Abstract:
A gas turbine engine system according to an exemplary aspect of the present disclosure includes, among other things, a nacelle assembly defined about an axis and a core engine positioned radially inward of the nacelle assembly and having a core passage and at least one core auxiliary duct passage. The at least one core auxiliary duct passage includes an inlet for receiving a portion of a core airflow from the core engine and an outlet for discharging the portion of the core airflow. At least one of the inlet and the outlet are selectively translatable to divert the portion of the core airflow into the at least one core auxiliary duct passage and a mixer disposed between the nacelle assembly and the core engine.

Description:
[0001]    This application is a continuation application of U.S. patent application Ser. No. 11/866,547, filed Oct. 3, 2007. 
     
    
     BACKGROUND 
       [0002]    This disclosure relates to a gas turbine engine having a core auxiliary duct passage for diverting a portion of a core airflow from the core engine of the gas turbine engine. 
         [0003]    In an aircraft gas turbine engine, such as a turbofan engine, air is pressurized in a compressor section and mixed with fuel in a combustor section for generating hot combustion gases. The hot combustion gases flow downstream through a turbine section that extracts energy from the gases. The turbine section powers a compressor section and a fan section disposed upstream of the compressor section. 
         [0004]    Fan bypass airflow is communicated through a fan bypass passage that extends between a nacelle assembly and a core engine. The fan bypass airflow is communicated through an annular fan exhaust nozzle defined at least partially by the nacelle assembly surrounding the core engine. A majority of propulsion thrust is provided by the pressurized fan air that is discharged through the fan exhaust nozzle. The combustion gases are discharged through a core exhaust nozzle to provide additional thrust. 
         [0005]    Mixed flow turbofan engines are known that include a mixer positioned between the nacelle assembly and the core engine at a position downstream from a turbine exit guide vane. The mixer typically includes a plurality of petals. The mixer drives core airflow from the core engine radially outward and into the petals of the mixer, and drives the fan airflow from the fan bypass passage radially inward to fill the petals of the mixer. The two airflow streams are co-mingled in the mixer and are subsequently communicated as a mixed stream through the exhaust nozzles of the gas turbine engine at a relatively equal velocity. 
         [0006]    Mixed flow turbofans are known to provide noise reductions and improved propulsion efficiency of gas turbine engines. However, noise and efficiency issues remain a common area of concern in the field of gas turbine engines. Attempts have been made to increase the beneficial results achieved by mixed flow turbofan engines. Disadvantageously, these attempts have not been successful. 
         [0007]    Accordingly, it is desirable to provide a gas turbine engine that achieves improved efficiency and noise reductions in a relatively inexpensive and non-complex manner. 
       SUMMARY 
       [0008]    A gas turbine engine system according to an exemplary aspect of the present disclosure includes, among other things, a nacelle assembly defined about an axis and a core engine positioned radially inward from the nacelle assembly and having a core passage and at least one core auxiliary duct passage. The at least one core auxiliary duct passage includes an inlet for receiving a portion of a core airflow from the core engine and an outlet for discharging the portion of the core airflow. At least one of the inlet and the outlet are selectively translatable to divert the portion of the core airflow into the at least one core auxiliary duct passage and a mixer disposed between the nacelle assembly and the core engine. 
         [0009]    In a further non-limiting embodiment of the foregoing gas turbine engine system, the inlet is positioned upstream from the mixer. 
         [0010]    In a further non-limiting embodiment of either of the foregoing gas turbine engine systems, the outlet is positioned downstream from the mixer. 
         [0011]    In a further non-limiting embodiment of any of the foregoing gas turbine engine systems, the inlet includes at least one door and a translating ring that selectively translates the at least one door. 
         [0012]    In a further non-limiting embodiment of any of the foregoing gas turbine engine systems, the outlet includes at least one door pivotable about a pivot. 
         [0013]    In a further non-limiting embodiment of any of the foregoing gas turbine engine systems, a fan bypass passage is disposed between the nacelle assembly and the core engine. 
