Thrust reverser cascade assembly with flow deflection shelf

An aircraft engine thrust reverser cascade assembly includes a plurality of circumferentially spaced cascade segments, each cascade segment including a plurality of spaced vanes, including an aft-most vane, and rails defining a series of cells or air passages therebetween. The cascade assembly also includes an aft cascade ring removably attached to the aft ends of the cascade segments. A flow deflection shelf is mounted to each of the cascade segments and includes a deflector portion that at least partially extends forward of a group of cells of the cascade segments along which the flow deflection shelf is mounted. The deflector portion is configured to at least partially redirect at least a portion of a volume of air forwardly as the air outwardly passes through the group of cells of the cascade segments.

FIELD OF THE INVENTION

The invention generally relates to thrust reversers for turbofan aircraft engines, and in particular relates to a thrust reverser cascade assembly including a flow deflection shelf that turns at least some of a turbofan engine's annular fan flow in the forward direction when the associated thrust reverser cascade is deployed.

BACKGROUND

Modern turbofan aircraft engines include thrust reversers that selectively reverse the direction of an engine's annular fan flow for use in decelerating an aircraft after touchdown. One type of thrust reverser for a turbofan engine includes a cascade array mounted in a selectively closable outlet opening in an engine's fan air duct. The cascade array includes a plurality of spaced, cascading vanes that redirect fan air flow along the engine's annular fan duct from an aftward direction to an outward and forward direction when the thrust reverser is deployed. Examples of various cascade-type thrust reversers are described and shown in, for example, U.S. Pat. No. 5,309,711; U.S. Pat. No. 6,170,254; and U.S. Pat. No. 6,546,715; all assigned to Rohr, Inc.

Portions of a typical cascade-type thrust reverser10for a turbofan aircraft engine5are shown inFIGS. 1A-1E. As shown inFIG. 1A, the cascade thrust reverser10includes a translating sleeve16that forms an aft portion of a nacelle surrounding the engine's annular fan duct13. The translating sleeve16is movably connected to the aft end of a stationary portion12of the nacelle. For normal aftward fan flow through the engine's fan duct13, the translating sleeve16is positioned immediately behind the stationary portion12of the nacelle and confines the fan flow within the fan duct13. As shown inFIGS. 1A-1C, when the thrust reverser10is deployed, the translating sleeve16is moved aftward, thus providing an outlet opening15between the stationary portion12and the forward end of the translating sleeve16. The outlet opening15typically extends on either side of a supporting engine pylon7, and around a substantial portion of the circumference of the engine5, and permits fan flow to be discharged from the engine's annular fan duct13to provide reverse thrust for slowing a landed aircraft. As shown inFIG. 1C, a plurality of blocker doors18proximate the forward end of the translating sleeve16are deployed to block aftward fan flow within the annular fan duct13, and to force the fan flow to exit the engine through the outlet opening15.

As shown inFIGS. 1A and 1B, a cascade assembly20is disposed within the exit opening15, and typically includes a plurality of circumferentially arranged cascade segments28. As shown inFIG. 1C, the cascade segments28include pluralities of spaced vanes25configured to turn the exiting fan flow to an at least partially forward direction in order to provide reverse thrust. The vanes25typically are supported between a plurality of longitudinal support members26. The aft ends of the cascade segments28are interconnected by an aft cascade ring30that ties the cascade segments28together, and stiffens the cascade assembly20against outward deflection. As shown inFIG. 1D, the aft end of each cascade segment can include an end flange29, and can be connected to the aft cascade ring30by a plurality of removable fasteners21.

In the embodiment shown inFIGS. 1C and 1D, the aft cascade ring30includes an outer portion36and an inner portion34that are each connected to opposed ends of a body portion32at right angles. The substantially Z-shaped cross-section of the cascade ring30provides the ring with substantial stiffness against bending and twisting, though all portions32,34and36of the ring are relatively thin. As also shown inFIGS. 1C and 1D, an aft vane27in each cascade segment28defines the rearmost extent11of the exhaust plume as the redirected fan flow exits the outlet opening15. As shown inFIG. 1D, the aft vane27is positioned forward of the aft cascade ring30, and the aft cascade ring30is positioned behind the rearmost extent11of the exhaust plume by a distance “a”. Accordingly, the aft cascade ring30has no substantial or direct effect on turning the exiting fan flow as the flow passes through the exit opening15.

