Cavity Acoustic Tone Suppression

Abstract

A cavity system for use in a vehicle is provided. The cavity has leading and / or trailing edges and longitudinal edges. The leading and / or trailing edges and longitudinal edges define an opening. The cavity comprises at least one elongated flow partition projecting from a surface adjacent each longitudinal edge of the cavity into a flow around the exterior of the cavity. The at least one flow partition comprises an interior surface facing primarily toward the cavity and an exterior surface facing primarily away from the cavity. An aircraft comprising the cavity system is also provided.

Description

[Technical field]

[0001] VEHICLE CAVITY SYSTEM FIELD OF THE DISCLOSURE The present invention relates to a cavity system for use in a vehicle. Exemplary vehicles include aircraft, and thus exemplary cavities include cavities in bays such as weapons bays and landing gear bays. [Background technology]

[0002] When a cavity is moving through a surrounding fluid, for example an aircraft bay moving through the air, a shear layer is formed between the moving surrounding air and the still air in the cavity (from the reference point of the aircraft). The shear layer is a thin region of concentrated vortex motion with a large change in tangential velocity component, located across the top of the bay, separating the high-speed and low-speed flows. The vortices shed from the front edge of the cavity and grow as they travel down the shear layer, impinging on the rear wall of the bay and causing noise emissions. The sound wave also returns upstream inside the bay. The pressure fluctuations of the sound wave can either cause vortices to shed from the cavity lip at the front edge or increase the rate of vortex growth, so that a series of vortices form down the shear layer at a favorable velocity related to the frequency of the upstream sound wave. The vortices grow into large-scale structures as they propagate downstream in the shear layer and then impinge on the rear wall of the bay at a characteristic velocity. This results in an acoustic noise being generated at a characteristic rate that can be described as an acoustic tone of a characteristic frequency.

[0003] These flow structures are difficult to predict and simulate. Similar problems are found in other types of vehicles, such as high performance automobiles with open roofs or windows, or marine vessels with open hatches where impinging wind velocities are high.

[0004] In aircraft, it is known to use spoiler arrangements to redirect the airflow above and beyond the cavity, i.e. above and beyond any boundary layers or expected shear layers, so that the effects described above do not occur. These spoilers are deployed either in front of the cavity or across it.

[0005] Cross flow (ie, transverse or lateral flow) also contributes to acoustic noise in the cavity and has been found to be unmitigated using existing spoiler designs.

[0006] Therefore, there is a need for a lightweight mitigation mechanism to reduce or control the effects of acoustic noise in a cavity caused by cross-flow. Summary of the Invention

[0007] According to a first aspect, there is provided a cavity system for use in a vehicle, the cavity system comprising: a cavity having a leading edge and / or a trailing edge and a longitudinal edge, wherein the leading edge and / or the trailing edge and the longitudinal edge define an opening; at least one elongated flow partition protruding from a surface adjacent each longitudinal edge of the cavity into a flow around the exterior of the cavity, wherein the at least one flow partition has an inboard surface facing primarily toward the cavity and an outboard surface facing primarily away from the cavity; Equipped with.

[0008] Advantageously, the presence of the flow divider tends to reduce the acoustic noise effects by lifting the shear layer above the cavity. Additionally, the simple design tends to swirl along the sides of the cavity, which provides some stability to the outer edges of the cavity flow, potentially maintaining the higher shear layer for longer than can be achieved with conventional spoilers.

[0009] The longitudinal edge may be parallel to the actual or intended direction of travel of the vehicle.

[0010] The inner surface may be parallel to the longitudinal edges of the cavity. Alternatively, the inner surface may be angled relative to the cavity. The inner surface may be at an angle of about 5 degrees to 45 degrees relative to the longitudinal edges of the cavity. More preferably, the inner surface may be at an angle of about 10 degrees to 25 degrees relative to the longitudinal edges of the cavity.

[0011] The cavity system may comprise a bay having a front wall, a rear wall, and at least one side wall, the top surfaces of the front wall, rear wall, and at least one side wall may comprise a leading edge, a trailing edge, and a longitudinal edge, respectively. There may be one continuous side wall, or two side walls joined by a bottom surface. The bay may be a rotating payload bay. Alternatively, the bay may be a fixed payload bay with at least one hinged door across an opening.

[0012] The at least one flow divider may protrude from an upper surface of the at least one sidewall. Alternatively, the at least one flow divider may protrude from an outer skin of the vehicle surrounding the cavity.

[0013] At least one flow partition may comprise a plurality of open flow passages between the inboard and outboard surfaces. The flow passages may be cylindrical with a circular cross section. Alternatively, the flow passages may be tessellated with one another. The flow passages may form a honeycomb structure. The flow passages may be hexagonal in cross section.

[0014] The inboard and / or outboard surface of the at least one flow divider may be non-planar. The inboard and / or outboard surface may be formed of a plurality of individual panels joined together at an oblique angle. The inboard and / or outboard surface may have a sawtooth or zigzag configuration. The inboard and / or outboard surface may be arcuate. The inboard and / or outboard surface may comprise a series of adjacent concave and convex surfaces.

[0015] The top surface of the at least one flow divider may be undulating in a vertical plane (i.e., undulating in height or variable in height). The top surface may comprise a sawtooth, zigzag, or sinusoidal shape. The top surface may comprise a square wave shape. The top surface may comprise at least one impact stabilizer.

[0016] The cavity system may include at least one impact stabilizer disposed on each side of the cavity to protrude into the surrounding flow. The cavity system may include multiple pairs of impact stabilizers, the impact stabilizers within each pair disposed on opposite sides of the cavity. The impact stabilizers within each pair may be offset from one another along a longitudinal axis of the flow divider.

[0017] The at least one impact stabilizer may be disposed on a top surface of the at least one flow partition. Alternatively, the at least one impact stabilizer may be disposed adjacent to an outboard surface of the at least one flow partition. The at least one impact stabilizer may be coupled to the outboard surface of the at least one flow partition. The at least one impact stabilizer may be integrally formed with the at least one flow partition.

[0018] Each impact stabilizer may include a plurality of peaks. The peaks may be sharp tips.

[0019] At least one impact stabilizer may have first and second outboard surfaces generally facing away from the cavity, the first and second outboard surfaces being inclined relative to one another about a horizontal axis of the impact stabilizer. The impact stabilizer may have an inboard surface facing toward the cavity, the first and second outboard surfaces may be coupled to respective edges of the inboard surface of the impact stabilizer or to the outboard surface of the at least one flow partition. The inboard surface of the impact stabilizer may be vertical. Alternatively, the inboard surface may be disposed at an angle relative to a vertical plane.

[0020] The inboard surface of the impact stabilizer may be angled relative to the longitudinal edge of the cavity such that the distance between the inboard surface and the cavity increases with distance along the impact stabilizer. Alternatively, the inboard surface of the impact stabilizer may be disposed parallel to the longitudinal edge of the cavity.

[0021] The first and second outboard faces may be inclined relative to one another about horizontal and vertical axes of the impact stabilizer. The inboard face may be trapezoidal or triangular.

[0022] The cavity system may include a third outboard surface disposed between the first outboard surface and the second outboard surface. The third outboard surface may be rectangular, square, or trapezoidal in shape.

