CN112597589B

CN112597589B - Wing design method

Info

Publication number: CN112597589B
Application number: CN202011554720.4A
Authority: CN
Inventors: 张澎; 景致; 张宗强
Original assignee: Shenyang Aircraft Design and Research Institute Aviation Industry of China AVIC
Current assignee: Shenyang Aircraft Design and Research Institute Aviation Industry of China AVIC
Priority date: 2020-12-24
Filing date: 2020-12-24
Publication date: 2022-09-20
Anticipated expiration: 2040-12-24
Also published as: CN112597589A

Abstract

The application belongs to the field of airplane structure design, and particularly relates to a wing design method. The method comprises the following steps: step S1, setting the leading edge of the wing to be a large-sweepback-angle circular arc-shaped structure with gradually changed thickness, wherein the thickness gradually decreases from front to back along the course, the sweepback angle is not less than 50 degrees, and the circular arc-shaped structure refers to circular arc connection of the upper surface and the lower surface of the leading edge of the wing; step S2, setting the wingtip of the wing as the wingtip leading edge and the wingtip trailing edge to carry out arc transition, constructing an arc contour line based on a 3-order NURBS curve, and determining the curvature radius R of the arc according to the wavelength of low-frequency electromagnetic waves; and step S3, determining that the front edge of the wing tip in the step S2 is parallel to the front edge line of the wing on the side, the rear edge of the wing tip is parallel to the front edge line of the wing on the other side, and determining the lengths of the front edge of the wing tip and the rear edge of the wing tip according to the curvature radius R. The method and the device effectively inhibit the strong scattering generated by the wingtips in the forward azimuth domain, and provide technical support for the low-frequency stealth design of the airplane.

Description

Wing design method

Technical Field

The application belongs to the field of airplane structure design, and particularly relates to a wing design method.

Background

As the detection threat increases, the aircraft's demand for stealth capability increases. Since most of the working frequency bands of the early warning radar are P, L wave bands with low frequencies, the stealth aircraft must also have corresponding low-frequency stealth capability.

For the aircraft with the layout without the tail flying wing, the aircraft can keep good stealth performance under the low-frequency condition by virtue of the simple layout appearance. Because the traditional strong scattering sources in the forward angular region are effectively suppressed, the sharp point scattering of the wing tips of the wings becomes a non-negligible scattering source. The electromagnetic wave will excite the traveling wave under the condition of glancing incidence along the wing leading edge, and the traveling wave will propagate backwards along the wing leading edge to generate echo scattering at the wing tip. For high-frequency electromagnetic waves, on one hand, the traveling wave effect is relatively weak, and on the other hand, the wing tip point scattering is not obvious due to the strong attenuation performance of the wave-absorbing material. For low-frequency electromagnetic waves with P, L wave bands, on one hand, the traveling wave effect is strong, and on the other hand, the wave absorbing performance of the stealth material is greatly reduced, so that the problem of wingtip scattering is highlighted.

Disclosure of Invention

In order to solve the above problems, the present application provides a wing design method capable of effectively suppressing low-frequency wing tip scattering, which mainly includes:

step S1, setting the leading edge of the wing to be a large-sweepback-angle circular arc-shaped structure with gradually changed thickness, wherein the thickness gradually changes to be gradually reduced from front to back along the course, the sweepback angle is not less than 50 degrees, and the circular arc-shaped structure refers to circular arc connection of the upper surface and the lower surface of the leading edge of the wing;

step S2, setting the wingtip of the wing as the wingtip leading edge and the wingtip trailing edge to carry out arc transition, constructing an arc contour line based on a 3-order NURBS curve, and determining the curvature radius R of the arc according to the wavelength of low-frequency electromagnetic waves;

and step S3, determining that the front edge of the wing tip in the step S2 is parallel to the front edge line of the wing on the side, the rear edge of the wing tip is parallel to the front edge line of the wing on the other side, and determining the lengths of the front edge of the wing tip and the rear edge of the wing tip according to the curvature radius R.

Preferably, in step S1, the trailing edge of the wing is designed to be a wedge, and the wing profile is smooth and continuous.

Preferably, in step S2, the radius of curvature R of the arc shape of the wing tip is set to be not lower than the wavelength of the low-frequency electromagnetic wave.

Preferably, when the frequency of the low-frequency electromagnetic wave is 0.3GHz, the curvature radius R of the arc of the wing tip is not less than 300 mm.

Preferably, when the frequency of the low-frequency electromagnetic wave is 0.6GHz, the curvature radius R of the arc of the wing tip is not less than 150 mm.

Preferably, when the frequency of the low-frequency electromagnetic wave is 0.9GHz, the curvature radius R of the arc of the wing tip is not less than 100 mm.

Preferably, when the frequency of the low-frequency electromagnetic wave is 1.5GHz, the curvature radius R of the arc of the wing tip is not less than 70 mm.

Preferably, when the frequency of the low-frequency electromagnetic wave is 2GHz, the curvature radius R of the arc of the wing tip is not less than 50 mm.

The technical scheme formed by the invention can effectively inhibit the wing tip from generating strong scattering in the forward azimuth angle region, and provides technical support for the low-frequency stealth design of the airplane.

