阅读说明：本技术 一种前缘变弯襟翼和前缘缝翼交界处流动优化方法及装置 (Method and device for optimizing flow at junction of leading edge bending flap and leading edge slat ) 是由 钟敏 华俊 郑遂 王浩 张国鑫 王钢林 李小飞 李岩 孙侠生 于 2019-07-16 设计创作，主要内容包括：本发明属于流动控制技术领域,提出一种优化航空飞行器机翼前缘变弯襟翼和前缘缝翼交界处的流动,抑制和推迟该区域流动分离的方法和装置。本发明经过流场分析、气动设计、装置安装、风洞试验、结果分析和相关调整等步骤,提出在机翼内侧前缘变弯襟翼和外侧前缘缝翼组合构型中,设置第一流动隔离片和第二流动隔离片。其中,所述的第一流动隔离片,位于前缘变弯襟翼和前缘缝翼之间,顺着缝翼前伸的方向布置；所述的第二流动隔离片也位于前缘变弯襟翼和前缘缝翼的交界处,在机翼下表面顺流向布置。本发明的流动优化装置有效地克服了前缘变弯襟翼和前缘缝翼交界处的流动不利干扰,推迟了上表面流动分离的发生,提高了飞机的最大升力系数。另外,本发明原理明确,结构简单,效果显著并得到风洞试验验证。(The invention belongs to the technical field of flow control, and provides a method and a device for optimizing flow at the junction of a bending flap and a leading edge slat of a leading edge of an aerocraft wing and inhibiting and delaying flow separation in the region. According to the invention, through the steps of flow field analysis, pneumatic design, device installation, wind tunnel test, result analysis, relevant adjustment and the like, a first flow spacer and a second flow spacer are arranged in the combined configuration of the inner leading edge bending flap and the outer leading edge slat of the wing. The first flow separation sheet is positioned between the leading edge bending flap and the leading edge slat and is arranged along the forward extending direction of the slat; the second flow isolation sheet is also positioned at the junction of the leading edge bending flap and the leading edge slat and arranged downstream on the lower surface of the wing. The flow optimization device effectively overcomes the adverse interference of flow at the junction of the leading edge bending flap and the leading edge slat, delays the occurrence of flow separation on the upper surface and improves the maximum lift coefficient of the airplane. In addition, the invention has the advantages of clear principle, simple structure and obvious effect and is verified by wind tunnel tests.)

1. a method for optimizing flow at the junction of a leading edge bending flap and a leading edge slat is characterized in that: in the combined configuration of the wing inner side leading edge bending flap and the wing outer side leading edge slat, aiming at the advanced separation of the flow by analyzing the flow field at the junction of the leading edge bending flap and the leading edge slat, two flow separation sheets are respectively arranged at the flow spreading flow positions at the junction of the leading edge bending flap and the leading edge slat, so that the flow field distribution at the junction is improved, and the flow field separation is inhibited.

2. The method of flow optimization at a leading edge bending flap and slat interface of claim 1, wherein: the two flow isolation sheets are respectively a first flow isolation sheet and a second flow isolation sheet, wherein the first flow isolation sheet is positioned between the leading edge bending flap and the leading edge slat and arranged along the forward extending direction of the slat; the second flow isolation sheet is also positioned at the junction of the leading edge bending flap and the leading edge slat and arranged downstream on the lower surface of the wing.

3. The method of flow optimization at a leading edge bending flap and slat interface of claim 2, wherein: the first flow spacing block and the second flow spacing block are both rigid sheet structures, the cross section of each rigid sheet structure is rectangular, and a round chamfer structure is additionally arranged at the edge connected with the airflow.

4. The method of flow optimization at a leading edge bending flap and slat interface of claim 2, wherein: in the down state of the flap, the leading edge of the first flow separation sheet is sealed with the innermost plane of the slat, the trailing edge of the first flow separation sheet is sealed with the outermost plane of the leading edge bending flap, the upper edge of the principle shape of the first flow separation sheet is connected with the rear edge point of the upper surface of the slat and the middle part of the upper surface of the leading edge bending flap, and the lower edge of the first flow separation sheet is connected with the rear edge point of the lower surface of the slat and the leading edge point of the sagging leading edge bending flap.

