A Design Strain Quantification Method for a Large-Scale Continuous Wind Tunnel Balance

Abstract

The invention discloses a method for quantifying design strain of a large-scale continuous wind tunnel balance, belonging to the technical field of wind tunnel balance design. It solves the problem that the traditional strain method in the existing technology for wind tunnel balance design does not fully meet the actual requirements of wind tunnel tests. The invention determines the overall repeatability characteristic value t of each measuring Wheatstone bridge and the measurement and control acquisition device of the wind tunnel balance, and calculates the dynamic pressure q in the test section. Combining with the requirements of the force measurement test accuracy index of the model test, the required resolution value of each component of the wind tunnel balance is calculated. Combining with the design load requirements of the wind tunnel balance, the minimum design strain requirements of each component of the wind tunnel balance under the wind tunnel test accuracy index are calculated. By applying the methods of material mechanics and finite element analysis, the layout mode and size parameters of the wind tunnel balance components are designed and determined to meet the design strain requirements of each component of the wind tunnel balance. The invention effectively quantifies the design strain requirements of each component of the wind tunnel balance and can be applied to the design of wind tunnel balances.

Description

Technical Field

[0001] The present invention relates to a method for quantifying design strain of a large continuous wind tunnel balance, belonging to the technical field of wind tunnel balance design. Background Art

[0002] In the development and modification of equipment models such as large transport aircraft and airliners, the solution of many aerodynamic phenomena and engineering problems relies on the experimental research of large continuous wind tunnels. Large continuous wind tunnels have technical advantages such as a wide Mach number range and good flow field quality. However, the quality and performance of the wind tunnel only represent an ability to reproduce the flight environment. The multi-component aerodynamic force measurement device in wind tunnel tests - the wind tunnel balance is the key factor determining the high-precision / high-efficiency measurement of aerodynamic forces of large aircraft. For example, during the modification process of large aircraft, the performance of different round-robin schemes tends to converge, and the drag coefficient of wind tunnel tests is often within 0.0003. Therefore, it is required that the accuracy of the synchronous repeatability of the drag coefficient in high-speed wind tunnel tests reaches 0.00005, and the accuracy of the non-synchronous repeatability of the drag coefficient reaches 0.0001. Therefore, it is necessary to develop a high-precision wind tunnel balance.

[0003] Design strain is an important index of the wind tunnel balance, which directly determines the test accuracy of the wind tunnel balance. In the prior art, considering the bonding strength of strain gauges and the maximum combined stress limit allowed by the balance body material, guiding suggestions for the design strain of the wind tunnel balance are proposed, that is, the design strain value range of the high-speed wind tunnel balance is 150 -500 and the design strain value range of the low-speed wind tunnel balance is 300 -1000 However, the above guiding suggestions mainly distinguish between high-speed wind tunnels and low-speed wind tunnels and give a suggested range for the design strain of the balance, without considering the operating modes of the wind tunnel, such as blowdown, pulse, and continuous, and do not fully respond to the actual needs of wind tunnel tests, and cannot effectively support the development of equipment models such as large transport aircraft and airliners.

[0004] In summary, a method for quantifying the design strain of a large continuous wind tunnel balance that meets the requirements of wind tunnel tests is needed. Summary of the Invention

[0005] A brief overview of the present invention is given below to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to identify the key or important parts of the present invention, nor is it intended to limit the scope of the present invention. Its purpose is only to present certain concepts in a simplified form as a prelude to the more detailed description to follow.

[0006] In view of this, to solve the problem that the traditional strain measurement method in the existing technology for the design of wind tunnel balances does not fully meet the actual requirements of wind tunnel tests, the present invention provides a method for quantifying the design strain of a large-scale continuous wind tunnel balance.

