Method for determining load distribution of trapezoidal horizontal tail

Abstract

The invention belongs to the field of comprehensive strength design, and relates to a method for determining load distribution of a trapezoidal horizontal tail. The method comprises the following steps: constructing a linear relation between chord load and chord length according to a trapezoidal horizontal tail structure, and setting a linear relation coefficient as k; determining the chord length relationship between the chord length corresponding to any position in the spanwise direction and the spanwise coordinates of the position; according to the chord length relation, the linear relation and the horizontal tail load Fz applied to the horizontal tail of the trapezoid, calculating a linear relation coefficient k, and further obtaining the relation between the coordinate of any position in the spanwise direction and the chord load corresponding to the chord where the position is located; and obtaining load distribution of any point of the horizontal tail according to the relationship between the spanwise coordinate and the chord load and the distribution rule of the load along the chord direction.

Description

Technical Field

[0001] The invention belongs to the field of comprehensive strength design and relates to a method for determining the load distribution of a trapezoidal horizontal tail. Background Art

[0002] As a horizontal stabilizer, the helicopter horizontal tail plays an important role in ensuring the stable flight of the helicopter and is an important part of the helicopter structure. In order to ensure the structural integrity of the helicopter horizontal tail and its connection, the static strength and fatigue strength of the horizontal tail need to be designed and verified. The load borne by the horizontal tail is mainly distributed load, and follows a certain distribution law. Different shapes have different distribution laws. Therefore, the law of the horizontal tail distributed load and how to apply it are of great significance to strength design.

[0003] Defects of background technology:

[0004] At present, most helicopters use rectangular tailplanes, whose distance from the leading edge to the trailing edge remains unchanged, and whose chord length does not change with the spanwise position. The calculation method for its pressure distribution is relatively simple and mature. With the development of technology, the design of helicopter tailplane configurations has also become diversified. In addition to the traditional rectangular tailplane, there is also a trapezoidal tailplane. The chord length of the trapezoidal tailplane varies with the spanwise position. There is no unified calculation method for the pressure distribution of the trapezoidal tailplane. Summary of the invention

[0005] Purpose of the invention: To provide a method for determining the law of distributed load of a trapezoidal horizontal tail and its load application, so as to provide support for strength design.

[0006] Technical solution:

[0007] A method for determining a load distribution of a trapezoidal horizontal tail is provided, comprising:

[0008] According to the trapezoidal tail structure, a linear relationship between the chord load and the chord length is constructed, and the linear relationship coefficient is set to k;

[0009] Determine the relationship between the chord length corresponding to any spanwise position and the spanwise coordinate of the position;

[0010] According to the chord length relationship, linear relationship, and the horizontal tail load F applied to the trapezoidal horizontal tail z , calculate the linear relationship coefficient k, and then obtain the relationship between the coordinates of any position in the span direction and the corresponding chord load of the chord at that position;

[0011] According to the relationship between the spanwise coordinate and the chord load, as well as the load distribution law along the chord direction, the load distribution at any point of the horizontal tail can be obtained.

[0012] Furthermore, the linear relationship is expressed as:

[0013] f(y)=k×w(y);

[0014] Where w(y) is the chord length, which is related to the spanwise coordinate y at any position; f(y) is the chord load, i.e., the load on the chord corresponding to the spanwise coordinate y.

[0015] Furthermore, the method further comprises:

[0016] A coordinate system for the trapezoidal horizontal tail is established, where the positive direction of the x-axis is ensured to be backward along the chord direction, and the positive direction of the y-axis is ensured to be outward along the span direction.

[0017] Furthermore, the expressions of the chord length relationship include:

[0018]

[0019] ΔX CA =X C -X A ;

[0020] ΔY CA =Y C -Y A ;

[0021] ΔX DB =X D -X B ;

[0022] ΔY DB =Y D -Y B ;

[0023] Among them, X A and Y A is the coordinate of the front end point A inside the trapezoidal tail, X B and Y B is the coordinate of the inner rear end point B of the trapezoidal tail, X C and Y C is the coordinate of the outer front end point C of the trapezoidal tail, X D and Y D is the coordinate of the outer rear end point D of the trapezoidal tail, ΔX CA is the difference in x-axis between C and A, ΔY CA is the difference in y-axis between C and A, ΔX DB is the x-axis difference between D and B, ΔY DB is the difference in y-axis between D and B; ΔX BA is the difference in x-axis between B and A.

[0024] Furthermore, the solution equation for k is:

[0025]

[0026] Furthermore, the method further comprises:

[0027] Taking the position of 0.1 times the chord length as the boundary, determine the pressure distribution on each chord.

[0028] Furthermore, the expression of pressure distribution p(x,y) is:

[0029]

[0030] Where x is the chord-wise coordinate of any position; x1 is the chord-wise coordinate of 0.1 times the chord length. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the distribution of horizontal tail load along the chord direction.

