Helicopter main blade dynamic balance test bench calibration method

Abstract

The invention provides a helicopter main blade dynamic balance test bench calibration method, which comprises static calibration and dynamic calibration, and is characterized in that the static calibration comprises calibration of lengths of a force measurement pull rod and a linear actuator, adjustment of a zero value position, and calibration of propeller pitches of a propeller hub at different positions; the dynamic calibration comprises the following steps: calibrating a force transducer of the force measuring system; the direction of the force transducer is calibrated according to the difference value of the torque measurement values under the conditions of 5 revolutions and 430 revolutions, and the influence of centrifugal force on hinge torque measurement is eliminated; the characteristics of the propeller hub and the standard propeller blades are calibrated; performing an original standard blade exchange test; calculating a propeller hub characteristic value and an original standard blade characteristic value; calibrating the standard paddle and the accompanying paddle; carrying out an exchange test on the standard blade; and obtaining a propeller hub correction value by using data of the exchange test. When the method is used for calibrating the test bed, the practicability is higher, the consistency and accuracy of the test performance of the test bed are ensured to the greatest extent, and the single blade interchange effect is also improved.

Description

Technical Field

[0001] This invention belongs to the field of helicopter main rotor blade dynamic balancing test technology, and particularly relates to a calibration method for a helicopter main rotor blade dynamic balancing test bench. Background Technology

[0002] The helicopter main rotor blade dynamic balancing test is a test of the dynamic performance of the helicopter rotor blades on a special test bench, and partial adjustments are made to the blades. The purpose is to reduce the imbalance of mass distribution and aerodynamic forces caused by manufacturing deviations, so as to ensure that the dynamic characteristics of the rotor blades delivered in production are basically consistent, realize the interchangeability of individual blades in the use and maintenance process, and effectively reduce the use and maintenance costs of helicopters.

[0003] The helicopter rotor blade dynamic balancing test bench is a large-scale testing device specifically designed for testing the dynamic balancing of helicopter main rotor blades. It is an essential prerequisite for ensuring the dynamic balancing testing and adjustment of rotor blades, the interchangeability of individual blades, and adjustments during field flight tests. Based on this, calibrating the helicopter rotor blade dynamic balancing test bench to eliminate systematic errors generated during use and ensure the consistency and accuracy of its testing performance is particularly important. However, existing technical documents regarding the calibration of rotor blade dynamic balancing test benches are lacking, and the relevant content is too general to be effectively implemented, failing to provide effective guidance for test bench calibration and subsequent verification. Summary of the Invention

[0004] To address the problem that existing technologies cannot effectively guide test bench calibration and subsequent verification, this invention provides a calibration method for a helicopter main rotor blade dynamic balancing test bench. The technical solution is as follows: Firstly, a calibration method for a helicopter main rotor blade dynamic balancing test bench is provided, including: static calibration and dynamic calibration. Static calibration includes: calibrating the length of the force measuring rod and the linear actuator, adjusting the zero position, and calibrating the pitch of the propeller hub at different positions; Dynamic calibration includes: calibrating the force sensor of the force measurement system; calibrating the direction of the force sensor based on the difference in torque measurement values ​​at 5 rpm and 430 rpm to eliminate the influence of centrifugal force on hinge torque measurement; calibrating the hub characteristics and standard blades; conducting a standard blade exchange test; calculating the hub characteristic values ​​and the standard blade characteristic values; calibrating the standard blades and accompanying blades; conducting a standard blade exchange test; and obtaining the hub correction value using the data from the exchange test.

[0005] Optionally, adjusting the zero value position specifically involves: a. Adjust the periodic pitch to zero: Use a spirit level and quadrant to measure the pitch dial, and adjust the periodic pitch actuator to return the periodic pitch to zero. The measurement should be performed in two mutually perpendicular directions. b. Adjust the total pitch to zero.