[0007] The technical solution is as follows: A method for quantifying the design strain of a large-scale continuous wind tunnel balance, comprising the following steps:

[0008] S1. Organize the repeatability test data in the completed large-scale continuous tests, and determine the overall repeatability characteristic value t of each measuring Wheatstone bridge and the measurement and control acquisition device of the wind tunnel balance;

[0009] S2. Conduct the design of the wind tunnel balance, collect the test requirements of the test section model area and the test model parameters of the model test, and calculate the dynamic pressure q of the test section;

[0010] S3. According to the test requirements of the test section model area and the dynamic pressure q of the test section, combined with the accuracy index requirements of the force measurement test of the model test, calculate the required resolution values of each component of the wind tunnel balance;

[0011] Specifically: The components of the wind tunnel balance include normal force, pitching moment, rolling moment, axial force, lateral force, and yaw moment;

[0012] S4. According to the required resolution values of each component of the wind tunnel balance and the overall repeatability characteristic value t, combined with the design load requirements of the wind tunnel balance, calculate the minimum design strain requirements of each component of the wind tunnel balance under the wind tunnel test accuracy index, and integrate them into the design strain requirements of each component of the balance;

[0013] S5. Apply the methods of material mechanics and finite element analysis to design and determine the layout method and size parameters of the wind tunnel balance components to meet the design strain requirements of each component of the wind tunnel balance.

[0014] Furthermore, in S2, collect the Mach number M, the total pressure in the forechamber of the test section model area of the model test, as well as the test model parameters, that is, the reference area s, the mean aerodynamic chord length of the wing and the wingspan L, and calculate the dynamic pressure q of the test section;

[0015] The dynamic pressure q of the test section is expressed as:

[0016] ;

[0017] Wherein, is the static pressure in the test section model area, .

[0018] Furthermore, in S3, the required resolution value of the normal force is expressed as:

[0019] ;

[0020] Resolution requirement value of pitching moment It is expressed as:

[0021] ;

[0022] Resolution requirement value of rolling moment It is expressed as:

[0023] ;

[0024] Resolution requirement value of axial force It is expressed as:

[0025] ;

[0026] Resolution requirement value of lateral force It is expressed as:

[0027] ;

[0028] Resolution requirement value of yaw moment It is expressed as:

[0029] ;

[0030] Among them, is the precision index requirement value of the normal force coefficient, is the precision index requirement value of the pitching moment coefficient, is the precision index requirement value of the rolling moment coefficient, is the precision index requirement value of the axial force coefficient, is the precision index requirement value of the lateral force coefficient, is the precision index requirement value of the yaw moment coefficient.

[0031] Furthermore, in the S3, the minimum design strain requirement of the normal force It is expressed as:

[0032] ;

[0033] The minimum design strain requirement of the pitching moment It is expressed as:

[0034] ;

[0035] The minimum design strain requirement of the rolling moment It is expressed as:

[0036] ;

[0037] Minimum design strain requirement for axial force It is expressed as:

[0038] ;

[0039] Minimum design strain requirement for lateral force It is expressed as:

[0040] ;

[0041] Minimum design strain requirement for yaw moment It is expressed as:

[0042] ;

[0043] Wherein, is the design load requirement for the normal force, is the design load requirement for the pitch moment, is the design load requirement for the roll moment, is the design load requirement for the axial force, is the design load requirement for the lateral force, is the design load requirement for the yaw moment, is the sensitivity of the strain gauge used in the measurement Wheatstone bridge for the normal force, is the sensitivity of the strain gauge used in the measurement Wheatstone bridge for the pitch moment, is the sensitivity of the strain gauge used in the measurement Wheatstone bridge for the roll moment, is the sensitivity of the strain gauge used in the measurement Wheatstone bridge for the axial force, is the sensitivity of the strain gauge used in the measurement Wheatstone bridge for the lateral force, is the sensitivity of the strain gauge used in the measurement Wheatstone bridge for the yaw moment.

