Patent Publication Number: US-2023151771-A1

Title: Cooling system for tail cone mounted generator

Description:
BACKGROUND 
     Exemplary embodiments pertain to the art of aircraft and, more particularly, to a cooling system for a tail cone mounted generator in an aircraft. 
     Many modern jet aircraft include generators that are driven by a turbine engine. The generator may be operated to provide electrical power to various aircraft systems. In many cases, the generator is driven by a shaft connected to a low pressure spool of the turbine engine. In some cases, the generator may be co-located with the turbine engine in a nacelle. During operation of the turbine engine and the generator a significant heat load is generated in the nacelle. A cooling system is employed to ensure operational integrity of the generator. 
     Typically, the cooling system relies on a liquid heat exchange medium, such as water or oil, that is passed through the generator. Liquid based cooling systems typically require support systems such as reservoirs, pumps, heat exchangers and the like. Further, flowing a liquid coolant between various members of a generator may reduce operating efficiency stemming from windage losses. In addition, generators are built to contain the liquid, typically oil, without leaking. 
     BRIEF DESCRIPTION 
     Disclosed in accordance with a non-limiting example, is an engine system including an engine duct and a tail cone arranged radially inwardly of the engine duct. The tail cone has an outer surface and an inner surface. A generator housing is arranged in the tail cone. The generator housing includes an outer surface portion spaced from the inner surface of the tail cone. A generator is mounted in the generator housing. An air duct extends from the generator, through the generator housing, through the tail cone, and through the engine duct. The air duct includes an opening exposed to an air stream passing over the engine duct. 
     Additionally, or alternatively, in this or other non-limiting examples, another air duct extends from the generator, through the generator housing, through the tail cone, and through the engine housing, the another air duct including another opening exposed to an air stream passing over the engine duct. 
     Additionally, or alternatively, in this or other non-limiting examples, the air duct comprises an inlet duct for directing an air flow into the generator housing and the another air duct comprises an outlet air duct for directing the air flow out from the generator housing. 
     Additionally, or alternatively, in this or other non-limiting examples, a plenum is defined between the outer surface portion of the generator housing and the inner surface of the tail cone. 
     Additionally, or alternatively, in this or other non-limiting examples, the outlet duct is fluidically connected to the plenum. 
     Additionally, or alternatively, in this or other non-limiting examples, the generator includes a drive shaft connectable to a low pressure spool of a turbine engine, the drive shaft having a hollow interior fluidically connected to the plenum through an outlet passage. 
     Additionally, or alternatively, in this or other non-limiting examples, the opening of the air duct faces a first direction relative to the engine duct and the another opening of the another air duct faces a second direction that is distinct from the first direction. 
     Additionally, or alternatively, in this or other non-limiting examples, the first direction is directly opposite the second direction. 
     Additionally, or alternatively, in this or other non-limiting examples, a plurality of electrical conductors connected to the generator, the plurality of electrical conductors pass from the generator through the air duct. 
     Also disclosed, in accordance with a non-limiting example, is an aircraft including a fuselage, a wing supported by the fuselage, and an engine system supported by the fuselage. The engine system includes a nacelle surrounding an engine including an engine duct. A tail cone is arranged radially inwardly of the engine duct. The tail cone has an outer surface and an inner surface. A generator housing is arranged in the tail cone. The generator housing includes an outer surface portion spaced from the inner surface of the tail cone. A generator is mounted in the generator housing. An air duct extends from the generator, through the generator housing, through the tail cone, and through the engine duct. The air duct includes an opening exposed to an air stream passing over the engine duct. 
     Additionally, or alternatively, in this or other non-limiting examples, another air duct extends from the generator, through the generator housing, through the tail cone, and through the engine housing, the another air duct including another opening exposed to an air stream passing over the engine duct. 
     Additionally, or alternatively, in this or other non-limiting examples, the air duct comprises an inlet duct for directing an air flow into the generator housing and the another air duct comprises an outlet air duct for directing the air flow out from the generator housing. 
     Additionally, or alternatively, in this or other non-limiting examples, a plenum is defined between the outer surface portion of the generator housing and the inner surface of the tail cone. 
     Additionally, or alternatively, in this or other non-limiting examples, the outlet duct is fluidically connected to the plenum. 
     Additionally, or alternatively, in this or other non-limiting examples, the generator includes a drive shaft connectable to a low pressure spool of a turbine engine, the drive shaft having a hollow interior fluidically connected to the plenum through an outlet passage. 
     Additionally, or alternatively, in this or other non-limiting examples, the opening of the air duct faces a first direction relative to the engine duct and the another opening of the another air duct faces a second direction that is distinct from the first direction. 
     Additionally, or alternatively, in this or other non-limiting examples, the first direction is directly opposite the second direction. 
     Additionally, or alternatively, in this or other non-limiting examples, a plurality of electrical conductors is connected to the generator, the plurality of electrical conductors pass from the generator through the air duct. 
     Additionally, or alternatively, in this or other non-limiting examples, the engine system is supported in a nacelle mounted to the fuselage. 
     Additionally, or alternatively, in this or other non-limiting examples, the wing is fixedly mounted to the fuselage. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
         FIG.  1    is a partial side view of an aircraft including a cooling system for a tail cone mounted generator, in accordance with a non-limiting example; 
         FIG.  2    depicts a cross-sectional side view of an engine of the aircraft of  FIG.  1    including the cooling system for a tail cone mounted generator, in accordance with a non-limiting example; 
         FIG.  3    depicts a cross-sectional side view of a tail cone mounted generator including a cooling system, in accordance with a non-limiting example; 
         FIG.  4    depicts an axial end view of the tail cone mounted generator supported in an engine housing without the tail cone, in accordance with a non-limiting example; 
         FIG.  5    is a schematic partial side view of a tail cone mounted generator including a cooling system in accordance with another non-limiting example; and 
         FIG.  6    depicts a cross-sectional side view of a tail cone mounted generator including a cooling system, in accordance with yet another non-limiting example. 
     
