Abstract:
An inlet tube supplies fuel to a manifold of a combustor in a gas turbine engine, the manifold defining a manifold plane. The inlet tube comprises a tube body having a channel providing fluid flow communication between first and second ends of the tube body. At least a portion of the channel defines a tube body plane which is spaced apart from the manifold plane.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application is a continuation of U.S. patent application Ser. No. 10/764,578 filed Jan. 27, 2004, the entire content of which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to gas turbine engines, and most particularly to fuel distribution to combustors of such engines.  
       BACKGROUND OF THE INVENTION  
       [0003]     In a gas turbine engine, fuel is generally supplied to a combustor through a plurality of fuel nozzles in fluid communication with a fuel manifold. The fuel manifold receives fuel from one or more fuel inlet tubes.  
         [0004]     Known inlet tubes generally have a single channel or two concentric channels, and the fuel is fed axially in each channel. The pressure of the axially fed fuel creates a considerable force along the axial direction of the tube which acts on the fuel manifold. This force is transferred to the support structure of the manifold, as well as the joints between the inlet tubes and the manifold, which can lead to a premature rupture thereof.  
         [0005]     Since the combustor operates at high temperatures, engine fuel system components must be adequately protected against heat damage. Heat shields are often provided on the inlet tubes for such protection. However, heat shields can represent a significant weight increase for the fuel system.  
         [0006]     Because of these high temperatures, a fuel leak could result in a fire. Thus, it is desirable that the fuel system be leak proof, and include a safe way to dispose of leaked fuel should a leak occur. A double walled construction is often used on inlet tubes and other conduits in order to provide an annular passageway for leaked fuel. Such a construction can also significantly increase the weight of the fuel system.  
         [0007]     Accordingly, there is a need for a heat shielded fuel inlet tube that can provide for adequate disposition of leaked fuel while having a minimal weight.  
         [0008]     There is also a need for a fuel inlet tube that can reduce the force transmitted along the axial direction of the tube to the manifold by fuel pressure.  
       SUMMARY OF INVENTION  
       [0009]     It is therefore an aim of the present invention to provide an improved fuel inlet conduit.  
         [0010]     Therefore, in accordance with the present invention, there is provided an inlet tube for supplying fuel to a manifold of a combustor in a gas turbine engine, the inlet tube comprising a tube body, a longitudinal primary channel defined in the tube body, the primary channel having first and second ends, the second end being in fluid communication with the manifold, and a side inlet defined in an outer surface of the tube body and being in fluid communication with the first end of the primary channel, such that fuel entering the side inlet is delivered in the primary channel with a fuel pressure being generally directed along a radial axis of the tube body, whereby the fuel enters the side inlet and travels through the primary channel to the manifold.  
         [0011]     Also in accordance with the present invention, there is provided an inlet tube for supplying fuel to a manifold of a combustor in a gas turbine engine, the inlet tube comprising a tube body, a heat shield surrounding at least part of the tube body such as to protect the at least part of the tube body from heat damage, a chamber defined by a free space between the heat shield and the tube body, the chamber being in fluid communication with potential fuel leak sources in the tube body, a drain channel defined in the tube body and having first and second ends, the first end being in fluid communication with the chamber such that any liquid contained in the chamber is directed in the drain channel, and a drain hole defined in an outer surface of the tube body remote from the at least part of the tube body surrounded by the heat shield and in fluid communication with the second end of the drain channel, such that any liquid contained in the drain channel is directed out of the tube body through the drain hole, whereby a fuel leak from any of the potential leak sources produces fuel which is received in the chamber and directed out of the tube body through the drain channel and the drain hole, such that the fuel coming out of the drain hole is safely disposed of and easily noticeable to allow detection of the leak.  
         [0012]     Further in accordance with the present invention, there is provided a method for feeding fuel to a manifold of a combustor in a gas turbine engine, the method comprising the steps of providing a fuel inlet tube defining a primary channel in fluid communication with the manifold, and feeding fuel under pressure in the primary channel through a side inlet defined in an outer surface of the fuel inlet tube in order to generally direct a pressure force produced by the fuel along a radial axis of the fuel inlet tube.  
