CN105905277B - A kind of aerodynamic configuration of aircraft using the rear edge support wing - Google Patents

Abstract

The invention discloses an aircraft aerodynamic layout adopting trailing edge supporting wings. The supporting wings are installed under the trailing edges of the main wings on both sides of the aircraft fuselage. The wing tip of the supporting wing is connected with the middle part of the trailing edge of the wing through the connecting section, and the wing root of the supporting wing is connected with the fuselage through the connecting section. The present invention rationally designs the relative position of the supporting wing and the main wing, so that the vertical distance between the centroids of the main wing section and the supporting wing section intercepted by the airflow flowing to the vertical plane during the flight of the aircraft along the span of the supporting wing is a% of the chord length of the main wing section, and a is a fixed value, in the range of 10 to 40; at the same time, the overlapping length of the projection of the chord line in the main wing section and the supporting wing section on the horizontal plane is b% of the chord length of the main wing section, and b is The fixed value is in the range of 0 to 15; thus, the lift-to-drag ratio of the overall layout can be improved to obtain better aerodynamic performance; at the same time, the purpose of strengthening the stiffness of the wing with a large aspect ratio can be achieved, and the overall structural efficiency of the aircraft can be improved.

Description

An Aircraft Aerodynamic Layout Using Trailing Edge Supported Wings

technical field

The invention belongs to the field of aircraft aerodynamic layout design, in particular to an aircraft aerodynamic layout adopting trailing edge support wings.

Background technique

The pursuit of a high lift-to-drag ratio has always been one of the main goals of aeronautical vehicle design. For fixed-wing aircraft with subsonic conventional layout, since the wing is its main lift component, in order to obtain a higher lift-to-drag ratio during design, the method of increasing the aspect ratio of the wing is usually adopted. The advantage of a wing with a large aspect ratio is that when the flying speed of the aircraft is low, for a wing with the same lift surface area, the use of a larger aspect ratio is beneficial to reduce the induced drag of the wing, so as to obtain a higher lift-to-drag ratio.

However, since the span length of a large aspect ratio wing is much larger than the thickness and chord length of the wing, there may be a problem of insufficient span-wise structural stiffness. During flight, the wing will undergo elastic deformation under the action of aerodynamic force, and this elastic deformation will in turn change the aerodynamic force accordingly, forming an aeroelastic phenomenon in which structural deformation and aerodynamic force interact. Aeroelasticity will have a significant impact on the maneuverability and stability of the aircraft, and in severe cases, it will damage the structure or cause flight accidents. If the method of strengthening the internal structure of the wing is directly adopted, the structural weight of the wing will be greatly increased, and the payload and structural efficiency of the entire aircraft will be reduced.

In order to solve the stiffness problem of the high-aspect-ratio wing mentioned above, NASA proposed a layout of adding support trusses under the wing in the Subsonic All-Green Vehicle Research (SUGAR) conducted in cooperation with Boeing. The layout includes the upper monoplane, the fuselage, the main bracket connecting the wing and the fuselage to share the bending load of the wing, and the vertical bracket connecting the wing and the main bracket. The connection point between the main support and the wing is located in the middle of the wing, and the position of the main support is directly below the wing. Compared with strengthening the internal structure of the wing, this method of adding support truss can greatly reduce the overall structural weight of the wing and improve the payload and structural efficiency of the aircraft. However, the added support truss will reduce the overall lift-to-drag ratio of the aircraft and reduce its aerodynamic efficiency. Although the optimized design of the airfoil and the supporting truss can make up for a certain amount of aerodynamic loss, according to the design experience of biplane aircraft, the aerodynamic efficiency is still relatively low if the lifting surface is arranged directly under the single wing.

Contents of the invention

The present invention starts from the perspective of aerodynamic design, according to the double-wing layout, the lower wing is located at the trailing edge of the upper wing to obtain better aerodynamic performance, and the addition of support trusses can strengthen the spanwise stiffness of the single wing, reduce the weight of the wing structure and improve the performance of the aircraft. Based on the technical experience of the payload, an aircraft aerodynamic layout using trailing edge support wings is proposed, which provides a technical solution with excellent structural performance and aerodynamic performance for the aircraft aerodynamic layout with large aspect ratio wings.

