Aircraft landing gear assembly

Abstract

An aircraft landing gear assembly 6 comprising; a noise-inducing component 8 which, in use, with the landing gear assembly deployed, has a front region and a back region separated by a pair of side re

Description

Background An aircraft can generate considerable noise during a landing approach. A significant portion of this noise is attributable to air flowing around the deployed landing gear. Although the aircraft may be travelling at around 80m / s during a landing sequence, localised airflow around a noise-inducing region of the landing gear may reach speeds of around 300m / s. The interaction between the landing gear and the airflow can lead to the generation of turbulent flow, vortex shedding, and boundary layer separation, all of which contribute to increased noise generation. This is known in the art, and will be referred to herein, as aero-acoustic noise. Aero-acoustic noise is particularly undesirable because airports are often located close to cities, or other densely populated areas. Attempts have been made to address aero-acoustic noise problems. For example, it is known to provide an aircraft landing gear with a fairing. A fairing is a generally rigid structure, usually made from metal or composite materials, arranged to shield a noiseinducing region of an aircraft landing gear from airflow during landing. However, landing gear fairings have demonstrated limited success, especially in reducing noise due to flow-induced acoustic sources such as vortex shedding. The interaction between the landing gear and airflow can induce turbulent flow, causing further vortex shedding and boundary layer separation, which contribute to an increased level of noise generation. Complications such as surface pressure fluctuations on the landing gear due to these turbulent flows and unsteady aerodynamic forces pose an even greater challenge to effective noise reduction using conventional methods. Moreover, the noise reduction achieved using conventional fairing methods addresses the problem only in the landing gear source level. Moreover, existing noise reduction solutions often lack versatility in terms of enabling noise reduction performance to be optimised across a variety of aircraft configurations, operational conditions, and types of landing gear, making it a challenge to achieve consistent optimal noise reduction performance. Summary In accordance with a first aspect of the present invention, there is provided an aircraft landing gear assembly according to claim 1. Thus, the aircraft landing gear assembly according to the first aspect of the invention includes a curved flow deflector positioned at a side region of a noise-inducing component. The present inventors have found that a curved flow as claimed can reduces aeroacoustic noise, in particular noise caused by vortex shedding from the landing gear during take-off and landing. The flow deflector is positioned to energise and deflect the flow to increases the regions of flow attachment toward the rear of the treated surfaces of the bluff body in order to control the wake of the treated surface and the landing gear. This solution can significantly improve an aircraft's aeroacoustic properties by reducing vortex shedding, effectively mitigating boundary layer turbulence, and surface pressure fluctuations. Moreover, at aircraft level, embodiments of the invention offer noise reduction by reducing the turbulence levels in the landing gear wake that interacts with the flap and flap trailing edge. The flow deflector system offers adaptability across different types of aircraft and operational conditions, enhancing noise reduction performance across a broad range of frequencies. Optional features are set out in the dependent claims. The noise inducing component can for example comprise some or all of the main strut, side stay, lock link, torque link, an axle, wheel assembly, brake assembly, hydraulic pipe, or the like. The flow deflector(s) can be used along with traditional landing gear fairings to improve the overall acoustic performance. In accordance with a second aspect of the present invention, there is provided an aircraft including one or more aircraft landing gear assemblies according to the first aspect. Brief Description of the Drawings By way of example only, certain embodiments of the invention will now be described by reference to the accompanying drawings, in which: Figure 1 is a diagram of an aircraft; Figures 2 and 3 are diagrams of a known aircraft landing gear assembly; Figure 4 is a diagram of typical wake flow characteristics of a cylinder, showing vortex shedding; Figure 5 is a diagram showing an aircraft landing gear assembly according to an embodiment of the invention including two flow deflectors; Figure 6 is a diagram showing