A high-precision drag balance for high-speed wind tunnel testing of civil aircraft

Abstract

The present invention discloses a high-precision drag balance for high-speed wind tunnel testing of civil aircraft. This balance belongs to the field of aerodynamic measurement technology and is proposed because traditional balance designs are no longer able to meet the requirements of high-speed wind tunnel testing of civil aircraft. The balance balance comprises: a cylindrical balance body with an integrated structure, wherein the intersection of the horizontal and longitudinal symmetry axes of the balance body is the center of the balance body, drag strain beams are symmetrically arranged on the left and right sides of the center, and a drag strain beam slit is provided at either the upper or lower end of each drag strain beam. The drag strain beam slit separates one end of the drag strain beam from the balance body, forming a T-shaped structure for the drag strain beam. The present invention improves the stability of the balance during use and the sensitivity of drag testing, and has the advantages of less mutual interference between structures, good overall rigidity of the balance, and reasonable coordination with relevant test pieces.

Description

Technical field:

[0001] The invention belongs to the technical field of aerodynamic measurement, and in particular relates to a high-precision drag balance for high-speed wind tunnel tests of civil aircraft. Background technology:

[0002] The drag experienced by civil aircraft during flight is a significant factor affecting operating costs, making accurate measurement of drag parameters particularly important during aircraft wind tunnel testing. Traditional wind tunnel balance design primarily considers the design matching of various aerodynamic components, often reducing the sensitivity of the drag element to achieve better overall mechanical performance. However, with the rapid development of the civil aircraft sector, the measurement standards for important parameters in civil aircraft wind tunnel testing are constantly improving, especially for drag parameters. Traditional balance design concepts can no longer meet the needs of high-precision testing, so there is an urgent need for targeted research and development and design of a high-precision drag balance suitable for civil aircraft high-speed wind tunnel testing to meet this demand. Summary of the invention:

[0003] In order to overcome the above-mentioned defects, the present invention provides a high-precision drag balance for civil aircraft high-speed wind tunnel tests. The high-precision drag balance improves the drag measurement accuracy and reduces structural interference by adjusting the drag strain beam structure.

[0004] The technical solution adopted by the present invention is: a high-precision drag balance for high-speed wind tunnel tests of civil aircraft, comprising: a cylindrical balance body with an integrated structure, the intersection of the horizontal symmetry axis and the longitudinal symmetry axis of the balance body being the center of the balance body, resistance strain beams being symmetrically arranged on the left and right sides of the center, and a resistance strain beam slit being provided at either the upper or lower end of each resistance strain beam, the resistance strain beam slit separating one end of the resistance strain beam from the balance body, so that the resistance strain beam forms a T-shaped structure.

[0005] Preferably, the resistance strain beam slit extends horizontally inward from the outer wall of the balance body and then extends vertically downward, and the longitudinal section of the resistance strain beam slit is an inverted L-shape as a whole.

[0006] Preferably, the gap between the resistance strain beams is 1 mm.

[0007] Preferably, a resistance element bridge wiring hole is processed on one side of the resistance strain beam, and the resistance element bridge wiring hole is opened at the intersection of the balance body slit and the balance body axis.

[0008] Preferably, equal-strength support beams, combined strain beams and conical surfaces are provided on both sides of the resistance strain beam in sequence from near to far, and are symmetrically arranged with respect to the center of the balance body. The front end of the resistance strain beam and the position distribution from near to far are defined as the front equal-strength support beam, the front combined strain beam and the front conical surface respectively, and the rear end of the resistance strain beam and the position distribution from near to far are defined as the rear equal-strength support beam, the rear combined strain beam and the rear conical surface respectively, and a through balance body slit is obliquely opened between the front equal-strength support beam and the rear equal-strength support beam.

[0009] Preferably, the gap between the balance body openings is 0.8 mm.

[0010] Preferably, a balance mounting wedge key hole for connecting the balance body to the test system is processed on the rear conical surface.

