Abstract:
A modulating fan air diverter and annular air-oil cooler for a gas turbine engine located in the inner fixed structure adjacent to the core cowl is provided. The fan air diverter modulates between an open position, corresponding to maximum fan nozzle area and airflow through the air-oil cooler, and a closed position, corresponding to minimum fan nozzle area and airflow through the air-oil cooler. As such, the device is capable of supporting dual functions of engine heat management as well as engine performance and fan stability.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a non-provisional US patent application claiming priority under 35 USC §119(e) to U.S. provisional Ser. No. 61/926,661 filed on Jan. 13, 2014. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    The present disclosure generally relates to gas turbine engines, and more particularly, to a dual function fan air diverter and variable area fan nozzle for use with gas turbine engines. 
       BACKGROUND OF THE DISCLOSURE 
       [0003]    A gas turbine engine is typically provided with an oil tank as well as means for cooling the oil circulated therethrough. In some configurations, a gas turbine engine may employ an annular-type air-oil cooler that is circumferentially positioned about the low pressure compressor in the inner fixed structure section of the inner cowl and provided with cooling fins disposed in general fluid communication with a fan duct and nozzle of the gas turbine engine. More specifically, the inner surface of the outer nacelle and the outer surface of the inner cowl at the low pressure compressor section define a fan duct and nozzle through which fan airflow is received. The air-oil cooler cooling fins extend into the fan duct so as to dissipate excess heat from the oil being circulated through the annular air-oil cooler into the fan airflow passing thereby. 
         [0004]    In some gas turbine engine configurations, an annular fan air diverter assembly is provided to modulate the amount of fan airflow which passes through a plurality of cooling fins of the annular air-oil cooler, and thereby modulate the oil temperature. The annular air-oil cooler in conjunction with the modulating fan air diverter is part of the engine heat management system. These configurations may also employ separate assemblies for modulating the fan nozzle area to improve performance and fan stability during operation of the gas turbine engine. Having assemblies that are separately installed and individually controlled come with increased costs, added complexity and other drawbacks. The present disclosure is directed at addressing one or more of these deficiencies. 
       SUMMARY OF THE DISCLOSURE 
       [0005]    In accordance with one aspect of the disclosure, a fan air diverter for a gas turbine engine having at least an inner cowl and an annular air-oil cooler is provided. The fan air diverter may include a nozzle flap disposed circumferentially about the inner cowl and coaxially adjacent to the annular air-oil cooler, and an actuator assembly operatively coupling the nozzle flap to the inner cowl. The nozzle flap may be pivotally coupled to the inner cowl and selectively movable relative to the annular air-oil cooler between an open position and a closed position. The actuator assembly may be configured to actuate the nozzle flap between the open position and the closed position. 
         [0006]    In accordance with another aspect of the disclosure, an oil cooling assembly for a gas turbine engine having at least an inner cowl is provided. The oil cooling assembly may include an annular air-oil cooler circumferentially disposed about the inner cowl, and a fan air diverter circumferentially disposed about the inner cowl and coaxially adjacent to the cooling fins. The annular air-oil cooler may include an integral annular oil tank and a plurality of cooling fins radially extending therefrom. The cooling fins may be disposed in at least partial communication with a fan duct and nozzle of the gas turbine engine for receiving fan airflow. The fan air diverter may be selectively movable relative to the cooling fins so as to modulate fan airflow. 
         [0007]    In accordance with yet another aspect of the disclosure, a gas turbine engine is provided. The gas turbine engine may include an outer nacelle and an inner cowl defining a fan duct and nozzle for receiving fan airflow, an annular air-oil cooler disposed circumferentially about the inner cowl and in communication with the fan duct and nozzle, at least one nozzle flap disposed circumferentially about the inner cowl and coaxially adjacent to the annular air-oil cooler, and an actuator assembly operatively coupling the nozzle flap to the inner cowl. The nozzle flap may be pivotally coupled to the inner cowl and selectively movable relative to the annular air-oil cooler between an open position and a closed position. The actuator assembly may be configured to actuate the nozzle flap between the open position and the closed position so as to modulate fan airflow through the air-oil cooler for heat management and to vary either the fan nozzle throat or exit area for engine performance and fan stability purposes. 