[0023] At least one impact stabilizer may include a straight upper edge that is angled toward the bottom surface of the impact stabilizer such that the height profile of the impact stabilizer decreases along its length. Instead of a straight upper edge, the impact stabilizer may include a pointed tip. The impact stabilizer may be pyramidal in shape.

[0024] At least one impact stabilizer may include a straight upper edge angled away from a vertical plane passing through the edge of the cavity so that the upper edge has increasing separation from the longitudinal edge of the cavity along its length. The straight upper edge may be angled away from the vertical plane and toward a bottom surface of the impact stabilizer.

[0025] The top edge of the at least one impact stabilizer and the longitudinal edge of the cavity may be positioned such that an angle between 5 degrees and 45 degrees is formed therebetween. More preferably, an angle between 10 degrees and 25 degrees is formed between the top edge of the at least one impact stabilizer and the longitudinal edge of the cavity. Even more preferably, an angle between 15 degrees and 20 degrees is formed between the top edge of the at least one impact stabilizer and the longitudinal edge of the cavity.

[0026] A top edge of the impact stabilizer may be disposed at an angle relative to a bottom edge of the inboard and third outboard surfaces such that the third outboard and inboard surfaces are twisted about a vertical axis.

[0027] At least one impact stabilizer may have an outboard surface facing generally away from the cavity, a front surface facing toward the actual or intended direction of travel of the vehicle, and a rear surface facing away from the actual or intended direction of travel of the vehicle, the front surface being concave in shape such that the impact stabilizer forms a bevel with respect to fluid flow approaching the actual or intended direction of travel of the vehicle. The front surface may be oriented to face the actual or intended direction of travel of the vehicle at an angle of between 5 and 20 degrees. More preferably, the front surface may be oriented to face the actual or intended direction of travel of the vehicle at an angle of between 5 and 10 degrees.

[0028] The cavity system may include a motor for driving the at least one impact stabilizer to be raised or lowered from or to a surface adjacent a longitudinal edge of the cavity. The surface may include at least one recess for receiving the at least one impact stabilizer. The recess may have a cover for closing the recess when the at least one impact stabilizer is stored.

[0029] The at least one impact stabilizer may be between 2cm and 20cm in height. The at least one impact stabilizer may be between one boundary layer thickness and six boundary layer thicknesses in height. Preferably, the at least one impact stabilizer is between 3cm and 15cm in height. More preferably, the at least one impact stabilizer is between 4cm and 12cm in height. More preferably, the at least one impact stabilizer is between 5cm and 10cm in height.

[0030] The cavity system may include three to six impact stabilizers disposed on either side of the cavity. Preferably, the cavity system includes four impact stabilizers disposed on either side of the cavity.

[0031] The impact stabilizers may be arranged in pairs, with one impact stabilizer of each pair being located on the opposite side of the cavity relative to the other. In other words, the cavity system may include multiple pairs of impact stabilizers, with the impact stabilizers in each pair being located on opposite sides of the cavity. Both impact stabilizers in a pair may be located at an equal distance from the end of the longitudinal edge of the cavity. Alternatively, the pairs of impact stabilizers may be staggered along the length of the cavity, with a first pair of each pair being a first distance from the end of the longitudinal edge and a second pair of each pair being a second distance from the end of the longitudinal edge. Each pair of impact stabilizers may be spaced apart at an equal distance.

[0032] The inboard surface of at least one flow partition may be at an acute angle to the longitudinal edge of the cavity. In other words, the flow partition may increase in distance from the edge of the cavity along the length of the flow partition from front to rear. Alternatively, the inboard surface may be parallel to the longitudinal edge of the cavity.

[0033] At least one flow partition may be between 2 cm and 20 cm high. More preferably, at least one flow partition is between 3 cm and 15 cm high. Even more preferably, at least one flow partition is between 3.5 cm and 12 cm high.

[0034] The cavity system may include a motor for driving at least one flow partition to raise or lower from or to a surface adjacent a longitudinal edge of the cavity.

[0035] Alternatively, the cavity system may include a motor and at least one flow partition may include a hinge, the motor configured to drive the at least one flow partition to rotate about the hinge to selectively position it in the surrounding flow or to position it so as to rest against a surface adjacent the cavity.

[0036] The cavity system may include transverse spoilers disposed across or in front of the cavity relative to the actual or intended direction of travel of the vehicle. The transverse spoilers may be disposed orthogonal to at least one flow partition.

[0037] The cavity system may include a releasable payload, which may be an ordinal such as a bomb or a missile.

[0038] According to a second aspect, there is provided an aircraft comprising a cavity system according to any one of claims 1 to 16. The cavity may be a weapons bay.

[0039] It will be appreciated that features described in relation to one aspect of the disclosure can be incorporated into other aspects of the disclosure. For example, the apparatus of the disclosure can incorporate any of the features described in the disclosure with reference to the method, and vice versa. Moreover, additional embodiments and aspects will become apparent from the following description, drawings, and claims. As can be appreciated from the foregoing and following description, any and all features described herein, and any and all combinations of two or more of such features, and any and all combinations of one or more values ​​defining ranges, are included within the present disclosure, unless the features included in such combinations are mutually inconsistent.

[0040] Embodiments will now be described, by way of non-limiting examples, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0041] [Figure 1] FIG. 2 illustrates a perspective view (not to scale) of a rotating payload bay having a cavity partition system according to an embodiment. [Diagram 2] FIG. 1 is a perspective view (not to scale) of a rotating payload bay having a cavity partition system according to another embodiment. [Diagram 3]FIG. 1 is a perspective view (not to scale) of a rotating payload bay having a cavity partition system according to another embodiment. [Figure 4a] FIG. 2 is a schematic diagram of the aircraft with rotating payload bay of FIG. 1 in a closed configuration. [Figure 4b] FIG. 2 is a schematic diagram of the aircraft with rotating payload bay of FIG. 1 in an open configuration. [Figure 5a] 1 is a cross-sectional view of a cavity divider according to an embodiment. [Figure 5b] 1 is a cross-sectional view of a cavity divider according to an embodiment. [Figure 6a] 11A-11C are perspective views of different designs of cavity divider surface geometries according to embodiments. [Figure 6b] 11A-11C are perspective views of different designs of cavity divider surface geometries according to embodiments. [Figure 6c] 11A-11C are perspective views of different designs of cavity divider surface geometries according to embodiments. [Figure 6d] 11A-11C are perspective views of different designs of cavity divider surface geometries according to embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] The same reference numbers are used throughout to denote features of like purpose.

[0043] It will be appreciated that relative terms such as horizontal and vertical, top and bottom, above and below, front and rear, etc., are used above merely for ease of reference to the figures, and that these terms are not so limiting, and that any two different orientations or positions, etc., may be realized, rather than truly horizontal and vertical, top and bottom, etc. In particular, for convenience, in FIG. 1, the cavity is shown opening to the top of the page, and therefore, for convenience, the word "top" is used to mean the opening of the cavity, and the word "above" means further away from the cavity. However, it will be appreciated that the present disclosure also refers to cavities positioned, for example, under the wing or fuselage of an aircraft, i.e., upside down from that shown in FIG. 1, but the descriptive use of the word "top" still refers to the opening of the cavity, and the descriptive use of the word "above" still refers to being away from the cavity.