an aircraft landing gear assembly according to an embodiment of the invention including four flow deflectors; Figure 7 is a diagram showing an aircraft landing gear assembly according to an embodiment of the invention including a single flow deflector; Figure 8 is a diagram showing an aircraft landing gear assembly according to an embodiment of the invention including two flow deflectors covered by perforated sheets; Figure 9 is a diagram showing a flow deflector of an aircraft landing gear assembly according to an embodiment of the invention including encased hydraulic pipes; Figures 10a and 10b are diagrams each showing two flow deflectors of an aircraft landing gear assembly according to an embodiment of the invention mounted with non-parallel slot spacings from the bluff body; Figure 11 is a diagram showing two flow deflectors of an aircraft landing gear assembly according to an embodiment of the invention mounted with parallel but asymmetric slot spacings from the bluff body; Figure 12 is a diagram showing two flow deflectors of an aircraft landing gear assembly according to an embodiment of the invention each having asymmetric flap angles along the flow deflector; Figures 13a and 13b are front and side view diagrams showing two flow deflectors of an aircraft landing gear assembly according to an embodiment of the invention mounted on supports configured as a vortex generator; Figures 14a to 14d are diagrams illustrating deflector mounting positions relative to a bluff body; and Figures 15 to 23 show wind tunnel test data for flow deflectors according to embodiments of the invention. Detailed Description By way of a non-limiting overview, embodiments of the invention relate to an aircraft landing gear assembly which includes a flow deflector system configured to reduce aero acoustic noise by modifying the wake flow of gear components. In known landing gear, interaction between the landing gear and the high-speed airflow can lead to turbulent wake flow, further vortex shedding, and boundary layer separation, all of which contribute to an increase in noise generation. Moreover, turbulent flow from the wake of the landing gear can interact with a fully deflected flap during take-off / landing, giving rise to additional noise at aircraft level. Surface pressure fluctuations on the landing gear due to these turbulent flows and unsteady aerodynamic forces give rise to increased noise. The use of flow deflectors can result in less flow suppression, thereby reducing the turbulent flow over the surface leading to noise reduction. Embodiments of the invention include one or more flow deflectors, strategically positioned at the side(s) of one or more landing gear components. Each flow deflector accelerates the flow over the landing gear component surface. This action serves to reduce the structure and energy associated with vortex shedding that typically occurs in the wake of the bluff body, consequently reducing noise. Embodiments of the invention can comprise one, two, three flow deflectors, strategically positioned around each side of the bluff body, near its wake, and away from the landing gear components. The deflectors function to redirect the flow at an angle between 30 to 90 degrees relative to the free stream flow. This realignment helps in delaying flow separation, reducing the low pressure behind the bluff body components, and decreasing the drag. This effect also mitigates vortex shedding, hence decreasing wake turbulence and preventing additional flow interactions and consequent noise due to wake flap interactions. Figure 1 is a diagram of an aircraft 2. The aircraft includes assemblies such as a nose landing gear 4 and a pair of main landing gear 6. The landing gear 4, 6 each includes a shock absorber strut for damping landing loads and supporting the weight of the aircraft 2 when it is on the ground. The term aircraft as used herein can include aeroplanes, helicopters and the like having mass in excess of 450kg. Figure 2 is an example of an aircraft landing gear assembly 6 which can include a flow deflector system according to an embodiment of the invention. It will however be appreciated that a flow deflector system according to embodiments of the invention can be used in a range of types of aircraft landing gear including main landing gear and nose landing gear, with one or more axles and include wheels or other ground contacting means. The aircraft landing gear assembly 6 is movable between a deployed condition, for take-off and landing, and a stowed condition for flight. The landing gear assembly includes a main shock absorber strut 8, comprising an outer cylinder and a sliding tube, a foldable stay 14, and a lock link 20. An upper end of the strut 8 is provided with a bearing 9 via which the strut 8 is pivotally coupled to