Abstract:
Aspects of the disclosure are directed to a tube assembly comprising: a first tube having a radial exterior surface, a second tube composed of a plurality of segments, the first tube co-axially nested within the second tube, at least a first spacer coupled to the first tube, and a second spacer coupled to the at least a first spacer, where a first segment of the plurality of segments is coupled to a first axial end of the second spacer, and a second segment of the plurality of segments is coupled to a second axial end of the second spacer.

Description:
BACKGROUND 
       [0001]    Gas turbine engines, such as those which power aircraft and industrial equipment, employ a compressor to compress air that is drawn into the engine and a turbine to capture energy associated with the combustion of a fuel-air mixture. One or more fluids are typically circulated throughout the engine. For example, oil may be supplied to one or more bearings in order to clean, cool, and lubricate the bearings. 
         [0002]    Referring to  FIG. 2A , the fluids are typically conveyed from a fluid source (e.g., an oil tank)  202  to the intended destination (e.g., the bearings or an associated bearing compartment)  206  by a supply tube  210 . The fluid is then returned from the destination  206  to the source  202  by a return tube  214 . In this manner, a closed-loop system  200  is established. There may be other components included; the system  200  is simplified for the sake of illustrative convenience. These other components may include additional tubes beyond the tubes  210  and  214 . 
         [0003]    Referring to  FIG. 2B , in order to enhance reliability and avoid a leak impacting the performance/operability of the engine, the tubes (e.g., the tube  210  or the tube  214 ) may be manufactured as a double walled tube, where the fluid is intended to be conveyed by a first tube  232 . A second tube  236  serves to contain any fluid that may leak from the first tube  232 . The double walled tube arrangement shown in  FIG. 2B  is frequently referred to as a “tube within a tube” as the tube  236  has a larger dimension/diameter than the tube  232  and the tube  232  is contained/nested within the tube  236 . In this respect, the tube  232  is an inner tube relative to the outer tube  236 . 
         [0004]    Referring to  FIG. 2C , a system  250  is shown. The system  250  is shown as including five tube assemblies, denoted as assemblies  251 ,  252 ,  253 ,  254 , and  255  (it is noted that the assemblies  252  and  253  may be implemented as a single assembly, resulting in four tube assemblies in  FIG. 2C ; for purposes of this disclosure, this distinction is of no import and is ignored going forward). Each of the assemblies  251 - 255  may correspond to a double walled arrangement as shown in  FIG. 2B . 
         [0005]    As shown in  FIG. 2C , the assemblies  251 - 255  are separated from one another by hardware  261 ,  262 ,  263 , and  264 . The hardware  261 - 264  may support the assemblies  251 - 255  and provide a location for clamping the tube assembly and mounting the tube assembly to an engine structure (e.g., an engine case). The use of the hardware  261 - 264  represents a penalty/cost in terms of weight and complexity. The hardware  261 - 264  can also weaken/compromise the assemblies  251 - 255  (e.g., the tube  232  of  FIG. 2B ) at the point where the hardware interfaces to the assemblies. 
       BRIEF SUMMARY 
       [0006]    The following presents a simplified summary in order to provide a basic understanding of some aspects of the disclosure. The summary is not an extensive overview of the disclosure. It is neither intended to identify key or critical elements of the disclosure nor to delineate the scope of the disclosure. The following summary merely presents some concepts of the disclosure in a simplified form as a prelude to the description below. 
         [0007]    Aspects of the disclosure are directed to a tube assembly comprising: a first tube having a radial exterior surface, a second tube composed of a plurality of segments, the first tube co-axially nested within the second tube, at least a first spacer coupled to the first tube, and a second spacer coupled to the at least a first spacer, where a first segment of the plurality of segments is coupled to a first axial end of the second spacer, and a second segment of the plurality of segments is coupled to a second axial end of the second spacer. In some embodiments, the tube assembly further comprises an end fitting coupled to the first tube. In some embodiments, the second tube is coupled to the end fitting. In some embodiments, the tube assembly further comprises a first ferrule coupled to the first tube. In some embodiments, the tube assembly further comprises a second ferrule coupled to the second tube. In some embodiments, a third segment of the plurality of segments is coupled to the second ferrule. In some embodiments, the at least a first spacer includes a first inner spacer and a second inner spacer. In some embodiments, a first center of the first inner spacer is aligned with a second center of the second inner spacer relative to an axial length of the first tube. In some embodiments, the first center and the second center are separated from one another by approximately one-hundred eighty degrees relative to a circumference of the first tube. In some embodiments, a first structure of the first inner spacer is separated from a second structure of the second inner spacer by a non-zero value of distance. In some embodiments, the first tube is configured to convey a fluid. In some embodiments, the fluid includes at least one of oil, fuel, hydraulic fluid, or air. In some embodiments, the second tube is configured to convey a second fluid. In some embodiments, the tube assembly is mounted to an engine of an aircraft. 