         [0013]     Further in accordance with the present invention, there is also provided a method for detecting a leak in an inlet tube supplying fuel to a manifold in a gas turbine engine, the method comprising the steps of providing a heat shield surrounding at least part of the inlet tube so as to protect the at least part of the inlet tube from heat, a free space between the heat shield and the inlet tube forming a chamber in fluid communication with a leak source, receiving fuel coming from the leak source in the chamber, directing the fuel from the chamber out of the inlet tube through a drain channel defining a drain hole in an outer surface of the inlet tube, and detecting the fuel coming out of the drain hole.  
         [0014]     Further yet in accordance with the present invention, there is provided an inlet tube for supplying fuel to a manifold of a combustor in a gas turbine engine, the inlet tube comprising a tube body, channel means defined in the tube body, the channel means being in fluid communication with the manifold, and side inlet means defined in an outer surface of the tube body and in fluid communication with the channel means, such that fuel entering the side inlet means is delivered to the channel means with a fuel pressure generally directed along a radial axis of the tube body, whereby the fuel enters the side inlet means and travels through the channel means to the manifold.  
         [0015]     Further yet in accordance with the present invention, there is also provided an inlet tube for supplying fuel to a manifold of a combustor in a gas turbine engine, the inlet tube comprising a tube body, heat protecting means surrounding at least part of the tube body, a chamber defined by a free space between the heat protecting means and the tube body, the chamber being in fluid communication with potential fuel leak sources in the tube body, and drain means in fluid communication with the chamber such that any liquid contained in the chamber is directed out of the tube body through the drain means, whereby a fuel leak from any of the potential leak sources produces fuel which is received in the chamber and directed out of the tube body through the drain means, such that the fuel coming out of the drain means is safely disposed of and easily noticeable to allow detection of the leak.  
         [0016]     There is provided, in accordance with an aspect of the present invention, an inlet tube for supplying fuel to a fuel manifold in a gas turbine engine, the fuel manifold lying in a plane substantially perpendicular to a central axis of the fuel manifold, the inlet tube comprising: a tube body defining a central axis extending between an inlet of the tube body and an outlet of the tube body; at least one fuel channel defined through the tube body between said inlet and said outlet, the outlet of the fuel channel being in fluid communication with the manifold; and at least a portion of the tube body being offset from said plane.  
         [0017]     There is also provided, in accordance with another aspect of the present invention, an inlet tube for supplying fuel to a manifold of a combustor in a gas turbine engine, the manifold defining a manifold plane, the inlet tube comprising: a tube body having a channel providing fluid flow communication between first and second ends of the tube body, the channel defining a channel axis extending between said first and second ends, at least a portion of the channel axis defining a tube body plane which is spaced apart from the manifold plane.  
         [0018]     There is further provided, in accordance with another aspect of the present invention, an inlet tube for supplying fuel to a manifold of a combustor in a gas turbine engine, the manifold defining a manifold plane, the inlet tube comprising a tube body having means for providing fluid flow communication between first and second ends of the tube body, and means for offsetting at least a portion of the tube body from the manifold plane.  
         [0019]     There is further provided, in accordance with another aspect of the present invention, a fuel manifold assembly for a combustor in a gas turbine engine, the fuel manifold assembly comprising: an internal fuel manifold ring having at least one fuel flow passage, the internal fuel manifold ring defining a manifold plane substantially perpendicular to a central manifold axis; and an inlet tube having a tube body extending between an inlet and an outlet, the outlet being engaged with the internal fuel manifold ring and being in fluid flow communication with said fuel flow passage, at least a portion of the tube body defining a tube body plane which is spaced apart from the manifold plane. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]     Having thus generally described the nature of the invention, reference will now be made to the accompanying drawings, showing by way of illustration a preferred embodiment thereof and in which:  
         [0021]      FIG. 1  is a side view of a gas turbine engine, in partial cross-section, exemplary of an embodiment of the present invention;  
         [0022]      FIG. 2  is a side view of a fuel inlet tube equipped with a heat shield, exemplary of a preferred embodiment of the present invention;  
         [0023]      FIG. 3  is a side view of the fuel inlet tube of  FIG. 2  with the heat shield removed;  
         [0024]      FIG. 4  is a front view, in cross-section, of the fuel inlet tube of  FIG. 2  connected to a fuel manifold; and  
         [0025]      FIG. 5  is a side view, in cross-section, of the fuel inlet tube and fuel manifold of  FIG. 4 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]      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 multistage compressor  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.  