5. The method of flow optimization at a leading edge bending flap and slat interface of claim 2, wherein: when the front edge bending flap is placed, the front part of the principle shape of the second flow spacer is sealed with the outermost plane after the front edge bending flap sags, the upper edge is sealed with the lower surface of the wing, and the lower edge is connected with the front edge point after the front edge bending flap sags and the lower surface of the spanwise aerofoil section by 30% of chord direction positions in a secondary curve mode.

6. The method of flow optimization at a leading edge bending flap and slat interface of claim 2, wherein: the first flow isolation sheet is fixedly arranged on the inner side surface of the leading edge slat and is folded and unfolded along with the slat, and the second flow isolation sheet is fixedly arranged on the outer side section of the leading edge bending flap or is arranged on the outer side section of the leading edge bending flap through a front hinge point and a rear hinge point and is folded and unfolded along with the droop of the leading edge bending flap.

7. The method of flow optimization at a leading edge bending flap and slat interface of claim 2, wherein: and opening a seam slightly wider than the first flow separation sheet and applying corresponding sealing on the leading edge fixing section at the innermost side of the slat, enabling the outer side of the second flow separation sheet to be in parallel contact with or leave a small gap with the first flow separation sheet arranged at the innermost side of the slat, and opening a seam slightly wider than the second flow separation sheet and applying corresponding sealing on the lower surface of the front part of the wing at the section.

8. The method of flow optimization at a leading edge bending flap and slat interface of claim 1 or 2, wherein: the method comprises the following steps:

Step 1: flow field analysis

analyzing the flow at the junction of the leading edge bending flap and the leading edge slat, when the incidence angle of the aircraft is increased to a certain degree, the flow of the local upper wing surface is separated in advance due to the interference of two spanwise branches, wherein one branch is the spanwise flow towards the outer wing direction along the concave area of the lower surface of the leading edge bending drooping flap, and the partial flow at the junction of the leading edge bending drooping flap and the leading edge slat overturns to the upper wing surface along the slat slot; the other part is an upper wing surface at the junction where the most inner slot airflow of the leading-edge slat flows to the direction component of the inner wing, and the comprehensive effect of the two airflows induces the advanced separation of the upper surface of the wing;

Step 2: flow spacer design

aiming at a generation mechanism of flow advance separation, two flow spacers for blocking flow spanwise impact are provided and designed, the two flow spacers are both of rigid sheet structures, the cross section of each flow spacer is rectangular, and chamfers are added at the edges of the flow spacers, which are connected with airflow;

And step 3: flow spacer mounting

Arranging a first flow spacer along the forward extending direction of the slat between the leading edge bending flap and the leading edge slat; arranging a second flow spacer on the lower surface of the wing along the flow direction at the junction of the leading edge bending flap and the leading edge slat;

and 4, step 4: wind tunnel test

And carrying out wind tunnel blowing tests on the leading edge bending flap and the leading edge slat which are provided with the flow spacers, and verifying the flow field distribution and the flow separation condition.

9. A flow optimization device at the interface of a leading edge bending flap and a leading edge slat is characterized in that: in the combined configuration of the wing inner side leading edge bending flap and the wing outer side leading edge slat, a first flow isolation sheet and a second flow isolation sheet are arranged, wherein the first flow isolation sheet is positioned between the leading edge bending flap and the leading edge slat and is arranged along the forward extending direction of the slat; the second flow spacer is also positioned at the junction of the leading edge bending flap and the leading edge slat and arranged along the lower surface of the wing, the cross sections of the first flow spacer and the second flow spacer are rectangular, and a chamfer structure is additionally arranged at the edge connected with the airflow.

10. The flow optimization device at the leading edge bending flap and slat interface of claim 2, wherein: the first flow spacer and the second flow spacer are of an integral structure.

Technical Field

The invention belongs to the technical field of flow control, and provides a method and a corresponding device for optimizing flow at the junction of a bending flap and a leading edge slat of a leading edge of an aerocraft wing and inhibiting and delaying flow separation in the region.