         [0008]    Aspects of the disclosure are directed to a method comprising: sliding a plurality of outer tube segments onto an inner tube, using an outer spacer to separate a first and a second of the plurality of outer tube segments, attaching at least one inner spacer to the inner tube, attaching the outer spacer to the at least one inner spacer, attaching the outer spacer to the first outer tube segment, and attaching the outer spacer to the second outer tube segment. In some embodiments, the method further comprises attaching the inner tube to an end fitting. In some embodiments, the method further comprises attaching the first outer tube segment to the end fitting. In some embodiments, the method further comprises attaching an inner ferrule to the inner tube. In some embodiments, the method further comprises attaching an outer ferrule to the second outer tube segment. In some embodiments, the method further comprises attaching an outer ferrule to a third outer tube segment of the plurality of outer tube segments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The present disclosure is illustrated by way of example and not limited in the accompanying figures in which like reference numerals indicate similar elements. The drawings are not necessarily drawn to scale unless specifically indicated otherwise. 
           [0010]      FIG. 1  is a side cutaway illustration of a geared turbine engine. 
           [0011]      FIG. 2A  illustrates a prior art system for circulating a fluid. 
           [0012]      FIG. 2B  illustrates a prior art double walled tube. 
           [0013]      FIG. 2C  illustrates a prior art system incorporating tube assemblies and associated hardware. 
           [0014]      FIGS. 3A-3G  illustrate components that may be used to manufacture a tube assembly in accordance with aspects of this disclosure. 
           [0015]      FIGS. 4A-4J  illustrate a tube assembly at various stages of manufacture. 
           [0016]      FIG. 5  illustrates a flow chart of an exemplary method that may be used to manufacture a tube assembly in accordance with aspects of this disclosure. 
           [0017]      FIG. 6  illustrates a tube assembly mounted to an engine in accordance with aspects of this disclosure. 
           [0018]      FIG. 7  illustrates an inner spacer with holes defined therein to enable a passage of fluid. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    It is noted that various connections are set forth between elements in the following description and in the drawings (the contents of which are included in this disclosure by way of reference). It is noted that these connections are general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. A coupling between two or more entities may refer to a direct connection or an indirect connection. An indirect connection may incorporate one or more intervening entities. 
         [0020]    In accordance with aspects of the disclosure, apparatuses, systems, and methods are directed to a double walled arrangement for a tube assembly. The tube assembly may include a first, inner tube surrounded by a second, outer tube. The outer tube may be composed of segments; the inner tube may be a unitary tube/piece. The tube assembly may include one or more spacers to couple the inner tube and the outer tube to one another. One or more attachment techniques, such as welding or brazing for example, may be used in the manufacture of the tube assembly. 
         [0021]    Aspects of the disclosure may be applied in connection with a gas turbine engine.  FIG. 1  is a side cutaway illustration of a geared turbine engine  10 . This turbine engine  10  extends along an axial centerline  12  between an upstream airflow inlet  14  and a downstream airflow exhaust  16 . The turbine engine  10  includes a fan section  18 , a compressor section  19 , a combustor section  20  and a turbine section  21 . The compressor section  19  includes a low pressure compressor (LPC) section  19 A and a high pressure compressor (HPC) section  19 B. The turbine section  21  includes a high pressure turbine (HPT) section  21 A and a low pressure turbine (LPT) section  21 B. 