         [0008]    These and other aspects of this disclosure will become more readily apparent upon reading the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a partial, cross-sectional view of the front section of a gas turbine engine having a fan air diverter in the closed position; 
           [0010]      FIG. 2A  is an axial, cross-sectional view of a section of an annular air-oil cooler; 
           [0011]      FIG. 2B  is an axial, cross-sectional view of a section of a dual function air-oil cooler with integral oil tank; 
           [0012]      FIG. 3  is a partial, cross-sectional view of a low pressure compressor section of a gas turbine engine having a fan air diverter in the opened position; 
           [0013]      FIG. 4  is a partial, cross-sectional view of a low pressure compressor section of a gas turbine engine having a fan air diverter with fore and aft nozzle flaps; 
           [0014]      FIGS. 5A-5C  are cross-sectional views of a fan air diverter with fore and aft nozzle flaps in fully open, intermediate and fully closed positions; 
           [0015]      FIGS. 6A-6C  are cross-sectional views of another fan air diverter with fore and aft nozzle flaps in fully open, intermediate and fully closed positions; 
           [0016]      FIGS. 7A-7C  are cross-sectional views of yet another fan air diverter with fore and aft nozzle flaps in fully open, intermediate and fully closed positions; 
           [0017]      FIG. 8  is an axial, cross-sectional view of one actuator assembly of a fan air diverter; 
           [0018]      FIG. 9  is a partial, cross-sectional view of the actuator assembly of  FIG. 8 ; 
           [0019]      FIG. 10  is an axial, cross-sectional view of another actuator assembly of a fan air diverter; and 
           [0020]      FIG. 11  is a partial, cross-sectional view of the actuator assembly of  FIG. 10 . 
       
    
    
       [0021]    While the present disclosure is susceptible to various modifications and alternative constructions, certain illustrative embodiments thereof have been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to be limited to the specific forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling with the spirit and scope of the present disclosure. 
       DETAILED DESCRIPTION 
       [0022]    Referring to  FIG. 1 , the front section of a gas turbine engine  100  having an exemplary oil cooling assembly  102  constructed in accordance with the present disclosure is provided. Among other things, the front section of the gas turbine engine  100  may generally include an outer nacelle  104 , an inner cowl  106 , a splitter  108 , fan blades  112 , exit guide vanes  114  and a fan duct and nozzle  110  associated therewith. Moreover, as indicated by the arrows shown, airflow  116  entering into the gas turbine engine  100  may be split by the splitter  108  into bypass or fan airflow  118  flowing through the fan duct and nozzle  110  and primary or core airflow  120  flowing into the low pressure compressor. 
         [0023]    The oil cooling assembly  102  of the gas turbine engine  100  of  FIG. 1  may be circumferentially disposed about an outer surface of the inner fixed structure in front of the inner cowl  106 , and generally composed of at least one annular air-oil cooler  122  and an annular fan air diverter  124  coaxially adjacent thereto. With further reference to the partial, axial cross-section provided in  FIG. 2A , the annular air-oil cooler  122  may include an arcuate finned oil channel  126  through which oil is circulated for cooling. The annular air-oil cooler  122  may further include a plurality of cooling fins  128  radially extending thereabout which conduct heat from the oil within the finned oil channel  126  and dissipate the heat into the bypass or fan airflow  118  passing thereby. In other embodiments, such as shown in the partial, axial cross-section provided in  FIG. 2B , an integral oil tank may be provided along the inner surface of the annular air-oil cooler  122 . 
         [0024]    As further shown in  FIG. 1 , the cooling fins  128  of the annular air-oil cooler  122  may extend into the fan duct and nozzle  110  and into the path of the fan airflow  118 . Correspondingly, the fan air diverter  124  may provide at least one nozzle flap  132  adjacent to the inlet-side of the cooling fins  128  of the annular air-oil cooler  122  in a manner which enables not only modulation of oil cooling, but also variability of the fan nozzle exit or throat area. Specifically, the nozzle flap  132  may be pivotally or otherwise movably disposed relative to the cooling fins  128 , and configured to selectively direct fan airflow  118  toward or away from the cooling fins  128 . Moreover, the nozzle flap  132  may be actuated into a fully closed position, as shown in  FIG. 1  for example, to divert fan airflow  118  away from the cooling fins  128 , minimize cooling and reduce the fan nozzle area. The nozzle flap  132  may also be actuated into a fully open position, as shown in  FIG. 3  for example, to completely expose the cooling fins  128  to the fan airflow  118 , maximize cooling and increase the fan nozzle area. The nozzle flap  132  may also be actuated into any intermediate position between the fully closed and fully open positions. 
         [0025]    In other embodiments, the fan air diverter  124  may optionally provide a nozzle flap  134  at the aft or outlet-side of the annular air-oil cooler  122  in addition to the nozzle flap  132  at the fore or inlet-side of the annular air-oil cooler  122  to provide further variability of the fan nozzle area, as shown for example in  FIG. 4 . In still further embodiments, the configuration of the fan air diverter  124  and each nozzle flap  132 ,  134  thereof may be varied as illustrated in  FIGS. 5-7 . In particular, each nozzle flap  132 ,  134  may be configured such that either the leading edge or trailing edge thereof is hinged relative to the inner cowl  106  or the cooling fins  128 . 
         [0026]    As shown in  FIGS. 5A-5C  for example, the trailing edge of the fore nozzle flap  132  is hinged or otherwise coupled to the inlet-side of the cooling fins  128  so as to open or close relative to the outer surface of the inner cowl  106 , while the leading edge of the aft nozzle flap  134  is hinged to the outlet-side of the cooling fins  128 . In the fully open positions of  FIG. 5A , the fan air diverter  124  may provide a generally converging fan airflow  118  through the fan nozzle  110  and the cooling fins  128 . In the intermediate positions of  FIG. 5B , the fan air diverter  124  may provide a moderately converging-diverging fan airflow  118 , or a fan airflow  118  which converges toward the outlet-side of the cooling fins  128 , and then diverges at least temporarily thereafter. The fully closed positions of  FIG. 5C  provide similar effects to the positions of  FIG. 5B  but to a greater degree, and thereby provides an increased converging-diverging fan airflow  118 . 