[0044] Cavities are typically accompanied by doors that partition the cavity flow into any external cross-flows. Doorless cavities do not consider partitioning the cavity flow into external cross-flows or using external flows to support a shear layer over the length of the cavity.

[0045] In general, embodiments relate to the use of longitudinal cavity fences to partition the external cross-flow from the unsteady flow of the cavity. These fences, or dividers, are elongated and positioned along and parallel to the longitudinal sides of the cavity, rather than at the front or back of the cavity.

[0046] 1 is a perspective view of a bay 100 (specifically a payload bay) having flow dividers 7a, 7b (generally 7) according to an embodiment. The bay 100 is illustrated for housing a payload 5, such as a missile or camera system, but it will be appreciated that in use the bay 100 may be empty or may be a recess in the structure. The payload 5 may be a deployable payload or an ordinate that is released from the bay 100.

[0047] The bay 100 comprises a cavity 2. The cavity 2 is defined by the inner surfaces of the walls of the bay 100. In use, the bay 100 has a fluid (e.g. air) passing through it, such that a main flow 3 of the fluid acts in a direction opposite to the actual or intended direction of movement of the bay 100. The bay 100 comprises a front (i.e. front) wall 8, a rear (i.e. rear) wall 10, and two side walls 12a, 12b (generally 12) defined relative to the actual or intended direction of the main flow 3. In the illustrated embodiment, the cavity 2 comprises a rectangular planar base 1 and has a rectangular opening (i.e. aperture). The side walls 12 and the rear wall 10 are perpendicular to the planar base 1, and the front wall 8 is angled relative to the base 1 such that the opening has a circumference greater than the circumference of the base 1. Each wall 8, 10, 12 has a respective upper surface, one edge of each of which defines a front edge 14, a rear edge 16 and side edges 18a, 18b (generally 18) of the cavity 2, i.e. the edges 14, 16, 18 of the cavity 2 define an opening to the cavity 2. The upper surface of each of the walls 8, 10, 12 is coplanar.

[0048] In the illustrated embodiment, the side walls 12 are shown as being longer than the front and rear walls 8, 10, although this may not be the case in other embodiments. For example, the cavity 2 may be relatively wide transversely (i.e., perpendicularly) to the direction of the main flow 3. In these embodiments, references below to "longitudinal edges" should be interpreted as "transverse edges", i.e. edges parallel to the direction of the main flow 3.

[0049] The bay 100 is a rotational bay having an axis of rotation 4. In the illustrated embodiment, the axis of rotation 4 is aligned with a central longitudinal axis of the bay 100. In other embodiments, the bay 100 may rotate about an axis that is offset to one side of the bay 100, for example, along a side edge 18 of the bay 100.

[0050] The bay 100 is driven to rotate about a pivot point 6 through which the axis of rotation 4 passes. As illustrated in Figures 4a and 4b, the bay 100 may be driven to rotate by a motor 9. The bay 100 rotates to expose the payload 5 to a surrounding flow (e.g., a surrounding air flow).

[0051] In use, there will be a cross-flow 13 acting on the bay 100. The cross-flow 13 is illustrated as being perpendicular to the actual or intended direction of travel of the bay 100 for purposes of defining the shapes and angles of the components of the bay 100, i.e., the cross-flow 13 is illustrated as being perpendicular to the main flow 3. However, in reality the cross-flow will approach the bay 100 over a range of angles.

[0052] One flow divider 7 is disposed on each side of the cavity 2 (i.e., parallel to the two longitudinal edges 18). In an alternative embodiment, the flow divider 7 is disposed on only one side of the cavity 2, which is less preferred. The flow divider 7 may extend over the entire length of the cavity 2, i.e., along the entire length of the longitudinal edges 18. In an alternative embodiment, the flow divider 7 may be shorter than the length of the cavity 2. For example, the flow divider 7 may be about half the length of the cavity 2 and may be centrally located along the length of the edges 18. More preferably, the forward edge of the flow divider 7 is aligned with the forward edge 14 of the cavity 2. Preferably, the flow divider 7 may extend to cover at least three-quarters (3 / 4) of the length of the cavity 2.

[0053] There may be more than one flow partition 7 along one side of the cavity 2. These multiple flow partitions 7 may be coaxial with each other.

[0054] Although the upper edge of each flow divider 7 is shown as being straight and parallel to the longitudinal edge 18 of the cavity 2 (i.e., with no slope or decline relative to the plane of the surface to which the flow divider is attached), in alternative embodiments, the flow dividers 7 may vary in height along their length. For example, the flow dividers may decrease in height from the front to the trailing edge 16 of the cavity 2 relative to the top surface of the sidewall 12.

[0055] The maximum height (i.e. vertical extent) of the flow partition 7 may be selected according to the geometric shape of the cavity 2. However, the maximum height of the flow partition 7 is in the order of about 3 cm to 20 cm.

[0056] The pattern along the longitudinal axis of the flow partition 7 may be uniform, i.e., zigzag with base triangles of constant width and length, or alternatively, the pattern along the longitudinal axis may be non-uniform, such as by having an odd number of protrusions at random locations.

[0057] The flow divider 7 has an inboard surface facing towards the cavity 2 (i.e., primarily towards the cavity 2, not primarily away from the cavity 2) and an outboard surface facing towards the impinging cross-flow (i.e., primarily towards the cavity 2, not primarily away from the cavity 2). The inboard surface is illustrated as being flush with the inner surface of the sidewall 12 of the cavity 2. In an alternative embodiment, the inboard surface of the flow divider 7 is positioned between 0 and 0.05 times the length of the cavity 2 from the cavity edge 18.

[0058] The inner surface is illustrated as being parallel to the longitudinal edge 18 of the cavity. In other embodiments, the flow divider 7 may be angled relative to the edge 18 of the cavity 2 such that an angle of up to 45 degrees is formed between the edge and the plane of the inner surface along its entire length. More preferably, an angle of about 20 degrees is formed between the plane of the inner surface and the edge 18. This means that the front of the flow divider 7 is closer to the cavity edge 18 than the rear of the flow divider 7.

[0059] The flow partitions 7 have a thickness (i.e., lateral extent) of 5 mm to 25 mm. While the flow partitions 7 in the illustrated embodiment have a constant thickness, in alternative embodiments, the flow partitions 7 may vary in thickness along their length. Thus, in cross section viewed from above, the flow partitions 7 may have an undulating shape (e.g., zigzag, sinusoidal, or stepped or tapered). In other words, the flow partitions 7 may have curved (i.e., non-planar, undulating) inboard and / or outboard surfaces. The inboard surface of the flow partition 7 may match the contour of the outboard surface, or one may be planar while the other may be undulating.

[0060] The inboard and outboard surfaces of the flow partition 7, in the illustrated embodiment, are continuous planes and extend from the surface to which the flow partition 7 is attached to the maximum height of the flow partition 7. In other words, the flow partition 7 resembles a solid wall.

