A transonic buffet control structure based on wing trailing edge bleed holes
By setting vents inside the trailing edge of the wing and using jets to suppress flutter, the problem of the significant impact of flutter control on lift characteristics in existing technologies has been solved, and a balance between flutter control and lift performance has been achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING INST OF TECH
- Filing Date
- 2021-01-27
- Publication Date
- 2026-05-19
AI Technical Summary
Existing technologies for controlling transonic buffeting can significantly impact the lift characteristics of aircraft, making it difficult to maintain lift performance while suppressing buffeting.
Ventilation holes are installed inside the trailing edge of the wing, with the diameter of the holes being equal to the thickness of the airfoil's trailing edge. The ventilation holes are connected to the blunt trailing edge on the upper surface of the airfoil to form a jet that hinders the fusion of the shock wave foot separation bubble and the trailing edge separation zone, suppressing flutter and reducing the impact on the high pressure on the lower surface.
It effectively suppresses buffeting, reduces lift loss, reduces the amplitude of lift coefficient fluctuation by 52%, and the time average value by only 0.7%, significantly reducing the impact on lift characteristics.
Smart Images
Figure CN112849388B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of aircraft flow control technology, specifically relating to a transonic flutter control structure based on the wing trailing edge ventilation holes. Background Technology
[0002] When an aircraft flies at transonic speeds, shock wave-boundary layer disturbances can cause flow separation and periodic self-excited oscillations of the shock wave, leading to transonic buffeting. Buffeting often generates large unsteady loads, adversely affecting flight performance and structural lifespan. Therefore, flow control is necessary to suppress transonic buffeting.
[0003] Mabey et al. proposed a flutter vent concept for shock wave oscillations in symmetrical airfoils (wing sections), as shown in the attached figure. Figure 1 As shown, by perforating the upper and lower surfaces of the airfoil downstream of the shock wave and connecting them internally, the pressure on the upper and lower surfaces of the airfoil can be transmitted, thereby eliminating or weakening the shock wave oscillation at zero angle of attack.
[0004] Based on Mabey's research, Jiang et al. developed a method that uses flutter vents that penetrate the upper and lower surfaces of the airfoil to separate the separated flow after the shock wave on the upper surface of the supercritical airfoil from the separation zone at the trailing edge of the airfoil, thus hindering their fusion and interaction and suppressing flutter.
[0005] While the flutter vent flow control technology studied by Mabey and Jiang et al. can effectively reduce shock wave oscillations in the airfoil and wing flow and suppress transonic flutter, it also significantly impacts the aerodynamic characteristics of the original airfoil. Numerical simulations show that the lift coefficient loss can exceed 10% when flutter loads are completely eliminated. This is unacceptable for aircraft designs that heavily rely on lift characteristics, such as commercial airliners. Summary of the Invention
[0006] In view of this, the present invention provides a transonic flutter control structure based on the wing trailing edge vent, which can reduce the impact on the original wing lift-drag characteristics while controlling flutter.
[0007] A transonic flutter control structure based on a vent on the trailing edge of an airfoil, wherein the flutter control structure is a vent located inside the trailing edge of the airfoil, one end of which communicates with the upper surface of the airfoil and the other end of which communicates with the blunt trailing edge of the airfoil; the diameter of the vent is on the same order of magnitude as the thickness of the trailing edge of the airfoil.
[0008] Furthermore, the vent is located in the middle and rear part of the wing airfoil.
[0009] Furthermore, the vents are oriented in the same direction as the curvature of the upper surface of the airfoil on the trailing edge of the wing.
[0010] Furthermore, the cross-sectional shape of the vent is circular or square.
[0011] Furthermore, the vent is presented as a through slot in the three-dimensional wing.
[0012] Beneficial effects:
[0013] 1. The flutter control structure of the present invention adopts a vent that connects the trailing edge of the wing and the upper surface of the wing. By utilizing the pressure difference between the trailing edge of the wing and the upper surface of the wing, a jet is generated in the vent that flows from the trailing edge of the wing to a certain point on the upper surface. This jet can hinder the fusion of the shock wave foot separation bubble and the trailing edge separation zone, thereby suppressing transonic flutter.