[0011] Preferably, the front combined strain beam and the rear combined strain beam both adopt a three-column beam structure with equal strength distribution.

[0012] Preferably, the front equal-strength support beam and the rear equal-strength support beam are both composed of five support pieces with equal strength distribution.

[0013] Preferably, the taper of the front cone is 1:5, and the taper of the rear cone is 1:10.

[0014] The beneficial effects of the present invention are:

[0015] 1. The present invention adopts an integrated structure, the overall rigidity of the balance body is good, and there is no influence of assembly error and assembly stress;

[0016] 2. The present invention separates one end of the resistance strain beam from the balance body by slitting the resistance strain beam, so that the resistance strain beam forms a T-shaped structure. Compared with the traditional strain beam, the T-shaped structure of the resistance strain beam has better anti-interference performance while ensuring higher sensitivity. In addition, the support beam is also optimized to achieve the best matching of structural dimensions, improve measurement sensitivity, and reduce mutual interference between the strain beam and the support beam.

[0017] 3. The structural space design of the present invention is reasonable, which is convenient for strain gauge bonding and test circuit layout;

[0018] 4. The present invention improves the stability of the balance and the sensitivity of the resistance test, has the advantages of less mutual interference between structures, better overall rigidity of the balance, and reasonable coordination with relevant test pieces. Description of the drawings:

[0019] Figure 1 It is a structural schematic diagram of the present invention;

[0020] Figure 2 It is a schematic diagram of the three-dimensional structure of the present invention;

[0021] Figure 3 for Figure 1 Cross-sectional view of AA;

[0022] Figure 4 for Figure 1 Cross-sectional view of the middle BB;

[0023] Figure 5 for Figure 1 Cross-sectional view of CC;

[0024] Among them: 1 front cone surface, 2 front combined strain beam, 3 front equal strength support beam, 4 resistance strain beam slit, 5 rear equal strength support beam, 6 rear combined strain beam, 7 rear cone surface, 8 balance body slit, 9 resistance strain beam, 10 resistance original bridge wiring hole, 11 balance installation wedge key hole, 12 center column beam, 13 side column beam. Specific implementation method:

[0025] like Figures 1 to 5 As shown, the present invention is a high-precision drag balance for high-speed wind tunnel tests of civil aircraft, comprising: a cylindrical balance body, which adopts an integrated structure. The integrated structure not only improves the overall rigidity of the balance body, but also avoids the problems of assembly errors and assembly stresses generated by multiple parts during the assembly process.

[0026] The intersection of the horizontal symmetry axis and the longitudinal symmetry axis of the balance body is the center of the balance body. A resistance strain beam 9 is symmetrically provided at the center. The resistance strain beam 9 is used to test the resistance of the balance.

[0027] A resistance strain beam slit 4 is provided at either the upper or lower end of the resistance strain beam 9. The resistance strain beam slit 4 extends horizontally inward from the outer wall of the balance body and then vertically downward. The longitudinal cross-section of the resistance strain beam slit 4 is generally inverted L-shaped, and the two resistance strain beam slits 4 are symmetrically arranged about the transverse axis of the balance body. This embodiment uses the resistance strain beam slit 4 located above the resistance strain beam 9 as an example. The same effect can be achieved when the resistance strain beam slit 4 is located below the resistance strain beam 9. The gap between the resistance strain beam slits 4 serves to separate the upper end of the resistance strain beam 9 from the balance body, thereby forming a T-shaped structure. This gap should not be too small to prevent the resistance strain beam 9 from colliding due to deformation under load, nor should it be too large to maximize the rigidity of the surrounding structure while also ensuring good processing characteristics. Therefore, in this embodiment, the gap is set to 1 mm. Since there are two resistance strain beams 9 of the T-shaped structure and they are symmetrically arranged on the left and right, compared with the traditional resistance strain beams, since there is a stress release effect at the intersection of the T-shaped structure, while ensuring good sensitivity, the resistance strain beam 9 should also have better anti-interference performance.