Another configuration of a known aft cascade ring60is shown inFIG. 1E. In this arrangement, each cascade segment58includes a rearward extending flange52for connection to a forward extending flange63of aft cascade ring60with a plurality of removable fasteners21. The aft cascade ring60generally includes a body portion69and opposed inner and outer portions67,65. Again, the cross-sectional shape of the ring60provides substantial stiffness, though the individual portions63,65,67and69of the ring60are relatively thin. As shown inFIG. 1E, the aft-most vane57is positioned forward of the ring60, and the ring60is positioned behind the rearmost extent11of the exhaust plume by a substantial distance “b”. Accordingly, like the aft cascade ring30described above, the ring60has no substantial or direct effect on turning the exiting fan flow as the flow passes through the exit opening15.

Though the aft cascade rings30,60described above can be used to securely and rigidly connect the aft ends of thrust reverser cascade segments, they have some shortcomings. First, as discussed above, the aft cascade rings30,60play no substantial or direct role in turning exiting fan flow, and thus are ancillary to the primary function of their cascade assemblies20,50. Second, because the aft cascade rings30,60are positioned aft of the aft-most cascade vanes27,57, the aft cascade rings30,60add to the overall length of the cascade assemblies20,50, as well as add extra weight to the cascades20,50without directly contributing to their air-turning function. Accordingly, at least for these reasons, there is a need for an improved thrust reverser cascade assembly with an improved aft cascade ring that directly contributes to the air-turning function of the cascade assembly, as well as for its primary function of offering structural support for the aft end of the cascade array. This effectively reduces the overall length and weight of the cascade assembly.

SUMMARY

In one embodiment, an aircraft engine thrust reverser cascade assembly includes a plurality of circumferentially spaced cascade segments, each cascade segment including a plurality of spaced vanes including an aft-most vane and an aft end. The cascade assembly can further include a flow deflection shelf that forms a rear or aft end of the cascade segment and removably attaches to an aft cascade ring. The flow deflection shelf generally includes an upstanding wall or body portion and a deflector portion that extends forwardly, away from the aft end of the cascade segment. The deflector portion of each flow deflection shelf can be configured to at least partially redirect, in the forward direction, at least a portion of the volume of fan air flow as the air flow passes through the aft-most cells or airflow passages defined between the aft-most vanes of the cascade segment and the body of the flow deflection shelf. The upstanding wall or body portion of each deflection shelf can define an aft connection area of each cascade segment to enable attachment of an aft cascade ring to the aft end of the cascade assembly.

In another embodiment, the aircraft engine thrust reverser cascade assembly can have a plurality of cascade segments, each including a plurality of spaced vanes and support rails defining cells or airflow passages therebetween, and at least one flow deflection shelf mounted along a section intermediate the forward and rearward ends of the cascade segment. In such an embodiment, the flow deflection shelf can include a substantially longitudinally projecting deflector portion that can be mounted to an intermediate cascade vane or can be formed with a body section defining the intermediate cascade vane. The deflector portion extends forwardly from the intermediate cascade vane, at least partially overlying a series of intermediate cells and is configured to redirect, in the forward direction, at least some of the air passing through the cascade segment forward of the flow deflection shelf. The flow deflection shelf can extend laterally so as to define a hoop support structure around the cascade assembly, assisting in the secure connection of the cascade segments and enabling a reduction in size and weight required for the aft cascade ring mounted about the aft end of the cascade assembly.

These and other aspects and features of the invention will be understood from a reading of the following detailed description, together with the drawings. Those skilled in the art further will appreciate the advantages and benefits of the various additional embodiments discussed herein upon reading the following detailed description of the embodiments with reference to the below-listed drawing figures.

According to common practice, the various features of the drawings discussed below are not necessarily drawn to scale. Dimensions of various features and elements in the drawings may be expanded or reduced to more clearly illustrate the embodiments of the disclosure.

DETAILED DESCRIPTION

One embodiment of a thrust reverser200including one embodiment of a cascade assembly100and with flow deflection shelf110according to the invention is shown inFIGS. 2A and 2B. The thrust reverser200generally includes a translating sleeve16movably attached to the aft end of a stationary portion12of a nacelle. InFIG. 2A, the translating sleeve16is shown in a retracted or stowed position, with blocker door(s)18stowed in a position adjacent to the interior surface of the translating sleeve. InFIG. 2B, the translating sleeve16is shown in a deployed position. In the deployed position, the blocker door(s)18is extended into the fan duct13to block fan flow through the duct13. As also shown inFIG. 2B, deployment of the translating sleeve16opens an air flow exit passage15in the nacelle structure, and exposes the cascade assembly100disposed within the exit passage15.

