Rear edge jet flow control device and method for improving aerodynamic performance of aircraft

Abstract

The invention provides a trailing edge jet flow control device and method for improving aerodynamic performance of an aircraft, the trailing edge jet flow control device comprises a jet flow unit, a jet flow direction calculation unit and a control unit, the jet flow unit is installed at the trailing edge of an aircraft wing, and the jet flow direction calculation unit calculates a jet flow direction according to a jet flow momentum coefficient, a lift coefficient increment and a flight attack angle. The jet flow direction angle of the jet flow unit is calculated and sent to the control unit, and the control unit controls the jet flow outlet of the jet flow unit to rotate according to the received jet flow direction angle information to complete jet flow of the corresponding angle. The defect that a traditional high-lift device brings large additional resistance is overcome, and the lift-drag ratio of the aircraft in the take-off stage and the cruise stage is effectively increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of aircraft design, and in particular relates to a trailing edge jet control device and method for improving the aerodynamic performance of an aircraft. Background Art

[0002] A Gurney flap is a strip arranged at the trailing edge of the lower surface of a wing, perpendicular to the chord direction of the wing. As a simple and effective high-lift device, the Gurney flap can increase the effective curvature of the airfoil and deflect the airflow at the trailing edge of the wing downward, thereby increasing the lift of the wing. However, while increasing lift, it will also bring about a significant increase in wing drag.

[0003] Active jet control is a typical active flow control technology. By injecting high-energy jets into the moving flow field, the flow state of the flow around the aircraft is changed, thereby changing the force state or motion state of the moving object. The role of active jet control technology in optimizing aerodynamic characteristics, assisting attitude control, and improving the efficiency of control surfaces is becoming increasingly significant. At present, the influence of parameters such as jet outlet shape, jet flow, and jet direction is not clear, so active jet control technology is rarely used in actual engineering. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a trailing edge jet control device and method for improving the aerodynamic performance of an aircraft. The solution of the present invention can solve the problems existing in the above-mentioned prior art.

[0005] The technical solution of the present invention:

[0006] According to a first aspect, there is provided a trailing edge jet control device for improving the aerodynamic performance of an aircraft, comprising a jet unit, a jet direction calculation unit, and a control unit. The jet unit is mounted on the trailing edge of an aircraft wing. The jet direction calculation unit calculates the jet direction angle of the jet unit according to the jet momentum coefficient, the lift coefficient increment, and the flight angle of attack, and sends the calculation to the control unit. The control unit controls the rotation of the jet outlet of the jet unit according to the received jet direction angle information to complete the jet at the corresponding angle.

[0007] Furthermore, the spanwise position and spanwise length of the jet unit should be consistent with those of a traditional Gurney flap.

[0008] Furthermore, the value of the jet outlet width is related to the shape of the aircraft wing.

[0009] Preferably, the plane shape of the aircraft wing is a rectangle or a parallelogram, then the jet outlet width b j It should be 1% of the wing chord length; if the aircraft wing plane shape is trapezoidal or triangular, then the jet outlet width b jIt should be 1% to 1.5% of the average aerodynamic chord of the wing, and not greater than 5% of the chord length of the airfoil in the section.

[0010] Furthermore, the calculation formula of the jet direction angle is:

[0011] Among them, β is the jet direction angle, c is the average aerodynamic chord length of the wing, α is the flight attack angle, C μ is the jet momentum coefficient.

[0012] According to a second aspect, there is provided a trailing edge jet control method for improving the aerodynamic performance of an aircraft, comprising the following steps:

[0013] The jet direction angle is obtained by calculating the jet momentum coefficient, lift coefficient increment and flight attack angle of the aircraft;

[0014] The direction of the jet outlet is controlled according to the jet direction angle, and a jet corresponding to the jet direction angle is emitted.

[0015] According to a third aspect, a method for designing a trailing edge jet control device for improving the aerodynamic performance of an aircraft is provided, comprising the following steps:

[0016] The position and length of the jet unit are designed according to the position of the traditional Gurney flap of the aircraft;

[0017] Design the jet outlet width of the jet unit according to the wing shape of the aircraft;

[0018] The control unit is designed according to the control accuracy and the jet outlet rotation angle requirements.

[0019] According to a fourth aspect, an aircraft is provided, wherein the aircraft is equipped with the above-mentioned trailing edge jet control device for improving the aerodynamic performance of the aircraft.