[0028] On both sides of the resistance strain beam 9, equal strength support beams, combined strain beams and conical surfaces are respectively arranged from near to far. The front end of the resistance strain beam 9 is defined as the front equal strength support beam 3, the front combined strain beam 2 and the front conical surface 1 according to the position distribution from near to far. The rear end of the resistance strain beam 9 is defined as the rear equal strength support beam 5, the rear combined strain beam 6 and the rear conical surface 7 according to the position distribution from near to far.

[0029] The front cone surface 1 has a taper of 1:5 and is used to connect the test model to the balance body, and the front cone surface 1 is locked by screws.

[0030] The taper of the rear conical surface 7 is 1:10, and a balance mounting wedge key hole 11 is processed on the rear conical surface 7. The wedge key hole taper of the balance mounting wedge key hole 11 is 1:6. The test system is locked with the balance body through the balance mounting wedge key hole 11.

[0031] The front equal-strength support beam 3 and the rear equal-strength support beam 5 are symmetrical about the center of the balance body, and a balance body slit 8 is obliquely opened between the front equal-strength support beam 3 and the rear equal-strength support beam 5. The balance body slit 8 is divided into two parts by the resistance strain beam 9. The front end of the balance body slit 8 is opened to the front equal-strength support beam 3, and the rear end of the balance body slit 8 is opened to the rear equal-strength support beam 5. The function of the balance body slit 8 is to divide the balance into two parts, the load-bearing end (the front end of the balance body) and the supporting end (the rear end of the balance body), so that the slit gap can increase the stiffness of the two parts themselves as much as possible under the premise that they do not collide under the load state, and at the same time have good processing characteristics. Therefore, in this embodiment, the slit gap of the balance body slit 8 is set to 0.8 mm.

[0032] Both the front composite strain beam 2 and the rear composite strain beam 6 utilize a three-column beam structure with equal strength distribution and are identical in structure. The front composite strain beam 2 and the rear composite strain beam 6 are symmetrical about the center of the balance body. This three-main beam structure comprises a central column beam 12 positioned on the balance's main axis and symmetrically arranged side column beams 13 on either side of the central column beam 12. Both the central column beam 12 and the two side column beams 13 have rectangular cross-sections. This structure is used to measure the five aerodynamic loads of the test model: lift, lateral force, pitching moment, yaw moment, and roll moment.

[0033] The front equal-strength support beam 3 and the rear equal-strength support beam 5 are both composed of five support plates with equal-strength distribution. Their structure is symmetrical about the center of the balance body. This structure is a support beam for resistance, which is used to share part of the resistance load and reduce the load borne by the resistance strain beam 9. At the same time, it is convenient to optimize the structural size. Its structure is in the form of equal strength. The advantage is that when the transverse and longitudinal interference loads are applied to the balance body, the farther away from the center of action, the greater the torque it bears. Similarly, the farther away from the center of action, the larger the load-bearing cross-sectional area of ​​the equal-strength beam. As a result, the support beams at different positions have the same structural stress, realizing equal-strength distribution of stress, making the stress distribution of the structure uniform after the load is applied, and reducing the influence of sudden stress on the test sensitivity.

[0034] A resistance element bridge wiring hole 10 is processed on one side of the resistance strain beam 9 .

[0035] The resistance element bridge wiring hole 10 is opened at the intersection of the balance body slit 8 and the balance body axis, and is used to arrange the two resistance element test bridge connection lines. The resistance element bridge wiring hole 10 increases the wiring space and facilitates the wiring operation of the staff.