         [0014]    In a further non-limiting embodiment of any of the foregoing gas turbine engine systems, a fan exhaust nozzle is positioned near a downstream end of the nacelle assembly and a core exhaust nozzle is positioned near a downstream end of the core engine. 
         [0015]    In a further non-limiting embodiment of any of the foregoing gas turbine engine systems, the at least one core auxiliary duct passage extends circumferentially about the core engine. 
         [0016]    In a further non-limiting embodiment of any of the foregoing gas turbine engine systems, the mixer includes a plurality of petals. 
         [0017]    In a further non-limiting embodiment of any of the foregoing gas turbine engine systems, the at least one core auxiliary duct passage is positioned radially inward of the core engine. 
         [0018]    A gas turbine engine system according to an exemplary aspect of the present disclosure includes, among other things, a nacelle assembly defined about an axis and a core engine positioned at least partially within the nacelle assembly and including at least one compressor section, a combustor section and at least one turbine section. The core engine includes a core passage and at least one core auxiliary duct passage having an inlet for receiving a portion of a core airflow from the core engine and an outlet for discharging the portion of the core airflow. A mixer is disposed between the nacelle assembly and the core engine. A controller produces a signal in response to detecting an operability condition and selectively translates the inlet and the outlet in response to the operability condition. 
         [0019]    In a further non-limiting embodiment of the foregoing gas turbine engine system, the operability condition includes a take-off condition. 
         [0020]    In a further non-limiting embodiment of either of the foregoing gas turbine engine systems, the inlet and the outlet are selectively translatable between a first position and a second position. 
         [0021]    In a further non-limiting embodiment of any of the foregoing gas turbine engine systems, the first position is a closed position and the second position is an open position. 
         [0022]    In a further non-limiting embodiment of any of the foregoing gas turbine engine systems, the system comprises a sensor that communicates with the controller. 
         [0023]    In a further non-limiting embodiment of any of the foregoing gas turbine engine systems, the inlet and the outlet are selectively moveable between a plurality of positions, and each of the plurality of positions allows a different amount of the core airflow to be communicated through the at least one core auxiliary duct passage. 
         [0024]    The various features and advantages of this disclosure will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIG. 1  illustrates a general perspective view of an example gas turbine engine; 
           [0026]      FIGS. 2A and 2B  illustrate an example gas turbine engine including a mixer section; 
           [0027]      FIG. 3  illustrates the example gas turbine engine of  FIGS. 2A and 2B  having a core auxiliary duct passage; 
           [0028]      FIG. 4  illustrates an inlet portion of the core auxiliary duct passage illustrated in  FIG. 3 ; and 
           [0029]      FIG. 5  illustrates an outlet portion of the core auxiliary duct passage illustrated in  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION 
       [0030]      FIG. 1  illustrates a gas turbine engine  10  that includes (in serial flow communication) a fan section  14 , a low pressure compressor  15 , a high pressure compressor  16 , a combustor  18 , a high pressure turbine  20  and a low pressure turbine  22  each disposed about an engine longitudinal centerline axis A. During operation, air is pressurized in the compressors  15 ,  16  and mixed with fuel in the combustor  18  for generating hot combustion gases. The hot combustion gases flow through the high and low pressure turbines  20 ,  22 , which extract energy from the hot combustion gases. The high pressure turbine  20  powers the high pressure compressor  16  through a high speed shaft  19  and the low pressure turbine  22  powers the fan section  14  and the low pressure compressor  15  through a low speed shaft  21 . The disclosure is not limited to the two-spool gas turbine architecture described and may be used with other architectures such as a single-spool axial design, a three-spool axial design and other architectures. That is, the present disclosure is applicable to any gas turbine engine, and to any application. 
         [0031]    The example gas turbine engine  10  is in the form of a high bypass ratio engine mounted within a nacelle assembly  26 , in which most of the air pressurized by the fan section  14  bypasses the core engine  28  for generating propulsion thrust. The nacelle assembly  26  partially surrounds the core engine  28 . The airflow entering the fan section  14  may bypass the core engine  28  via a fan bypass passage  27  that extends between the nacelle assembly  26  and the core engine  28  for receiving and communicating a discharge airflow F 1 . The high bypass flow arrangement provides a significant amount of thrust for powering the aircraft. 