[0020] The beneficial effects of the present invention compared with the prior art are as follows:

[0021] The present invention utilizes the jet at the trailing edge of the wing to replace the traditional Gurney flap by adjusting the flow rate and the jet direction angle of the jet, thereby overcoming the disadvantage of the traditional high-lift device causing large additional resistance and effectively improving the lift-to-drag ratio of the aircraft during the take-off and cruising stages. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The included drawings are used to provide a further understanding of the embodiments of the present invention, which constitute a part of the specification, are used to illustrate the embodiments of the present invention, and together with the text description, explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1-Figure 3 The spanwise and chordwise positions of the jet unit provided in an embodiment of the present invention are shown;

[0024] Figure 4 A schematic diagram of jet direction angle definition according to an embodiment of the present invention is shown;

[0025] Figure 5 A schematic diagram of a mechanism for implementing a jet control method according to an embodiment of the present invention is shown.

[0028] The above drawings contain the following reference numerals:

[0029] 1. Jet unit; 2. Wing; 3. Traditional Gurney flap; 4. Jet; 5. Jet direction angle; 6. Transmission system components; 7. Shell; 8. Flow control components; 9. Auxiliary jet control system; 10. Auxiliary jet control valve; 11. Jet direction control plate; 12. Coanda trailing edge; 13. Jet outlet. DETAILED DESCRIPTION

[0030] It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0032] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0033] like Figure 1 As shown, according to the first aspect of an embodiment of the present invention, there is provided a trailing edge jet control device for improving the aerodynamic performance of an aircraft, comprising a jet unit, a jet direction calculation unit, and a control unit. The jet unit is mounted on the trailing edge of the aircraft wing. The jet direction calculation unit calculates the jet direction angle of the jet unit according to the jet momentum coefficient, the lift coefficient increment, and the flight angle of attack, and sends it to the control unit. The control unit controls the rotation of the jet outlet of the jet unit according to the received jet direction angle information to complete the jet at the corresponding angle.

[0034] By applying this setting, the trailing edge jet of the wing is used to replace the traditional Gurney flap, overcoming the disadvantage of the traditional high-lift device bringing large additional drag, and effectively improving the lift-to-drag ratio of the aircraft during the take-off and cruising stages.

[0035] In a further embodiment, the spanwise position and spanwise length of the jet unit should be consistent with those of a conventional Gurney flap. By applying this setting, a lift increment of the same magnitude as that of a conventional Gurney flap is obtained.

[0036] Further in one embodiment, the value of the jet outlet width is related to the shape of the aircraft wing.

[0037] In a preferred embodiment, the aircraft wing plane shape is a rectangle or a parallelogram, then the jet outlet width b j It should be 1% of the wing chord length; if the aircraft wing plane shape is trapezoidal or triangular, then the jet outlet width b j It should be 1% to 1.5% of the average aerodynamic chord of the wing, and no more than 5% of the chord of the airfoil in the section. Applying this setting, the maximum lift-to-drag ratio increment can be obtained under the condition of a constant jet momentum coefficient.

[0038] Further in one embodiment, the calculation formula of the jet direction angle is:

[0039] Among them, β is the jet direction angle, c is the average aerodynamic chord length of the wing, α is the flight attack angle, C μ is the jet momentum coefficient.

[0040] Preferably, the jet momentum coefficient C of the aircraft at different dynamic pressures is μ It can be obtained by formula ①:

[0041]

[0042] Among them, Q j is the jet mass flow rate, p ∞ is the dynamic pressure of the aircraft, and c is the average aerodynamic chord length of the wing.

[0043] Aircraft lift coefficient increment ΔC L The variation law with different jet direction angles can be obtained from formulas ② to ⑥:

[0044] ΔC L =-K1(β-90°-K2) 2 +K3 ②

[0045]

[0046]

[0047]

[0048] Where α is the flight angle of attack, C L0 is the lift coefficient of the aircraft when there is no jet.

[0049] According to formula ②, the lift coefficient increment ΔC brought by the jet at the trailing edge of the aircraft wing is L There is a maximum value, at which the optimal solution of the jet direction angle can be obtained by formula ⑥:

[0050]

[0051] According to formula ⑥, the optimal jet direction angle changes with the change of the flight angle of attack and the jet mass flow rate. When the flight angle of attack of the aircraft changes, the jet direction angle should be adjusted to achieve the best lift-enhancing effect.