[0061] The flow divider 7 can be made of any material that has sufficient strength to withstand high speed free stream flow and high noise. For example, the flow divider 7 can be made of titanium or composite materials such as carbon fiber. Alternatively, the flow divider 7 can be formed of plastic or aluminum. The flow divider 7 can be made of the same material as the skin of the vehicle to which it is attached. The flow divider 7 can be formed of gauze or mesh.

[0062] Although the flow dividers 7 are shown as protruding from or attached to the top surface of the sidewalls 12, in embodiments where the cavity 2 is an aperture in the skin of the vehicle, the flow dividers may protrude from or be attached to the skin. The flow dividers 7 may be integrally formed with the skin of the vehicle or the sidewalls 12 of the bay 100. The flow dividers 7 form a seal with the top of the cavity walls 12 or adjacent skin to prevent external cross-flow 13 from leaking into the cavity 2.

[0063] In one embodiment, each flow partition 7 includes a hinge. The hinge is positioned to allow the flow partition 7 to pivot about its longitudinal axis, so that in the stowed configuration, the flow partition 7 does not substantially protrude into the cross-flow 13, and in the deployed configuration, the flow partition 7 extends into the cross-flow 13. In the stowed configuration, the flow partition 7 lies flat against the upper surface of the sidewall 12 or the skin of the vehicle. In other words, the inboard or outboard surface of the flow partition 7 is flush with the upper surface of the sidewall 12 or the skin of the vehicle. In the deployed configuration, the flow partition 7 is positioned as illustrated in FIG. 1. The pivot axis of the hinge may be coaxial with the axis of the edge 18 or may be within the cavity 2, such that in the stowed configuration, the flow partition 7 folds into the cavity 2. The flow divider 7 may instead be slidably attached to the inner surface of the cavity wall 12 so that the flow divider 7 can be slid to protrude into the cross-flow 13 .

[0064] The hinge or sliding mechanism may be motorised, may be mechanically actuated by the movement of the door covering the cavity 2, or may be spring loaded.

[0065] Although not shown, in the preferred embodiment, a conventional front edge 14 relief design is also located across the transverse axis of the cavity 2 .

[0066] The presence of the flow divider 7 tends to help lift the shear layer above the cavity 2, i.e., giving the shear layer a greater reach and reducing its impact on the equipment and payload 5 within the cavity. This prevents the external cross-flow 13 from interfering with the cavity flow circulation, thus removing a layer of uncertainty within the cavity flow, i.e., the cavity flow circulation is driven solely by the shear layer and external influences are removed. Similarly, the simple design provides some stability to the outer edges of the cavity flow, providing for a vortex to roll along the sidewalls 12 of the cavity 2, along with the possibility of sustaining a higher shear layer potentially for longer. Additionally, this vortex will further assist in blocking the external cross-flow 13 entering the cavity 2.

[0067] 2 illustrates another example of a bay 100 with flow partitions 7 according to an embodiment. Here, each flow partition 7a, 7b (generally 7) comprises a series of perforations 9 (i.e. holes) extending across the entire width of the flow partition 7. The perforations may be between 0.5 cm and 2 cm in diameter. Preferably, the perforations 9 are between 1 cm and 1.5 cm in diameter. More preferably, the perforations 9 are at most 0.5 boundary layer lengths in diameter.

[0068] The perforations 9 may comprise elements that extend into the main flow 3. In other words, the perforations 9 may extend laterally from the outboard surface of the flow divider 7.

[0069] The perforations 9 may be randomly distributed over the surface of the flow partition 7 .

[0070] Although the perforations 9 are illustrated as having a circular cross-section, in other embodiments the perforations 9 may have alternative cross-sections such as hexagonal, triangular, or square. The perforations 9 may be tessellated or may form a honeycomb structure within the flow partition 7.

[0071] In another embodiment, one flow divider 7 may take the shape illustrated in FIG. 2 and the other flow divider 7, if present, may take the shape described with reference to FIGS.

[0072] In general, it will be appreciated that any non-uniformity introduced into the shape of one or more of the individual perforations 9, and / or between one or more of the different perforations 9, and / or their relative arrangement / location, etc., will tend to provide a potential change in the source or increase in the number of fine-scale turbulence, with a corresponding increase in the number of small eddies, and / or thicker shear layers, and / or an increased breakdown in the temporal coherence of the small eddies. Any such effects may further improve the suppression performance of the bay 100.

[0073] 3 illustrates a flow divider 7 used in conjunction with multiple impact stabilizers. In the illustrated embodiment, four impact stabilizers 7 are positioned to protrude from each side of the bay 100 into the surrounding surrounding flow when in use. Impact stabilizers 15 are disposed on the upper surface of the sidewall 12. Impact stabilizers 15 are not disposed forward of cavity 2 as defined by leading edge 8.

[0074] In the preferred embodiment illustrated, the impact stabilizers 15 are positioned such that one side of each is parallel to the outboard surface of the flow partition 7. In other embodiments, the impact stabilizers 15 are offset laterally from the flow partition 7.

[0075] Since the impact stabilizer 15 will interact with high energy currents when installed in the fighter aircraft 400, suitable materials of construction include titanium, steel, or composites such as carbon fiber composites. The impact stabilizer 15 may be made of the same material as the skin of the vehicle in which the bay 100 is installed. If the bay 100 is installed in an environment with reduced flow velocities and energies, such as in a low performance automobile, materials that are not known for their strength or life characteristics, such as plastics, may be used.

[0076] As will be explained in more detail when discussing Figures 5a and 5b, the impact stabilizer 7 may be integrated into the upper surface of the flow divider 7.

[0077] Further designs of the impact stabilizer 15 are explained later with reference to Figures 6a-6d. In Figure 3, the impact stabilizer 15 takes the shape of a pyramid with a triangular base, i.e. a right-angled pyramid. One side (i.e. an edge) of the triangular base is arranged parallel to the outboard surface of the flow partition 7. One face of the pyramid is formed by the outer surface of the flow partition 7. Two triangular panels (i.e. right-angled triangular shaped panels) are inclined towards the cavity 2 and connected to the outboard surface of the flow partition 7 and to each other. The impact stabilizer 15 may be open-bottomed, such that the "bottom surface" described above is the periphery of the opening.

[0078] The two triangular panels generally facing towards the impinging cross-flow 13 (i.e. away from the cavity 2) are preferably positioned at an angle of 15-70 degrees to the cross-flow 13. In other words, the bottom surface has two edges positioned at an angle of 20-75 degrees to the axis of the flow divider 7.

[0079] The height of the impact stabilizer 15 is preferably between 4 cm and 20 cm in height, preferably between 6 cm and 12 cm in height. The width and depth of the impact stabilizer 15 is preferably in the range of 2 cm to 20 cm. The impact stabilizer 15 may have a shape thickness that may be constant, tapered, or irregular.

[0080] The spires (i.e., pointed tips) on the top of the impact stabilizer 15 tend to increase the flow in cavity 2 through means of inducing vortices. The latter tend to help suppress shear layer acoustic effects. Flow mixing is the introduction of new flow components with different direction, circulation, and / or energy to existing flow structures.

[0081] The impact stabilizer 15 utilizes the energetic cross-flow 13 to energize the shear layer and generate an impact at the foot (i.e., bottom) of the impact stabilizer 15. Therefore, it is advantageous to increase the surface area of ​​the impact stabilizer 15 that faces towards the impinging cross-flow 13.