[0006] Optionally, the pitch of the propeller hub at different positions is specifically calibrated as follows: a. Install horizontal supports under the three propeller hubs, and install the quadrant clamps on the propeller hubs. Use the quadrant to measure and adjust the horizontal supports so that the radial level of the propeller hubs is within 0°±5'. b. Position the force-measuring linkage of the yellow propeller hub to the left of the cycle, measure the angle of attack of the yellow propeller hub, and adjust the overall pitch to make the angle of attack 4°±5´. At this point, the overall pitch is 0°. c. Rotate the rotor head and measure the angle of attack at the forward, right, and rear cyclic positions. The angle of attack error at each measurement position shall not exceed ±5'. d. When the angle of attack error exceeds the standard, adjust the periodic pitch actuator to make it acceptable. e. Check the consistency of the total pitch and the three hubs. If they are consistent, proceed to the next step; if they are inconsistent, repeat steps a through e. f. While ensuring that the maximum angle of attack error of each propeller hub at different positions does not exceed 5', check the error between the three propeller hubs; the error between them should also not exceed 5'. g. Position the yellow propeller hub to the left during the period, and measure the angle of attack of the yellow propeller hub. h. Control the total pitch so that the measured total pitch value increases from 0° in 1° increments to 10°, and mark the accurate position of the pitch scale. i. Measure the angle of attack of the blue and red propeller hubs at 0° and 10°, with the error between the two and the yellow propeller hub not exceeding ±5'. j. If the angle of attack difference exceeds ±5', check whether the link length and the length of the linear actuator are within the standard range.

[0007] Optionally, the force sensor used to calibrate the force measurement system is specifically: a. Disconnect the lower connecting pin of the force-measuring linkage of the force-measuring system, and use a support block to suspend the force-measuring linkage. b. Zero the force measurement system. c. Suspend a standard weight on the force-measuring linkage, adjust the amplification factor of the force-measuring cabinet to make the side force sensor reading the standard value, and complete the calibration of the three force-measuring cabinets in sequence. d. Repeat 2-3 times until the fluctuation between the force sensor value and the standard value is less than 0.1 N·m.

[0008] Optionally, based on the difference in torque measurements at 5 revolutions and 430 revolutions, the orientation of the force sensor is calibrated to eliminate the influence of centrifugal force on the hinge torque measurement, specifically as follows: a. Assume the periodic pitch is 1° in the previous period. b. Adjust the dynamic zero point at 5 revolutions. c. Remove the force-measuring linkage at 0 revolutions and record the static zero point. d. Measure the direct reading of the hinge torque at 5 revolutions. e. Measure the direct reading of the hinge torque at 430 rpm, and calculate the hinge torque difference ΔMNR between 430 rpm and 5 rpm. f. If ΔMNR exceeds ±0.5 N·m, depending on the magnitude of the deviation and experience, decide to change the orientation of one or two force sensors, approximately 45° each time. g. If the error still exceeds the tolerance, repeat steps b to f until the error is within tolerance.

[0009] Optionally, when calibrating the hub characteristics and standard blades, the calibration parameters are: a forward cycle of 1° and a rotational speed of the rated speed.

[0010] Optionally, during the original standard blade replacement test, the three original standard blades are numbered P1, P2, and P3, and the three hubs are defined as J (yellow hub), B (blue hub), and R (red hub), and the following test is performed: a. Install the original standard blades in the following positions: install P1 on the yellow hub, P2 on the blue hub, and P3 on the red hub. b. Adjust the initial installation angles of the blue and red rotor hubs at a total pitch of 1° to balance the conicity. c. Measure the hinge torque and conic cone data every 2° from the total pitch of 1° to 9°. d. Install the original standard blades in the following positions: install P1 on the red hub, P2 on the yellow hub, and P3 on the blue hub. Repeat steps b and c. e. Install the original standard blades in the following positions: install P1 on the blue hub (B), install P2 on the red hub, and install P3 on the yellow hub. Repeat steps b and c.