[0052] According to a second aspect of the embodiment, there is provided a trailing edge jet control method for improving the aerodynamic performance of an aircraft, comprising the following steps:

[0053] Step 1, calculating the jet direction angle according to the jet momentum coefficient, lift coefficient increment and flight attack angle of the aircraft;

[0054] In one preferred embodiment, the jet momentum coefficient C of the aircraft at different dynamic pressures isμ It can be obtained by formula ①:

[0055]

[0056] Among them, Q j is the jet mass flow rate, p ∞ is the dynamic pressure of the aircraft, and c is the average aerodynamic chord length of the wing.

[0057] Aircraft lift coefficient increment ΔC L The variation law with different jet direction angles can be obtained from formulas ② to ⑥:

[0058] ΔC L =-K1(β-90°-K2) 2 +K3 ②

[0059]

[0060]

[0061]

[0062] Where α is the flight angle of attack, C L0 is the lift coefficient of the aircraft when there is no jet.

[0063] According to formula ②, the lift coefficient increment ΔC brought by the jet at the trailing edge of the aircraft wing is L There is a maximum value, at which the optimal solution of the jet direction angle can be obtained by formula ⑥:

[0064]

[0065] According to formula ⑥, the optimal jet direction angle changes with the change of the flight angle of attack and the jet mass flow rate. When the flight angle of attack of the aircraft changes, the jet direction angle should be adjusted to achieve the best lift-enhancing effect.

[0066] Step 2: Control the direction of the jet outlet according to the jet direction angle, and emit a jet corresponding to the jet direction angle.

[0067] According to a third aspect embodiment, a method for designing a trailing edge jet control device for improving the aerodynamic performance of an aircraft is provided, comprising the following steps:

[0068] S1 designs the position and length of the jet unit according to the position of the traditional Gurney flap of the aircraft;

[0069] In a preferred embodiment, the spanwise position and spanwise length of the jet unit should be consistent with those of a traditional Gurney flap.

[0070] S2 designs the jet outlet width of the jet unit according to the wing shape of the aircraft;

[0071] In a preferred embodiment, the aircraft wing plane shape is a rectangle or a parallelogram, then the jet outlet width b j It should be 1% of the chord length of the wing. If the plane shape of the aircraft wing is trapezoidal or triangular, then the jet outlet width b j It should be 1% to 1.5% of the average aerodynamic chord of the wing, and not greater than 5% of the chord length of the airfoil in the section.

[0072] S3 designs the control unit according to the control accuracy and jet outlet rotation angle requirements.

[0073] According to a fourth aspect of the embodiment, an aircraft is provided, wherein the aircraft is equipped with the above-mentioned trailing edge jet control device for improving the aerodynamic performance of the aircraft.

[0074] In order to have a further understanding of the trailing edge jet control device for improving the aerodynamic performance of an aircraft provided by the present invention, a detailed description is given below in conjunction with specific examples and drawings.

[0075] Taking the trailing edge jet control device installed on a certain type of aircraft to improve the aerodynamic performance of the aircraft as an example, the jet unit and the control unit can achieve the jet mass flow rate Q by changing the local structure in the airfoil j and the adjustment of the jet direction angle β, such as Figure 5 As shown, it includes a transmission system component 6, a housing 7, a flow control component 8, an auxiliary jet control system 9, an auxiliary jet control valve 10, a jet direction control plate 11, a Coanda trailing edge 12 and a jet outlet 13.

[0076] The spanwise position and spanwise length of the jet area should be consistent with those of the traditional Gurney flap, such as Figure 1 The cross-sectional airfoil of the trailing edge jet region is shown in Figure 1. Figure 2-3 As shown in Figure 2. The traditional Gurney flap is located at the trailing edge of the airfoil, such as Figure 2 As shown in Figure 3, similar to the traditional Gurney flap, the jet outlet should be arranged at the trailing edge of the airfoil, such as Figure 3 As shown in Figure 4.

[0077] If the aircraft wing plane shape is a rectangle or parallelogram, the jet outlet width b j It should be 1% of the wing chord length. If the aircraft wing plane shape is trapezoidal or triangular, the jet outlet width b j It should be 1% to 1.5% of the average aerodynamic chord of the wing, and not greater than 5% of the chord length of the airfoil in the section.

