Prediction method of critical angle of attack of moment lift for wing-wing aircraft

Abstract

The present invention belongs to the technical field of aircraft design, and discloses a method for predicting the critical angle of attack of moment lift of an aircraft with a slat wing layout, including determining the basic aerodynamic shape of the aircraft with a slat wing layout; calculating the spectral structure of the slat vortex of the basic aerodynamic shape of the aircraft with a slat wing layout; obtaining the theoretical path of the development of the slat vortex; establishing a critical angle of attack prediction formula; conducting a wind tunnel test; and obtaining the critical angle of attack prediction formula. The method for predicting the critical angle of attack of moment lift of an aircraft with a slat wing layout of the present invention is based on calculation and experiment, and on the basis of clarifying the development mechanism of the slat vortex, numerical simulation analysis is carried out on the basic aerodynamic shape of the aircraft with a slat wing layout to obtain the critical angle of attack of the basic aerodynamic shape and the longitudinal distance of the development of the vortex core streamline corresponding to the critical angle of attack, and is used to predict the critical angle of attack of moment lift corresponding to the aerodynamic shape of different slat wing positions, thereby improving the aerodynamic design efficiency of the aircraft with a slat wing layout, and having engineering practical value.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft design, and in particular relates to a method for predicting a critical angle of attack of moment lift of an aircraft with a winglet layout. Background Art

[0002] The winglet and tail rudder layout of the rotating body is a widely used aerodynamic layout form for winglet layout aircraft. The winglet can provide a large overload capacity for the winglet layout aircraft under the limited spanwise dimension constraint. However, this layout form will cause a sudden upward pitch moment characteristic due to the development of the winglet vortex and the aerodynamic interference to the tail rudder at medium angles of attack, which has a great impact on the aerodynamic performance and use limit of the winglet layout aircraft. The rapid prediction of the critical angle of attack of the moment upward is of great significance to improving the efficiency of aerodynamic design and the rapid finalization of the winglet configuration.

[0003] Currently, there is an urgent need to develop a method to predict the critical angle of attack of the moment lift of a wing-slatted aircraft. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for predicting the critical angle of attack of moment lift of an aircraft with a wing-slat layout, so as to realize the prediction of the critical angle of attack of moment lift.

[0005] The slat-wing aircraft has a rotating body, on which are arranged centrally symmetrical slats and corresponding tail rudders. During the flight of the slat-wing aircraft, due to the separation of airflow, a vortex structure, namely the slat vortex, is formed at the leading edge of the slat. The slat vortex develops along the slat toward the tail rudder and interferes with the aerodynamic characteristics of the tail rudder. At a specific angle of attack, this interference will rapidly reduce the nose-down moment generated by the tail rudder and cause the moment of the slat-wing aircraft to rise. The angle of attack corresponding to the moment rise is called the critical angle of attack, which is directly related to the shape parameters of the slat, and the installation position of the slat is the main factor affecting the critical angle of attack.

[0006] The method for predicting the moment-up critical angle of attack of a wing-slat layout aircraft of the present invention comprises the following steps:

[0007] S10. Determine the basic aerodynamic shape of the wing configuration aircraft;

[0008] The basic aerodynamic shape of the winglet layout aircraft has a rotating body, on which are arranged four winglets and corresponding four tail rudders in a centrally symmetrical manner;

[0009] S20. Calculate the vortex spectrum structure of the side slats of the basic aerodynamic shape of the side slats layout aircraft;

[0010] The vortex spectrum structure of the side wing layout aircraft's basic aerodynamic shape is calculated through numerical simulation;

[0011] S30. Obtain the theoretical path of leading-edge vortex development;

[0012] Analyze the leading-edge vortex spectrum structure, obtain the theoretical path of leading-edge vortex development, and draw a schematic diagram of the theoretical path of leading-edge vortex development; define the lateral distance Δx as the distance from the trailing edge of the leading-edge wing to the leading edge of the tail rudder, and the longitudinal distance ΔH as the longitudinal development distance of the vortex core line of the leading-edge vortex from the trailing edge of the leading-edge wing to the leading edge of the tail rudder. The included angle between Δx and ΔH;

[0013] S40. Establish a critical angle of attack prediction formula;

[0014] The included angle of the vortex core line and the angle of attack α of the basic aerodynamic shape of the leading-edge wing layout aircraft has the following corresponding relationship:

[0015] ;

[0016] The corresponding relationship between the lateral distance Δx, the longitudinal distance ΔH, and the included angle of the vortex core line is as follows:

[0017] ;

[0018] Define as the critical angle of attack, as the critical longitudinal distance, then:

[0019] ;

[0020] S50. Conduct a wind tunnel test;