[0011] Optionally, the hub characteristic value and the original standard blade characteristic value are calculated, specifically as follows: Let B2 represent the difference reading of the original standard blade P2 on the blue hub, and B and J represent the inherent characteristic values ​​of the blue and yellow hubs, respectively. The difference obtained after each blade swap is expressed as follows: First experiment: B2=(B+P2)-(J+P1)(1) R3=(R+P3)-(J+P1)(2) Second experiment: B3=(B+P3)-(J+P2)(3) R1=(R+P1)-(J+P2)(4) Third experiment: B1=(B+P1)-(J+P3)(5) R2=(R+P2)-(J+P3)(6) In the formula, B+P2 represents the actual value of blade P2 on the blue hub, J+P1 represents the actual value of blade P1 on the yellow hub, and the difference between the two is the difference reading of blade P2 on the blue hub relative to P1. The difference in characteristic values ​​between the blue and yellow propeller hubs is represented by (BJ), and the difference in characteristic values ​​between the red and yellow propeller hubs is represented by (RJ). By adding equations (1), (3), and (5), and by adding equations (2), (4), and (6), the propeller hub characteristic values ​​are obtained: (BJ)=(B1+B2+B3)÷3(7) (RJ)=(R1+R2+R3)÷3(8) The length of the rotor hub tie rod is corrected based on the obtained rotor hub characteristic value: Substitute the initial installation angle adjustment obtained from each test into equation (7) and equation (8) to obtain the zero position deviation of the blue rotor hub and red rotor hub relative to the yellow rotor hub, and use this value to correct the length of the blue rotor hub and red rotor tie rod. Let Ai represent the characteristic values ​​of the torque and taper of the i-th original standard blade, and let P1, P2, and P3 represent the values ​​of the three original standard blades themselves. The value of the interaction between these three original standard blades is obtained and defined as the characteristic value of the original standard blade, denoted by Ai. Ai = Pi - (P1 + P2 + P3) / 3 (9) In the formula, i = 1, 2, 3, representing three original standard blades. Adding equations (7) and (8) together, we get: R1+ B1=(R+P1)-(J+P2)+ (B+P1)-(J+P3), Simplifying, we get: {B1+R1-[(BJ)+(RJ)]} / 3=P1-(P1+P2+P3) / 3=A1. Let K = (BJ) + (RJ). Equation (9) can be transformed into: Ai=(Bi+Ri-K) / 3 (i=1, 2, 3) (10) Determine the average value Am of the reference blade characteristic values: the taper slope is represented by ΔEHθ, which is the difference between the taper height under large pitch and small pitch. The characteristic value of the original standard blade with EHθ closest to zero is taken as the average value of the original standard blade characteristic values.

[0012] Optionally, when calibrating the standard blade and accompanying blade, the original standard blade with the conicity slope characteristic value closest to 0 is removed, and the standard blade is installed on the yellow hub. The other two original standard blades are installed in the same position and state as the removed original standard blade on the yellow hub. The calibration process is as follows: a. At rated speed, record the static zero point and adjust the dynamic zero point; b. Install the blades; c. With a total pitch of 1° and at the rated speed, adjust the installation angle of the standard blade so that its conic height is in the middle of the two original standard blades; d. Adjust the initial installation angle of the two original standard blades to achieve a balance in their conicity; e. Measure the conicity and torque values ​​for each pitch, determine and adjust the standard blades, and adjust the tolerance to half of the batch production test tolerance; f. If the tolerance requirements are met, the standard blade calibration is considered complete. The same method is used for the accompanying blades, following steps a to f. g. Read the initial installation angle of the standard blade and correct it using the batch production correction value of the initial installation angle.