[0082] The shock stabilizers 15 in the described embodiment are essentially vortex generators. Vortex generators are traditionally used to maintain areas of attached flow to support vehicle control surfaces (i.e., whereby the boundary layer has a positive velocity profile from the surface to the free stream flow). They have not been considered to aid mixing within the flow system of the cavity 2. The shock stabilizers 15 induce a stationary shock that tends to reposition the shear layer to a higher position above the cavity 2, stabilizing the area of ​​unsteady flow (i.e., the shear layer moves away so that it does not penetrate into the cavity 2). Unsteady flow is a highly non-linear and turbulent flow. A stationary shock tends to make the effect of the unsteady flow system beyond the shear layer more uniform and consistent. In turn, it allows for better prediction of the flow's impact on the payload 5 in the cavity 2 or structures adjacent to the cavity 2.

[0083] Additionally, these systems of shock stabilizers 15 tend to reduce the effect of transient shocks on the payload 5 immediately after release from the cavity 2, either by eliminating the transient shocks or by limiting their movement. The shock stabilizers 15 introduce shocks at a transient position relative to the plane of the opening of the cavity 2, which has the desired effect of either eliminating the transient shocks or subjecting them to excessive force, ensuring that they have little effect on the dropped payload 5.

[0084] The shock generated by the shock stabilizer 15 has a fixed position in the volume above the cavity 2. Thus, the released payload 5 interacts with the shock generated by the shock stabilizer 15 at a known position in the flow volume. Without the shock stabilizer 15, expansion (a form of shock where the flow is accelerated as opposed to compression where the flow is decelerated) may result from undulations in the shear layer and may transition in the horizontal plane (i.e., across the opening of the cavity 2). Thus, the location of these perturbations / oscillations, or even temporary shocks, makes it difficult to predict where the payload 5 will interact with the shock in the surrounding flow outside the cavity 2.

[0085] Application of the described impact stabilizer 15 therefore tends to aid in the release of the payload 5 and reduces deleterious acoustic effects in the cavity flow by inducing mixing.

[0086] A conventional spoiler for deflecting the fluid flow and thus raising the shear layer may also be present in the region of the leading edge 14 of the cavity 2. For example, a spoiler may be located forward of the leading edge 14. A conventional spoiler is generally disposed across the cavity 2, i.e., along a transverse axis relative to the impinging main flow 3.

[0087] The four impact stabilizers 15 are illustrated as being equidistantly spaced along the length of the cavity 2. However, in other embodiments, the impact stabilizers 15 may be irregularly spaced. At a minimum, the impact stabilizers 15 are spaced a distance apart equal to the maximum height of the impact stabilizers 15.

[0088] Although four impact stabilizers 15 are illustrated on each side of the cavity 2, in other embodiments, there may be one or more impact stabilizers 15 on each side of the cavity 2. Preferably, there are between three and six (inclusive) impact stabilizers 15 on each side of the cavity 2. However, in some embodiments, there may be more impact stabilizers 7 on each side of the cavity 2, for example, up to 20 on each side. The impact stabilizers 15 on one side 12 of the cavity 2 are illustrated as being positioned diametrically opposite, i.e., the same distance from the front edge 14 of the cavity, as the impact stabilizers 15 on the other side 12 of the cavity 2. In other embodiments, the impact stabilizers 15 on opposing sides 18 of the cavity 12 are not positioned opposite one another, i.e., they may be offset from one another along the longitudinal axis of the bay 100.

[0089] 4a-4b, the operation of the bay 100 will now be described. Here, a fighter aircraft 400 having the bay 100 is illustrated, however, it will be appreciated that the bay 100 may be installed in other forms of vehicles. The bay 100 is shown in cross section, with the remainder of the aircraft 400 shown in schematic form.

[0090] 4a shows the bay 100 in a closed configuration, where the side of the bay 100 having the opening, i.e. the aperture defined by the edges 14, 16, 18 of the cavity 2, faces the inside of the aircraft 400. The exterior surface of the base 1 of the bay 100 faces towards the surrounding atmosphere outside the aircraft 400.

[0091] The bay 100 is shown installed in the belly of the fuselage of the aircraft 400. The bay 100 may alternatively be installed in the shoulder of the fuselage or in a wing of the aircraft 400.

[0092] The shaft 11 couples the bay 100 to the motor 9 at the pivot point 6. The motor 9 is, for example, an electric motor. When actuated, the motor 9 drives the shaft 11 to rotate, thereby opening or closing the bay 100. In other embodiments, the motor 9 may be directly coupled to the pivot point 6. Again, in other embodiments, the bay 100 may comprise a motor 9 mechanically coupled to a fixed point in the body of the aircraft 400. In use, the bay 100 may be configured to extend into the surrounding flow or to retract into the interior of the aircraft 400 before rotating to the open configuration. The bay 100 may translate and rotate simultaneously. Alternatively, the bay 100 may be configured to rotate about only one axis 4.

[0093] The outer edge of the bottom surface 1, when in the closed configuration, may form a relatively tight seal with the skin of the aircraft 400 surrounding the bay 100. The bottom surface 1 may extend beyond the shape defined by the outer surfaces of the walls 8, 10, 12 of the bay 100. In other words, the outer surface of the bottom surface 1 may conform to the skin of the aircraft 400.

[0094] 4b illustrates the bay 100 in an open configuration, where the motor 9 drives and rotates the bay 100 such that the opening of the cavity 2 faces towards the surrounding atmosphere, exposing the payload 5. The flow dividers 7 coupled to the side walls 18 of the bay 100 are therefore shown protruding into the surrounding airflow.

[0095] It will be appreciated that the particular design features will depend on the cavity system and its operating environment, ie, air, land, or sea.

[0096] 5a and 5b illustrate a further modification to the flow partition 7 illustrated in Figs. 1-3. Here, the flow partition 7 comprises a body 72 and a series of undulations 71 at the top of the body 72 (i.e., the undulations 71 form the top edge shape of the flow partition 7 and vary in the vertical plane). In other words, the flow partition 7 has a variable height along its length. These undulations 71, particularly in the form of teeth, tend to act as additional sources of fine-scale turbulence that give rise to even smaller vortices and therefore tend to provide even further loss of temporal coherence. This acoustically reduces the effect of dispersing the shear layer for situations where high-energy flows would cause the flow partition 7 to arch. In other words, the undulations 71 act as an impact stabilizer 15 as described with reference to Fig. 3. By providing an undulating shape at the top edge of the flow partition 7, the effect of the flow partition 7 in lifting the shear layer is improved.

[0097] In other words, the undulations 71 impart a disturbance or change to the direction of the cross-flow 13, deflecting it both into and out of the cavity 2. The undulations 71 may increase the deflection of vortices into and / or out of the cavity 2, thereby further enhancing the thickening of the shear layer. The additional swirling motion to neighboring flow structures is enhanced by the raised shape of the flow partition 7, which helps to maintain the stability of the shear layer at the edge 18 of the cavity 2. In addition, the vortices act as a virtual barrier to the cross-flow 13 at the top and around the flow partition 7. Thus, the blocking effect of the flow partition 7 is believed to be higher above the vehicle skin than the actual measurable height of the flow partition 7 in the same plane.