[0044] The beneficial effects of the present invention are as follows: A method for designing and quantifying the strain of a large continuous wind tunnel balance provided by the present invention carefully sorts out and analyzes the repeated test data in previous large continuous tests, and accurately obtains the overall repeated characteristic values of the wind tunnel balance test system; the present invention fully responds to the actual needs of wind tunnel tests, accurately quantifies the design strain requirements of each component of the balance corresponding to the wind tunnel test accuracy index, and effectively supports the development of equipment models such as large transport aircraft and airliners. Description of the Drawings

[0045] The drawings described herein are used to provide a further understanding of the present invention, and constitute a part of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention, and do not constitute an improper limitation to the present invention. In the drawings:

[0046] Figure 1 It is a schematic flow diagram of a strain quantification method designed for a large-scale continuous wind tunnel balance;

[0047] Figure 2 It is a schematic structural diagram of a wind tunnel balance with a diameter of 50 mm. Specific implementation manners

[0048] In order to make the technical solutions and advantages in the embodiments of the present invention clearer and more understandable, the following further elaborates on the exemplary embodiments of the present invention with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than an exhaustive list of all embodiments. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0049] Refer to Figure 1 - Figure 2 This embodiment is elaborated in detail. A strain quantification method for the design of a large-scale continuous wind tunnel balance includes the following steps:

[0050] S1. Sort out the repeatability test data in the completed large-scale continuous tests, and determine the overall repeatability characteristic value t of each measurement Wheatstone bridge and measurement and control acquisition device of the wind tunnel balance, t = 0.5, and the unit is ;

[0051] S2. Conduct the design of the wind tunnel balance, collect the test requirements of the test section model area and the test model parameters of the model test, and calculate the dynamic pressure q of the test section;

[0052] S3. According to the test requirements of the test section model area and the dynamic pressure q of the test section, combined with the force measurement test accuracy index requirements of the model test, calculate the resolution requirement values of each component of the wind tunnel balance;

[0053] Specifically: The components of the wind tunnel balance include normal force, pitching moment, rolling moment, axial force, lateral force, and yaw moment;

[0054] S4. According to the resolution requirement values of each component of the wind tunnel balance and the overall repeatability characteristic value t, combined with the design load requirements of the wind tunnel balance, calculate the minimum design strain requirements of each component of the wind tunnel balance under the wind tunnel test accuracy index, and integrate them into the design strain requirements of each component of the balance;

[0055] S5. Apply the methods of material mechanics and finite element analysis to design and determine the layout method and dimension parameters of the wind tunnel balance components to meet the design strain requirements of each component of the wind tunnel balance.

[0056] Furthermore, in the said S2, collect the Mach number M of the test section model area of the model test, the total pressure of the front chamber test requirements and the test model parameters, that is, the reference area s, the mean aerodynamic chord length of the wing Together with the wingspan L, the dynamic pressure q in the test section is calculated;

[0057] The dynamic pressure q in the test section is expressed as:

[0058] ;

[0059] Wherein, is the static pressure in the model area of the test section, .

[0060] Furthermore, in the step S3, the required resolution value of the normal force is expressed as:

[0061] ;

[0062] The required resolution value of the pitching moment is expressed as:

[0063] ;

[0064] The required resolution value of the rolling moment is expressed as:

[0065] ;

[0066] The required resolution value of the axial force is expressed as:

[0067] ;

[0068] The required resolution value of the side force is expressed as:

[0069] ;

[0070] The required resolution value of the yaw moment is expressed as:

[0071] ;

[0072] Wherein, is the required accuracy index value of the normal force coefficient, is the required accuracy index value of the pitching moment coefficient, is the required accuracy index value of the rolling moment coefficient, is the required accuracy index value of the axial force coefficient, is the required accuracy index value of the side force coefficient, is the required accuracy index value of the yaw moment coefficient;

[0073] Specifically, in this embodiment, M = 1.4, = 104000, in the unit of Pa, s = 0.2391814, in the unit of , = 0.259, in the unit of m, L = 1.142857, in the unit of m, q = 44838.4, in the unit of Pa, = 0.001, = 0.0004, = 0.00006, = 0.00016, = 0.0004, = 0.0001, = 10.72, in the unit of N, = 1.11, in the unit of N.m, = 0.74, in the unit of N.m, = 1.72, in the unit of N, = 4.28, in the unit of N, = 1.23, in the unit of N.m.