Background

With the higher requirements of green aviation on the design of new-generation aircrafts, seamless leading-edge flaps capable of reducing aerodynamic noise and optimizing surface flow are increasingly gaining attention. Among these, integrally-flapped leading-edge flaps, which can simplify the kinematics, have already started to be applied on the inner wings of the latest large civil aircraft; the new continuous bending type leading edge droop flap (hereinafter referred to as a leading edge bending flap) can further keep the continuous transition of the outer surface of the leading edge, and is more beneficial to realizing the design of laminar flow wings, so that the flap becomes a current research hotspot.

In the practice of the design research of the high lift device of the advanced high-performance commercial aircraft, in order to utilize the advantages of the leading edge bending flap and obtain higher maximum lift coefficient, the novel combined configuration that the leading edge bending flap is adopted on the inner wing of the wing, and the conventional leading edge slat is adopted on the outer wing is provided, so that the effect of comprehensive optimization is achieved. However, it has been found in research that at the spanwise junction of these two types of leading edge flaps, owing to the differences in flap type and the discontinuities in geometry, complex flow phenomena occur and lead to a premature separation of the flow at the upper surface of the wing at this location when the angle of attack increases.

For the airplane with the wing-mounted engine nacelle, the two leading edge flaps can be separated through the design of the engine pylon, but for the airplane without the wing-mounted engine, the improvement cannot be realized through the design of the engine pylon at present, and the problem of flow separation at the spanwise junction of the two leading edge flaps is difficult to effectively solve.

Disclosure of Invention

The invention aims to: the method and the corresponding device can effectively optimize the flow at the junction of the leading edge bending flap and the leading edge slat, inhibit and delay the flow separation of the region, and carry out wind tunnel test verification.

The technical scheme of the invention is as follows: a method for optimizing the flow of the juncture of a leading edge bending flap and a leading edge slat is characterized in that in the combined configuration of the leading edge bending flap and the leading edge slat on the inner side of a wing, two flow separation sheets are respectively arranged at the flow spreading flow positions of the juncture of the leading edge bending flap and the leading edge slat aiming at the generation mechanism of flow advance separation by analyzing the flow field of the juncture of the leading edge bending flap and the leading edge slat, so that the flow field distribution of the juncture is improved, and the flow field separation is inhibited.

The two flow isolation sheets are respectively a first flow isolation sheet and a second flow isolation sheet, wherein the first flow isolation sheet is positioned between the leading edge bending flap and the leading edge slat and arranged along the forward extending direction of the slat; the second flow isolation sheet is also positioned at the junction of the leading edge bending flap and the leading edge slat and arranged downstream on the lower surface of the wing.

the first flow isolating piece and the second flow isolating piece are both of rigid sheet structures, the cross section of each rigid sheet structure is rectangular, and chamfers or fillets are added to the edges connected with the airflow.

in the down state of the flap, the leading edge of the first flow separation sheet is sealed with the innermost plane of the slat, the trailing edge of the first flow separation sheet is sealed with the outermost plane of the leading edge bending flap, the upper edge of the principle shape of the first flow separation sheet is connected with the rear edge point of the upper surface of the slat and the middle part of the upper surface of the leading edge bending flap, and the lower edge of the first flow separation sheet is connected with the rear edge point of the lower surface of the slat and the leading edge point of the sagging leading edge bending flap.

when the front edge bending flap is placed, the front part of the principle shape of the second flow spacer is sealed with the outermost plane after the front edge bending flap sags, the upper edge is sealed with the lower surface of the wing, and the lower edge is connected with the front edge point after the front edge bending flap sags and the lower surface of the spanwise aerofoil section by 30% of chord direction positions in a secondary curve mode.

The first flow isolation sheet is fixedly arranged on the inner side surface of the leading edge slat and is folded and unfolded along with the slat, and the second flow isolation sheet is fixedly arranged on the outer side section of the leading edge bending flap or is arranged on the outer side section of the leading edge bending flap through a front hinge point and a rear hinge point and is folded and unfolded along with the droop of the leading edge bending flap.

And opening a seam slightly wider than the first flow separation sheet and applying corresponding sealing on the leading edge fixing section at the innermost side of the slat, enabling the outer side of the second flow separation sheet to be in parallel contact with or leave a small gap with the first flow separation sheet arranged at the innermost side of the slat, and opening a seam slightly wider than the second flow separation sheet and applying corresponding sealing on the lower surface of the front part of the wing at the section.