[0098] The body 72 takes the general shape of the flow divider 7, as previously described. The body 72 may be formed of a series of connected panels. The panels may be arranged at an oblique angle to one another.

[0099] The undulations 71 and the body 72 may be integrally formed, i.e. formed as one piece. Alternatively, the undulations 71 may be applied separately to the upper surface of the body 72. The undulations 71 may take the form of impact stabilizers 15 as described with reference to Figures 3 and 6a-6d, where the impact stabilizers 15 are arranged such that their inboard panels 61 face in the same direction as the inboard surface of the flow divider 7.

[0100] The undulations 71 may be of the same width (i.e. lateral extent) as the body 72. Alternatively, the undulations 71 may be narrower or wider than the body 72. The inboard and outboard surfaces of the undulations 71 may match the inboard and outboard contours of the body 72, respectively. By introducing undulations into the flow divider 7 in the horizontal plane, the cross-flow 13 impinging on the undulations 71 in the vertical plane tends to impinge on the first undulation before the adjacent undulations, which introduces a change in the creation of vortices.

[0101] The undulations 71 may not reach the full depth of the flow partition 7. Preferably, the depth of the undulations 71 is limited to the depth of the body 72 minus one boundary layer height (i.e. about 2 cm from the bottom of the flow partition 7). The undulations 71 are illustrated as forming about 15% of the total surface area of ​​the flow partition 7. This is for illustrative purposes only. The undulations 71 can be smaller or larger than illustrated, such that 1% to 75% of the surface area of ​​the flow partition 7 is formed by the undulations 71. Preferably, 5% to 15% of the surface area of ​​the flow partition 7 is formed by the undulations 71.

[0102] The undulations 71 are shown as being uniform, i.e., the notches are of the same depth and length throughout. In other embodiments, the undulations 71 are irregular, i.e., have variable depths and / or lengths.

[0103] In figure 5a the undulations 71 are essentially sinusoidal, in other words in cross section the upper edge of the flow divider 7 is formed by a series of connected convex and concave curves.

[0104] In figure 5b the undulations 71 are provided with sharp teeth in cross section, in other words the undulations 71 form a sawtooth or zigzag edge.

[0105] In the illustrated embodiment, the teeth are all of the same longitudinal cross-sectional shape as each other (triangles with substantially equilateral sides when viewed from the front along the direction of the cross-flow 13) and are all of the same size as each other. Instead of being triangular, the teeth may be rectangular, circular, semicircular, irregular, or square in longitudinal cross-section (i.e., when viewed from the front along the direction of the cross-flow 13). In other words, the teeth may take a curved or rounded shape or a flat shape rather than the pointed teeth illustrated. The teeth may be much wider (i.e., longer in the direction of the longitudinal axis of the flow divider 7) than those illustrated. The teeth may have a flat upper surface.

[0106] In alternative embodiments, some teeth, or even one tooth in a set of teeth, may have a different cross-sectional shape or surface area than the other teeth. For example, a first tooth may be semicircular in cross-section and an adjacent second tooth may be rectangular in cross-section.

[0107] In one embodiment, the teeth are positioned on the body 72 so that the face of each tooth is parallel to the portion of the body 72 to which it is attached, i.e., so that the front plane of each tooth is generally perpendicular to the direction of the cross-flow 13.

[0108] In this embodiment, the teeth are all arranged in a symmetrically evenly spaced arrangement, i.e., the teeth are evenly distributed across the body 72. One tooth is shown directly bonded to an adjacent tooth. Alternatively, there may be a regular gap between each tooth.

[0109] The teeth may extend to different heights relative to one another, for example a first tooth may have a height x, a second adjacent tooth may have a different height y, and another tooth adjacent to the second tooth may have a height x.

[0110] In the above embodiment, the inboard and outboard surfaces of the undulations 71 are disposed parallel to the plane of the inboard and outboard surfaces of the body 72 at the point where the tooth is connected to the body 72. In other words, if the inboard surface of the body 72 is parallel to the longitudinal edge 18, then the inboard surface of the undulations 71 is parallel to the longitudinal edge 18. However, this does not have to be the case and in other embodiments, one or more of the undulations 71 (i.e., the teeth) may be twisted relative to the body 72, i.e. a transverse plane through the tooth may not be parallel to a transverse plane through the body 72.

[0111] Now, with reference to Figures 6a-6d, several impact stabilizer 15 designs will be described. These designs may apply to separate impact stabilizers 15 used in addition to the flow partition 7, as described with reference to Figure 3, or to undulations 71 integrated with the flow partition 7. In other words, the teeth described above with reference to Figure 5b may take the shapes described below with reference to Figures 6a-6d.

[0112] Each of these designs tends to have its own advantages, but the concept is not necessarily limited to these designs.

[0113] In these figures, the impact stabilizer 15 is shown having an inboard panel 61 (which may be formed by the outboard surface of the flow divider 7 in which the impact stabilizer 15 is disposed) facing toward the cavity 2, an outboard panel 62 facing toward the impinging crossflow 13, a front panel 63 facing generally toward the intended direction of travel of the bay 100 (into the main flow 3), and a rear panel 64 facing generally away from the intended direction of travel of the bay 100. Rather than the sharp edges of the impact stabilizer 15 shown in Figure 3, the impact stabilizer 15 of Figures 6a-6d is multi-sided. Although the impact stabilizer 15 is illustrated and described as comprising separate joined panels, it may instead be integrally formed.

[0114] 6a illustrates an impact stabilizer 15 in the shape of a "ski slope." The impact stabilizer 15 comprises an inboard panel 61 whose plane is orthogonal to the surface to which the impact stabilizer 15 is attached. In other words, in the illustrated embodiment, the inboard panel 61 comprises a vertical plane that is parallel to the plane of the cavity sidewall 12. Here, the outboard panel 62 is parallel to the inboard panel 61 and is transversely offset from the inboard panel 61. The inboard panel 61 and the outboard panel 62 are planar.

[0115] The front panel 63 is connected to the leading edge of each of the inboard panel 61 and the outboard panel 62, and the rear panel 64 is connected to the trailing edge of the inboard panel 61 and the outboard panel 62. The front panel 63 has a curved surface presented to the main flow 3. The front panel 63 is concave so as to curve inward toward the rear of the impact stabilizer 15. In the illustrated embodiment, the front panel 63 is shown facing perpendicular to the direction of travel of the cavity, i.e., facing forward toward the impinging main flow 3, but in other embodiments, the front panel 63 is oriented toward the main flow 3. In a preferred embodiment, the front panel 63 is positioned such that its surface is oriented at 5 to 20 degrees relative to the direction of the main flow 3. More preferably, the front panel 63 is positioned such that its surface is oriented at 5 to 10 degrees relative to the direction of the main flow 3. This increases the surface area of ​​the impact stabilizer 15 that interacts with the cross flow 13.

[0116] The rear panel 64 is planar and disposed perpendicular to the surface to which the impact stabilizer 15 is attached. However, in other embodiments, the rear panel 64 may be curved, similar to the front panel 63, or may be planar and beveled relative to the surface to which the impact stabilizer 15 is attached. The rear panel 64 is rectangular in shape.