Drawings

FIG. 1 is a schematic view of a wing structure according to the wing design method of the present application.

FIG. 2 is a schematic view of the tip structure of the embodiment of FIG. 1 of the present application.

Wherein, 1-wing body, 2-wing tip, 21-wing tip front edge, 22-wing tip rear edge and 23-circular arc.

Detailed Description

In order to make the implementation objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the accompanying drawings in the embodiments of the present application. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are implementations that are part of this application and not all implementations. The embodiments described below with reference to the drawings are exemplary and intended to be used for explaining the present application, and should not be construed as limiting the present application. All other embodiments obtained by a person of ordinary skill in the art without any inventive work based on the embodiments in the present application are within the scope of protection of the present application. Embodiments of the present application will be described in detail below with reference to the drawings.

The application provides a wing design method, which mainly comprises the following steps:

Fig. 1 shows a wing designed based on the wing design method of the present application, and the present application is described in detail with reference to fig. 1.

The design is mainly performed on a wing body and a wing tip of a wing, as shown in fig. 1, for the wing body 1, since traveling waves causing scattering of the wing tip are generated by excitation of a wing leading edge cylindrical surface, before designing the wing tip, a wing with high stealth appearance layout characteristics needs to be designed as a carrier for wing tip research. The front edge of the wing adopts the arc design of the large sweepback angle (more than 50 degrees) with gradually changed thickness (the thickness is reduced from front to back), the effective shielding of the rear edge can be realized under the condition of small pitching, the rear edge adopts the wedge-shaped design, and the curved surface of the wing appearance is smooth and continuous.

The greatest difference for the tip 2 of the design of the present invention compared to conventional tips is that the tip region is designed in an arc shape, and as shown in fig. 2, the main design parameters of the tip are the length a of the tip leading edge 21, the length b of the tip trailing edge 22, and the radius of curvature R of the arc 23. The wing tip leading edge 21 is an extension line of the wing leading edge, and the wing tip trailing edge 22 is parallel to the wing leading edge on the symmetrical side, so that the wing tip edge scattering can be merged into the wing scattering; the tip circular arc contour line is constructed based on a 3-order NURBS curve, and the main control parameter is the curvature radius R of the curve. When the R value is too small, the wing tip is close to a sharp point, so that the scattering of the wing tip is difficult to completely eliminate, and when the R value is too large, the scattering of the side direction is increased, so that the principle to be followed in the selection of the cambered surface curvature radius R is that the R value is as small as possible on the basis of ensuring that the scattering of the wing tip can be eliminated. Considering that the wavelength of low-frequency electromagnetic waves is 150-600 mm, and the curvature radius R of the wing tip cannot be obviously smaller than the wavelength of the electromagnetic waves, the effective inhibition on the scattering of the wing tip can be ensured, the minimum R value required by the hidden design of the wing tip at different frequency points is given in the table 1. Once the value of R is determined, the values of a and b are determined.

TABLE 1 design parameters for tip curvature radius of different frequencies

The implementation effect of the invention is as follows: the arc design of the wingtip completely eliminates the strong scattering generated by the traditional wingtip under the condition of low frequency.

In one specific example, three comparison schemes were devised, R200 mm, R100 mm and R0 (tip is the point, traditional tip form).

The method comprises the steps of carrying out RCS simulation calculation of 0.6GHz, and according to RCS simulation curves of 3 wing tips with different curvature radiuses, knowing that the traditional wing tip with the R equal to 0 generates obvious strong scattering in the range of 23-33 degrees, adopting the design of an arc wing tip can effectively inhibit the wing tip scattering, wherein the wing tip scattering can not be completely eliminated due to the fact that an arc transition region is small in the wing tip scheme with the R equal to 100mm, and the wing tip scattering can be completely eliminated due to the wing tip scheme with the R equal to 200 mm.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method of designing an airfoil, comprising:

step S3, determining that the front edge of the wing tip in the step S2 is parallel to the front edge line of the wing on the side, the rear edge of the wing tip is parallel to the front edge line of the wing on the other side, and determining the lengths of the front edge of the wing tip and the rear edge of the wing tip according to the curvature radius R;

the arc-shaped curvature radius R of the wing tip is set to be not lower than the wavelength of low-frequency electromagnetic waves, when the frequency of the low-frequency electromagnetic waves is 0.3GHz, the arc-shaped curvature radius R of the wing tip is not lower than 300mm, when the frequency of the low-frequency electromagnetic waves is 0.6GHz, the arc-shaped curvature radius R of the wing tip is not lower than 150mm, when the frequency of the low-frequency electromagnetic waves is 0.9GHz, the arc-shaped curvature radius R of the wing tip is not lower than 100mm, when the frequency of the low-frequency electromagnetic waves is 1.5GHz, the arc-shaped curvature radius R of the wing tip is not lower than 70mm, and when the frequency of the low-frequency electromagnetic waves is 2GHz, the arc-shaped curvature radius R of the wing tip is not lower than 50 mm.

2. The method of claim 1, wherein in step S1, the trailing edge of the wing is designed to be a wedge shape, and the wing profile is smooth and continuous.