The flow optimization method at the junction of the leading edge bending flap and the leading edge slat comprises the following steps: the method comprises the following steps:

Step 1: flow field analysis

Analyzing the flow at the junction of the leading edge bending flap and the leading edge slat, when the incidence angle of the aircraft is increased to a certain degree, the flow of the local upper wing surface is separated in advance due to the interference of two spanwise branches, wherein one branch is the spanwise flow towards the outer wing direction along the concave area of the lower surface of the leading edge bending drooping flap, and the partial flow at the junction of the leading edge bending drooping flap and the leading edge slat overturns to the upper wing surface along the slat slot; the other part is an upper wing surface at the junction where the most inner slot airflow of the leading-edge slat flows to the direction component of the inner wing, and the comprehensive effect of the two airflows induces the advanced separation of the upper surface of the wing;

Step 2: flow spacer design

Aiming at a generation mechanism of flow advanced separation, two flow spacers for blocking flow spanwise impact are provided and designed, the two flow spacers are both of rigid sheet structures, the cross section of each flow spacer is rectangular, and chamfers or fillets are added at the edges of the flow spacers, which are connected with airflow;

And step 3: flow spacer mounting

Arranging a first flow spacer along the forward extending direction of the slat between the leading edge bending flap and the leading edge slat; arranging a second flow spacer on the lower surface of the wing along the flow direction at the junction of the leading edge bending flap and the leading edge slat;

And 4, step 4: wind tunnel test

And carrying out wind tunnel blowing tests on the leading edge bending flap and the leading edge slat which are provided with the flow spacers, and verifying the flow field distribution and the flow separation condition.

a leading edge bending flap and leading edge slat boundary flow optimizing device is characterized in that a first flow separation sheet and a second flow separation sheet are arranged in a combined configuration of the leading edge bending flap and the leading edge slat on the inner side of a wing, wherein the first flow separation sheet is positioned between the leading edge bending flap and the leading edge slat and arranged along the forward extending direction of the slat; the second flow isolation sheet is also positioned at the junction of the leading edge bending flap and the leading edge slat and arranged downstream on the lower surface of the wing, the first flow isolation sheet and the second flow isolation sheet are both rigid sheet structures, the cross section of each rigid sheet structure is rectangular, and a chamfer angle or a fillet structure is added to the edge connected with airflow.

The first flow spacer and the second flow spacer are of an integrated structure, so that the mechanism is simplified, and the structure is optimized.

The invention has the advantages that:

According to the flow optimization method and device for the junction of the leading edge bending-variable flap and the leading edge slat, the flow adverse interference at the junction of the leading edge bending-variable flap and the leading edge slat is effectively overcome through the combined design of the leading edge bending-variable flap and the leading edge slat on the inner side of the wing and the optimized design of the flow isolation sheet, the occurrence of upper surface flow separation is delayed, the maximum lift coefficient of the airplane is improved, and the practicability of an advanced leading edge bending-variable flap and leading edge slat combined high lift system is promoted. In addition, the invention provides a flow optimization method and a device based on flow mechanism analysis, which have the advantages of clear principle, advanced algorithm, simple mechanism, strong pertinence and obvious effect, and are verified by wind tunnel tests.

Drawings

FIG. 1 is a schematic view of the present invention, wherein 101 is a leading edge bending flap (looking from the wing tip to the wing root) in a sagging state; 102 is a leading-edge slat and is in a down state; 103 is a front edge fixed section; 104 is the wall surface of the wing body fairing (the wall surface of the wing body fairing is referred to, and the arc line at the upper part of the wall surface is the connecting line of the wing body fairing and the fuselage); 105 is the wall surface of the fuselage (namely the surface of the cylindrical section of the fuselage); 106 is the lower surface of the wing; 107 is a trailing edge flap which is in a laid-down state; 108 is the incoming flow direction.