    
    
     DETAILED DESCRIPTION 
     A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
     An aircraft, in accordance with a non-limiting example, is indicated generally at  10  in  FIG.  1   . Aircraft  10  includes a fuselage  12  that supports a wing  14 . An engine system  20  including a nacelle  24  is supported by wing  14 . Nacelle  24  surrounds and protects engine system  20 . At this point, it should be understood that engine system  20  may also be directly supported by fuselage  12  or be mounted to tail surfaces (not shown) of aircraft  10 . Referring to  FIG.  2   , and with continued reference to  FIG.  1   , engine system  20  includes a turbine engine  28  supported within nacelle  24 . Turbine engine  28  includes a high pressure spool  30  connected to a low pressure spool  32 . A low pressure spool shaft  34  extends from low pressure spool  32 . An engine duct  36  including an outer surface section  37  and an inner surface section  38  extends about turbine engine  28  and provides a pathway for air flow. 
     In a non-limiting example, turbine engine  28  includes a tail cone  40  having an outer surface  42  and an inner surface  44 . A generator housing  48  is arranged within tail cone  40 . Referring to  FIG.  3   , generator housing  48  takes the form of a service frame (not separately labeled) having a first outer surface portion  52  and a first inner surface portion  54 . A second outer surface portion  55  is spaced from first inner surface portion  54 . A second inner surface portion  56  extends about a generator  58   
     In a non-limiting example, generator  58  includes a stator  63  including a stator winding (not separately labeled) supported by second inner surface portion  56 . A rotor  65  including a rotor winding (also not separately labeled) is supported on a shaft  67  within stator  63 . Shaft  67  is supported in generator housing  48  through a first bearing  69  and a second bearing  71 . Generator  58  is also shown to include a secondary stator  74  axially spaced from stator  63 . A second rotor  76  is supported on shaft  67  axially spaced from rotor  65  and is rotatable within secondary stator  74 . 
     In a non-limiting example, a first air duct  80  extends from within generator housing  48 . First air duct  80  includes a first end  82  positioned inwardly of second inner surface portion  56  and a second end  84  ( FIG.  2   ) that is positioned outwardly of engine duct  36  as shown in  FIG.  2   . First air duct  80  extends through generator housing, tail cone  40  and engine duct  36  with second end  84  being exposed to an air stream passing over turbine engine  28 . That is, second end  84  of first air duct  80  includes an opening  86  that faces a first direction and defines an inlet (not separately labeled) that receives air flowing over turbine engine  28 . The air passes through first air duct  80  and into generator housing  48 . The air passes between rotor  65  and stator  63  as well as over stator  63 . The air also passes between secondary stator  74  and second rotor  76 . In a non-limiting example, portions of first air duct  80  that extend between tail cone  40  and engine duct  36  may include an aerodynamic profile as shown in  FIG.  4   . 
     In a non-limiting example, a second air duct  92  may extend from within generator housing  48 . Second air duct  92  includes a first end section  96  that may be positioned between first outer surface portion  52  of generator housing  48  and inner surface  44  of tail cone  40  and a second end section  98  that is arranged outwardly of engine duct  36 . Second end section  98  includes an opening  100  ( FIG.  2   ) that faces a second direction opposite to that of opening  86  and defines an outlet. In this manner, air that has exchanged heat with internal components of generator  58  may be expelled into tail cone  40 , through second air duct  92 , and into an airstream passing over turbine engine  28 . At this point, it should be understood that the number, orientation, and circumferential location of air ducts may vary. 
     In a non-limiting example depicted in  FIG.  5   , wherein like reference numbers represent corresponding parts in the respective views, first air duct  80  is shown to also act as a conduit  108  that carries electrical conductors  109  from a first terminal block (not shown) positioned on generator housing  48  to a second terminal block (also not shown) that may be arranged in nacelle  24  and or wing  14 .  FIG.  6    depicts a generator housing  48  in which air passes not only between stator  63 /rotor  65  and secondary stator  74 /second rotor  79  but also through rotor  65  and second rotor  76  in order to further improve cooling. There may be rotor cooling channels formed in rotor lamination for air to flow through the rotor and provide cooling. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof. 
     While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.