Patent Application
20080010969
In the exemplary embodiment, core gas turbine engine 20 is enclosed in an annular core cowl 22, and a fan nacelle 24 surrounds the fan 16 and a portion of the core engine 20. An annular bypass duct 26 is defined between a forward portion of core cowl 22 around core gas turbine engine 20 and the aft inner surface of nacelle 24 spaced radially outwardly therefrom.
During operation, ambient air 28 enters an inlet 30 of gas turbine engine assembly 10 and flows past fan 16. A first portion 32 of airflow 28 is channeled through core gas turbine engine 20, compressed, mixed with fuel, and ignited for generating combustion gases 34 which are discharged from a core nozzle 36 of core gas turbine engine 20. A second portion 38 of airflow 28 is channeled downstream through bypass duct 26 to an exemplary assisted lift thrust reverser assembly 100.
In the exemplary embodiment, assisted lift thrust reverser assembly 100 includes an annular aft cowl 102 which is movably coupled to a stationary forward cowl 104 to form nacelle 24. Aft cowl 102 has an aft or downstream end defining, with a portion of the core cowl 22, a discharge fan nozzle 106 having a area such that during operation airflow second portion 38 that is channeled through bypass duct 26 may be discharged through fan nozzle 106 during selected operation. In the exemplary embodiment, assisted lift thrust reverser assembly 100 also includes a cowl moving apparatus 110 that is coupled to aft cowl 102 to facilitate selectively axially translating aft cowl 102 relative to forward cowl 104.
In the exemplary embodiment, apparatus 110 includes a plurality of circumferentially spaced apart actuators or motors 112, a plurality of extending rods 114, such as ball screws, that are each coupled to a respective motor 112 and also to aft cowl 102 such that energizing motors 112 facilitates moving or translating aft cowl 102 in either a forward direction 120 or an aft direction 122. In the exemplary embodiment, cowl moving apparatus 110 may be electrically pneumatically, or fluidly powered to facilitate axially translating aft cowl 102 from a first position 130 which is fully retracted against the forward cowl 104, to a second position 132 (shown in
Assisted lift thrust reverser assembly 100 also includes a plurality of cascade turning vanes 140, referred to herein as a cascade box 140 that are disposed between or at the juncture of the aft and forward cowls 102 and 104 and are selectively uncovered upon axial translation of aft cowl 102 as will be discussed later herein. As shown in
As shown in
First portion 170 includes a first plurality of cascade turning vanes 180 that are oriented to channel airflow 38 within bypass duct 26 through cascade box 140 in a substantially aftward direction 122 with respect to core gas turbine engine 20, a second plurality of cascade turning vanes 182 that are oriented to channel airflow 38 within bypass duct 26 through cascade box 140 in a substantially forward direction 120 with respect to core gas turbine engine 20, and a divider 184 coupled therebetween as shown in
Second portion 172 does not include cascade turning vanes 180, but rather includes a blank or blocking device 175 that facilitates preventing airflow 38 that is channeled through bypass duct 26 from being discharged through cascade box 140 when aft cowl 102 is in a predetermined configuration discussed below. More specifically, airflow blocking device 175 is coupled substantially coaxially with the first plurality of turning vanes 180 and extends substantially semi-circumferentially around the gas turbine engine such that such that the blocking device 175 substantially prevents airflow from flowing through at least a portion of cascade box 140. In the exemplary embodiment, airflow blocking device 175 facilitates preventing airflow through a portion of cascade box 140 when aft cowl 102 is in the second operation position 132 since the second operational position 132 is utilized to provide additional airflow in the aftward direction 122 and thus across wing 12 to supplement lift.
Second portion 172 also includes second plurality of cascade turning vanes 182 that are oriented to channel airflow 38 within bypass duct 26 through cascade box 140 in a substantially forward direction 120 with respect to core gas turbine engine 20 as shown in
For example, during a first mode of operation, aft cowl 102 is positioned in the first or stowed position 130, as shown in
Optionally, when the aircraft is preparing to land, for example, an operator may choose to move aft cowl 102 from the first or stowed position 130 to the second operational position 132, shown in
More specifically, aft cowl moving apparatus 110 is operated to facilitate moving aft cowl 102 from the first operational position 130 to the second operational position 132. As shown in
Optionally, when the aircraft has landed, and an operator desires to effect reverse thrust, an operator may choose to move aft cowl 102 from either the first or second position 130 and 132, respectively, to the third operational position 134, shown in
More specifically, aft cowl moving apparatus 110 is operated to facilitate moving aft cowl 102 to the third operational position 134. As shown in
Described herein is an assisted lift thrust reverser assembly that may be utilized on a wide variety of gas turbine engines coupled to an aircraft. Specifically, the thrust reverser described herein includes an intermediate operational position that permits a portion of fan flow to exit the nacelle through a portion of the cascade box set to effect lift. Specifically, the turning vanes that effect lift may be oriented in a plurality of circumferential angles to divert up to 180 degrees of engine flow towards the wing trailing edge such that the airflow is directed to an area that is aftward from a point that is approximately 70% of the wing chord to facilitate adding energy to the boundary layer at either the upper or lower surface of the wing and thus increase lift. The other 180 degrees of the engine may include blank-off boxes to prevent airflow from leaving the nacelle since the airflow discharged from the lower portion of the gas turbine engine is not directed at the wing trailing edge to effect lift in an underwing engine application. This intermediate mode of operation may be selected by the pilot/control during take-off and approach. Whereas, when the aft cowl is fully extended to expose substantially all of the turning vanes, the thrust reverser operation is effected. Moreover,when the aft cowl is fully retracted, the nacelle operates at cruise performance similar to the current production ncaelles.
The assisted lift thrust reverser assembly described herein utilizes a minimum quantity of parts to effected the assisted lift mode into the thrust reverser while maintaining aerodynamic performance. During aircraft operations when the aircraft speed is sufficiently reduced to facilitate takeoff or landing procedures, channeling airflow across the surface of the wing increases lift. As such, the engine power may be maintained at an optimal power for takeoff and landing, i.e. the power may not need to be increased, to facilitate increasing the velocity of the airflow across the wings and thus increase lift during all takeoff and landing procedures.
While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.