[0013] Optionally, Conduct a standard blade exchange test, specifically as follows: a. After calibrating the standard blades, exchange the two original standard blades; b. Keeping the standard blade installation angle unchanged, adjust the initial installation angle of the blue and red blade hubs at 366 rpm and 1° total pitch to balance the conicity; c. Increasing the total pitch to 9° with a step size of 2°, and collecting conicity and torque data; The hub correction value is calculated using data from the exchange test, specifically as follows: Let the standard blade, balanced together with the two reference blades P1 and P2, be designated as Pm. The characteristic value of this blade should be the average of the characteristic values ​​of the reference blades. First experiment: The blade PI on the blue rotor hub arm is: Bi = (PI+B)-(S+J). The blade PJ on the red rotor hub arm: Rj = (PJ+R)-(S+J). Second experiment: The blade PJ:Bj = (PJ+B)-(S+J) on the blue hub support arm. The blade PI on the red rotor hub arm: Ri = (PI+R)-(S+J). Calculate the average value of the characteristic values ​​of the two reference blades: Am = -(AI + AJ) For the given blue propeller hub support arm, we get: Correction factor = (AI - Bi + AJ - Bj) / 2 = -(Am + Bi + Bj) / 2, Correction value = (Am + bi + bj) / 2 In the formula: Bi represents the measurement value of the reference blade P1 mounted on the blue hub. PI represents the intrinsic value of the reference blade P1 mounted on the blue hub. PJ represents the intrinsic value of the reference blade P2 mounted on the red hub. S represents the inherent value of the standard blade mounted on the yellow hub. Rj represents the measurement value of the P2 reference blade mounted on the red hub. R represents the inherent value of the red propeller hub itself.

[0014] The beneficial effects of this invention are at least as follows: The blade dynamic balancing test bench calibration method provided by this invention features detailed operational descriptions and high feasibility. It solves the problem of previous blade dynamic balancing test bench calibration methods lacking relevant technical documentation, with overly general content that was difficult to implement and effectively guide test bench calibration and subsequent verification. This method offers greater practicality, maximizing the consistency and accuracy of test bench performance and improving the interchangeability of individual blades. Attached Figure Description

[0015] Figure 1 This is a diagram showing the installation sequence of the original standard blade replacement test blades; Figure 2 This is a flowchart of a calibration method for a helicopter main rotor blade dynamic balancing test bench. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0018] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited from each other.

[0019] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0020] Based on existing main propeller blade dynamic balancing test technology, this invention provides a feasible calibration method for a propeller blade dynamic balancing test bench. It outlines both static and dynamic calibration aspects of the test bench, including requirements for propeller blade dynamic balancing test equipment, calibration requirements, test bench hub calibration method, standard blade calibration method, and correction value determination method. Furthermore, a verification method is used to practically verify the calibration effect of the test bench, eliminating systematic errors generated during use and ensuring the consistency and accuracy of its test performance.

[0021] See Figure 2 An embodiment of the present invention provides a calibration method for a helicopter main rotor blade dynamic balancing test bench, which may specifically include the following steps: I. Calibration Procedure (a) Calibration preparation Prepare the fixtures, tools, instruments and meters required for test bench calibration; Check the performance of the test bench's mechanical system, control system, and measurement system.

[0022] (II) Calibration Process 1) Static calibration – pitch system calibration.

[0023] ① Use calibration fixtures to calibrate the lengths of the force measuring rod and the linear actuator.

[0024] ② Adjust the zero value position: a. Adjust the periodic pitch to the zero position: Use a level and quadrant to measure the pitch plate, and adjust the periodic pitch actuator to bring the periodic pitch back to zero. The measurement should be performed in two mutually perpendicular directions.

[0025] b. Adjust the total pitch to the zero position. The adjustment process can be referred to existing technology and will not be described here.

[0026] ③ Calibrate the pitch of the propeller hub at different positions.

[0027] a. Install horizontal support 1 under the three propeller hubs, install the quadrant clamp on the propeller hubs, use the quadrant to measure and adjust the horizontal support 1 so that the radial level of the propeller hubs is within 0°±5´.

[0028] b. Position the force-measuring linkage of the yellow propeller hub to the left cycle, measure the angle of attack of the yellow propeller hub, and adjust the total pitch to make the angle of attack 4°±5´. At this point, the total pitch is 0°.

[0029] c. Rotate the rotor head and measure the angle of attack at the forward, right, and rear cyclic positions. The angle of attack error at each measurement position should not exceed ±5'.

[0030] d. When the angle of attack error exceeds the standard, adjust the periodic pitch actuator to make it acceptable.