         [0022]    The engine sections  18 - 21  are arranged sequentially along the centerline  12  within an engine housing  22 . Each of the engine sections  18 - 19 B,  21 A and  21 B includes a respective rotor  24 - 28 . Each of these rotors  24 - 28  includes a plurality of rotor blades arranged circumferentially around and connected to one or more respective rotor disks. The rotor blades, for example, may be formed integral with or mechanically fastened, welded, brazed, adhered and/or otherwise attached to the respective rotor disk(s). 
         [0023]    The fan rotor  24  is connected to a gear train  30 , for example, through a fan shaft  32 . The gear train  30  and the LPC rotor  25  are connected to and driven by the LPT rotor  28  through a low speed shaft  33 . The HPC rotor  26  is connected to and driven by the HPT rotor  27  through a high speed shaft  34 . The shafts  32 - 34  are rotatably supported by a plurality of bearings  36 ; e.g., rolling element and/or thrust bearings. Each of these bearings  36  is connected to the engine housing  22  by at least one stationary structure such as, for example, an annular support strut. 
         [0024]    During operation, air enters the turbine engine  10  through the airflow inlet  14 , and is directed through the fan section  18  and into a core gas path  38  and a bypass gas path  40 . The air within the core gas path  38  may be referred to as “core air”. The air within the bypass gas path  40  may be referred to as “bypass air”. The core air is directed through the engine sections  19 - 21 , and exits the turbine engine  10  through the airflow exhaust  16  to provide forward engine thrust. Within the combustor section  20 , fuel is injected into a combustion chamber  42  and mixed with compressed core air. This fuel-core air mixture is ignited to power the turbine engine  10 . The bypass air is directed through the bypass gas path  40  and out of the turbine engine  10  through a bypass nozzle  44  to provide additional forward engine thrust. This additional forward engine thrust may account for a majority (e.g., more than 70 percent) of total engine thrust. Alternatively, at least some of the bypass air may be directed out of the turbine engine  10  through a thrust reverser to provide reverse engine thrust. 
         [0025]      FIG. 1  represents one possible configuration for an engine  10 . Aspects of the disclosure may be applied in connection with other environments, including additional configurations for gas turbine engines. Aspects of the disclosure may be applied in connection with non-geared engines. 
         [0026]    Referring to  FIGS. 3A-3G , various components used in the manufacture of a tube assembly are shown. In particular,  FIGS. 3A-3G  illustrate an end fitting  302 , an outer tube segment  308 , an inner tube  314 , a portion of a first (inner) spacer  320 , a second (outer) spacer  326 , a first (inner) ferrule  332 , and a second (outer) ferrule  338 , respectively. 
         [0027]      FIG. 4A-4J  illustrate a tube assembly at various stages of manufacture, where the tube assembly is manufactured using the components depicted in  FIGS. 3A-3G . The manufacture of the tube assembly is further described in relation to the method  500  of  FIG. 5 . 
         [0028]    In block  500 A (corresponding to  FIG. 4A ), outer tube segments  308 - 1  and  308  may be slid onto/on top of an inner tube  314 . Outer spacers  326  may be used to separate the segments  308 - 1  and  308  from one another. 
         [0029]    In block  500 B (corresponding to  FIG. 4B ), the inner tube  314  may be attached (e.g., welded) to an end fitting  302 . 
         [0030]    In block  500 C (corresponding to  FIG. 4C ), the outer tube segment  308 - 1  may be attached (e.g., welded) to the end fitting  302 . 
         [0031]    In block  500 D (corresponding to  FIG. 4D ), two inner spacers  320 - 1  and  320 - 2  may be attached (e.g., welded) to the inner tube  314 . The respective centers of the spacers  320 - 1  and  320 - 2  may be substantially aligned with one another relative to an axial length of the inner tube  314  and separated from one another by approximately one-hundred eighty degrees relative to a circumference of the inner tube  314 . The structures of the spacers  320 - 1  and  320 - 2  may be separated from one another by a distance  420 . Any non-zero value of the distance  420  may allow any fluid that escapes from/leaks out of the inner tube  314  to traverse the region between the inner pipe  314  and the outer pipe (or the outer pipe segments  308 ,  308 - 1 ,  308 - 2 : see also  FIG. 4H ). Stated slightly differently, providing for a non-zero value of the distance  420  may help to prevent a build-up of any leaking fluid at the spacers  320 - 1  and  320 - 2  by providing a path for that leaked fluid to flow. 