         [0032]    The discharge airflow F 1  is discharged from the engine through a fan exhaust nozzle  30  positioned adjacent a downstream end  32  of the nacelle assembly  26 . Meanwhile, core airflow F 2  is communicated through a core passage  34  of the core engine  28 . Core airflow F 2  is discharged from the core engine  28  through a core exhaust nozzle  36  that is defined between the core engine  28  and a tail cone  38  disposed coaxially therein around the longitudinal centerline axis A of the gas turbine engine  10 . A bypass ratio is defined that represents the ratio of the fan discharge airflow F 1  relative to the core airflow F 2 . 
         [0033]      FIGS. 2A and 2B  illustrates a mixer section  40  of the gas turbine engine  10 . In this example, the gas turbine engine  10  is in the form of a mixed flow turbofan engine. The mixer section  40  includes a plurality of petals  42 . The mixer section  40  communicates the fan airflow F 1  radially inwardly from the fan bypass passage  27  into the petals  42  of the mixer section  40 . Meanwhile, the mixer section  40  communicates the core airflow F 2  radially outwardly from the core passage  34  into the petals  42 . The mixer section  40  operates to mix the two gas flows and communicate the mixed gas flow through the exhaust nozzles  30 ,  36  at a relatively equal velocity. In certain applications, the mixing is helpful because the two gas flows are communicated at widely varying temperatures and pressures and by being combined together, form a single homogenous flow of gases to reduce overall engine noise. 
         [0034]      FIG. 3  illustrates a core auxiliary duct passage  44  positioned within the core engine  28 . The core auxiliary duct passage  44  is designed to increase the engine bypass ratio during certain operability conditions and thereby reduce engine noise, as is further discussed below. In one example, the core auxiliary duct passage  44  extends circumferentially about the entire circumference of the core engine  28 . In another example, the core auxiliary duct passage  44  is an annular duct. In yet another example, the core auxiliary duct passage  44  includes a plurality of individual ducted passages disposed circumferentially about the engine centerline axis A. It should be understood that the example core auxiliary duct passage  44  is not shown to the scale it would be in practice. Instead, the core auxiliary duct passage  44  is shown larger than in practice to better illustrate its function. A worker of ordinary skill in this art will be able to determine an appropriate duct passage volume for a particular application, and thereby appropriately size the duct passage(s)  44 . 
         [0035]    The core auxiliary duct passage  44  includes an inlet  46  and an outlet  48 . In one example, the inlet  46  is positioned upstream from the mixer section  40 . In another example, the inlet  46  is positioned on the core engine  28  between a turbine exit guide vane  45  and the mixer section  40 . The outlet  48  is positioned downstream from the mixer section  40 , in this example. However, it should be understood that the inlet and outlet  46 ,  48  may be positioned at other locations of the gas turbine engine  10  and that these locations may vary depending upon design specific parameters including, but not limited to, the efficiency and noise requirements of the gas turbine engine  10 . 
         [0036]    The inlet  46  of the core auxiliary duct passage  44  selectively receives a portion F 3  of the core airflow F 2  that is communicated through the core passage  34  of the core engine  28  in response to specific operability conditions. The portion F 3  of the core airflow F 2  is communicated through the core auxiliary duct passage  44  and is discharged via the outlet  48 . 
         [0037]    Diverting a portion F 3  of the core airflow F 2  through the core auxiliary duct passage  44  increases the gas turbine engine  10  bypass ratio and thereby improves overall engine efficiency and reduces engine noise. Specifically, communicating airflow through the core auxiliary duct passage  44  enables an increased core airflow F 2  through the core passage  34  and reduces any backpressure (e.g., pressure losses that result in reductions in engine efficiency) experienced by the low pressure turbine  22 . In addition, diverting core airflow F 2  away from the mixer section  40  enables the fan bypass airflow F 1  to increase, thereby improving engine efficiency. 