[0074] Further, in the said S3, the minimum design strain requirement of the normal force is expressed as:

[0075] ;

[0076] The minimum design strain requirement of the pitching moment is expressed as:

[0077] ;

[0078] The minimum design strain requirement of the rolling moment is expressed as:

[0079] ;

[0080] The minimum design strain requirement of the axial force is expressed as:

[0081] ;

[0082] The minimum design strain requirement of the lateral force is expressed as:

[0083] ;

[0084] The minimum design strain requirement of the yaw moment is expressed as:

[0085] ;

[0086] Wherein, is the design load requirement for the normal force, is the design load requirement for the pitching moment, is the design load requirement for the rolling moment, is the design load requirement for the axial force, is the design load requirement for the lateral force, is the design load requirement for the yaw moment, is the sensitivity of the strain gauge used in the Wheatstone bridge for measuring the normal force, is the sensitivity of the strain gauge used in the Wheatstone bridge for measuring the pitching moment, is the sensitivity of the strain gauge used in the Wheatstone bridge for measuring the rolling moment, is the sensitivity of the strain gauge used in the Wheatstone bridge for measuring the axial force, is the sensitivity of the strain gauge used in the Wheatstone bridge for measuring the lateral force, is the sensitivity of the strain gauge used in the Wheatstone bridge for measuring the yaw moment;

[0087] Specifically, = 15000, = 800, = 700, = 1200, = 5000, = 400;

[0088] Since the strain gauges used in the Wheatstone bridges for measuring each component of the wind tunnel balance are the same, = 2, = 2, = 2, = 2, = 2, = 2;

[0089] The minimum design strain requirements for each component of the wind tunnel balance are calculated, and the units are all , = 349.7, = 180, = 238, = 174.8, = 236.3, = 81.6;

[0090] Refer to Figure 2, considering the dimensional space inside the integrated aircraft model for installing the wind tunnel balance, the diameter of the wind tunnel balance is determined to be 50, with the unit of mm. The measuring elements for normal force, pitching moment, rolling moment, side force, and yaw moment are rectangular beams, and the axial force element is a "T"-shaped beam. The shape and measuring elements of the wind tunnel balance are designed by applying the mechanics of materials and finite element analysis methods. Among them, the distance L between the rectangular beams is 140 mm, the length L1 of the rectangular beam is 15 mm, the width b1 of the rectangular beam is 23.5 mm, the height h1 of the rectangular beam is 38 mm, the height L2 of the support beam is 22 mm, the width b2 of the support beam is 13 mm, the thickness h2 of the support beam is 1.5 mm, the height L3 of the measuring beam of the "T"-shaped beam is 11 mm, the long-side width b3 of the measuring beam of the "T"-shaped beam is 10 mm, the short-side width b4 of the measuring beam of the "T"-shaped beam is 3 mm, the thickness h3 of the measuring beam of the "T"-shaped beam is 3.4 mm, the thickness h4 of the cross beam of the "T"-shaped beam is 0.7 mm, and the length L4 of the cross beam of the "T"-shaped beam is 33 mm. The designed strain for the normal force is 945, with the unit of , the designed strain for the pitching moment is 722, with the unit of , the designed strain for the rolling moment is 669, with the unit of , the designed strain for the axial force is 617, with the unit of , the designed strain for the side force is 470 and the designed strain for the yaw moment is 559, with the unit of , fully meeting and exceeding the minimum designed strain requirements obtained.

[0091] Although the present invention has been described in terms of a limited number of embodiments, those skilled in the art in this technical field will understand, based on the above description, that other embodiments can be conceived within the scope of the present invention thus described. In addition, it should be noted that the language used in this specification is mainly selected for the purpose of readability and teaching, rather than for the purpose of explaining or limiting the subject matter of the present invention. Therefore, many modifications and variations will be obvious to those of ordinary skill in this technical field without departing from the scope and spirit of the appended claims. For the scope of the present invention, the disclosure of the present invention is illustrative rather than restrictive, and the scope of the present invention is defined by the appended claims.