[0014] 2. The inlet of the vent of the present invention is located at the blunt trailing edge of the airfoil, and the diameter of the vent is on the same order of magnitude as the thickness of the trailing edge of the airfoil. Therefore, it has little impact on the high pressure on the lower surface of the airfoil, thereby reducing the lift loss caused by flow control to the airfoil. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of the structure of a flutter vent on an airfoil in the prior art;
[0016] Figure 2 This is a graph showing the time-averaged pressure distribution on the airfoil surface under transonic conditions.
[0017] Figure 3 This is a schematic diagram of the transonic chattering control structure of the present invention;
[0018] Figure 4 This is a magnified view of the outlet and inlet of the trailing edge vent.
[0019] Figure 5 This is a comparison chart of the airfoil lift coefficient-time curves. Detailed Implementation
[0020] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.
[0021] This invention provides a transonic flutter control structure based on vents on the trailing edge of an airfoil. For a supercritical airfoil, the surface time-averaged pressure distribution under transonic conditions is as follows: Figure 2 As shown. The pressure on the upper surface of the airfoil is relatively low, gradually increasing from the low-pressure "plateau" to the trailing edge. A schematic diagram of the wing trailing edge vents proposed in this invention is shown below. Figure 3As shown, the cross-sectional shape of the vent is circular. For ease of illustration, the airfoil has been thickened in the figure. The trailing edge vent is located in the middle-rear part of the airfoil, connecting the blunt trailing edge (point B) to point A on the upper surface of the airfoil where the pressure is lower. Because the pressure at point B is higher than at point A, a flow from B to A is generated in the vent under the pressure difference, forming a jet perpendicular to the airfoil chord direction at point A. This jet can hinder the merging of the shock wave foot separation bubble and the airfoil trailing edge separation zone, weakening the unsteadiness of the separation zone and suppressing transonic fluttering of the airfoil. Simultaneously, since the vent inlet is located at the blunt trailing edge of the airfoil, and the vent diameter d is on the same order of magnitude as the airfoil trailing edge thickness t, as shown in the attached figure... Figure 4 As shown, the impact on the high pressure on the lower surface of the airfoil is relatively small, thus reducing the lift loss caused by flow control to the airfoil.
[0022] Appendix Figure 5 Numerical simulations are presented, comparing the lift coefficient-time curves of the OAT15A airfoil under transonic flight conditions (Mach number Ma = 0.73, angle of attack α = 3.5°) with the uncontrolled case, using the flapping control structure with trailing edge vents proposed in this invention for flow control. It can be seen that with flow control via trailing edge vents, the unsteady lift coefficient fluctuation amplitude of the airfoil is reduced by approximately 52%, indicating effective flapping control; simultaneously, the time-averaged lift coefficient is reduced by only about 0.7%, which is an order of magnitude less impact on lift characteristics compared to traditional flapping vent technology. These results demonstrate that the flapping controller based on trailing edge vents proposed in this invention can significantly reduce the impact on the original airfoil's lift-drag characteristics while controlling flapping.
[0023] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A transonic flutter control structure based on wing trailing edge ventilation holes, characterized in that, The flutter control structure is a vent located inside the trailing edge of the wing. One end of the vent communicates with the upper surface of the airfoil, and the other end communicates with the blunt trailing edge of the airfoil. The inlet of the vent is located at the blunt trailing edge of the airfoil, and a jet perpendicular to the chord direction of the airfoil is formed at the outlet of the vent. This jet can prevent the fusion of the shock wave foot separation bubble and the airfoil trailing edge separation zone. The diameter of the vent is on the same order of magnitude as the thickness of the airfoil trailing edge. The vent is located in the middle and rear part of the wing airfoil; the cross-sectional shape of the vent is circular or square.
2. The transonic flutter control structure based on wing trailing edge vents as described in claim 1, characterized in that, The vents are oriented in the same direction as the curvature of the upper surface of the airfoil on the trailing edge of the wing.
3. The transonic flutter control structure based on wing trailing edge vents as described in claim 2, characterized in that, The ventilation holes appear as through slots on a three-dimensional wing.