High-performance airfoil suitable for active stability augmentation of fueling cone

Abstract

The application discloses a high-performance airfoil suitable for active stability of a refueling cone, and meets the following conditions: the maximum relative thickness of the airfoil is 5.6%, the position of the maximum relative thickness is located at 10% of a chord length; the maximum relative camber of the airfoil is 4%, the position of the maximum relative camber is located at 31% of the chord length; the relative leading edge radius of the airfoil is 0.0081, and the relative trailing edge thickness of the airfoil is 1%. The airfoil designed in the application can realize that the lift force keeps linear variation with the angle of attack in the range of 16 degrees at the flight speed of 0.2-0.3 times the sound speed and the flight height of 1-4 kilometers, and can provide a large lift force for a cone cuplet, so as to provide effective support for suppressing the drift and swing of the cone during the oil adding / receiving process.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of airfoil design, and particularly relates to a high-performance airfoil suitable for active stabilization of a refueling cone. BACKGROUND

[0002] Air refueling technology can effectively improve the range and time of an aircraft, so that the aircraft has a greater flight radius and a longer stay time, and effectively relieves the pressure of airport construction. The hose-type refueling has the advantages that a refueling system is relatively simple, a platform is convenient to modify, a donor aircraft does not need to keep a relative position unchanged during refueling, and multiple receiver aircrafts can be refueled at the same time, and thus is a refueling mode suitable for unmanned autonomous refueling. However, since a refueling hose and a cone are easily affected by atmospheric turbulence and swing at high speed, and the cone will vibrate due to the head wave effect when a receiver aircraft approaches, it is difficult to align the receiver aircraft and the cone during docking, thereby leading to low efficiency of the hose-type refueling. Therefore, developing an active stabilization cone to suppress the swing amplitude of the hose cone is an effective means to improve the efficiency of the hose-type refueling. The principle of active stabilization of the refueling cone is to increase the damping of the refueling cone itself, thereby suppressing the swing of the cone. One of the most effective ways to suppress the swing of the cone is to install a winglet on the cone cup and generate different control forces by changing the relative position of the winglet. At present, the airfoil adopted by the winglet of the active stabilization cone is mostly a flat airfoil, and such an airfoil has insufficient lift and a small stall angle, and thus the generated control force is insufficient. The aerodynamic characteristics of an airfoil mainly depend on its geometric shape. The aerodynamic characteristics of the airfoil determine the ability of the winglet to suppress the swing of the cone, and therefore, designing a high-performance airfoil suitable for active stabilization of the refueling cone is the basis for developing the active stabilization cone.

[0003] In summary, a high-performance airfoil suitable for active stabilization of the refueling cone has a flight speed and height determined by the flight state of a donor aircraft and a receiver aircraft. Since the swing suppression of the cone mainly relies on the control force generated by the winglet, the airfoil needs to have high lift characteristics. Since the relative position of the winglet of the cone changes greatly, the airfoil needs to have a large stall angle, so that the lift changes linearly with the change of the relative position, which is beneficial to the design of a control law. At the same time, in order for the winglet and the cone cup to be coordinated in space, the airfoil should be as thin as possible on the basis of meeting the above conditions. The present application designs a high-performance airfoil suitable for active stabilization of the refueling cone according to the above design requirements. SUMMARY

[0004] The present application aims to provide a high-performance airfoil suitable for active stabilization of a refueling cone, which effectively enhances the lift of the winglet of the cone, thereby improving the active stabilization ability of the refueling cone.

[0005] To achieve the above object, the present application provides the following technical scheme:

[0006] A high-performance airfoil suitable for active stability augmentation of fueling cone, which meets the aerodynamic / geometric constraints, sets the maximum relative thickness of the airfoil as 5.6%, and the maximum relative thickness position at 10% chord length; sets the maximum relative camber of the airfoil as 4%, and the maximum relative camber position at 31% chord length; sets the relative leading edge radius of the airfoil as 0.0081, and the relative thickness of the trailing edge of the airfoil as 1%.

[0007] Further, the airfoil has a higher stalling angle of attack, and the stalling angle of attack is 16° when the cruise Mach number is 0.25.

[0008] Further, the airfoil has a larger maximum lift coefficient, and the maximum lift coefficient is about twice that of the initial airfoil of the conelet when the cruise Mach number is 0.25.