In the aerodynamic layout of the aircraft of the present invention, support wings are installed below the rear edges of the main wings on both sides of the aircraft fuselage. The wing tip of the supporting wing is connected with the middle part of the trailing edge of the wing through the streamlined wing tip connecting section, and the wing root of the supporting wing is connected with the fuselage through the streamlined wing root connecting section.

In each main wing section and supporting wing section intercepted by the airflow along the vertical plane during the flight of the supporting wing span, the vertical distance between the centroids is a% of the chord length of the main wing section, and a is a fixed value. In the range of 10 to 40; at the same time, there is an overlapping part between the leading edge of the supporting wing and the trailing edge of the main wing, and the designed supporting wing span upwards each section of the main wing taken along the vertical plane of the airflow during the flight of the aircraft and the section of the supporting wing The overlapping length of the projection of the chord line on the horizontal plane is b% of the chord length of the main wing section, and b is a fixed value in the range of 0-15.

The advantages of the present invention are:

1. The present invention adopts the aerodynamic layout of the aircraft with trailing edge support wings. In terms of structural performance, it proposes an aerodynamic layout scheme to solve the problem of insufficient stiffness of the wing with a large aspect ratio, which can reduce the structural weight of the wing and improve the overall performance of the aircraft. Payload and structural efficiency;

2. The present invention adopts the aircraft aerodynamic layout of the trailing edge support wing. In terms of aerodynamic performance, the layout scheme of the support wing can make the whole wing The lift coefficient and the lift-to-drag ratio at small angles of attack are improved, making it close to the maximum lift-to-drag ratio of the unsupported single-wing layout, maintaining the overall aerodynamic efficiency of the aircraft.

3. The invention adopts the aerodynamic layout of the aircraft with trailing edge support wings, which can achieve the purpose of strengthening the stiffness of the straight wing with a large aspect ratio, and at the same time enable the aircraft to take into account both aerodynamic efficiency and structural efficiency.

Description of drawings

Fig. 1 is the overall schematic diagram of the aerodynamic layout of the aircraft of the present invention;

Fig. 2 is a schematic diagram of the overall top view of the aerodynamic layout of the aircraft of the present invention;

Fig. 3 is the schematic diagram of the overall side view of the aerodynamic layout of the aircraft of the present invention;

Fig. 4 is a schematic diagram of the overall side front view of the aerodynamic layout of the aircraft of the present invention;

Fig. 5 is that in the aerodynamic layout of the aircraft of the present invention, the vertical direction distance between the centroids and the chord line of the main wing and the supporting wing section in the main wing section and the supporting wing section intercepted by the air flow along the air flow to the vertical plane in the aircraft aerodynamic layout upwards Schematic diagram of overlapping length;

Fig. 6a is a graph showing the variation of the lift coefficient with the angle of attack of the comparison of the aerodynamic layout of the aircraft of the present invention and the single-wing layout;

Figure 6b is a graph showing the variation of the lift-to-drag ratio of the aircraft with the angle of attack compared with the aerodynamic layout of the aircraft of the present invention;

Fig. 7a is the variation curve of the lift coefficient with the installation angle difference between the main wing section and the supporting wing section under two different attack angles in the aerodynamic layout of the aircraft of the present invention;

Fig. 7b is the lift-drag ratio variation curve with the installation angle difference between the main wing section and the supporting wing section under two different attack angles for the aerodynamic layout of the aircraft of the present invention;

In the picture:

1-Main Wing 2-Fuselage 3-Support Wing

4-Wing tip connection section 5-Wing root connection section

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

In the aerodynamic layout of the aircraft of the present invention, the aircraft adopts a straight main wing 1 with a large aspect ratio, a conventional cylindrical fuselage 2, and a support wing 3 with a large dihedral angle, as shown in FIGS. 1-4 . Wherein, there are two main wings 1, which are symmetrically installed on the left and right sides of the fuselage 2 respectively. There are two supporting wings 3, which are arranged symmetrically on both sides of the fuselage, and are respectively located at the rear edge of the two main wings 1, that is, the supporting wings 3 are located downstream of the main wing 1 with respect to the incoming flow direction 8. The wing tip of the supporting wing 3 is connected to the middle part of the trailing edge of the wing 1 through the streamlined wing tip connecting section 4, and the wing root of the supporting wing 3 is connected with the fuselage 2 through the streamlined wing root connecting section 5; and the section chord line of the supporting wing 3 is located at Below the chord line of the main wing 1 section. The above-mentioned two main wings 1 are arranged as an upper single wing, and the two supporting wings 3 are arranged as a lower single wing, so that when the wing 1 and the supporting wing 3 are connected with the fuselage 2, adverse effects on the volume and structure of the fuselage 2 can be avoided. The cross-sectional airfoils of the main wing 1 and the supporting wing 3 can be specifically designed according to the requirements of aerodynamic design, but in the cross-sections of the main wing 1 and the supporting wing 3 taken along the vertical plane during the flight of the aircraft along the span of the supporting wing 3, The chord length of the supporting wing 3 needs to be smaller than the chord length of the main wing 1 .

The specific relative positions of the two supporting wings 3 and the main wing 1 are closely related to the overall aerodynamic performance of the aircraft and must be determined according to the requirements of the aerodynamic design. The specific determination method is: for the wing 1 with a large aspect ratio, due to its spanwise flow can be ignored, so the determination of the relative position between the main wing 1 and the supporting wing 3 can be analyzed according to the two-dimensional situation, and the overall lift-drag ratio of the aircraft can be obtained through simulation. When the lift-drag ratio is the largest, the section between the main wing and the supporting wing is at the optimum relative position. Then design support wing 3 span upwards in the main wing 1 cross-section and support wing 3 cross-sections intercepted by the airflow during the flight of the aircraft to the vertical plane, the vertical distance between the centroids is the main wing 1 section chord length of a%, and a is a fixed value, in the range of 10-40. Simultaneously, there is an overlapping portion between the leading edge of the supporting wing 3 and the trailing edge of the main wing 1, and the design of the supporting wing 3 spans upwards along the chord of the main wing 1 section and the supporting wing 3 section taken along the vertical plane during the flight of the aircraft. The overlapping length L ₂ projected by the lines on the horizontal plane is b% of the chord length of the main wing 1 section, and b is a fixed value within the range of 0-15. Finally, it is extended to the three-dimensional situation, and the configuration of the supporting wing 3 is obtained, as shown in Fig. 4 .

Above-mentioned supporting wing 3 can be designed to be identical with main wing 1 installation angle or different, when supporting wing 3 and main wing 1 installation angles are different, make supporting wing 3 have the angle of attack different from main wing 1 under the flying condition of aircraft, in aircraft of the present invention Under the aerodynamic layout, choosing an appropriate installation angle of the support wing 3 can improve the overall aerodynamic performance of the aircraft within a large range of angle of attack.

Embodiment 1: Both the main wing 1 and the supporting wing 3 adopt Clark-Y airfoil; the chord length of the main wing 1 is 2m, and the reference length of the chord length of the supporting wing 3 is 1m; the supporting wing 3 is designed to span upward in the model of the supporting wing 3 In each section of the main wing 1 and the section of the supporting wing 3 taken along the vertical plane during the flight of the aircraft, the vertical distance between the centroids is 10% of the chord length of the main wing 1 section, and the chord line of the section of the main wing 1 and the supporting wing The 3-section chord overlaps the length of the 1-section chord of the main wing by 11%. Figures 6a and 6b respectively show the two-dimensional analysis curves of the lift coefficient and lift-to-drag ratio of the above-mentioned supported wing 3 layout compared with the unsupported single-wing layout. The lift of the supported wing layout is the sum of the lift of the two wings. The reference lengths of wing 3 and the single wing are both taken as 1m. It can be seen that compared with the single-wing layout, when the supporting wing 3 of the layout in the present invention is located at a reasonable position, the lift coefficient of the overall layout is significantly improved, and the lift-to-drag ratio is improved at a small angle of attack, while the Its maximum lift-to-drag ratio is close to that of an unsupported monoplane. This shows that the layout of the supporting wing of the present invention can obtain better aerodynamic efficiency than that of the single wing layout when it is properly designed.