[0078] The jet direction angle β is defined as the angle between the jet outlet velocity vector and the tangent direction of the airfoil surface, as Figure 4As shown in Figure 5. When the jet exit velocity vector moves backward along the tangent line of the airfoil surface, β is 0°, and β gradually increases in the clockwise direction, with a value range of 0°<β<180°.

[0079] The jet momentum coefficient C of the aircraft at different dynamic pressures μ It can be obtained by formula ①:

[0080]

[0081] Among them, Q j is the jet mass flow rate, p ∞ is the dynamic pressure of the aircraft, and c is the average aerodynamic chord length of the wing.

[0082] Aircraft lift coefficient increment ΔC L The variation law with different jet direction angles can be obtained from formulas ② to ⑥:

[0083] ΔC L =-K1(β-90°-K2) 2 +K3 ②

[0084]

[0085]

[0086]

[0087] Where α is the flight angle of attack, C L0 is the lift coefficient of the aircraft without jet.

[0088] According to formula ②, the lift coefficient increment ΔC brought by the jet at the trailing edge of the aircraft wing is L There is a maximum value, at which the optimal solution of the jet direction angle can be obtained by formula ⑥:

[0089]

[0090] According to formula ⑥, the optimal jet direction angle changes with the change of the flight angle of attack and the jet mass flow rate. When the flight angle of attack of the aircraft changes, the jet direction angle should be adjusted to achieve the best lift-enhancing effect.

[0091] In summary, the trailing edge jet control device for improving the aerodynamic performance of an aircraft provided by the present invention has at least the following advantages over the prior art:

[0092] The present invention utilizes the jet at the trailing edge of the wing to replace the traditional Gurney flap by adjusting the flow rate and the jet direction angle of the jet, thereby overcoming the disadvantage of the traditional high-lift device causing large additional resistance and effectively improving the lift-to-drag ratio of the aircraft during the take-off and cruising stages.

[0093] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A trailing edge jet control device for improving the aerodynamic performance of an aircraft, characterized in that: The invention comprises a jet unit, a jet direction calculation unit and a control unit. The jet unit is installed at the trailing edge of the aircraft wing. The jet direction calculation unit calculates the jet direction angle of the jet unit according to the jet momentum coefficient, the lift coefficient increment and the flight attack angle, and sends the calculation to the control unit. The control unit controls the rotation of the jet outlet of the jet unit according to the received jet direction angle information to complete the jet at the corresponding angle.

2. A trailing edge jet control device for improving the aerodynamic performance of an aircraft according to claim 1, characterized in that: The spanwise position and spanwise length of the jet unit should be consistent with those of a traditional Gurney flap.

3. The trailing edge jet control device for improving the aerodynamic performance of an aircraft according to claim 2, characterized in that: The value of the jet outlet width is related to the shape of the aircraft wing.

4. The trailing edge jet control device for improving the aerodynamic performance of an aircraft according to claim 3, characterized in that: If the plane shape of the aircraft wing is a rectangle or a parallelogram, then the jet outlet width b j It should be 1% of the wing chord length; if the aircraft wing plane shape is trapezoidal or triangular, then the jet outlet width b j It should be 1% to 1.5% of the average aerodynamic chord of the wing, and not greater than 5% of the chord length of the airfoil in the section.

5. The trailing edge jet control device for improving the aerodynamic performance of an aircraft according to claim 1, characterized in that: The calculation formula of the jet direction angle is: Among them, β is the jet direction angle, c is the average aerodynamic chord length of the wing, α is the flight angle of attack, C μ is the jet momentum coefficient.

6. A method for controlling a trailing edge jet for improving the aerodynamic performance of an aircraft using the trailing edge jet control device according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: The jet direction angle is obtained by calculating the jet momentum coefficient, lift coefficient increment and flight attack angle of the aircraft; The direction of the jet outlet is controlled according to the jet direction angle, and a jet corresponding to the jet direction angle is emitted.

7. A method for designing a trailing edge jet control device for improving the aerodynamic performance of an aircraft as described in any one of claims 1 to 5, characterized in that: The method comprises the following steps: The position and length of the jet unit are designed according to the position of the traditional Gurney flap of the aircraft; Design the jet outlet width of the jet unit according to the wing shape of the aircraft; The control unit is designed according to the control accuracy and the jet outlet rotation angle requirements.

8. An aircraft, characterized in that: The aircraft is equipped with a trailing edge jet control device for improving the aerodynamic performance of the aircraft as described in any one of claims 1-5.

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