[0117] FIG. 6b illustrates an impact stabilizer 15 similar to that shown in FIG. 3, but extending in the direction of the main flow 3. The front panel 63 and the rear panel 64 of the impact stabilizer 15 are in the shape of an isosceles triangle. In another embodiment, the front panel 63 and the rear panel 64 of the impact stabilizer 15 are in the shape of an equilateral triangle. The front panel 63 and the rear panel 64 have the same height and width as each other. The bottom edges of the front panel 63 and the rear panel 64 are not parallel to each other, but instead tend to face each other. In another embodiment, the bottom edges of the front panel 63 and the rear panel 64 are parallel to each other. The front panel 63 and the rear panel 64 are generally vertical, but are inclined inward to form an acute angle with the longitudinal edge of the flow divider 7. The inboard sides of the front panel 63 and the rear panel 64 are spaced apart more than the outboard sides.

[0118] The outboard panel 62 is rectangular or square in outline and is joined to the outboard side of each of the front and rear panels 63, 64. The inboard panel 61 is generally rectangular in shape and has a surface area greater than the surface area of ​​the outboard panel 62. The inboard and outboard panels 63, 64 slope towards each other and meet at an apex. The apex is thus an elongated peak. The bottom surface of the impact stabilizer 15 is trapezoidal in shape. In embodiments where the front and rear panels 63, 64 are parallel to each other, the bottom surface forms a parallelogram (such as a square or rectangle).

[0119] Although the upper edge of the impact stabilizer 15 (i.e., the side of the impact stabilizer 15 where the inboard panel 61 and the outboard panel 62 meet) is illustrated as being parallel to the flat upper surface of the body 72 of the flow partition 7, due to the front panel 63 and the rear panel 64 being the same height, the upper edge of the impact stabilizer 15 may instead be sloped such that the shape of the impact stabilizer 15 reduces in height along its length (i.e., with distance from the leading edge 8 of the cavity 2).

[0120] FIG. 6c illustrates an impact stabilizer 15 similar in design to the impact stabilizer 15 of FIG. 6b, and common descriptions will not be repeated. Here, the front panel 63 and the rear panel 64 are inclined with respect to a vertical axis and disposed at an acute angle with respect to the longitudinal edge of the flow partition (i.e., the longest edge, i.e., the upper edge of the inboard face of the flow partition 7, which in the illustrated embodiment is parallel to the cavity edge 18). Preferably, the panels 64 are oriented at about 30 degrees to 60 degrees with respect to both axes, more preferably at about 45 degrees with respect to both axes. Thus, the inboard panel 61 and the outboard panel 62 connecting the front panel 63 and the rear panel 64 are trapezoidal in shape.

[0121] By angling the front panel 63 and rear panel 64 with respect to the horizontal and vertical axes, linear slopes tend to be provided which increase the volume of attached flow on the ridges (i.e., apexes), generating small vortices to enhance mixing.

[0122] Figure 6d illustrates the impact stabilizer 15 twisted about its vertical axis (i.e., an axis perpendicular to the surface to which the impact stabilizer 15 is attached). The front panel 63 and rear panel 64 are generally triangular in shape, similar to the impact stabilizer 15 of Figure 6c. The inboard panel 61 and outboard panel 62 are trapezoidal in shape in the preferred embodiment, but may be rectangular or square in shape.

[0123] Here, the bottom sides of the front panel 63 and the rear panel 64 are parallel to one another in a horizontal plane (i.e., the plane of the surface to which the impact stabilizer 15 is attached). The front panel 63 and the rear panel 64 are joined together by the inboard panel 61 and the outboard panel 62. Thus, the bottom surface of the impact stabilizer 15 defined by the panels 61, 62, 63, 64 is generally rectangular. However, in other embodiments, the front panel 63 and the rear panel 64 may be inclined towards one another in the horizontal plane, making the bottom surface trapezoidal.

[0124] The inboard panel 61 and the outboard panel 62 are inclined inwardly with respect to a vertical plane and meet at an apex (i.e., defining the upper edge of the impact stabilizer 15). The apex is angled with respect to the longitudinal edge of the flow partition 7 in the horizontal plane (i.e., has zero vertical inclination). In other words, the upper edge of the impact stabilizer 15 is not parallel to the longitudinal edge of the flow partition. The apex of the impact stabilizer 15 is at an angle of about 20 degrees with respect to the longitudinal edge of the flow partition 7 (and thus the edge 18 of the cavity 2 in the illustrated embodiment) such that its forward end is closer to the edge 18 than its aft end. This therefore causes the inboard panel 61 and the outboard panel 62 to be torqued (i.e., twisted and deformed). The axes passing through the apexes of the triangles forming the front panel 63 and the rear panel 64 and perpendicular to the planes of the respective panels 63, 64 are not coaxial. An axis passing through the ends of the bottom edges of the front and back panels 63, 64 and the second outboard surface (ie, the axis passing through the bottom edges of the inboard and outboard panels 61, 62) is disposed obliquely relative to the apex axis.

[0125] In a preferred embodiment, the axis of the apex of the impact stabilizer 15 is at an angle of about 20 degrees relative to the longitudinal edge of the flow partition 7, however, the axis of the apex (i.e., the top edge of the impact stabilizer 15) may be at an angle of about 5 degrees to 45 degrees relative to the edge, and more preferably, at an angle of about 10 degrees to 30 degrees relative to the edge. This assumes that the edge of the flow partition 7 is straight and parallel to the cavity edge 18. If the flow partition 7 itself is undulating in the horizontal plane, then the apex should be angled as above relative to the cavity edge 18.

[0126] This design tends to be particularly advantageous in controlling the flow of fluid impinging on the bay 100. It has been found that the twisted inboard panel 61 tends to draw the generated vortices towards the outer edges 14, 16, 18 of the cavity 2. In other words, the shear layer tends to be lifted out of the cavity 2.

[0127] In other words, it has been found that the impact stabilizer 15 controls the flow over the outer edges 14, 16, 18 of the cavity 2 by inducing and retaining a vortex there. This vortex then acts as a virtual barrier, preventing the external flow from flowing into the cavity 2 and enveloping it in the vortex itself. The elimination of the cross flow then removes that disturbance to the shear layer, allowing the vortex to grow in height more uniformly across the width of the cavity 2. Thus, the payload 5 and other components within the cavity 2 that are co-located with the sidewall 12 are better protected. The angle of the ridges (i.e., apexes) is designed to shed the vortex with a directional component away from the cavity 2. This is to prevent the vortex from penetrating into the cavity 2.

[0128] Further designs not illustrated may include impact stabilizers 15 having multiple peaks to increase shear layer mixing. The impact stabilizers 15 may be cylindrical. Again alternatively, the impact stabilizers may be rectangular. It will be appreciated that combinations of these designs of impact stabilizers 15, and those shown in the figures, are within the scope of this disclosure. For example, the impact stabilizer 15 design of FIG. 6c may have a flat top rather than a sharp apex so as to be more rectangular in nature. Additionally, twisting may be introduced along the vertical axis (i.e., the axis perpendicular to the surface to which the impact stabilizer is attached) of the pyramidal design shown in FIG. 3 to distort the inboard panel similar to that of FIG. 6d.