[0031] e. Check the consistency of the total pitch and the three hubs. If they are consistent, proceed to the next step; if they are inconsistent, repeat steps a through e.

[0032] f. While ensuring that the maximum error of the angle of attack of each propeller hub at different positions does not exceed 5', check the error between the three propeller hubs. The error between them should also not exceed 5'.

[0033] g. Position the yellow propeller hub to the left during the cycle and measure the angle of attack of the yellow propeller hub.

[0034] h. Control the total pitch so that the total pitch measurement value increases from 0° in 1° increments to 10°, and mark the accurate position of the pitch scale.

[0035] i. Measure the angle of attack of the blue and red propeller hubs at 0° and 10°, and their error with that of the yellow propeller hub should not exceed ±5'.

[0036] j. If the angle of attack difference exceeds ±5', check whether the link length and the length of the linear actuator are within the standard range.

[0037] 2) Dynamic calibration – calibration of the force measurement system ① The force sensor for calibrating the force measurement system.

[0038] a. Disconnect the lower connecting pin of the force measuring rod of the force measuring system, and use a support block to suspend the force measuring rod.

[0039] b. Zero the force measurement system.

[0040] c. Suspend a standard weight on the force measuring rod, adjust the amplification factor of the force measuring cabinet to make the side force sensor value the standard value, and complete the calibration of the three force measuring cabinets in sequence.

[0041] d. Repeat 2-3 times until the fluctuation between the force sensor value and the standard value is less than 0.1 N·m.

[0042] ② Based on the difference in torque measurement values ​​at 5 revolutions and 430 revolutions, calibrate the direction of the force sensor to eliminate the influence of centrifugal force on the hinge torque measurement.

[0043] a. The periodic pitch is 1° of the previous period.

[0044] b. Adjust the dynamic zero point at 5 revolutions.

[0045] c. Remove the force measuring rod at 0 revolutions and record the static zero point.

[0046] d. Measure the direct reading of the hinge torque at 5 revolutions.

[0047] e. Measure the direct reading of the hinge torque at 430 rpm. Calculate the hinge torque difference ΔMNR between 430 rpm and 5 rpm.

[0048] f. If ΔMNR exceeds ±0.5 N·m, depending on the magnitude of the deviation and experience, decide to change the orientation of one or two force sensors, approximately 45° each time.

[0049] g. If the error still exceeds the tolerance, repeat steps b to f until the error is within tolerance.

[0050] ③ Calibrate the hub characteristics and standard blades.

[0051] The calibration parameters are: initial cycle 1°, and rotation speed is the rated speed.

[0052] ④ Conduct the original standard blade exchange test.

[0053] See Figure 1 The three original standard blades were numbered P1, P2, and P3, and the three hubs were defined as J (yellow hub), B (blue hub), and R (red hub). The following experiment was conducted: a. Install the original standard blades in the following positions: install P1 on J (yellow hub), install P2 on B (blue hub), and install P3 on J (red hub).

[0054] b. Adjust the initial installation angles of the blue and red rotor hubs at a total pitch of 1° to balance the conicity.

[0055] c. Measure the hinge torque and conicity data every 2° from the total pitch of 1° to 9°.

[0056] d. Install the original standard blades in the following positions: install P1 on R (red hub), P2 on J (yellow hub), and P3 on B (blue hub). That is, P1->R, P2->J, P3->B. Repeat steps b and c.

[0057] e. Perform the original standard blade installation. The installation positions are as follows: install P1 on B (blue blade hub), install P2 on R (red blade hub), and install P3 on J (yellow blade hub). Repeat steps b and c.

[0058] ⑤ Calculate the characteristic values ​​of the propeller hub and the original standard propeller blade.

[0059] Let B2 represent the difference reading of the original standard blade P2 on the blue hub, and B and J represent the inherent characteristic values ​​of the blue and yellow hubs, respectively. Each time, according to... Figure 1 The difference obtained by exchanging the blades can be expressed as follows: First experiment: B2=(B+P2)-(J+P1)(1) R3=(R+P3)-(J+P1)(2) Second experiment: B3=(B+P3)-(J+P2)(3) R1=(R+P1)-(J+P2)(4) Third experiment: B1=(B+P1)-(J+P3)(5) R2=(R+P2)-(J+P3)(6) In the formula, "B+P2" represents the actual value of blade P2 on the blue hub, "J+P1" represents the actual value of blade P1 on the yellow hub, and the difference between the two is the difference reading of blade P2 on the blue hub relative to P1.