Claims

1. A method for quantifying design strain of a large-scale continuous wind tunnel balance, characterized in that, Including the following steps: S1. Organize the repeatability test data in the completed large-scale continuous tests, and determine the overall repeatability characteristic value t of each measuring Wheatstone bridge and the measurement and control acquisition device of the wind tunnel balance, where t = 0.5 and the unit is μV / V; S2. Conduct the design of the wind tunnel balance, collect the test requirements in the test section model area of the model test and the test model parameters, and calculate the dynamic pressure q in the test section; S3. According to the test requirements in the test section model area and the dynamic pressure q in the test section, combined with the accuracy index requirements of the force measurement test in the model test, calculate the required resolution values of each component of the wind tunnel balance; Specifically: The components of the wind tunnel balance include normal force, pitching moment, rolling moment, axial force, lateral force, and yaw moment; S4. According to the required resolution values of each component of the wind tunnel balance and the overall repeatability characteristic value t, combined with the design load requirements of the wind tunnel balance, calculate the minimum design strain requirements of each component of the wind tunnel balance under the wind tunnel test accuracy index, and integrate them into the design strain requirements of each component of the balance; S5. Apply the methods of mechanics of materials and finite element analysis to design and determine the layout mode and dimensional parameters of the wind tunnel balance components to meet the design strain requirements of each component of the wind tunnel balance.

2. The strain quantification method for the design of a large-scale continuous wind tunnel balance according to claim 1, characterized in that, In S2, collect the test requirements of the Mach number M and the total pressure P0 in the test section model area of the model test, as well as the test model parameters, namely the reference area s, the mean aerodynamic chord length b of the wing a and the wingspan L, and calculate the dynamic pressure q in the test section; The dynamic pressure q in the test section is expressed as: q = 0.7P CT M 2 Among them, P CT is the static pressure in the test section model area, P CT = P0 / (1 + 0.2M 2 ) 3.5 .

3. A strain quantification method for the design of a large continuous wind tunnel balance according to claim 2, characterized in that In S3, the required resolution value Y of the normal force fb is expressed as: Y fb = Cyqs Resolution requirement value M of pitching moment zfb It is expressed as: M zfb = m z qsb a Resolution requirement value M of rolling moment xfb It is expressed as: M xfb = m x qsL Resolution requirement value X of axial force fb Expressed as: X fb = C x qs Resolution requirement value Z of lateral force fb It is expressed as: Z fb = Czqs Resolution requirement value M of yaw moment yfb It is expressed as: M yfb = m y qsL Among them, C y is the required value of the accuracy index of the normal force coefficient, m z is the required value of the accuracy index of the pitching moment coefficient, m x is the required value of the accuracy index of the rolling moment coefficient, C x is the required value of the accuracy index of the axial force coefficient, C z is the required value of the accuracy index of the side force coefficient, m y is the required value of the accuracy index of the yaw moment coefficient.

4. A method for quantifying design strain of a large continuous wind tunnel balance according to claim 3, characterized in that, In S3, the minimum design strain requirement ε of the normal force Y is expressed as: ε Y = YT / (Y fb K Y ) Minimum design strain requirement for pitching moment Expressed as: Minimum design strain requirement for rolling moment Expressed as: Minimum design strain requirement ε for axial force X Expressed as: ε X = XT / (X fb K X ) Minimum design strain requirement ε for lateral force Z Expressed as: ε Z = ZT / (Z fb K Z ) Minimum design strain requirement for yaw moment Expressed as: Among them, Y is the design load requirement of the normal force, M z is the design load requirement of the pitching moment, M x is the design load requirement of the rolling moment, X is the design load requirement of the axial force, Z is the design load requirement of the lateral force, M y is the design load requirement of the yaw moment, K Y is the sensitivity of the strain gauge used in the Wheatstone bridge for measuring the normal force, K Mz is the sensitivity of the strain gauge used in the Wheatstone bridge for measuring the pitching moment, K Mx is the sensitivity of the strain gauge used in the Wheatstone bridge for measuring the rolling moment, K X is the sensitivity of the strain gauge used in the Wheatstone bridge for measuring the axial force, K Z is the sensitivity of the strain gauge used in the Wheatstone bridge for measuring the lateral force, K My is the sensitivity of the strain gauge used in the Wheatstone bridge for measuring the yaw moment.

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