[0036] Working principle:

[0037] A wind tunnel strain balance is a sensor device that converts aerodynamic loads into electrical signals during wind tunnel testing, allowing for direct measurement. The strain-sensitive element structure of the balance is designed based on the laws governing the structural strain generated by various aerodynamic loads acting on a structure, ensuring that it meets the strain sensitivity measurement requirements under aerodynamic loads. This embodiment primarily comprises two strain structure components. The first component is a T-shaped resistance strain beam 9, which, along with the front and rear equal-strength support beams 3 and 5, bears the resistance force. The dimensions of the T-shaped resistance strain beam 9 are precisely designed based on the principle of stiffness matching to meet the experimental test sensitivity requirements. The second component is a three-column beam structure, formed by the centrally symmetrical front and rear combined strain beams 2 and 6, based on the principles of material mechanics. A central column beam 12 and two side beams 13, each with a rectangular cross-section, are used to measure the remaining five aerodynamic components, excluding the resistance force. During use, strain gauges are attached to the surfaces of the symmetrically distributed resistance strain beams 9 according to a specific pattern. These strain gauges then form a corresponding bridge based on the test requirements. This bridge converts the structural strain generated by the load on the balance into a voltage signal, which is directly captured by the signal acquisition system. Finally, using a prescribed calculation method, the collected voltage signal is converted into a balance calculation formula for use in wind tunnel testing. The T-shaped resistance strain beams 9 reduce interference between the strain beams and the support beams during axial force detection, thereby improving the balance's measurement sensitivity and operational stability.

[0038] The foregoing are merely preferred embodiments of the present invention. These embodiments are all different implementations based on the overall concept of the present invention. The scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A high-precision drag balance for high-speed wind tunnel testing of civil aircraft, characterized in that: include: A cylindrical balance body of an integrated structure, wherein the intersection of the horizontal symmetry axis and the longitudinal symmetry axis of the balance body is the center of the balance body, resistance strain beams (9) are symmetrically provided on the left and right sides of the center, and a resistance strain beam slit (4) is provided at either upper or lower end of each resistance strain beam (9), wherein the resistance strain beam slit (4) separates one end of the resistance strain beam (9) from the balance body, so that the resistance strain beam (9) forms a T-shaped structure; The resistance strain beam slit (4) extends horizontally inward from the outer wall of the balance body and then extends vertically downward, and the longitudinal section of the resistance strain beam slit (4) is in an inverted L shape as a whole; The gap between the resistance strain beam opening (4) is 1 mm; On both sides of the resistance strain beam (9), equal strength support beams, combined strain beams and conical surfaces are respectively provided from near to far, and are symmetrically arranged with respect to the center of the balance body. The front end of the resistance strain beam (9) is defined as a front equal strength support beam (3), a front combined strain beam (2) and a front conical surface (1) according to the position distribution from near to far, and the rear end of the resistance strain beam (9) is defined as a rear equal strength support beam (5), a rear combined strain beam (6) and a rear conical surface (7) according to the position distribution from near to far. A through balance body slit (8) is obliquely provided between the front equal strength support beam (3) and the rear equal strength support beam (5); The gap between the balance body opening (8) is 0.8 mm; The front combined strain beam (2) and the rear combined strain beam (6) both adopt a three-column beam structure with equal strength distribution; The front equal-strength support beam (3) and the rear equal-strength support beam (5) are both composed of five support pieces with equal strength distribution.

2. A high-precision drag balance for high-speed wind tunnel testing of civil aircraft according to claim 1, characterized in that: A resistance element bridge wiring hole (10) is processed on one side of the resistance strain beam (9), and the resistance element bridge wiring hole (10) is opened at the intersection of the balance body slit (8) and the balance body axis.

3. A high-precision drag balance for high-speed wind tunnel testing of civil aircraft according to claim 2, characterized in that: A balance mounting wedge key hole (11) for connecting the balance body to the test system is processed on the rear conical surface (7); the wedge key hole taper of the balance mounting wedge key hole (11) is 1:

6.

4. A high-precision drag balance for high-speed wind tunnel testing of civil aircraft according to claim 3, characterized in that: The taper of the front conical surface (1) is 1:5, and the taper of the rear conical surface (7) is 1:10.

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