         [0032]    Referring to  FIG. 7 , in some embodiments a single/unitary inner spacer  320  may be used where the inner spacer  320  has one or more holes  720  through it to enable a passage of fluid therethrough. The use of the holes  720 /unitary inner spacer  320  shown in  FIG. 7  may represent an alternative to the use of the distance  420 /multiple inner spacers  320 - 1  and  320 - 2  shown in  FIG. 4D . 
         [0033]    Referring back to  FIG. 5 , in block  500 E (corresponding to  FIG. 4E ), the outer spacer  326  may be attached (e.g., welded) to the inner spacers  320 - 1  and  320 - 2 . The attachment of block  500 E may occur at the locations  424 - 1  and  424 - 2 . 
         [0034]    In block  500 F (corresponding to  FIG. 4F ), the outer spacer  326  may be attached (e.g., welded) to the outer tube segment  308 - 1 . The attachment of block  500 F may occur at the location  426 . 
         [0035]    In block  500 G (corresponding to  FIG. 4G ), the outer spacer  326  may be attached (e.g., welded) to the (next) outer tube segment  308 . The attachment of block  500 G may occur at the location  428 . 
         [0036]    Referring to  FIG. 4H , the tube assembly is shown as a result of having substantively repeated an execution of the blocks  500 D- 500 G for successive instances of the inner spacers  320 , the outer spacers  326 , and outer tube segments  308 , in relation to the inner tube  314 . In  FIG. 4H , the right-most outer-tube segment is denoted as segment  308 - 2  for purposes of further description/illustration in relation to  FIGS. 4I-4J  and blocks  500 I- 500 J below. 
         [0037]    In block  500 I (corresponding to  FIG. 4I ), an inner ferrule  332  may be attached (e.g., welded) to the inner tube  314 . 
         [0038]    In block  500 J (corresponding to  FIG. 4J ), an outer ferrule  338  may be attached (e.g., welded) to the outer tube segment  308 - 2 . 
         [0039]    The order of the blocks/operations of the method  500  shown in  FIG. 5  is illustrative. In some embodiments, one or more blocks (or one or more portions thereof) may execute in an order or sequence that is different from what is shown. One or more blocks (or one or more portions thereof) may be optional. 
         [0040]    Referring to  FIGS. 5-6 , a tube assembly  602  manufactured via the method  500  is shown in a mounted state relative to a portion of an engine  610  (where the engine  610  may correspond to the engine  10  of  FIG. 1 ). 
         [0041]    The sizes/dimensions of the various components used in the manufacture of a tube assembly may be adapted to adhere to the particular application environment (e.g., engine) that the tube assembly is to be deployed on. 
         [0042]    A tube assembly may convey one or more fluids, such as for example oil, fuel, hydraulic fluid, air, etc. The fluids may be conveyed by/within one or more of the tubes of the assembly. For example, in some embodiments a first tube may convey a first fluid and a second tube may convey a second fluid; the second fluid may be different from the first fluid. 
         [0043]    One or more materials may be used in the manufacture of a tube assembly. For example, a component of the tube assembly may include one or more of steel, nickel, titanium, or aluminum. 
         [0044]    Technical effects and benefits of this disclosure include a tube assembly that is less susceptible to leaking fluid relative to conventional tube assemblies. A tube assembly in accordance with aspects of this disclosure is also less complex, thereby reducing the manufacturing cost. A tube assembly in accordance with aspects of this disclosure is lighter than a conventional tube assembly, thereby increasing engine performance/efficiency. 
         [0045]    Aspects of the disclosure have been described in terms of illustrative embodiments thereof. Numerous other embodiments, modifications, and variations within the scope and spirit of the appended claims will occur to persons of ordinary skill in the art from a review of this disclosure. For example, one of ordinary skill in the art will appreciate that the steps described in conjunction with the illustrative figures may be performed in other than the recited order, and that one or more steps illustrated may be optional in accordance with aspects of the disclosure. One or more features described in connection with a first embodiment may be combined with one or more features of one or more additional embodiments.