[0009] The beneficial effects of the present application are:

[0010] A high-performance airfoil suitable for active stability augmentation of fueling cone, which can realize that the lift keeps linear variation with the angle of attack in the range of 16° at the flight speed of 0.2-0.3 times the speed of sound and the flight height of 1-4 km, and provides larger lift for the conelet, thereby providing effective support for suppressing the drift and swing of the cone during fueling. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 The initial airfoil geometry of the conelet;

[0012] Figure 2 The airfoil geometry designed by the present application;

[0013] Figure 3 The lift characteristics comparison diagram of the flat plate airfoil and the airfoil designed by the present application.

[0014] Wherein, the reference signs are: 1, leading edge point; 2, camber line; 3, camber; 4, upper surface; 5, trailing edge thickness; 6, lower surface; 7, chord line; 8, maximum thickness; 9, head curvature circle. DETAILED DESCRIPTION

[0015] The present application will be further described in detail below in combination with the drawings and embodiments:

[0016] Because the cone needs to be retracted into the belly during the cruise of the refueling machine, and because the oil delivery mechanism needs to be arranged in the cone cup, the aileron cannot be retracted into the cone cup, so the aileron area of the cone will be constrained, and thus the aileron airfoil needs to have the characteristics of high lift at low speed. In addition, because the refueling cone active stability principle mainly relies on the change of the relative position of the aileron, and the position and posture of the cone will also change during the cone stability process, the above reasons cause the aileron angle of attack to change in a large range, so the aileron airfoil needs to have a large stall angle of attack, so as to ensure that the aileron control force has good linearity.

[0017] The initial airfoil of the aileron of the cone is shown in Figure 1 to be a flat and symmetrical shape. Such an outline usually generates a small maximum lift and a small stall angle of attack, so the generated control force cannot effectively suppress the cone from rolling and pitching. Therefore, taking the initial airfoil as the initial state, a high-performance airfoil suitable for active stability of the refueling cone is designed.

[0018] The main parameters of the airfoil design are shown in Figure 2 , including a leading edge point 1, a camber line 2, a camber 3, an upper surface 4, a trailing edge thickness 5, a lower surface 6, a chord line 7, a maximum thickness 8, and a head curvature circle 9.

[0019] The airfoil is designed according to 0.25 times the sound speed flying speed and 2 km flying height. Under the condition of satisfying the aerodynamic / geometric constraints, the maximum relative thickness of the airfoil is set to 5.6%, the maximum relative thickness position is located at 10% of the chord length, the relative leading edge radius of the airfoil is set to 0.0081, the relative trailing edge thickness of the airfoil is 1%, the head radius of the airfoil is large, and the curvature changes slowly after the maximum radius, so the airfoil has good stall characteristics. The maximum relative camber of the airfoil is set to 4%, the maximum relative camber position is located at 31% of the chord length, and the lift of the airfoil is increased.

[0020] To further illustrate the advantages of a high-performance airfoil suitable for active stability of the refueling cone, Figure 3 the law of the lift coefficient of the airfoil and the initial airfoil changing with the angle of attack under the design state is given. As can be seen from Figure 3 , the stall angle of attack of the airfoil of the present application is 16°, which is much larger than the stall angle of attack of the initial airfoil, and the maximum lift coefficient of the airfoil of the present application is about twice that of the initial airfoil.

[0021] The above-described is only an embodiment of the present application, and well-known specific technical solutions and / or common knowledge of characteristics in the scheme are not described in detail. It should be noted that for those skilled in the art, without departing from the technical solutions of the present application, a number of modifications and improvements can be made, which should also be considered as the protection scope of the present application, and these will not affect the effect and practicality of the patent. The protection scope claimed in the present application should be subject to the content of its claims, and the specific implementation mode and the like recorded in the specification can be used to explain the content of the claims.

Claims

1. A high-performance airfoil suitable for active stabilization of a refueling drogue, characterized by: Under aerodynamic / geometric constraints, the maximum relative thickness of the airfoil is set to 5.6%, and the maximum relative thickness is located at 10% of the chord length; the maximum relative camber of the airfoil is set to 4%, and the maximum relative camber is located at 31% of the chord length; the relative leading edge radius of the airfoil is set to 0.0081, and the relative thickness of the trailing edge of the airfoil is set to 1%; the airfoil has a stall angle of attack, and the stall angle of attack is 16° when the cruise Mach number is 0.25; the airfoil has a maximum lift coefficient, and the maximum lift coefficient when the cruise Mach number is 0.25 is approximately twice that of the initial airfoil of the drogue winglet.

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