The cascade assembly100includes a plurality of cascade segments102. As indicated inFIGS. 2A-3A, each cascade segment102includes a body103having longitudinally extending support ribs or rails104and a plurality of spaced, generally laterally extending vanes105each configured to turn the flow of air being exhausted through the exit passage15(FIGS. 2A-2B) toward an at least partially forward direction. The cascade segments102also include aft-most vanes107. The vanes105generally have a curved, concave configuration, although other configurations also can be provided. As shown inFIGS. 3A and 4A, each cascade segment102includes an aft or rear end108, a forward end109, and a series of cells or flow passages106defined between the support rails104and spaced vanes105. The forward end109of each cascade segment102generally is removably connected to one or more flanges14on the aft end of the stationary portion12of the nacelle structure. The forward end of each cascade segment102can be connected to the flange or flanges14by one or more removable fasteners23of a type or types known in the art.

In one embodiment of the cascade assembly102illustrated inFIGS. 3A-3B, the aft end108of each cascade segment102can include a flow deflection shelf110that is mounted to the aft ends of the support rails104in a position spaced from the aft-most vanes107. The flow deflection shelf110can be mounted to the aft end of its associated cascade segment such as by fasteners, adhesives, welding or other attachment or joining means as understood by those skilled in the art. Each flow deflection shelf110can be formed from a lightweight, substantially rigid and high-strength material, including various metals or metal alloys such as aluminum, titanium, steel or similar metal materials, or can be formed from various high-strength composites or synthetic materials. As shown inFIGS. 3A-3B, the flow deflection shelf110has a substantially orthogonal, L-shaped configuration, including a generally longitudinally oriented, forwardly extending deflector portion112, and an upstanding body or wall portion113. Other configurations are within the scope of the invention, such as configurations that are not perfectly orthogonal.

FIG. 3Bshows an enlarged detail of one configuration of the aft end108of a cascade segment102of the embodiment of the cascade assembly100described above. In this embodiment, the aft end of each cascade segment102to which the aft cascade ring120mounts is defined by the upstanding body or wall portion113of the flow deflection shelf110. The body portion113of this embodiment is generally configured to provide a substantially flat rear or aft wall to the aft end of each cascade segment, and is spaced axially rearward of the aft-most vanes107so as to define aft cells or air passages114for each cascade segment. As shown inFIG. 3A, the vanes105, including aft-most vanes107, and the body portion113of the flow deflection shelf of each cascade segment102can be supported by two or more spaced apart and longitudinally extending support rails104. By providing space between the aft-most vane107and the deflection shelf110, exiting fan flow can pass through the aft-most cells or air passages114therebetween, as indicated inFIG. 3Bby dashed arrow115.

Additionally, in the present embodiment, as indicated inFIG. 3B, the forwardly extending deflector portion112of the flow deflection shelf110is shown as oriented at a 90° angle with respect to its body portion113, although it will be understood that the deflector portion also can be oriented at greater or lesser angles. In embodiments utilizing the 90° angle configuration, the deflector portion112of flow deflection shelf110is closely spaced from and generally oriented substantially flush with the upper edges of the support rails of its associated cascade segment. Optionally, the deflector portion112of each flow deflection shelf110has an arcuate configuration that closely matches the arcuate configuration of its associated cascade segment, across the width of the segment. As such, the deflector portion112abuts the body103of each cascade segment, thereby forming a supporting hoop structure that provides structural support to the cascade segments in their connected configuration.

The body portion113of the flow deflection shelf110includes a flat aft end wall113, thus defining a substantially flat mounting surface117for attachment of an aft cascade ring120to the aft end of each cascade segment. By providing such a flat wall113and its associated flat mounting surface117, the aft cascade ring120is in flat lying contact or flush mounting abutment with the body portion of the flow deflection shelf, thus placing the aft cascade ring into a closer, tighter engagement with the aft ends of the cascade segments as compared to prior art structures. This can significantly reduce the amount of longitudinal space required within the nacelle for the aft cascade ring when mounted to the cascade segments, and accordingly provide increased clearance for operation of the thrust reverser and cascade structure.