[0060] The difference in characteristic values ​​between the blue and yellow propeller hubs is represented by (BJ), and the difference in characteristic values ​​between the red and yellow propeller hubs is represented by (RJ). Adding equations (1), (3), and (5), and adding equations (2), (4), and (6), and then rearranging, we obtain the propeller hub characteristic values: (BJ)=(B1+B2+B3)÷3(7) (RJ)=(R1+R2+R3)÷3(8) The length of the rotor hub tie rod is corrected based on the obtained rotor hub characteristic value: Substitute the initial installation angle adjustment obtained from each test into equation (7) and equation (8) to obtain the zero position deviation of the blue rotor hub and red rotor hub relative to the yellow rotor hub, and use this value to correct the length of the blue rotor hub and red rotor hub tie rod.

[0061] Let Ai represent the characteristic values ​​of the torque and taper of the i-th original standard blade, and let P1, P2, and P3 represent the values ​​of the three original standard blades themselves. However, due to the influence of factors such as the blade hub, these values ​​are mixed with the values ​​of the blade hub itself and cannot be measured. Therefore, only the value of the interaction between these three original standard blades can be obtained, defined as the characteristic value of the original standard blade, denoted by Ai: Ai = Pi - (P1 + P2 + P3) / 3 (9) In the formula, i = 1, 2, 3, representing three original standard blades.

[0062] Equation (9) is the expression for the characteristic value of the original standard blade. The characteristic value of the original standard blade is only related to the three original standard blades. Adding equations (7) and (8) gives: R1+ B1=(R+P1)-(J+P2)+ (B+P1)-(J+P3) Simplifying, we get: {B1+R1-[(BJ)+(RJ)]} / 3=P1-(P1+P2+P3) / 3=A1 Let K = (BJ) + (RJ). Equation (9) can be transformed into: Ai=(Bi+Ri-K) / 3 (i=1, 2, 3) (10) Determine the average value Am of the reference blade characteristics: The taper slope is represented by ΔEHθ, which is the difference between the taper height at large pitch and small pitch. The characteristic value of the original standard blade with EHθ closest to zero is taken as the average value (Am) of the original standard blade characteristics.

[0063] ⑥ Calibrate the standard blades and accompanying blades.

[0064] Remove the original standard blade whose conicity slope characteristic value is closest to 0, and install the standard blade on the yellow hub. Install the other two original standard blades in the same position and state as the removed original standard blade on the yellow hub.

[0065] a. At rated speed, record the static zero point and adjust the dynamic zero point; b. Install the blades; c. With a total pitch of 1° and at the rated speed, adjust the installation angle of the standard blade so that its conic height is in the middle of the two original standard blades; d. Adjust the initial installation angle of the two original standard blades to achieve a balance in their conicity; e. Measure the conicity and torque values ​​for each pitch, determine and adjust the standard blades, and adjust the tolerance to half of the batch production test tolerance; f. Once the tolerance requirements are met, the standard blade calibration is considered complete. The same method is used for the accompanying blades, referring to steps a to f. g. Determine the initial installation angle of the standard blade and correct it using the batch production correction value of the initial installation angle.

[0066] ⑦ Conduct a standard blade exchange test. The test method and the data to be measured are the same as in step ⑥.

[0067] a. After calibrating the standard blades, exchange the two original standard blades; b. Keep the installation angle of the standard blade unchanged.

[0068] c. At 366 rpm and 1° total pitch, adjust the initial installation angle of the blue and red rotor hubs to balance the conicity; d. With a step size of 2°, increase the total pitch to 9° and collect conicity and torque data.