         [0027]     Referring to  FIGS. 4-5 , a fuel inlet tube generally indicated at  20  has a distal end  26  and a proximal end  27 . The distal end  26  is connected to a fuel manifold  21  which usually surrounds the combustor  16  and delivers fuel to a plurality of fuel nozzles located within the combustor. The inlet tube  20  preferably comprises a primary channel  22  and a secondary channel  23 , both channels being axially defined in the tube and being located side by side. In the present text, the terms “axial” and “radial” are defined relative to the inlet tube  20  and correspond, respectively, to the directions indicated by arrows A and R in  FIG. 4 . The channels  22 , 23  are in fluid communication with the manifold  21 . The inlet tube  20  is covered by a heat shield  24  at the distal end  26 , the heat shield  24  being in contact with the manifold  21  in order to protect the inlet tube  20  against heat damage. The inlet tube  20  can include a bend  25 , which is defined along an axis perpendicular to a plane including the axes of both channels  22 , 23 , in order to compensate for an offset between the fuel manifold and the fuel source without compromising a fuel flow in the channels  22 , 23 . Such a bend eliminates the need for a multi-piece assembly and thus reduces the need for weld or braze during assembly.  
         [0028]     Referring to FIGS.  2  to  5 , two circumferential grooves  30 , 32  are defined in the inlet tube  20  near the proximal end  27 . Into the upper circumferential groove  30  is defined a first side feed inlet  34  which is in fluid communication with the secondary channel  23 . Similarly, a second side feed inlet  36  is defined in the lower circumferential groove  32  and is in fluid communication with the primary channel  22 . When the tube  20  is installed in the engine casing, a mating part (not shown) will close the grooves  30 , 32 , thereby forming circumferential channels. Sealing the two grooves  30 , 32  are a series of o-rings (not shown) seated in grooves  38 .  
         [0029]     Referring to  FIGS. 4-5 , a free space between the heat shield  24  and the tube  20  defines a chamber  48 . The chamber  48  is adapted to receive fuel which might leak from the joint between the inlet tube  20  and the manifold  21 . A drain channel  50  is provided in the inlet tube  20  and is in fluid communication with the chamber  48 . The drain channel  50  reaches the outer surface of the inlet tube  20 , defining therein a drain hole  52 . The chamber  48 , drain channel  50  and drain hole  52  form a drain system effectively directing leaked fuel along a determined leak path directing the fuel overboard.  
         [0030]     In operation, fuel is injected in the grooves  30 , 32  and enters the channels  22 , 23  through the side feed inlets  34 , 36 . The side feed inlets  34 , 36  allow the pressure of the injected fuel to be generally directed in a radial direction, thereby reducing the axial force produced by the fuel pressure. This reduces the axial force acting on the manifold  21 . The fuel then travels through the channels  22 , 23  and enters the manifold  21  to be delivered to fuel nozzles.  
         [0031]     If a leak happens at the joint between the inlet tube  20  and the manifold  21 , the leaked fuel is received in the chamber  48 . The leaked fuel is then evacuated overboard through the drain channel  50  and drain hole  52 , where it is safely disposed of and can be easily noticed. The drain system therefore provides for ready leak detection without the need to disassemble the inlet tube  20 .  
         [0032]     The inlet tube  20  is preferably manufactured by turning, then drilling of the channels, and finally bending of the tube if required.  
         [0033]     The present invention therefore provides for a reduction of the axial force reacting on the manifold, thus reducing the wear of the manifold and its supporting means which increases their useful life. The present invention also provides for a heat shield that ensures protection from heat damage as well as fuel leakage control, combining two functions in one component and thus reducing the weight of the fuel inlet tube.  
         [0034]     Although a preferred embodiment of the invention includes both primary and secondary channels  22 , 23 , it is also contemplated to provide an inlet tube  20  having a single channel with a side feed inlet, or any other number of similar channels.  
         [0035]     The embodiments of the invention described above are intended to be exemplary. Those skilled in the art will therefore appreciate that the forgoing description is illustrative only, and that various alternatives and modifications can be devised without departing from the spirit of the present invention. Accordingly, the present is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.