One embodiment of an aft cascade ring120for use with a cascade assembly100such as described above is generally shown inFIGS. 2A-2Band5. As shown inFIG. 5, though the aft cascade ring120is referred to herein as a “ring,” the aft cascade ring120can be constructed in two or more arcuate parts which may or may not combine to form a complete 360-degree ring structure. For example, the aft cascade ring120can include two or more arcuate parts or sections120a,120bthat are mirror images of either, each including a body portion122, an outer or “deflector” portion126, and an inner portion124. In the embodiment shown inFIG. 5, the body portion122is substantially flat, and lies in a plane that is substantially transverse to the longitudinal axis of an associated aircraft engine, with a plurality of mounting holes or openings123for use in removably fastening the ring120to the cascade segments102. The inner portion124of the ring120can be substantially cylindrical in shape, and can rearwardly extend from an inner edge of the body portion122, with the inner portion124arranged substantially perpendicular to the body portion122.

In prior art structures such as shown inFIG. 1D, the cascade segments often require an additional rear wall that is mounted behind the aft-most vane (indicated at27) to enable connection of the aft cascade ring to the cascade segments. Alternatively, as indicated inFIG. 1E, if the aft-most vane57of the cascade segments comprises the rear or aft wall of the cascade segments, the curved construction of the vanes generally requires the cascade ring to be connected to the aft-most vanes of the cascade segments by horizontally extending flanges52and63attached via fasteners21. In addition to significantly reducing the horizontal space and enabling a closer fit and engagement between the cascade ring and aft end of the cascade segments to which it is attached, the present invention eliminates the need for such additional attachment flanging, such as shown inFIG. 1E, and the requirement for an additional aft wall portion as shown inFIG. 1D. This in turn helps provide significant weight reduction and enables the aft cascade ring to be formed in varied sizes (e.g., being made taller) as needed to increase aerodynamic operation of the thrust reverser.

As indicated inFIG. 3B, the body portion113of each flow deflection shelf110can be removably connected to the aft cascade ring120, such as by one or more removable fasteners125of a type or types known in the art. For example, the aft end of each cascade segment102can be removably connected to the aft cascade ring120by one or more sets of nuts and bolts or can be more permanently attached such as by rivets, etc. The connection of the aft cascade ring120to the body portion113of the flow deflection shelf110by fasteners125further is illustrated as being a longitudinally extending connection whereby the fasteners125extend in a forward direction through the body of the aft cascade ring and the body portions of the flow deflection shelves. This longitudinal connection aligns the fasteners in a shear-loading orientation to provide added strength, as opposed to a tension loaded attachment such as created by the connection illustrated in the prior art structure ofFIG. 1E. The attachment of the aft cascade ring120to the cascade segments ties the aft ends108of the cascade segments102together, adds stiffness to the cascade assembly100, and restrains the outward deflection of the cascade segments102when the cascade segments102are exposed to high velocity air flow passing through the exit passage15. The flow deflection shelf110further can assist in providing structural continuity and support to the connected cascade segments, which in turn can enable a reduction in size, and thus weight of the aft cascade ring.

In operation, as the thrust reverser is engaged, the fan air flow is directed radially outwardly toward the cells or airflow passages106and114defined between the vanes and support rails of the cascade segments. The substantially curved or arcuate configuration of the vanes causes the airflow to be redirected in the forward direction to provide reverse thrust. The aft-most airflow, indicated by dashed lines115inFIG. 3B, flows into the aft-most cells114and is directed substantially forwardly by impingement against the underside surface of the deflector portion112of the flow deflection shelf110.

The aft cascade ring120further can include an angled deflector portion126that extends forwardly at a desired angle to assist in deflection of the aft-most air flow. As shown inFIGS. 3B and 5, the deflector portion126of one embodiment of the aft cascade ring120can generally extend in the forward direction from the outer edge of the body portion122. The deflector portion126can extend at an angle “θ” relative to the body portion122. In the embodiment shown, the angle “θ” between the deflector portion126and the body portion122is less than 90 degrees. In one embodiment, the angle “θ” is between about 60 degrees and about 90 degrees, though angles less than 60 degrees may also be used. In one embodiment of the aft cascade ring120, the deflector portion126can have a substantially frusto-conical shape having a largest diameter at its forward edge. Alternatively, the deflector portion126can have other shapes, such as a substantially arcuate shape. This deflector portion126also can be of an extended length, and generally is of a length greater than the deflector portion112of the flow deflection shelf110against which it is mounted so as to substantially overlap the deflector portion112of the flow deflection shelf110and further help direct the aft-most airflow forwardly during a reverse thrust operation.