the airframe of the aircraft 2. A lower end of the strut 8 is provided with a wheel and brake assembly 30. A retraction actuator 12 is provided for moving the landing gear between the deployed condition and the stowed condition. The retraction actuator can have one end coupled to the airframe 11 and another end coupled to the strut 8. The stay 16 serves to support the orientation of the strut 8 when the landing gear is in the deployed condition. The stay 18 generally includes a two-bar linkage 16, 18 that can be unfolded to assume a generally straight or aligned, over centre condition in which the stay 18 is locked to inhibit movement of the outer cylinder, as shown in Figure 2. When the stay is broken, it no longer inhibits pivotal movement of the strut 8 about the mounting bearing and strut 8 can be moved by the retraction actuator 12 towards the stowed condition. The lock link 20 has an elongate upper link arm having a lower end pivotally coupled to an upper end of an elongate lower link arm via a pivot pin. The link arms can therefore pivotally move relative to one another about the pivot pin. The lock link is pivotally coupled to the strut 8 and one of the stay arms 16. When the lock link 20 is in the locked condition, as illustrated in Figure 2, the upper and lower link arms are generally longitudinally aligned or coaxial, and can be 'over-centre', such that the lock link 20 is arranged to oppose a force attempting to break or fold the stay 14. The lock link 20 must be broken to enable the stay 14 to be broken and folded, thereby permitting the strut 6 to be moved by the retraction actuator 12 towards the stowed condition. The down lock assist in moving the landing gear assembly to the deployed condition and locking it in that state by making the lock link 20. Down lock springs also inhibit the lock link 20 accidentally being broken / unlocked. A lock stay actuator 22 is coupled between the stay 14 and lock link 20 and arranged to pivotally move the link arms so as to make and break the lock link 20. The lock stay actuator 22 can break the lock link 20 against the down lock spring bias, allowing the landing gear assembly to be folded and stowed as described previously. Referring additionally to Figure 3, the outer cylinder 24 and sliding tube 26 of the strut 8 can be coupled via a set of torque links 28 which permit relative axial movement but inhibit relative rotational movement between the outer cylinder 24 and sliding tube 26. Wheel and brake assemblies 10 can be mounted on axles 30 which in turn are mounted at end regions of a bogie beam 32. The bogie beam 32 is pivotally coupled near its centre to the sliding tube 26 via a bogie pivot pin 34. Brake rods 36 can be provided to anchor the brake packs to the sliding tube 26 to react brake torque. As will be appreciated by the skilled person, the above-mentioned landing gear components can, in use, result in generation of aeroacoustic noise. Such noiseinducing components define bluff bodies, where a significant portion of the surface area is separated flow. Figure 4 is a schematic cross-sectional diagram through a cylindrical noise-inducting component B of a deployed landing gear assembly, illustrating the typical flow around the bluff body B. Reference sign A indicates the direction of airflow. As will be appreciated, with the landing gear assembly deployed, the noise-inducting component B has a front region BF and a back region BB separated by a pair of side regions BSA, BSB such that flight motion of the aircraft causes airflow A to encounter the front region BF followed by the side regions BSA, BSB, followed (to some extent) by the back region BB. As can be seen, a significant portion of the surface area, namely the back region BB and parts of the side regions BSA, BSB adjacent to the back region result in separated flow. Reference sign C indicates the presence of a turbulent wake with vortex shedding occurring in the wake of the bluff body B. Flow separation and vortex shedding are common phenomena in bluff bodies, such as landing gear components, where the aerodynamic shape of the body causes the airflow to separate from the body's surface and form vortices in the wake region. These vortices, when shed, generate a significant portion of the noise emanating from the aircraft during take-off and landing. Figure 5 is a schematic diagram of an aircraft landing gear assembly according to an embodiment of the invention, including two flow deflectors. Reference sign A indicates the direction of the airflow. Reference sign B indicates the bluff body. A first flow deflector FA is mounted adjacent to and spaced from a first side region BSA, the first flow deflector FA having a curved profile towards the back region BB so as to redirect airflow adjacent the first side region BSA at an angle between 30 to 90 degrees relative to a free stream flow A. A second flow deflector FB is mounted adjacent to and spaced from a second side regions BSB, the second flow deflector FB having a curved profile towards the back region BB so as to redirect airflow adjacent the second side region BSB at an angle between 30 to 90 degrees relative to a free stream flow A. Reference sign D depicts the reduced flow recirculation region, highlighting minimized vortex shedding due to the implementation of the flow deflectors FA, FB. Thus, strategic lateral placement and curved design of flow deflectors FA, FB can greatly enhance aerodynamic efficiency and noise reduction. Figure 6 is a schematic diagram of an aircraft landing gear assembly according to another embodiment of the invention, including four flow deflectors. Reference sign A indicates the direction of the airflow. Reference sign B indicates the bluff body. The first and second flow deflectors FA, FB are arranged in the same or a similar configuration as the embodiment of Figure 5 but can have longer tail portions. A third flow deflector FC is mounted adjacent to and spaced from the first side region BSA between the first flow deflector FA and the first side region BSA. The third flow deflector FC has a curved profile towards the back region BB so as to redirect airflow adjacent the first side region BSA at an angle between 30 to 90 degrees relative to a free stream flow A. The third flow deflector FC is orientated to have a greater airflow redirection angle than the first flow deflector FA and is positioned in a downstream but parallel position such that the airflow A encounters the first flow deflector FA followed by the third flow deflector FC. A fourth flow deflector FD is mounted adjacent to and spaced from the second side regions BSB between the second flow deflector FB and the second side regions BSB. The fourth flow deflector FB has a curved profile towards the back region BB so as to redirect airflow adjacent the second side region BSB at an angle between 30 to 90 degrees relative to a free stream flow A. The fourth flow deflector FD is orientated to have a greater airflow redirection angle than the second flow deflector FB and is positioned in a downstream but parallel position such that the airflow A encounters the second flow deflector FB followed by the fourth flow deflector FD. Thus, in each case, the forward flow deflector can have a smaller angle of deflection while the rearward deflector can have a higher angle, or vice versa. This dynamic configuration enables higher flow control depending on the type of bluff body and the landing gear component that is being treated. The four flow deflators FD-FD therefore work in pairs to reenergize the flow and delay flow separation over the bluff body B. The third and fourth flow deflectors FC, FD suppress the recirculation region and reduce vortex shedding. Thus, the staggered flow deflector system is designed to control the flow velocity and turbulent kinetic energy interacting with the landing gear. The placement of the rear deflector can also control the boundary layer around the landing gear, reducing vortex shedding and dissipating turbulent kinetic energy in the wake flow. This can result in a reduction of flow impingement velocity and a more uniform and less turbulent flow field around the landing gear, significantly reducing flow-induced noise. In other embodiments, the deflector system can comprise three flow deflectors at one or both side regions of a bluff body, acting in unison, each deflector varying in its angular deflection range in comparison to the upstream deflector. In any embodiment, each deflector on the same side of a bluff body can vary in shape and / or size, which can aid in the reduction of noise from the deflectors themselves. It is recognized that certain landing gear components generate noise due to unsteady surface pressure fluctuations due to flow separations. By delaying flow separation and supressing vortex shedding noise reduction can be achieved. Figure 7 is a schematic diagram of an aircraft landing gear assembly according to another embodiment of the invention, including a single flow deflector. Reference sign A indicates the direction of the airflow. Reference sign B indicates the bluff body. The single flow deflector FS is arranged in the same or a similar configuration as the first flow deflector FA in the embodiment of Figure 5 but can have longer tail portion. As will be appreciated, in other embodiments the single flow deflector FS can instead be arranged in the same or a similar configuration as the second flow deflector FB embodiment of Figure 5. The single flow deflector system functions to reenergize the flow, delay flow separation over the bluff body B and suppress the recirculation region, ultimately reducing vortex shedding and leading to a decrease in generated noise. One flow deflector might be used due to the landing gear geometry or weight restrictions for example. Figure 8 is a schematic diagram of an aircraft landing gear assembly according to another embodiment of the invention, including two flow deflectors connected by perforated sheets. Reference sign A indicates the direction of the airflow. Reference sign B indicates the bluff body. The first and second flow deflectors FA, FB are arranged in the same or a similar configuration as the embodiment of Figure 5. A first perforated sheet fairing PSI is positioned at the front of the bluff body B, spanning between the first and second flow deflectors FA, FB. The first perforated sheet fairing PSI can reduce flow impingement noise and enhance the overall acoustic characteristics of the system. A second perforated sheet fairing PS2 is positioned at the back of the bluff body B, spanning between the first and second flow deflectors FA, FB, in the wake of the flow field. The second perforated sheet fairing PS2 can improve aerodynamics, suppress vortex shedding, and ultimately decrease the noise output of the aircraft during operation. Any suitable perforated sheet can be used for the perforated sheet fairings PSI, PS2, for example perforated sheets with different types of porosity, different types of hole shapes (various geometric shapes and sizes), different types of porous patterns such as regular irregular patterns. Thus, the self-noise mechanism of the deflector themselves can be reduced by the use of different types of materials such as perforated material for the leading and trailing edge of the deflector. Such perforated sheets can be applied to any embodiment. Figure 9 is a schematic diagram of an aircraft landing gear assembly according to another embodiment of the invention where aircraft landing gear hydraulic pipes H are located and encased within a flow deflector FA. As will be appreciated, this feature can be applied to any embodiment of the invention. In some embodiments, hydraulic tubes can be shaped to mirror the shape of the flow deflector, and the deflector housing the hydraulic tubes could be hermetically sealed for enhanced durability and performance. Figures 10a and 10b are front view diagrams showing two options for how flow deflectors can be orientated relative to the bluff body for any embodiment of the invention. In these two examples, a double flow deflector is shown encompassing a standard landing gear component. Reference sign B signifies the component that is being treated with the flow deflectors FA, FB. FAI represents one end of the first flow deflector FA and FA2 denotes the other end of the same flow deflector FA. As shown, the flow deflector FA is mounted to form an angle a relative to the component. This angle a controls both the mass flow and velocity passing through the slot S between the deflector FA and the component B, effectively directing the flow either towards or away from the ground. This control over the flow direction can be important in noise reduction, mitigating the noise produced due to landing gear wake interaction. Figure 11 is a front view diagram showing another manner in which flow deflectors can be orientated relative to the bluff body for any embodiment of the invention, with an asymmetric but parallel flow deflector spacing from the bluff body. In this example, a double flow deflector is shown encompassing a standard landing gear component. Reference sign B designates the component being treated with the flow deflectors FA, FB. The flow deflectors FA, FB are positioned with differing slot gaps Gl, G2. This distinction in slot gaps allows for the tailored manipulation of airflow, thereby enabling more efficient noise reduction depending on the specific aerodynamic requirements of the landing gear. Thus, as illustrated in Figures 10a to 11, the slot gap can exhibit uniform or non-uniform spacing along the length of the component, tailored to the specific needs of the aircraft and the landing gear. Through implementing an asymmetric slot gap design, the system can proficiently deflect the airflow towards the ground, reducing the effort required to direct the flow and thus minimizing the noise generated. The slot geometry can differ on the two sides, enabling the deflection of flow towards the undercarriage of the aircraft. A combination of strategically spaced slot gaps between both sides and longitudinally can facilitate the deflection of airflow towards the ground and aircraft underbelly, thereby aiding in noise reduction at the aircraft level by minimizing landing gear wake and flap interactions. Figure 12 is a front view diagram showing a pair of flow deflectors FA', FB' having asymmetric flap angles between the top FAI', FBI' and bottom FA2', FB2' ends of each deflector. The trailing edge of the curved shape is designed to possess a differing angle of deflection at one end when compared to the opposite end of the flow deflector. The distinct angling can effectively manipulate the mass flow and velocity through the slot, compelling the flow to divert towards or away from the ground, depending on the specific requirements of the noise reduction strategy. Figures 13a and 13b show supports S for attaching the flow deflectors FA, FB to the bluff body B. The supports S can be engineered to function as vortex generators, enhancing flow attachment and delaying separation. An added functionality of the supports can be the lateral deflection of the flow towards the ground. More specifically, the supports S for the flow deflectors are designed to mimic the shape of vortex generators to promote enhanced attachment of the boundary layer, increasing the overall efficacy of the system. A sequence of vortex generators can be employed ahead of the flow deflectors, configured to guide a significant portion of the airflow towards the deflectors and maintain the attachment of the boundary layer. These vortex generators serve dual purposes - not only do they assist in directing the airflow effectively but also provide structural support to the flow deflectors. In addition to facilitating boundary layer attachment and supporting the flow deflectors, the vortex generators can be configured to direct the flow towards the ground, mitigating wake flap interactions and consequently reducing noise generation. The flow deflectors themselves can be equipped with integrated vortex generators, which can delay flow separation on the deflector surface, enhancing their noise reduction capabilities. Figure 14a to 14d illustrate deflector mounting positions relative to a bluff body, where each is mounted at a side region of the bluff body. The angles of the flow deflector specified can be relative to the centre of the component being treated. In any embodiment, the flow deflector(s) can each have with an aerofoil or teardrop shape. A flow deflector can for example have a highly cambered aerofoil shape, but other forms of aerofoils and teardrop shapes can also be employed. In any embodiment, the front, back and side regions of the bluff body can be defined by a quadrant. In any embodiment, the leading and / or trailing edges of the deflectors can be covered with perforated materials, which can help in reducing the sound produced by air impinging and flowing over these edges. Additionally, the leading and trailing edges of the deflectors can be provided with wavy or serrated patterns. The entire deflector can have a wavy pattern rather than having smooth curved surfaces. These measures can mitigate self-noise, enhancing the overall noise reduction capabilities of the deflector system. In any embodiment including two or more flow deflectors on the same side of the bluff body, the design and structure of forward and rearward pairs of flow deflectors can be specifically tailored based on the individual components and areas of the landing gear that are targeted for noise reduction. Each deflector can be independently shaped or can have the same shape, offering flexibility in customization. The rearward flow deflector can have a shape and size that vastly differ from the forward one. In both bideflector and tri-deflector systems, the units can either be mounted independently or interconnected, further enhancing the adaptability of the system. In any embodiment, a flow deflector can be configured to provide an asymmetric flow deflection angle along the length of the slot on the treated component. This allows the system to direct the airflow at various angles relative to the free-stream flow, not strictly confined to a uniform angle along the length of the landing gear or treated component. The deflection angle can be fine-tuned depending on specific requirements and region of the treated location, which can range between 30 to 90 degrees. By employing asymmetric flow deflection angles, the system can adeptly manipulate the airflow to minimize its impact on the landing gear components, thereby substantially reducing the generated noise. This flexible and adjustable deflection capability contributes to the system's overall efficiency and effectiveness in noise reduction. In any embodiment, one or more of the flow deflectors can each possess unique properties in terms of chord length, thickness, and overall aerofoil shape. The selection of these properties can be tailored based on the aerodynamic characteristics of the aerofoil, as well as, in some embodiments, the type of hydraulic systems enclosed on each side of the treated component. This allows for a tailored approach that can optimise the noise reduction performance of the system, based on the specific configuration and requirements of the landing gear component being treated. In any embodiment, the deflectors can be positioned around the component being treated, to not only reduce flow separation on the landing gear component but also suppress vortex shedding from the large landing gear structure being treated. The boundary layer on the landing gear's bluff body can also be controlled by enclosing the component with a single or staggered flow deflector system. In any embodiment, the attachment connectors of the flow deflectors to the targeted landing gear components can be integrated with a rotary ball bearing system. This advanced setup allows the flow deflectors to self-adjust dynamically based on the direction of incoming airflow. Through automatic repositioning, the system ensures optimal alignment for maximum aerodynamic efficiency and noise reduction, regardless of changes in flow direction or velocity. This self-orienting feature can enhance the system's performance across a variety of operating conditions. Thus, embodiments of the invention enable a flexible design approach, allowing for various configurations such as a single, double, or three flow deflector system, along with the use of vortex generators, and the potential to adopt asymmetric deflector and slot geometries. These design considerations provide the ability to adapt to the specific aerodynamic needs of various aircraft models and landing gear configurations, enhancing the practical applicability of the invention. Referring to Figures 15 to 23, wind tunnel test data is shown. A series of aeroacoustic wind tunnel tests were conducted to assess the effectiveness of the flow deflector system. A cylinder with a diameter of 20mm and a span length of 500mm served as the test object, evaluated both with and without the application of flow deflectors, referred to as aerofoils. Eight distinct flow deflector configurations were examined during the experimental campaign. The aerofoils used for the flow deflectors were designed based on the NACA 6412 profile, a highly cambered aerofoil. The tests were conducted at two different heights, T1 and T2, measured from the base of the aerofoil to the cylinder. These heights were normalized based on the thickness of the aerofoil t = 1.5mm. Specifically, the two normalized heights tested were T1 = h / t = 1 and T2 = h / t = 2. The aerofoil configurations were tested under three different flow velocities: 20 m / s, 30 m / s, and 35 m / s. These various conditions were selected to provide a broad understanding of how the flow deflectors perform under different aerodynamic environments, thus giving insights into their effectiveness for noise reduction and aerodynamic improvement. The measurements were carried out using far field microphones placed at a distance of 1.7m from the cylinder. A total of 21 microphones were used and it was placed between an angle of 40 and 140 degrees with a resolution of 5 degrees. The wind tunnel tests yielded several important findings. Most notably, the doublesided aerofoils effectively eliminated vortex shedding in all cases and provided a substantial reduction in noise, thus emerging as the superior design choice for landing gear components. When considering the height-to-thickness ratio (h / t) of the aerofoils, those placed at a ratio of 2 (h / t=2) demonstrated overall superior performance in terms of aerodynamic behaviour and noise suppression. Furthermore, for the aerofoils at this height-to-thickness ratio, even a single-sided aerofoil oriented at 90 degrees was sufficient to mitigate vortex shedding, indicating a degree of design flexibility. The orientation of single-sided aerofoils also influenced their efficacy. For aerofoils at h / t=l, a +45 degree orientation was generally more effective, whereas a -45 degree orientation yielded better results at h / t=2. Significantly, across all test configurations, there was a visible reduction in noise levels when compared to a plain cylinder. It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be capable of designing many alternative embodiments without departing from the scope of the invention as defined by the appended claims. In the claims, any reference signs placed in parenthesis shall not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps other than those listed in any claim or the specification as a whole. The singular reference of an element does not exclude the plural reference of such elements and vice-versa. Parts of the invention can be implemented by means of hardware comprising several distinct elements. In a device claim enumerating several parts, several of these parts can be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be 5 used to advantage.

Claims

1. An aircraft landing gear assembly comprising:a ground contacting assembly;a main strut;a mounting bearing arranged for coupling the landing gear assembly to an aircraft such that the main strut supports the aircraft on the ground when the ground contacting assembly is in contact with the ground;a noise-inducing component which, in use, with the landing gear assembly deployed, has a front region and a back region separated by a pair of side regions, such that flight motion of the aircraft causes airflow to encounter the front region followed by the side regions, followed by the back region; anda first flow deflector mounted adjacent to and spaced from a first side region, the first flow deflector having a leading edge and a trailing edge separated by first and second sides and being shaped with a curved profile between the leading edge and trailing edge that is curved towards the back region of the noise-inducing component so as to redirect airflow adjacent to the first side region at an angle between 30 to 90 degrees relative to a free stream flow.

2. The aircraft landing gear assembly according to claim 1, further comprising:a second flow deflector mounted adjacent to and spaced from a second one of the side region opposite to the first side region, the second flow deflector having a leading edge and a trailing edge separated by first and second sides and being shaped with a curved profile between the leading edge and trailing edge that is curved towards the back region of the noise-inducing component so as to redirect airflow adjacent to the first side region at an angle between 30 to 90 degrees relative to a free stream flow.

3. The aircraft landing gear assembly according to claim 2, further comprising:a third flow deflector mounted adjacent to and spaced from the first side region, the third flow deflector having a leading edge and a trailing edge separated by first and second sides and being shaped with a curved profile between the leading edge and trailing edge that is curved towards the back region of the noise-inducing component so as to redirect airflow adjacent the first side region at an angle between 30 to 90 degrees relative to a free stream flow; anda fourth flow deflector mounted adjacent to and spaced from the second one of the side region, the fourth flow deflector having a leading edge and a trailing edge separated by first and second sides and being shaped with a curved profile betweenthe leading edge and trailing edge that is curved towards the back region of the noiseinducing component so as to redirect airflow adjacent the first side region at an angle between 30 to 90 degrees relative to a free stream flow, wherein the third flow deflector is mounted downstream with respect to the first flow deflector and between the first flow deflector and the noise-inducing component and the fourth flow deflector is mounted downstream with respect to the second flow deflector and between the second flow deflector and the noise-inducing component.

4. The aircraft landing gear assembly according to claim 3, wherein the first and third flow deflectors are shaped to redirect airflow adjacent the first side region at different angles and the second and fourth flow deflectors are shaped to redirect airflow adjacent the second side region at different angles.

5. The aircraft landing gear assembly according to any of claims 3 and 4, wherein the first and third flow deflectors have different lengths with respect to one another and the second and fourth flow deflectors have different lengths with respect to one another.

6. The aircraft landing gear assembly according to any preceding claim, wherein the leading edge of the first flow deflector is straight and the leading edge of the second flow deflector is straight.

7. The aircraft landing gear assembly according to claim 6, wherein the leading edge of the first flow deflector is mounted parallel with respect to the noise-inducing component with a first spacing and the leading edge of the second flow deflector is mounted parallel with respect to the noise-inducing component with a second spacing, wherein the first and second spacings are not equal.

8. The aircraft landing gear assembly according to claim 6, wherein the leading edge of the first flow deflector is mounted non-parallel with respect to the noiseinducing component and the leading edge of the second flow deflector is mounted non-parallel with respect to the noise-inducing component, wherein the leading edge of the first and second flow deflectors are non-parallel.

9. The aircraft landing gear assembly according to any preceding claim, wherein one or more of the flow deflectors each has an asymmetric flap angle between the first and second sides.

10. The aircraft landing gear assembly according to any preceding claim when dependent on claim 2, wherein the landing gear assembly further comprises a perforated sheet fairing connecting the first and second flow deflectors.

11. The aircraft landing gear assembly according to any preceding claim, wherein one or more of the flow deflectors are mounted by supports configured as vortex generators.

12. The aircraft landing gear assembly according to any preceding claim, wherein one or more of the flow deflectors each has an aerofoil or teardrop shape.

13. The aircraft landing gear assembly according to any preceding claim, further comprising hydraulic piping and wherein one or more of the flow deflectors each encases a portion of the hydraulic piping.

14. The aircraft landing gear assembly according to any preceding claim, wherein the ground contacting assembly comprises a wheel and brake assembly.

15. The aircraft landing gear assembly according to any preceding claim, wherein the main strut comprises a shock absorbing strut such as an oleo pneumatic shock strut.

16. The aircraft landing gear assembly according to any preceding claim, wherein the mounting bearing is arranged to pivotally couple the landing gear assembly to the aircraft for movement between a deployed condition for take-off and landing and a stowed condition for flight.

17. An aircraft including one or more aircraft landing gear assemblies according to any preceding claim.

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