FIG. 2 is a schematic view of a flow optimization device of the present invention, shown at 102 as a leading edge slat; slat medial side 201; 202 is a schematic outline of a first flow spacer; 101 is a leading edge bending flap (looking from the wing root to the wing tip); 104 is the wall surface of the wing body fairing; 203 is a lower surface concave area of the droop state of the leading edge bending flap; 204 is the principle appearance of the second flow spacer; 106 is the lower surface of the wing; 103 is the leading edge fixed segment and 108 is the incoming flow direction.

FIG. 3-1 is a surface flow spectrum of a no-flow optimizer, where it can be seen that there is a distinct flow separation zone at the leading edge bending flap and slat interface;

FIG. 3-2 is a surface flow chart of the installed flow optimization device, where it can be seen that the flow separation at the interface has disappeared;

FIG. 4 is a schematic view of an embodiment of the present invention, shown at 102 as a leading-edge slat; slat medial side 201; 202 is a schematic outline of a first flow spacer; 101 is a leading edge bending flap; 104 is the wall surface of the wing body fairing; 401 is the overall structural outline of the first flow spacer (thick long dashed line); 402 is a second flow spacer scheme-overall structural outline (heavy short dashed line); 403 and 404 are two hinge locations for the first second flow spacer mounting scheme; 204 is the principle profile of the second flow spacer and 108 is the incoming flow direction.

FIG. 5 is a schematic view of a second embodiment of the invention, in which 101 is a leading edge bending flap; 102 is a leading-edge slat; 103 is a front edge fixed section; 107 is a trailing edge flap; 501 is the overall structural shape of the second flow spacer scheme two (thick short dashed line), and 108 is the incoming flow direction.

FIG. 6 is a schematic diagram of the effect of the present invention, taken from the curves of lift coefficient CL and angle of attack AoA of a wind tunnel test, where curve A is the curve for installing the flow optimization device, the lift line has a long linear section and a high maximum lift coefficient; curve B is the result of the no-flow optimization device, the lift line turns ahead, and the maximum lift coefficient is low.

Detailed Description

The invention is further illustrated with reference to the following figures and examples:

Aiming at the problem of flow separation at the juncture of the bending flap and the slat of the leading edge, the flow optimization method at the juncture of the bending flap and the slat of the leading edge adopts Computational Fluid Dynamics (CFD) software to carry out flow analysis on the flow field at the juncture of the bending flap and the slat of the leading edge in the design process, researches the mechanism of flow advance separation at the juncture of the bending flap and the slat of the leading edge, accordingly provides a theory principle and an inhibition method for delaying separation, and designs a corresponding flow control scheme and a flow optimization device. Aiming at the generation mechanism of flow advance separation, two spacers with specific structures and shapes are respectively arranged at different positions of the junction of a front edge bending flap and a leading edge slat, CFD analysis and design optimization are carried out on the provided flow optimization device, a wind tunnel test model with a full-machine high lift device is processed after the theoretical shape is determined, a blowing test is developed in a large-scale production type wind tunnel, the practical effect of the invention is verified, the flow field distribution of the junction is improved, the flow field separation is inhibited, the maximum lift coefficient of an airplane is greatly improved, the pneumatic performance is improved, and the practicability of an advanced leading edge bending flap and leading edge slat combined high lift system is promoted.

The invention relates to a flow optimization method at the junction of a leading edge bending flap and a leading edge slat, which comprises the following specific implementation processes:

Step 1: flow field analysis

Referring to fig. 1, for the novel wing leading edge lift-increasing device with a combined leading edge bending flap and leading edge slat, the take-off and landing configuration calculation of the full-aircraft-band lift-increasing device is carried out by using a CFD method based on a reynolds average NS equation, and the mechanism analysis is carried out on the flow details at the junction of the leading edge bending flap and the leading edge slat, and it is found that when the aircraft incidence angle is increased to a certain degree, the flow of the local upper airfoil surface is separated in advance, as shown in fig. 3-1, and at the same time, the lift curve has small fluctuation and turning, as shown in a curve B in fig. 6. Detailed flow detail analysis indicates that the pre-separation is mainly caused by two local spanwise flow branches, wherein one branch is the spanwise flow towards the outer wing along the concave region of the lower surface of the leading edge bending droop flap (see the positions indicated in fig. 1-101 and fig. 2-203), and the partial flow is overturned to the upper wing surface along the slat slot at the interface with the leading edge slat; the other is that the inward-wing direction component of the flow of the slot path at the innermost side of the leading-edge slat (see the positions indicated by fig. 1-102) flows to the upper wing surface at the junction, and the combined effect of the two flows induces the advanced separation of the upper surface of the wing.