In an additional embodiment of the cascade assembly100illustrated inFIGS. 4A and 4B, a flow deflection shelf210can be mounted along an intermediate portion211of an associated cascade segment102, spaced axially forward of the aft-most vanes of the cascade segment and the aft cascade ring120. In this embodiment, the flow deflection shelf210can include a deflector portion212that is mounted to the upper ends of an intermediate vane213of its associated cascade segment, or, alternatively, can be integrally formed as a unitary structure with the intermediate vane, wherein the intermediate vane213defines a body portion of the flow deflection shelf. In this embodiment, the deflector portion212of each flow deflection shelf210generally will comprise a substantially longitudinally oriented shelf or projection that will extend forwardly, at least partially overlying or covering the intermediate cells or flow passages214located directly in front of the flow deflection shelf. The deflector portion212is preferably integral with the intermediate vanes213and redirects at least a portion of the volume of an airflow215passing therethrough in a forward direction. Additionally, in the construction of the flow deflection shelf wherein the flow deflection shelf is integrally formed with the intermediate vane213of its associated cascade segment, the flow deflection shelf can also include a substantially straight, vertically extending body portion or wall as well.

As further illustrated inFIG. 4B, each cascade segment102typically can include a substantially flat rear wall portion220, which can be formed from a light weight material, and to which the aft cascade ring120is attached via fasteners221, with the fasteners generally being oriented in a shear loading arrangement. The deflector portions of the flow deflection shelves for each of the cascade segments will extend laterally across their associated cascade segments, and will be arranged in a substantially flush mounting against the upper edges of the rails and intermediate vanes. The ends of these deflector portions can be connected in series so as to define or help provide a supporting hoop structure that extends about the cascade segments. Such a construction provides enhanced structural continuity for the attached cascade segments, effectively forming a structural band or hoop that can help tie the cascade segments together. By providing this additional frame continuity or hoop structure for the cascade segments, the aft cascade ring can be reduced in size and thus reduced in weight as some of the structural load for maintaining the cascade segments connected in series is being taken up by the flow deflection shelf. Such reduction in size and weight of the aft cascade ring can offset any further weight from the addition of back wall sections of the cascade segments to which the aft cascade ring is attached.

Still further, it will be understood by those skilled in the art that a plurality of flow deflection shelves can be used with the cascade segments formed according to the principles of the present invention. For example, a first flow deflection shelf can be mounted at the aft end of its associated cascade segment, as illustrated inFIGS. 3A and 3B, to provide a substantially flat connection surface for the aft cascade ring and provide the desired redirection of the air flowing through the aft-most cells or air passages114. In addition, one or more additional flow deflection shelves can be mounted at various intermediate locations along the length of the cascade segments, with these additional flow deflection shelves generally being spaced forwardly from the aft mounted flow deflection shelf. The use of the intermediate flow deflection shelves further can provide the desired enhancements in structural hoop continuity for the cascade array, while additionally enabling the flow deflection shelves and/or the aft cascade ring to be made from light weight materials to help reduce the overall weight of the cascade assembly, without an undesirable reduction in the structural strength and hoop continuity of the attached cascade segments.

The use of one or more flow deflection shelf110according to the principles of the present invention thus can help minimize the weight of the cascade assembly, by enabling the thickness or thicknesses of the body portion122, the inner portion124, the outer portion126, and any other portions of the aft cascade ring to be substantially minimized. The present invention further can facilitate the use of varied configuration and size aft cascade rings that can further help substantially reduce the length and weight of the cascade assembly100. In addition, the cross-sectional shape of the aft cascade ring120can be configured to provide adequate stiffness against bending and twisting, while also minimizing weight. For example, the aft cascade ring120can be constructed of composite materials in a single piece using known composite fabrication processes. Alternatively, the aft cascade ring120can be constructed of strong and lightweight material or combination of materials, such as aluminum, titanium, composites or the like, and also can be constructed in a single piece, or fabricated by joining multiple pieces or sections together.

The embodiments of the invention described above are intended to illustrate various features and aspects of the invention. Persons of ordinary skill in the art will recognize that various changes and modifications can be made to the described embodiments without departing from the invention. For example, though various embodiments of an aft cascade ring have been described as having particular cross sectional shapes and specific portions, an aft cascade ring according to the invention can include various cross sectional shapes and/or portions that are different from the specifically described embodiments. All such changes and modifications are intended to be within the scope of the appended claims.