         [0027]    In  FIGS. 6A-6C , the leading edge of the fore nozzle flap  132  is hinged to the inner cowl  106 , while the leading edge of the aft nozzle flap  134  is hinged to the outlet-side of the cooling fins  128 . As in  FIGS. 5A-5C , the fully open, intermediate and fully closed positions of  FIGS. 6A-6C  may similarly provide generally converging, moderately converging-diverging and increased converging-diverging fan airflows  118 , respectively. Furthermore, in  FIGS. 7A-7C , the leading edge of the fore nozzle flap  132  is hinged to the inner cowl  106  as in  FIGS. 6A-6C , while the trailing edge of the aft nozzle flap  134  is hinged to the inner cowl  106 . Similar to previous embodiments, the fully open, intermediate and fully closed positions of  FIGS. 7A-7C  may provide generally converging, moderately converging-diverging and increased converging-diverging fan airflows  118 , respectively. By adjusting the contour of the inner cowl  106  and/or outer nacelle  104  in the vicinity of the annular air-oil cooler  122  and fan air diverter  124 , other nozzle configurations can also be realized. Other alternate combinations of positions or other intermediate positions not shown will be apparent to those of skill in the art. 
         [0028]    Turning now to  FIGS. 8 and 9 , cross-sectional views of one exemplary embodiment of an actuation system assembly  136  for the fan air diverter  124  are provided. As shown, the actuation system assembly  136  may include a sync ring  138  that is circumferentially and coaxially disposed between the low pressure compressor and the nozzle flap  132 , and configured to be rotatable between a first angular position and a second angular position about the engine axis. The actuation system assembly  136  may further include a plurality of idler links  140  radially coupling the sync ring  138  to the nozzle flaps  132  as shown. Moreover, each idler link  140  may be pivotally configured such that rotating the sync ring  138  in the first direction or toward the first angular position moves the nozzle flap  132  into the open position, and rotating the sync ring  138  in the opposing, second direction or toward the second angular position moves the nozzle flap  132  into the closed position. The actuation system assembly  136  may further include a plurality of roller guides  142  rotatably disposed relative to the sync ring  138  to enable rotation of the sync ring  136  with reduced friction. The roller guides  142  may be radially provided along the inner edge of the sync ring  136  as shown and/or along the outer edge thereof. 
         [0029]    Referring to  FIGS. 10 and 11 , axial and side cross-sections of another exemplary embodiment of an actuation system assembly  136  are provided. As in the embodiment of  FIGS. 8 and 9 , the actuation system assembly  136  of  FIGS. 10 and 11  may employ a sync ring  138  and a plurality of idler links  140  radially disposed between the sync ring  138  and the nozzle flaps  132 . Rather than roller guides  142 , however, the actuation system assembly  136  may employ a plurality of bumpers  144  radially distributed between the sync ring  138  and a guide ring  146 . In one possible implementation, each idler link  140  may include ball ends  148  which pivotally couple to each of the nozzle flap  132  and the sync ring  138  as shown in  FIG. 11  to form ball joints  150 . Furthermore, the bumpers  144  may be formed of a low-friction material with shock absorbent properties. The bumpers  144  may also be shimmed to allow clearance adjustments between the sync ring  138  and the guide ring  146 . 
         [0030]    As in previous embodiments, the actuation system assembly  136  of  FIGS. 10 and 11  may be similarly configured such that rotating the sync ring  138  in the first direction or toward the first angular position pivots the idler links  140  in a manner which moves the nozzle flap  132  into the open position, and rotating the sync ring  138  in the opposing, second direction or toward the second angular position pivots the idler links  140  in a manner which moves the nozzle flap  132  into the closed position. The actuation system assemblies  136  of  FIGS. 8-11  may also be implemented using any other kinematic mechanism for converting linear or rotary motion of an actuator into a rotation of the sync ring  138 , or any other suitable means for modulating the nozzle flaps  132 ,  134  on demand. Furthermore, the modulating fan air diverter  124  and the associated actuation system assembly  136  may be installed in the stationary portion of the inner cowl  106 , or the inner fixed structure, so as not to be impacted by or in otherwise interference with the opening of associated engine core cowl doors. Still further, while the foregoing actuation system assemblies  136  were disclosed in relation to fore or inlet-side nozzle flaps  132 , similar actuator assemblies may be separately provided and appropriately configured for any aft or outlet-side nozzle flaps  134 . 
         [0031]    The foregoing disclosure is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be understood that within the scope of the appended claims, the present disclosure may be practiced other than as specifically described. For that reason, the appended claims should be studied to determine true scope and content.