[0021] Manufacture a wind tunnel test model of the basic aerodynamic shape of the leading-edge wing layout aircraft, conduct a wind tunnel test, obtain the curve of the pitching moment coefficient mz varying with the angle of attack α, and obtain the critical angle of attack value of the basic aerodynamic shape of the leading-edge wing layout aircraft from the curve of the pitching moment coefficient mz varying with the angle of attack α. Fit to obtain the engineering estimation formula between the included angle of the vortex core line and the angle of attack α of the basic aerodynamic shape of the leading-edge wing layout aircraft as follows:

[0022] ;

[0023] where A, B, and C are all fitting parameters; is the critical lateral distance;

[0024] S60. Obtain the critical angle of attack prediction formula;

[0025] Keeping the basic aerodynamic shape of the winglet layout aircraft, the shape of the rotating body, the four winglets and the corresponding four tail rudders unchanged, changing the position of the four winglets, that is, changing the lateral distance Δx, the critical angle of attack of different winglet positions is The engineering estimation formula is as follows:

[0026] .

[0027] The method for predicting the critical angle of attack of moment lift of an aircraft with a slat wing layout of the present invention is based on a large number of calculations and experimental studies. On the basis of clarifying the development mechanism of the slat vortex, a numerical simulation analysis is carried out on the basic aerodynamic shape of the aircraft with a slat wing layout to obtain the critical angle of attack of the basic aerodynamic shape and the longitudinal distance of the development of the vortex core streamline corresponding to the critical angle of attack. The method is used to predict the critical angle of attack of moment lift corresponding to the aerodynamic shape of different slat wing positions, thereby improving the aerodynamic design efficiency of the aircraft with a slat wing layout and can be extended to the aerodynamic design of aircraft with similar layouts, which has practical engineering value. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A flow chart of a method for predicting the critical angle of attack of moment lift for a wing-slat layout aircraft;

[0029] Figure 2 A schematic diagram of the layout of the slats and tail rudder of an aircraft with a slat layout;

[0030] Figure 2 In the middle, 1. Rotating body; 2. Side slats; 3. Tail rudder;

[0031] Figure 3 Schematic diagram of the theoretical path of the slat vortex development for a slat-wing aircraft;

[0032] Figure 4 The curve of pitch moment coefficient versus angle of attack for a wing-slat aircraft.

[0033] Figure 5 It is a schematic diagram of the aerodynamic shape of the wing-layout aircraft of Example 1 when the distance from the tail of the wing to the leading edge of the tail rudder is L;

[0034] Figure 6 The curve of the pitching moment coefficient changing with the angle of attack when the distance from the tail of the slat to the leading edge of the tail rudder is L for the slat layout aircraft of Example 1;

[0035] Figure 7 This is a schematic diagram of the aerodynamic shape of the wing layout aircraft of Example 1 when the distance from the tail of the wing to the leading edge of the tail rudder is L / 2. DETAILED DESCRIPTION

[0036] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0037] like Figure 1 As shown, the method for predicting the moment-up critical angle of attack of a wing-slat layout aircraft of the present invention comprises the following steps:

[0038] S10. Determine the basic aerodynamic shape of the wing configuration aircraft;

[0039] like Figure 2 As shown, the basic aerodynamic shape of the winglet layout aircraft has a rotating body 1, on which four winglets 2 and corresponding four tail rudders 3 are arranged in a centrally symmetrical manner;

[0040] S20. Calculate the vortex spectrum structure of the side slats of the basic aerodynamic shape of the side slats layout aircraft;

[0041] The vortex spectrum structure of the side wing layout aircraft's basic aerodynamic shape is calculated through numerical simulation;

[0042] S30. Obtaining the theoretical path of the development of the strip vortex;

[0043] Analyze the spectral structure of the side strip vortex, obtain the theoretical path of the side strip vortex development, and draw the following Figure 3 The schematic diagram of the theoretical path of the slat vortex development is shown in FIG. 1 ; the lateral distance Δx is defined as the distance from the tail of the slat wing 2 to the leading edge of the tail rudder 3, the longitudinal distance ΔH is the longitudinal development distance of the vortex core line of the slat vortex from the tail of the slat wing 2 to the leading edge of the tail rudder 3, and the vortex core line angle is defined as is the angle between Δx and ΔH;

[0044] S40. Establish a critical angle of attack prediction formula;

[0045] Vortex core line angle The corresponding relationship between the angle of attack α of the basic aerodynamic shape of the wing configuration aircraft is as follows:

[0046] ;

[0047] Transverse distance Δx, longitudinal distance ΔH and vortex core line angle The corresponding relationship is as follows:

[0048] ;

[0049] definition is the critical angle of attack, is the critical longitudinal distance, then:

[0050] ;

