line. The delivery scoop may be stationary as shown in the figures or placed on a counter-rotating or co-rotating shaft surrounding the shaft having the fluid exhaust. 
     The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. Other modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims.