阅读说明：本技术 空气动力学本体 (aerodynamic body ) 是由 惠欣宇 艾伦·曼 于 2018-03-22 设计创作，主要内容包括：提出了一种用于在飞行器上使用的空气动力学本体。该空气动力学本体包括至少第一穿孔表面部分(25)和防冰系统(31)。第一穿孔表面部分(25)具有穿孔,防冰系统(31)包括可致动元件(33),并且该可致动元件(33)能够在第一位置与第二位置之间移动或者变形。在第一位置中,可致动元件(33)的至少一部分热联接至第一穿孔表面部分(25)并且构造成防止在外部空气动力学气流的边界层与空气动力学本体之间穿过穿孔中的至少一个穿孔的进气或排气。在第二位置中,可致动元件(33)的至少一部分与第一穿孔表面部分(25)间隔开并且构造成允许从外部空气动力学气流的边界层穿过穿孔中的至少一个穿孔而进入空气动力学本体的进气。(An aerodynamic body for use on an aircraft is presented. The aerodynamic body comprises at least a first perforated surface portion (25) and an anti-icing system (31). The first perforated surface portion (25) has perforations, the anti-icing system (31) includes an actuatable element (33), and the actuatable element (33) is movable or deformable between a first position and a second position. In the first position, at least a portion of the actuatable element (33) is thermally coupled to the first perforated surface portion (25) and configured to prevent intake or exhaust of air between the boundary layer of the external aerodynamic flow and the aerodynamic body through at least one of the perforations. In the second position, at least a portion of the actuatable element (33) is spaced from the first perforated surface portion (25) and is configured to allow intake air from a boundary layer of the external aerodynamic air flow to enter the aerodynamic body through at least one of the perforations.)

1. An aerodynamic body for use on an aircraft, wherein the aerodynamic body comprises at least a first perforated surface portion and an anti-icing system,

Wherein the anti-icing system comprises an actuatable element,

Wherein the actuatable element is movable or deformable between a first position and a second position,

Wherein, in the first position, at least a portion of the actuatable element is thermally coupled to the first perforated surface portion and is configured to prevent intake or exhaust of air between a boundary layer of an external aerodynamic flow and the aerodynamic body through at least one of the perforations,

wherein in the second position, at least a portion of the actuatable element is spaced apart from the first perforated surface portion and is configured to allow the intake or exhaust of air.

2. The aerodynamic body of claim 1, wherein the actuatable element comprises an electrical heating element.

3. The aerodynamic body of claim 1 or 2, wherein the aerodynamic body is at least one of the group consisting of an aircraft main wing, a horizontal stabilizer, a vertical tail and a leading edge high lift device.

4. The aerodynamic body of any preceding claim, wherein the actuatable element is movable in rotation and/or translation between the first and second positions.

5. The aerodynamic body of any preceding claim, wherein the aerodynamic body defines a leading edge and at least a portion of a local chord length extending between the leading edge and a trailing edge, and wherein the first perforated surface portion extends around the leading edge beyond the local chord length by 3% or less.

6. The aerodynamic body of any preceding claim, wherein the anti-icing system comprises a securing element located at a rear portion of the actuatable element, wherein the securing element is permanently thermally coupled to a non-perforated surface portion of the aerodynamic body.

7. The aerodynamic body of claim 6, wherein the aerodynamic body comprises at least a second perforated surface portion located aft of the non-perforated surface portion.

8. The aerodynamic body of any preceding claim, wherein the aerodynamic body comprises an active suction system for generating and/or maintaining air intake or exhaust between a boundary layer of an external aerodynamic flow and the aerodynamic body through at least one of the perforations, and wherein the actuatable element is configured to be sucked to the second position by the active suction system.

9. the aerodynamic body of any preceding claim, wherein the aerodynamic body comprises a solenoid, and wherein the actuatable element is configured to be moved to the second position by the solenoid.

10. The aerodynamic body of any preceding claim, wherein the actuatable element comprises a bimetallic component that is deformable upon temperature change, wherein the bimetallic component is configured to deform the actuatable element to the first position when the anti-icing system is in use, and wherein the bimetallic component is configured to deform the actuatable element to the second position when the anti-icing system is not in use.

11. the aerodynamic body of any preceding claim, wherein the actuatable element is spring loaded towards the first position or the second position.

12. The aerodynamic body of any preceding claim, wherein at least some of the perforations comprise microperforations.

13. a method for generating and/or maintaining laminar flow around an aerodynamic body, the method comprising:

providing an aerodynamic body comprising at least a first perforated surface portion and an anti-icing system, and wherein the anti-icing system comprises an actuatable element,

Actuating the actuatable element to move or deform to a first position, wherein in the first position at least a portion of the actuatable element is thermally coupled to the first perforated surface portion and prevents intake or exhaust air passing through at least one of the perforations between the boundary layer of the external aerodynamic flow and the aerodynamic body,

heating the first perforated surface portion to prevent icing,

actuating the actuatable element to move or deform to a second position, wherein in the second position at least a portion of the actuatable element is spaced from the first perforated surface portion and allows intake or exhaust air passing through at least one of the perforations between the boundary layer of the external aerodynamic flow and the aerodynamic body.

14. The method of claim 13, comprising the steps of:

Providing an active suction system for generating and/or maintaining an intake or an exhaust gas passing through at least one of said perforations between a boundary layer of an external aerodynamic flow and said aerodynamic body,

Wherein actuating the actuatable element to move or deform to the second position comprises pumping the actuatable element to the second position by the active pumping system.

15. The method according to claim 13 or 14, comprising the steps of:

-providing a solenoid which is operated by a solenoid,

Wherein actuating the actuatable element to move or deform to the second position comprises moving the actuatable element to the second position by the solenoid.

16. The method according to any one of claims 13 to 15, comprising the steps of:

Providing a bimetal component contained in the actuatable element,

wherein actuating the actuatable element to move or deform to the first position comprises heating the bimetallic component and thereby deforming the actuatable element to the first position,

Wherein actuating the actuatable element to move or deform to the second position comprises cooling the bimetallic component and thereby deforming the actuatable element to the second position.

Technical Field

the present disclosure generally relates to an aerodynamic body having a leading edge and designed to provide laminar flow over at least a portion of a surface of the aerodynamic body.

Background

Since the main component of the operating costs of a commercial aircraft is fuel and aerodynamic drag is a major factor in fuel consumption, reducing aerodynamic drag is a major goal in the design of aerodynamic surfaces of commercial aircraft. Laminar boundary layer flow, or simply laminar flow, over an aerodynamic surface is generally associated with less resistance than turbulent flow over the aerodynamic surface. Techniques for achieving laminar flow generally fall into the following categories: (i) natural Laminar Flow (NLF), which is established by aerodynamic shape and surface quality without any active or dynamic means; (ii) active Laminar Flow (ALF), which requires active or powered devices to establish or maintain laminar flow; and (iii) mixed laminar flow (HLF), which may be a combination of NLF and ALF or include other means of influencing or controlling the boundary layer. HLF also sometimes refers to the coexistence of laminar and turbulent flow regimes, using techniques intended to delay the onset of turbulent boundary layers by establishing and maintaining a certain laminar flow regime prior to the onset of turbulent layers. A known mechanism to achieve a certain laminar flow regime is to delay the onset of boundary layer transition by suppressing the growth of small disturbances in the boundary layer by suction through micro-perforations on the surface.

WO 03/089295 describes an outer skin of an aerodynamic body with perforations for controlling laminar flow by suction of boundary layer air.

EP 1019283B 1 describes an aerodynamic body with a high-lift portion, wherein at least a major part of the upper surface of the high-lift portion is permeable or perforated.

these known solutions comprise a plurality of suction chambers across a large part of the upper surface to control the pressure distribution. Multiple suction chambers add complexity and weight and make integration of the anti-icing system more difficult.

US 6,202,304B 1 describes a movable sheet that serves as an integral retractable shroud for protecting the suction support structure of the wing from contamination, and also as a movable electrically conductive substrate for deicing by resistance heating or hot gas heating. This solution is very complex and requires the installation of the movable skin sheet in the shape of a scroll.

disclosure of Invention

Embodiments of the present invention provide an aerodynamic body with a laminar leading edge that is less complex and lighter weight and includes an integrated anti-icing system.

according to a first aspect of the invention, an aerodynamic body for use on an aircraft is provided, the aerodynamic body comprising at least a first perforated surface portion and an anti-icing system,

Wherein the anti-icing system includes an actuatable element,

Wherein the actuatable element is movable or deformable between a first position and a second position,

Wherein in the first position, at least a portion of the actuatable element is thermally coupled to the first perforated surface portion,

wherein in the second position, at least a portion of the actuatable component is spaced apart from the first perforated surface portion.

at least some of the perforations may comprise microperforations.

Herein, "perforated" or "perforation" shall mean a plurality of holes distributed over the surface portion. Alternatively, the shape of the perforations of the first flow surface portion may be circular, slit-shaped, oval or any geometric shape allowing air intake. The orientation, shape and/or size of the perforations may be the same for all perforations, or the orientation, shape and/or size of the perforations may vary gradually or non-gradually over the first flow surface portion or between sub-portions of the first flow surface. "microperforated" or "microperforations" shall mean pores having one or more sizes in the sub-millimeter range, the microperforations may have sizes ranging from 20 μm to 100 μm, such as 50 μm, and may be located at relative distances of 100 μm to 1000 μm, such as 500 μm, from one another.

"thermally coupled" or "in thermal contact" shall mean any form of direct or indirect contact that allows for efficient heat transfer.

The actuatable element of the anti-icing system may provide heat to the first perforated surface portion prior to or during takeoff of the aircraft. The actuatable element of the anti-icing system may be moved or deformed to a second position to allow air intake or exhaust between the external aerodynamic flow and the aerodynamic body through at least one of the perforations when the aircraft is in cruise mode at an altitude where anti-icing is not required. Such intake or exhaust may create or maintain laminar flow around the aerodynamic body by delaying the onset of turbulent stratification. Thus, for example, the aerodynamic body may generate less drag in cruise mode while reducing the fuel consumption of the aircraft.

optionally, the actuatable element comprises an electrical heating element. The electric heating element can be lighter and simpler than a hot air system. The electrical heating element may be a heating mat. The actuatable element may be hinged and/or connected to the fixed element to allow a defined and repeatable path for movement or deformation between the first and second positions.

Optionally, the aerodynamic body is at least one of the group comprising an aircraft main wing, a horizontal stabilizer, a vertical tail and a leading edge high lift device. Thus, the aircraft may comprise one or more aerodynamic bodies having such features. Leading edge devices such as slats are particularly suitable for housing deformable actuatable elements because only limited space is available within such devices.

Optionally, the actuatable element is movable in rotation and/or translation between the first position and the second position. The actuatable element may be rotatable within the single pumping chamber and/or the actuatable element is caterpillar-like to move within the single pumping chamber.

Optionally, the aerodynamic body defines a leading edge and at least a portion of a local chord length extending between the leading edge and the trailing edge, and wherein the first perforated surface portion may extend around the leading edge more than 3% or less of the local chord length. The restricted first microperforated surface portion may facilitate the use of a passive pressure differential with a single suction chamber to draw intake air from the boundary layer. An active suction system may not be required, particularly in the case of leading edge devices, due to the limited space within the leading edge device.

Optionally, the anti-icing system includes a securing element located at a rear portion of the actuatable element. The fixation element may be permanently thermally coupled to the non-perforated surface portion of the aerodynamic body. Aft of the laminar leading edge, i.e. at a distance from the leading edge that can exceed 3% of the local chord length, the skin can have a surface quality that allows NLF without controlling any boundary layer by suction. The anti-icing system may therefore comprise a fixing element to heat such non-perforated surface portions.

optionally, the aerodynamic body comprises at least a second perforated surface portion located aft of the non-perforated surface portion. Aft of the non-perforated surface portion, i.e. at a distance from the leading edge that may exceed 10% of the local chord length, a second perforated surface portion may be used to further delay the onset of boundary layer transition by suction. The anti-icing system is not required at a distance of more than 10% of the local chord length from the leading edge, such that neither the actuatable element nor the fixed element of the anti-icing system requires heating of the second perforated surface portion.

Optionally, the aerodynamic body comprises an active suction system for generating and/or maintaining an air intake from a boundary layer of the external aerodynamic flow into the aerodynamic body through at least one of the perforations, and wherein the actuatable element is configured to be sucked to the second position by the active suction system. Sometimes, for example when the leading edge is part of a main wing without a slat, such as for a wing with a krueger flap, an active suction device may be required to generate or maintain suction by the ALF or HLF. In this case, an active pumping system may be used to pump the actuatable element to the second position. The actuatable element can be moved and/or deformed within the single pumping chamber, and the active pumping system can pneumatically actuate the actuatable element.

optionally, the aerodynamic body comprises a solenoid, wherein the actuatable element is configured to be moved to the second position by the solenoid. The solenoid may maintain pneumatic actuation, or may be used as an alternative to pneumatic actuation. This is particularly useful when active pumping systems are not used.

Optionally, the actuatable element comprises a bimetal component deformable upon a change in temperature, wherein the bimetal component is configured to deform the actuatable element to the first position when the anti-icing system is in use, and wherein the bimetal component is configured to deform the actuatable element to the second position when the anti-icing system is not in use. Such an embodiment is very compact and may therefore be useful in slats where little internal space may be used for the actuation system. The bi-metallic component that is part of the actuatable element does not require any substantial space and can either curl the actuatable element away from the skin to the second position or straighten the actuatable element to bring the actuatable element into thermal contact with the skin to heat the skin for anti-icing.

Optionally, the actuatable element is spring loaded towards the first position. The spring may provide additional force to achieve a good thermal coupling between the actuatable element and the skin. To actuate the actuatable component toward the second position, a pneumatic force and/or a magnetic force and/or a deforming force may be required that is high enough to overcome the spring force of the bias toward the first position.

According to a second aspect of the present disclosure, there is provided a method for generating and/or maintaining a laminar flow around an aerodynamic body, the method comprising:

Providing an aerodynamic body comprising at least a first perforated surface portion and an anti-icing system, wherein the anti-icing system comprises an actuatable element,

Actuating the actuatable element to move or deform to a first position, wherein in the first position at least a portion of the actuatable element is thermally coupled to the first perforated surface portion,

Heating the first perforated surface portion to prevent icing,

Actuating the actuatable element to move or deform to a second position, wherein in the second position at least a portion of the actuatable element is spaced apart from the first perforated surface portion.

optionally, the method comprises providing an active suction system for generating and/or maintaining intake or exhaust air between the boundary layer of the external aerodynamic flow and the aerodynamic body through at least one of the perforations, wherein actuating the actuatable element to move or deform to the second position comprises suctioning the actuatable element to the second position by the active suction system.

Optionally, the method includes providing a solenoid, wherein actuating the actuatable element to move or deform to the second position includes moving the actuatable element to the second position via the solenoid.

Optionally, the method includes providing a bimetal component of the actuatable element, wherein actuating the actuatable element to move or deform to the first position includes heating the bimetal component and thereby deforming the actuatable element, wherein actuating the actuatable element to move or deform to the second position includes cooling the bimetal component and thereby deforming the actuatable element.

Drawings

embodiments of the present disclosure will now be described, by way of example only, with reference to the following drawings, in which:

fig. 1 is a schematic perspective view of an aircraft having an aerodynamic body according to an example of the present disclosure;

FIG. 2 is a top view of an aircraft having an aerodynamic body according to an example of the present disclosure;

FIG. 3 is a top view of a wing of an aircraft having an aerodynamic body according to an example of the present disclosure;

FIG. 4 is a cross-sectional view of a forward portion of an aircraft wing with a slat as an example of an aerodynamic body according to the present disclosure;

FIG. 5 is a cross-sectional view of a forward portion of an aircraft wing as an aerodynamic body according to an example of the present disclosure;

Fig. 6 is a cross-sectional view of a front portion of an aerodynamic body according to an example of the present disclosure, with a deformable actuatable element in a first position;

Fig. 7 is a cross-sectional view of a front portion of an aerodynamic body according to an example of the present disclosure, with a deformable actuatable element in a second position;

FIG. 8 is a cross-sectional view of a front portion of an aerodynamic body with a solenoid as an actuator and a hinged actuatable element in a first position according to an example of the present disclosure;

FIG. 9 is a cross-sectional view of a front portion of an aerodynamic body with a solenoid as an actuator and a hinged actuatable element in a second position in accordance with an example of the present disclosure;

FIG. 10 is a cross-sectional view of a front portion of an aerodynamic body with a suction system as an actuator and a hinged actuatable element in a first position according to an example of the present disclosure;

FIG. 11 is a cross-sectional view of a front portion of an aerodynamic body with a suction system as an actuator and a hinged actuatable element in a second position according to an example of the present disclosure;

FIG. 12 is a cross-sectional view of a slat as an example of an aerodynamic body according to the present disclosure, wherein the deformable actuatable element is in a first position;

FIG. 13 is a cross-sectional view of a slat as an example of an aerodynamic body according to the present disclosure, wherein the deformable actuatable element is in a second position; and

Fig. 14 is a schematic illustration of method steps for creating and/or maintaining laminar flow around an aerodynamic body according to examples of the present disclosure.

Detailed Description

Fig. 1 shows an aircraft 1, which aircraft 1 comprises a fuselage 3 and a wing 5, to which wing 5 an engine 7 is attached. The right-hand cartesian coordinate system shows the x-axis as the longitudinal axis of the aircraft, also known as the roll axis, pointing in the direction of flight; the y-axis is shown as the transverse axis of the aircraft, also called the pitch axis, pointing substantially in the spanwise direction of the wing 5 on the right-hand side of the aircraft 1; the Z-axis is shown as the vertical axis of the aircraft, also referred to as the yaw axis, pointing downwards. This coordinate system is used throughout fig. 1 to 13, wherein the wing 5 on the right-hand side of the aircraft 1 is used for a detailed description of the present disclosure. The reader will readily understand that the invention is symmetrically applicable to the wing 5 on the left hand side of the aircraft 1 or other aerodynamic bodies such as a horizontal tail or a vertical tail. The term "aerodynamic body" herein may denote any aerodynamically active part of an aircraft, and may thus be selected from at least one of the group comprising: the aircraft comprises an aircraft main wing, a horizontal stabilizer, a vertical tail wing and a leading edge high-lift device.

fig. 2 shows more details of the wing 5 of the aircraft 1, such as the high lift device 9 at the leading edge 11 of the wing 5. Such high lift leading edge devices 9 are also known as slats which can increase lift during takeoff and landing of the aircraft and can be retracted to reduce drag during cruise of the aircraft. Other trailing edge high lift devices 13, commonly referred to as flaps, located at the trailing edge 15 of the wing have a similar purpose. The wing 5 extends from a wing root 17 attached to the fuselage 3 to a wing tip 19.

Fig. 3 shows a right-hand wing 5 of an aircraft 1, which right-hand wing 5 comprises a wing comprising a main wing part 21, a leading edge high lift device 9 and a trailing edge high lift device 13. The trailing edge 15 of the wing 5 may be defined by a trailing edge lift device 13, a main wing section 21, or other control surfaces such as ailerons or spoilers, depending on the spanwise location along the y-axis. In fig. 3, the transverse position Y in the spanwise direction along the Y-axis is arbitrarily selected to show the local chord length c (Y) between the leading edge 11 and the trailing edge 15 at position Y. The local chord length c (y) is typically a length that depends on the lateral position y in the spanwise direction along the y-axis. Chord length is to be understood as the feature of the airfoil of the aerodynamic body during cruise, i.e. the direct distance in the x-z plane between the leading edge 11 and the trailing edge 15 of the wing when the high lift devices 9 and 13 are retracted.

Fig. 4 is a detailed cross-sectional view of the front of the wing 5 with the high leading edge lift device 9, also known as a slat, in a retracted position close to the main wing portion 21. The leading edge high lift device 9 is movably coupled to the main wing portion 21 via a deployment system 23. The deployment system 23 is shown as a rail system (dashed lines), but the deployment system 23 may be any type of linkage system that allows the leading edge high lift devices 9 to move between a retracted cruise position and a deployed high lift position for takeoff and landing.

The local chord length c (y) is shown as a linear dash-dot line between the leading edge 11 and the trailing edge 15 (not shown in fig. 4). A dashed plane X perpendicular to the local chord length c (y) and located at a distance d of 0.03 × c (y) defines an upper boundary line a and a lower boundary line B on the skin of the leading-edge high-lift device 9. A first perforated surface portion 25 is positioned around the leading edge, and the first perforated surface portion 25 extends between an upper boundary line a and a lower boundary line B. The first perforated surface portion 25 may cover less than the entire skin portion between the upper and lower boundary lines a, B. The limitation of the first perforated surface portion 25 has the following advantages: the entire internal volume of the leading edge high lift device 9 can be used as a single suction chamber 27 for passive HLF without an active suction system. Thus, no complex multiple pumping chambers are required.

The leading edge high lift device 9 is provided with at least one outlet 29, the air pressure at said at least one outlet 29 being lower than the pressure at the perforations for suction by active or passive HLF control. The pressure differential may be actively maintained by an active suction system or may be passively maintained by the external aerodynamic flow in flight. For passive HLF control, the position of the outlet 29 is chosen to be in a low pressure position, depending on the design of the aerodynamic body. Such a low pressure position may be at the rear surface of the high edge lift device 9, as shown in fig. 4. Alternatively or additionally, an outlet may be provided at the skin of the aerodynamic body, the outlet having a substantially rearwardly directed opening such that the in-flight external aerodynamic flow provides a low pressure point at the outlet.

An anti-icing system 31 in the form of an electrical wing anti-icing system with electrical heating elements (eWIPS) is positioned in thermal contact with the leading edge skin of the leading edge high lift device 9 and a major part of the upper skin of the leading edge high lift device 9. The anti-icing system 31 has a front portion and a rear portion. The front portion of the anti-icing system 31 includes an actuatable element 33, at least a portion of the actuatable element 33 being thermally coupled to the first perforated surface portion 25. The actuatable element 33 is movable and/or deformable between a first position in thermal contact with the first perforated surface portion 25 (as shown in fig. 4 and 13) and a second position spaced from the first perforated surface portion 25 (as shown in fig. 13). The rear part of the anti-icing system 31 comprises a fixing element 35, which fixing element 35 is permanently thermally coupled to a non-perforated surface part 37 of the leading edge high lift device 9. The non-perforated surface portion 37 and the fixation element 35 may extend between 3% and 10% of the local chord length c (y). At the rear of the non-perforated surface portion 37 and the fixing element 35, e.g. at a distance from the leading edge 11 exceeding 10% of the local chord c (y), the leading edge high lift device 9 comprises a second perforated surface portion 39 for HLF control which does not require anti-icing.

Fig. 5 is a detailed cross-sectional view of the forward portion of the wing 5 as an aerodynamic body without a slat, wherein the main wing portion 21 defines the leading edge 11. Similar to fig. 4, a dashed line X perpendicular to the local chord length c (y) and positioned at a distance d of 0.03 × c (y) defines an upper boundary line a and a lower boundary line B on the skin for the first perforated surface portion 25. The first perforated surface portion 25 may cover less than the entire skin portion between the upper and lower boundary lines a, B. The single suction chamber 27 of the wing 5 in fig. 5 may be defined by the inner wall 28 rather than using the entire slat volume. As in fig. 4, the limitation of the first perforated surface portion 25 has the following advantages: a single pumping chamber 27 may be used for passive HLF control without an active pumping system. Thus, no complex multiple pumping chambers are required.

at least a portion of the actuatable element 33 of the eWIPS 31 is thermally coupled to the first perforated surface portion 25. The actuatable component 33 is movable and/or deformable between a first position in thermal contact with the first perforated surface portion (as shown in fig. 5) and a second position spaced from the first perforated surface portion (as shown in fig. 7). The rear part of the anti-icing system 31 comprises a fixing element 35, which fixing element 35 is permanently thermally coupled to a main part of the upper skin of the leading edge high lift device 9. The fixation element 35 may extend between 3% and 10% of the local chord length c (y). Aft of the non-perforated surface portion 37 and the fixed element 35, e.g. over 10% of the local chord length c (y) from the leading edge 11, the wing 5 comprises a second perforated surface portion 39 for HLF control which does not require anti-icing.

The airfoil 5 is provided with at least one outlet 29, the air pressure at said at least one outlet 29 being lower than the pressure at the perforations where suction is applied by active or passive HLF control. The pressure differential may be actively maintained by an active suction system or may be passively maintained by the external aerodynamic flow in flight. For passive HLF control, the position of the outlet 29 is selected to be in a low pressure position according to the design of the aerodynamic body. As shown in fig. 5, such a low pressure position may be at the rear surface of the single suction chamber 27. Alternatively or additionally, an outlet 29 may be provided at the skin of the aerodynamic body, which outlet 29 has a substantially rearwardly directed opening, so that the in-flight external aerodynamic flow provides a low pressure point at the outlet 29.

Fig. 6 and 7 illustrate two positions of the actuatable element 33, a first position in fig. 6 and a second position in fig. 7. The actuatable element 33 of the eWIPS 31 comprises a bimetal member that is deformable upon a change in temperature. Upon heating (as shown in fig. 6), such as prior to or during takeoff of the aircraft 1, the bimetallic component pulls the actuatable element 33 to the first position, in thermal contact with the first perforated surface portion 25, to heat the first perforated surface portion 25 to prevent ice from accumulating on the first perforated surface portion 25. The perforations of the first perforated surface portion 25 are closed from the inside by the actuatable element 33 in the first position, so that intake air from the boundary layer of the external aerodynamic flow through the perforations into the aerodynamic body is prevented.

When the eWIPS 31 is not used, for example during cruising of the aircraft 1, the bimetal member cools and curls the actuatable element 33 away from the first perforated surface portion 25. In the second position as shown in fig. 7, the actuatable element 33 opens the perforations of the first perforated surface portion 25 and allows intake air from the boundary layer of the external aerodynamic flow through the first porous surface portion 25. Fig. 6 and 7 also show a second perforated surface section 39 located behind the non-perforated surface section 37. Thus, the region with eWIPS 31 and the region with laminar flow control can be separated to reduce complexity at the rear of the leading edge region, for example at a distance of more than 3% of the local chord length from the leading edge 11.

the difference between fig. 8 and 9 and fig. 6 and 7 is that the actuatable element 33 in fig. 8 and 9 is now hinged on the hinge 40. The actuatable element 33 can be rotated by means of the solenoid 41 from the first position in fig. 8 to the second position in fig. 9. The solenoid 41 may magnetically push and/or pull the actuatable element 33 between the first and second positions, or work against a spring force if the actuatable element is spring-loaded towards the first position. The hinged actuatable element 33 may also be deformable and include a bi-metallic component.

Fig. 10 and 11 show an actuatable element 33 that can be pneumatically actuated. In the event that an active suction system is required to provide the necessary suction, a conduit may be connected to the single suction chamber 27. Such ducts may comprise a main duct 43 extending substantially spanwise and a collector duct 45 extending substantially chordwise. The actively reduced pressure in the collector duct 45 may pneumatically draw the actuatable element 33 from the first position toward the second position. The actuatable element 33 may be spring loaded toward the first position.

Fig. 12 and 13 show in more detail how the actuatable element 33 is actuated in the case of a slot wing 9 as in fig. 4 as an aerodynamic body. Without an active suction system, the entire internal volume of the slat 9 may be used as a single suction chamber 27 for passive HLF. This is particularly advantageous because the space within the slat 9 is very limited and cannot accommodate the ducts or complex multiple suction chambers of an active suction system. The least space consuming actuation option is to use a bimetal component in the actuatable element 33 that is deformable upon temperature changes. In fig. 12, the slats 9 may be deployed on the ground during take-off or landing or immediately prior to take-off. Anti-icing may be required to ensure flight safety. The bimetal member is then heated for anti-icing purposes such that the bimetal member pulls the actuatable element 33 up to a first position where the actuatable element 33 is in thermal contact with the first perforated surface portion 25. Further, the actuatable element 33 in the first position internally closes the aperture of the first aperture surface portion 25 to prevent a boundary layer of external aerodynamic flow from passing through the aperture into the air intake of the slat.

in fig. 13, the slat 9 may be retracted in cruise mode at altitudes where ice protection is not required. The bimetal component is not heated and may cool such that the bimetal component curls the actuatable element 33 to a second position where the actuatable element 33 is spaced apart from the first perforated surface portion 25. Accordingly, the actuatable element 33 in the second position opens the perforations of the first perforated surface portion 25 so as to allow a boundary layer of external aerodynamic flow to pass through the perforations into the air intake of the slat. The delayed onset of boundary layer transition in cruise mode reduces the drag of the aerodynamic body and saves fuel consumption.

Fig. 14 illustrates an example of method steps for generating and/or maintaining a laminar flow around an aerodynamic body. In step 1401, an aerodynamic body is provided, the aerodynamic body comprising at least a first perforated surface portion 25 and an anti-icing system 31. The first perforated surface portion 25 has perforations and the anti-icing system 31 comprises an actuatable element 33 according to the above figures. In step 1403, the actuatable component 33 is actuated to move or deform to a first position. In the first position, at least a portion of the actuatable element 33 is thermally coupled to the first perforated surface portion 25 and prevents intake or exhaust air passing through at least one of the perforations between the boundary layer of the external aerodynamic flow and the aerodynamic body. In step 1405, the first perforated surface portion 25 is heated for anti-icing. In step 1407, the actuatable element 33 is actuated to move or deform to the second position. In the second position, at least a portion of the actuatable element 33 is spaced from the first perforated surface portion 25 and allows intake air from the boundary layer of the external aerodynamic flow to enter the aerodynamic body through at least one of the perforations. The delay in boundary layer transition begins to generate and/or maintain laminar flow around the aerodynamic body, thereby saving fuel consumption.

as part of step 1403, the bi-metallic component of the actuatable element 33 (step 1409) can be heated such that the actuatable element 33 deforms to the first position (as shown in fig. 6 and 12). Alternatively or in addition to step 1409, the actuatable element 33 may be spring loaded towards a first position in which the actuatable element 33 is in thermal contact with the first perforated surface portion 25 and closes the perforations from the inside.

As part of step 1407, there are different actuation options shown as step 14011, step 1413, and step 1415, which may be applied as alternatives to each other or in any combination with each other to effectively implement step 1407. In step 14011, an active pumping system is provided and used to pneumatically pump the actuatable element 33 to the second position (as shown in fig. 11). In step 1413, a solenoid 41 is provided, the solenoid 41 being used to magnetically move the actuatable element 33 to the second position (as shown in FIG. 9). In step 1415, the bi-metallic component used to deform the actuatable component 33 to the first position in step 1409 is not heated so that the bi-metallic component can cool to deform the actuatable component 33 to the second position.

where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents.

it is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. While at least one exemplary embodiment has been shown and described, it should be understood that other modifications, substitutions, and alternatives are apparent to one of ordinary skill in the art and may be made without departing from the scope of the subject matter described herein, and this application is intended to cover any adaptations or variations of the specific embodiments discussed herein.

in addition, "a" or "an" does not exclude a plurality. Furthermore, features or steps which have been described with reference to one of the above exemplary embodiments may also be used in combination with other features or steps of other exemplary embodiments described above. The method steps may be applied in any order or in parallel, or may form part of another method step or a more detailed version. It should be understood that all such modifications should be reasonably and properly included within the scope of the warranted patent as a contribution to the art. Such modifications, substitutions and alternatives can be made without departing from the spirit and scope of the invention.