[0129] Although the cavity 2 is illustrated as having a rectangular bottom surface 1 and defined by vertical side walls 12, a vertical rear wall 10, and a sloped front wall 8, it will be appreciated that the impact stabilizer 15 is applicable to other cavity 2 shapes. For example, all walls 8, 10, 12 may be disposed perpendicular to the horizontal bottom surface 1, or some or all of the walls 8, 10, 12 may be disposed at an acute angle to the horizontal bottom surface 1. The cavity 2 may comprise a circular bottom surface 1, a triangular bottom surface 1, a square bottom surface 1, or an irregularly shaped bottom surface 1. In other words, for example, if the bottom surface 1 is triangular, one of the front wall 8 and the rear wall 10 may not be present, i.e., the longitudinal walls 12 may be inclined inwardly toward each other.

[0130] While the embodiments described above relate to a rotating payload bay 100 having an impact stabilizer 15 suitable for use in an aircraft 400, such as a commercial airliner, a military fighter jet, or a helicopter, in other embodiments, the impact stabilizer 15 is suitable for use in other forms of bays 100 and with other forms of vehicles. For example, the bay 100 may be a wheel well, the interior of an automobile (i.e., the opening in cavity 2 may be a window or sunroof), an open superstructure, or any other bay 100 through which a fluid passes or over which a fluid passes. The rotating payload bay 100 is applicable to land vehicles such as trains and high performance automobiles, as well as naval vessels such as yachts and submarines.

[0131] While the embodiments described above relate to a rotating payload bay 100 having a flow divider 7 suitable for use in an aircraft 400, such as a commercial airliner, a military fighter, or a helicopter, in other embodiments the flow divider 7 is suitable for use in other forms of bays 100 and with other forms of vehicles. For example, the bay 100 may be a wheel well, the interior of an automobile (i.e. the opening of the cavity 2 may be a window or sunroof), an open superstructure, or any other bay 100 through which a fluid passes or over which a fluid passes. The rotating payload bay 100 is applicable to land vehicles such as trains and high performance automobiles, as well as naval vessels such as yachts and submarines.

[0132] The bay 100 may be fixed (i.e., static) instead of rotating and therefore permanently open, or may be provided with a hinged door. A flow divider 7 may be disposed within the hinged door to prevent cross-flow 13 from leaking into the cavity 2 through a gap under the door.

[0133] Alternatively, the flow dividers 7 may be motorized and positioned to lower into their own cavity when the bay 100 is closed. In other words, the flow dividers 7 may lower into the walls 12 of the bay 100, or into the surface surrounding the cavity 2. The flow dividers 7 may be driven upwards to extend into the surrounding flow when the bay 100 is open.

[0134] The opening of the cavity 2 may be formed by the skin of the vehicle, i.e. the aircraft 400. In other words, the cavity 2 may not have walls 8, 10, 12 as such, but may be formed integrally with the vehicle.

[0135] The ambient fluid through which the bay 100 passes is described above as an airflow (ie, air stream), but could instead be water.

[0136] Although the bay 100 is shown as being rectangular in cross section along its longitudinal axis (i.e., where the base 1 and the two side walls 12 meet at right angles), it will be appreciated that the present disclosure encompasses other bay designs, such as those having a semicircular cross section. Such designs would effectively have one continuous side wall 12, but would have two top surfaces to which the impact stabilizers 15 are attached.

[0137] Although the present invention has been described in relation to some embodiments, it is not intended to be limited to the specific form described herein. Rather, the scope of the present invention is limited only by the appended claims. In addition, although features may appear to be described in relation to certain embodiments, those skilled in the art will recognize that various features of the described embodiments may be combined in accordance with the present invention. In the claims, the term "comprising" does not exclude the presence of other elements or steps.

[0138] Adjacent impact stabilizers 15 may have different shapes.

[0139] A singular reference does not exclude a plurality, thus references to "a", "an", "first", "second", etc. do not exclude a plurality. In the claims, the terms "comprise" or "include" do not exclude the presence of other elements.

[0140] In the above description, where integers or elements having known, obvious, or foreseeable equivalents are referred to, such equivalents are incorporated herein as if set forth individually. Reference should be made to the claims to determine the true scope of the present disclosure, which should be interpreted to encompass any such equivalents. The reader will also recognize that integers or features of the present disclosure described as optional do not limit the scope of the independent claims. Moreover, it should be understood that such optional integers or features may be advantageous in some embodiments of the present disclosure, but may not be desirable and therefore may not be present in other embodiments.

Claims

1. 1. A cavity system for use in a vehicle, comprising: a cavity having a leading edge and / or a trailing edge and a longitudinal edge, wherein the leading edge and / or the trailing edge and the longitudinal edge define an opening; at least one elongated flow partition protruding from a surface adjacent each longitudinal edge of the cavity into a flow around the exterior of the cavity, wherein at least one of the flow partitions has an interior surface facing primarily toward the cavity and an exterior surface facing primarily away from the cavity; A cavity system comprising:

2. 2. The cavity system of claim 1, comprising a bay having a front wall, a rear wall, and at least one side wall, upper surfaces of the front wall, rear wall, and at least one side wall comprising the leading edge, the trailing edge, and the longitudinal edge, respectively.

3. The cavity system of claim 2 , wherein the bay is a rotating payload bay.

4. The cavity system of claim 2 or 3, wherein at least one of the flow dividers protrudes from an upper surface of at least one of the side walls.

5. The cavity system of any one of claims 1 to 4, wherein at least one of the flow dividers comprises a plurality of open flow passages between the inboard surface and the outboard surface.

6. The cavity system of any one of claims 1 to 5, wherein the inboard and / or outboard surface of at least one of the flow partitions is non-planar.

7. The cavity system of any one of claims 1 to 6, wherein an upper surface of at least one of the flow dividers is contoured in a vertical plane.

8. A cavity system according to any one of claims 1 to 7, comprising at least one impact stabilizer arranged on either side of the cavity so as to protrude into the surrounding flow.

9. The cavity system of claim 8 , wherein at least one said impact stabilizer is disposed on the top surface of at least one said flow partition.

10. The cavity system of claim 8 , wherein at least one said impact stabilizer is disposed adjacent the outboard surface of at least one said flow partition.

11. The cavity system of any one of claims 1 to 10, wherein the inboard surface of at least one of the flow partitions is at an acute angle to the longitudinal edge of the cavity.

12. 12. The cavity system according to any one of the preceding claims, wherein at least one said flow partition is between 2cm and 20cm in height.

13. 13. The cavity system of claim 1, comprising a motor for driving at least one of the flow partitions to raise or lower from or to the surface adjacent a longitudinal edge of the cavity.

14. 13. The cavity system of any one of claims 1 to 12, comprising a motor, and at least one of the flow partitions comprises a hinge, the motor configured to drive at least one of the flow partitions to rotate about the hinge to selectively position it in the surrounding flow or to position it to rest against the surface adjacent the cavity.

15. A cavity system as claimed in any preceding claim, comprising transverse spoilers positioned across or in front of the cavity relative to the actual or intended direction of travel of the vehicle.

16. A cavity system according to any preceding claim comprising a releasable payload.

17. An aircraft comprising a cavity system according to any one of claims 1 to 16.

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