Dual function air diverter and variable area fan nozzle

[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.

[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.

[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.

[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.

[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.

[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.