[0032] Figure 2 This is a schematic diagram of the trapezoidal horizontal tail structure. DETAILED DESCRIPTION

[0033] The specific steps are as follows:

[0034] a) Determine the distribution law of the horizontal tail distributed load along the chord direction. The distribution law is shown in Figure 1 shown.

[0035] b) Determine the reference coordinate system of the trapezoidal horizontal tail and extract the geometric eigenvalues, including:

[0036] Point A: [X a ,Y a ], set point A as the origin of the reference coordinate system.

[0037] Point B: [X b ,Y b ]

[0038] Point C: [X c ,Y c ]

[0039] Point D: [X d ,Y d ]

[0040] Trapezoidal tail structure Figure 2 shown.

[0041] c) Determine the expressions for the geometric characteristic lines AC and BD of the rectangular horizontal tail, where AC represents the leading edge and BD represents the trailing edge:

[0042] The characteristic line AC expression is:

[0043]

[0044] Required symbols:

[0045] ΔX CA =X C -X A

[0046] ΔY CA =Y C -Y A

[0047] Then the characteristic line AC expression is simplified as:

[0048]

[0049] The characteristic line BD expression is:

[0050]

[0051] Required symbols:

[0052] ΔX DB =X D -X B

[0053] ΔY DB =Y D -Y B

[0054] ΔX BA =X B -X A

[0055] Then the characteristic line BD expression is simplified as:

[0056]

[0057] e) Express the chord length corresponding to a certain position in the span direction as an expression about the span direction coordinate:

[0058]

[0059] f) Establish the relationship between the chord load and the chord length, that is, establish the proportionality coefficient k

[0060] f(y)=k×w(y)

[0061] Express the chord load in spanwise coordinates,

[0062]

[0063] g) Determine the proportionality factor k, which is obtained by integrating the chord load over the span and summing it up to the horizontal tail load Fz.

[0064]

[0065] The proportionality coefficient k can be determined from the above formula.

[0066] h) Determine the pressure distribution from the leading edge to the position of 0.1 times the chord length

[0067] Load distribution along the chord direction Figure 1 shown.

[0068] From this pressure distribution, it can be seen that the chord load can be expressed as:

[0069] f(y)=0.6×w(y)×h

[0070] The relationship between k and h can be determined,

[0071] k = f(y) / w(y) = 0.6 × h

[0072] For the leading edge to 0.1 times the chord length, that is,

[0073] The pressure distribution expression is:

[0074] p(x,y)=1.5×h=2.5×k

[0075] For 0.1 times the chord length to the trailing edge, that is

[0076]

[0077] i) According to g), the distributed load p(x,y) of the trapezoidal horizontal tail can be obtained.

Claims

1. A method for determining the load distribution of a trapezoidal horizontal tail, characterized in that: include: According to the trapezoidal tail structure, a linear relationship between the chord load and the chord length is constructed, and the linear relationship coefficient is set to k; Determine the relationship between the chord length corresponding to any spanwise position and the spanwise coordinate of the position; According to the chord length relationship, linear relationship, and the horizontal tail load F applied to the trapezoidal horizontal tail z , calculate the linear relationship coefficient k, and then obtain the relationship between the coordinates of any position in the span direction and the corresponding chord load of the chord at that position; According to the relationship between the spanwise coordinate and the chord load, as well as the load distribution law along the chord direction, the load distribution at any point of the horizontal tail can be obtained.

2. The method according to claim 1, characterized in that The linear relationship expression is: f(y)=k×w(y); Where w(y) is the chord length, which is related to the spanwise coordinate y at any position; f(y) is the chord load, i.e., the load on the chord corresponding to the spanwise coordinate y.

3. The method according to claim 2, characterized in that The method further comprises: A coordinate system for the trapezoidal horizontal tail is established, where the positive direction of the x-axis is ensured to be backward along the chord direction, and the positive direction of the y-axis is ensured to be outward along the span direction.

4. The method according to claim 3, characterized in that Expressions for chord length relationships include: ΔX CA =X C -X A ; ΔY CA =Y C -Y A ; ΔX DB =X D -X B ; ΔY DB =Y D -Y B ; Among them, X A and Y A is the coordinate of the front end point A inside the trapezoidal tail, X B and Y B is the coordinate of the inner rear end point B of the trapezoidal tail, X C and Y C is the coordinate of the outer front end point C of the trapezoidal tail, X D and Y D is the coordinate of the outer rear end point D of the trapezoidal tail, ΔX CA is the difference in x-axis between C and A, ΔY CA is the difference in y-axis between C and A, ΔX DB is the x-axis difference between D and B, ΔY DB is the difference in y-axis between D and B; ΔX BA is the difference in x-axis between B and A.

5. The method according to claim 4, characterized in that The equation to solve for k is:

6. The method according to claim 5, characterized in that The method further comprises: Taking the position of 0.1 times the chord length as the boundary, determine the pressure distribution on each chord.

7. The method according to claim 6, characterized in that The expression of pressure distribution p(x,y) is: Where x is the chord-wise coordinate of any position; x1 is the chord-wise coordinate of 0.1 times the chord length.

8. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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