         [0038]    The inlet  46  and the outlet  48  are selectively translated to divert the portion F 3  of the core airflow F 2  into the core auxiliary duct passage  44 . For example, opening the inlet  46  and the outlet  48  permits an airflow F 3  to enter the core auxiliary duct passage  44 , and closing the inlet  46  and the outlet  48  blocks any airflow 
         [0039]    F 3  from entering the core auxiliary duct passage  44 . The inlet  46  and the outlet  48  are selectively moveable between a first position X (i.e., a closed position, represented by phantom lines) to a second position X′ (an open position, represented by solid lines) in response to detecting an operability condition of a gas turbine engine  10 , for example. In another example, the inlet  46  and the outlet  48  are selectively moveable between a plurality of positions, each allowing a different amount of airflow F 3  to enter the core auxiliary duct passage  44 . 
         [0040]    In one example, the operability condition includes a takeoff condition. However, the inlet  46  and the outlet  48  may be selectively opened to the second position X′, or to any intermediate position between the first position X and the second position X′, in response to any known operability condition. In one example, a sensor  52  detects the operability condition and communicates a signal to a controller  54  to move the inlet  46  and the outlet  48  between the first positions X and the second positions X′ via an actuator assembly  56 . Of course, this view is highly schematic. 
         [0041]    It should be understood that the sensor  52  and the controller  54  may be programmed to detect any known operability condition. Also, the sensor  52  can be replaced by any control associated with the gas turbine engine  10  or an associated aircraft. In fact, the controller  54  itself can generate the signal to cause the actuation of the inlet  46  and the outlet  48 . The actuator assembly  56  returns the inlet  46  and the outlet  48  to the first position X during normal cruise operation (e.g., a generally constant speed at a generally constant, elevated altitude), in one example. The actuator assembly  56  may include any known type of actuator or combination of actuators that include hydraulic and electric actuation systems. In another example, the inlet  46  and the outlet  48  are returned to the first position X in response to detecting a climb condition. 
         [0042]      FIG. 4  illustrates the inlet  46  of the core auxiliary duct passage  44 . In one example, the inlet  46  includes a door  60  and a door translating ring  62 . The door  60  is selectively axially translatable in a direction X by the door translating ring  62  to expose the core auxiliary duct passage  44  and allow airflow F 3  to be diverted from the core airflow F 2 . The door  60  is moved in a Y direction to return the inlet  46  to a closed position. Although only one door  60  is illustrated, it should be understood that a plurality of doors may be included depending upon the design and configuration of the core auxiliary duct passage  44 . In an open position of the inlet  46  (i.e., the X′ position), the door  60  is stored within a cavity  64  disposed within the core engine  28 . A person of ordinary skill in the art having the benefit of this disclosure would understand that other methods may be utilized to translate the inlet  46  between the first position X and the second position X′. 
         [0043]      FIG. 5  illustrates the outlet  48  of the example core auxiliary duct passage  44 . In the illustrated example, the outlet  48  includes a door  70  pivotable about a pivot  72 . Although only one door  60  is illustrated, it should be understood that the outlet  48  can include a plurality of doors. The door  70  is pivotally mounted to the core engine  28  and is selectively moveable between the first position X and the second position X′ to permit the airflow F 3  that is communicated through the core auxiliary duct passage  44  to be discharged. In one example, the second position X′ is counterclockwise from the first position X. In another example, the second position X′ is clockwise from the first position X. The sensor  52  detects an operability condition, such as a takeoff condition, and communicates with a controller  54  to open the outlet via the actuator assembly  56 . A person of ordinary skill in the art having the benefit of this disclosure would understand that other methods may be utilized to translate the outlet  46  between the first position X and the second position X′. 
         [0044]    Although the different examples have the specific components shown in the illustrations, embodiments of this invention are not limited to those particular combinations. It is possible to use some of the components or features from one of the examples in combination with features or components from another one of the examples. 
         [0045]    The foregoing description shall be interpreted as illustrative and not in any limiting sense. A worker of ordinary skill in the art would recognize that certain modifications would come within the scope of this disclosure. For that reason, the following claims should be studied to determine the true scope and content of this disclosure.