[0051] S50. Conduct wind tunnel tests;

[0052] The wind tunnel test model of the basic aerodynamic shape of the winglet layout aircraft was processed and the wind tunnel test was carried out to obtain the following Figure 4 The variation curve of the pitch moment coefficient mz with the angle of attack α shown in FIG. 1 is used to obtain the critical angle of attack value of the basic aerodynamic shape of the wing configuration aircraft. , the vortex core line angle is obtained by fitting The engineering estimation formula between the angle of attack α of the basic aerodynamic shape of the wing-slat layout aircraft is as follows:

[0053] ;

[0054] Among them, A, B, and C are fitting parameters; is the critical lateral distance;

[0055] S60. Obtaining a critical angle of attack prediction formula;

[0056] Keep the basic aerodynamic shape of the wing layout aircraft, the shape of the rotating body 1, the four wing 2 and the corresponding four tail rudders 3 remain unchanged, change the position of the four wing 2, that is, change the lateral distance Δx, then the critical angle of attack of different wing 2 positions The engineering estimation formula is as follows:

[0057] .

[0058] Example 1: Figure 5 As shown, the lateral distance Δx=L of the basic aerodynamic shape of the winglet layout aircraft of this embodiment is obtained through wind tunnel tests as follows Figure 6 The curve of pitch moment coefficient changing with angle of attack is shown, and the critical angle of attack of the moment rise of the basic aerodynamic shape of the wing-wing layout aircraft is obtained to be 14°, and the values ​​of the fitting parameters are obtained as follows:

[0059] A=1.045; B=1.045; C=0.195.

[0060] Example 2: Figure 7 As shown, the lateral distance Δx=L / 2 of the basic aerodynamic shape of the strake wing layout aircraft of this embodiment is calculated as follows:

[0061] ;

[0062] Therefore, the critical angle of attack of the moment lift corresponding to the aerodynamic shape of the wing-type aircraft with Δx=0.5L is 16.9°.

[0063] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and implementation modes. For those familiar with the art, without departing from the principles of the present invention, all features disclosed in the present invention, or steps in all methods or processes disclosed, except for mutually exclusive features and / or steps, can be combined in any way. The present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for predicting the critical angle of attack of moment lift of a wing-slat layout aircraft, characterized in that: The following steps are involved: S10. Determine the basic aerodynamic shape of the wing configuration aircraft; The basic aerodynamic shape of the winglet layout aircraft comprises a rotating body (1), on which four winglets (2) and corresponding four tail rudders (3) are arranged in a centrally symmetrical manner; S20. Calculate the vortex spectrum structure of the side slats of the basic aerodynamic shape of the side slats layout aircraft; The vortex spectrum structure of the side wing layout aircraft's basic aerodynamic shape is calculated through numerical simulation; S30. Obtaining the theoretical path of the development of the strip vortex; Analyze the spectral structure of the slat vortex, obtain the theoretical path of the slat vortex development, and draw a schematic diagram of the theoretical path of the slat vortex development; define the lateral distance Δx as the distance from the tail of the slat wing (2) to the leading edge of the rudder (3), the longitudinal distance ΔH as the longitudinal development distance of the vortex core line of the slat vortex from the tail of the slat wing (2) to the leading edge of the rudder (3), and the vortex core line angle is the angle between Δx and ΔH; S40. Establish a critical angle of attack prediction formula; Vortex core line angle The corresponding relationship between the angle of attack α of the basic aerodynamic shape of the wing configuration aircraft is as follows: ； Transverse distance Δx, longitudinal distance ΔH and vortex core line angle The corresponding relationship is as follows: ； definition is the critical angle of attack, is the critical longitudinal distance, then: ； S50. Conduct wind tunnel tests; Process the wind tunnel test model of the basic aerodynamic shape of the wing-wing layout aircraft, conduct wind tunnel tests, obtain the variation curve of the pitch moment coefficient mz with the angle of attack α, and obtain the critical angle of attack of the basic aerodynamic shape of the wing-wing layout aircraft through the variation curve of the pitch moment coefficient mz with the angle of attack α. The value is fitted to obtain the vortex core line angle The engineering estimation formula between the angle of attack α of the basic aerodynamic shape of the wing-slat layout aircraft is as follows: ； Among them, A, B, and C are fitting parameters; is the critical lateral distance; S60. Obtaining a critical angle of attack prediction formula; The basic aerodynamic shape of the aircraft with a wing layout is maintained unchanged, including the shape of the rotating body (1), the four wing strips (2) and the corresponding four tail rudders (3), and the positions of the four wing strips (2) are changed, that is, the lateral distance Δx is changed. Then, the critical angle of attack of different wing strip (2) positions is The engineering estimation formula is as follows: 。

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