Embodiment 2: the main wing and the supporting wing all adopt the Clark-Y airfoil; the chord length of the main wing is 2m, and the chord length of the supporting wing is 1m; in the model of the supporting wing 3, the design supporting wing 3 spreads upwards and each along the airflow during the flight of the aircraft In the section of the main wing 1 and the section of the supporting wing 3 intercepted by the flow direction vertical plane, the vertical distance between the centroids is 40% of the chord length of the section of the main wing 1, and the overlapping length of the chord line of the main wing 1 section and the section chord of the supporting wing 3 is 0% of the chord line of the main wing 1 section, that is, the two do not overlap; the installation angle of the main wing 1 section is φ ₁ = 0°, and the installation angle of the support wing 3 section is φ ₂ , then the difference between the installation angles of the main wing 1 and support wing 3 sections is Δφ=φ ₂ −φ ₁ . Figures 7a and 7b show the two-dimensional analysis curves of the lift coefficient and lift-to-drag ratio as a function of Δφ of the above-mentioned support wing 3 layout embodiment at two different angles of attack, wherein the definition of the lift coefficient is the same as that in Embodiment 1. The angles of attack for the overall layout are 0° and 8°, respectively. It can be seen that when the overall attack angle of the layout is 0°, the lift coefficient and lift-to-drag ratio increase monotonously within a considerable range of Δφ; when the attack angle is 8°, the lift-drag ratio does not have a monotonous change with Δφ sex. This shows that the installation angle of the support wing 3 can be determined comprehensively according to the design requirements, so that the overall arrangement of the trailing edge support wing can obtain relatively ideal aerodynamic performance in a relatively large range of attack angles.

To sum up, the present invention increases the support wing 3 at the rear edge position below the main wing 1, and reasonably designs the relative position of the support wing 3 and the main wing 1, while strengthening the stiffness of the main wing 1 with a large aspect ratio, it can improve the layout The overall lift-to-drag ratio can achieve better aerodynamic performance; at the same time, it can achieve the purpose of strengthening the stiffness of the wing with a large aspect ratio and improve the overall structural efficiency of the aircraft.

Claims (3)

1. A kind of aircraft aerodynamic layout structure adopting trailing edge supporting wing, it is characterized in that: supporting wing is installed below the main wing trailing edge, both sides of aircraft fuselage; The wing root of the supporting wing is connected with the fuselage through the streamlined wing root connection section; the main wing section and the supporting wing section taken along the vertical plane of the airflow during the flight of the aircraft along the span of the supporting wing, the chord length of the supporting wing needs to be less than the chord length of the main wing; In each main wing section and supporting wing section intercepted by the airflow along the vertical plane during the flight of the supporting wing span, the vertical distance between the centroids is a% of the chord length of the main wing section, and a is a fixed value. In the range of 10 to 40; at the same time, there is an overlapping part between the leading edge of the supporting wing and the trailing edge of the main wing, and the designed supporting wing span upwards each section of the main wing taken along the vertical plane of the airflow during the flight of the aircraft and the section of the supporting wing The overlapping length of the projection of the chord line on the horizontal plane is b% of the chord length of the main wing section, and b is a fixed value in the range of 0-15. 2. A kind of aircraft aerodynamic layout structure adopting trailing edge support wing as claimed in claim 1, is characterized in that: main wing is arranged as upper single wing, and support wing is arranged as lower single wing. 3. A kind of aircraft aerodynamic layout structure adopting trailing edge support wing as claimed in claim 1, is characterized in that: support wing has the installation angle different from main wing.