Step 2: spacer design

aiming at the generation mechanism of the flow advance separation, the invention provides and designs a flow optimization device at the junction of the bending flap and the slat of the leading edge, and the optimized flow separation sheet is utilized to inhibit the flow separation of the junction area, please refer to fig. 2.

Flow analysis shows that when the flap is laid down, the flow in the slat and main wing slot channel can generate strong outward spreading flow at two ends of the non-closed slat. Wherein the first flow separation sheet is a rigid sheet structure and is located between the leading edge bending flap 101 and the leading edge slat 102 and arranged along the extending direction of the leading edge slat (as shown in fig. 2-202). In the flap down state, the leading edge of the principle shape of the first flow separation sheet is sealed with the innermost side surface 201 of the leading edge slat, the trailing edge of the first flow separation sheet is sealed with the outermost side plane of the leading edge bending flap 101, the upper edge of the first flow separation sheet is connected with the rear edge point of the upper surface of the leading edge slat and the middle part of the upper surface of the leading edge bending flap, and the lower edge of the first flow separation sheet is connected with the rear edge point of the lower surface of the leading edge slat and the leading edge point of the sagging leading edge bending flap. CFD analysis shows that the principle shape, installation position and structural design of the first flow spacer can effectively prevent the air flow of the innermost slot of the leading edge slat 102 from flowing towards the inner wing to the upper wing surface of the leading edge bending flap at the junction, and guide the air flow to better turn towards the downstream direction of the upper surface of the wing along the flowing direction.

Flow analysis shows that higher pressure in the recessed area of the lower surface of the leading edge bending flap in the flap-down state causes the flow in this area to generate a significant spanwise flow component in the outboard direction, which at the outermost end of the leading edge bending flap flows through the slat and main wing slot into the upper surface of the junction of the two flaps, thereby inducing flow separation. The primary function of the second flow spacer of the present invention is to block the flow component of the spanwise flow in the concave region of the lower surface of the leading edge curved flap from flowing through the slot of the slat and main wing into the upper surface of the junction of the two flaps. The second flow spacer is also of a rigid sheet structure, is located at the junction of the leading edge bending flap 101 and the leading edge slat 102, is arranged in the downstream direction of the lower surface of the wing (as shown in fig. 2-204), and in the state that the leading edge bending flap is placed, the front part of the principle shape of the second flow spacer is sealed with the outermost plane of the sagging leading edge bending flap, the upper edge is sealed with the lower surface of the wing, the lower edge is in a crescent arc shape, and the front edge point of the sagging leading edge bending flap and the 30% chord-wise position of the lower surface of the spanwise wing section are connected by a secondary curve. CFD analysis shows that the principle appearance, the installation position and the structural design of the second flow spacer can effectively block the outward wing direction of the lower surface concave area 203 after the leading edge bending flap droops from flowing in the spanwise direction, and guide the lower surface of the turning wing to better turn to flow in the downstream direction along the flowing direction.

the first flow isolation sheet and the second flow isolation sheet are both of rigid sheet structures, and the thickness of the full-size airplane with the average aerodynamic chord of 4.2 m is about 5 mm, and the thickness can be changed correspondingly according to different wing sizes and materials. The typical cross section of the spacer is rectangular, and the edge of the spacer, which is connected with the air flow, is added with a chamfer so as to be beneficial to the air flow, so that the air flow is smoother when the air flow bypasses the spacer, meanwhile, the ground maintenance can be avoided from hurting the crew, the chamfer is preferably circular, the flow field is smoother at the moment, and the flow separation can be better inhibited.

CFD analysis shows that the invention can effectively guide the airflow at the junction of the leading edge bending flap and the leading edge slat, inhibit the development of unfavorable flow and effectively delay the occurrence of separation by the arrangement and combination of the two optimized flow spacers.

And step 3: spacer mounting

the invention provides two embodiments for designing and installing a spacer by using a flow optimization device at the junction of a leading edge bending flap and a leading edge slat.