[0069] ⑧ The hub correction value was calculated using the data from the exchange test: Let the standard blade, which is balanced with the two reference blades P1 and P2, be Pm. The characteristic value of this blade should be the average value (Am) of the characteristic values ​​of the reference blades.

[0070] First experiment: The blade PI on the blue rotor hub arm: Bi = (PI+B)-(S+J) The blade PJ on the red rotor hub arm: Rj = (PJ+R)-(S+J) Second experiment: The blade PJ:Bj on the blue rotor hub arm = (PJ+B)-(S+J) The blade PI on the red rotor hub arm: Ri = (PI+R)-(S+J) Calculate the average of the characteristic values ​​of the two reference blades: Am = -(AI + AJ) For the given (blue) rotor hub arm, we get: Correction factor = (AI - Bi + AJ - Bj) / 2 = -(Am + Bi + Bj) / 2 Correction value = (Am + bi + bj) / 2 In the formula: Bi represents the measurement value of the reference blade P1 mounted on the blue hub. PI represents the intrinsic value of the reference blade P1 mounted on the blue hub. PJ represents the intrinsic value of the reference blade P2 mounted on the red hub. S represents the inherent value of the standard blade mounted on the yellow hub. Rj represents the measurement value of the P2 reference blade mounted on the red hub. R represents the inherent value of the red propeller hub itself.

[0071] II. Check the balance (a) Check the influence of total pitch on the measurement.

[0072] When the total pitch changes, check the linearity of the hinge torque Mθ and ΔMθ.

[0073] At a first cycle of 1° and at rated speed 1) Measure the direct reading of the hinge torque when the total pitch is 0°, 1°, ... 9°, N° (N value is generally 1~2° larger than the required value for each model); 2) Calculate ΔMθ = MN° - M0°; 3) Inspection: The hinge torque deviation between each propeller pitch is ≤ ±1 N·m, the maximum deviation of each propeller hub is ≤ ±1.5 N·m, and ΔMθ is ≤ ±1 N·m; 4) If 3) is not met, then it is not qualified.

[0074] (ii) Inspect the effect of the periodic pitch on the measurement.

[0075] 1) Measure the direct reading of the hinge torque at a total pitch of 0° and rated speed. Record the direct reading value of the hinge torque when the previous cycle is 1°; Record the direct reading value of the hinge torque when the left cycle is 1°; Record the direct reading value of the hinge torque at 1° after the cycle ends; Record the direct reading value of the hinge torque when the right cycle is 1°.

[0076] Judgment: Regardless of the variation in periodic pitch, a maximum deviation of ≤±0.5 N·m in the measured values ​​at each hub is considered acceptable.

[0077] (iii) Check the effect of different rotation speeds on the measurement.

[0078] 1) With a pre-cycle of 1° and a total pitch of 0°, The rotational speed is the rated speed minus 100 rpm, and the direct reading of the hinge torque of the three propeller hubs is measured. The rotational speed is the rated speed, and the direct reading of the hinge torque of the three propeller hubs is measured. The rotational speed is the rated speed + 100 rpm, and the direct reading of the hinge torque of the three propeller hubs is measured. 2) Calculate ΔM=M 大转速 -M 小转速 M 大转速 and M 小转速 For any two of the three hinge torque direct readings measured in step 1), choose the hinge torque direct reading at the larger speed and the smaller speed. 3) If the difference between the measured values ​​of the blue and red propeller hubs and the measured value of the yellow propeller hub at each speed is ≤1 N·m, that is, all three ΔM values ​​are ≤1 N·m, then the requirement is met.

[0079] This invention provides a calibration method for a helicopter main rotor blade dynamic balancing test bench. Based on the calibration results, it includes both static and dynamic calibration, and provides theoretical analysis and practical verification of the calibration effect. The operational details are described in detail, making it highly feasible. This method is more practical for calibrating rotor blade dynamic balancing test benches, eliminating systematic errors generated during use and ensuring the consistency and accuracy of its test performance.

[0080] The above description merely illustrates embodiments of the present invention and is quite specific and detailed; however, it should not be construed as limiting the scope of the patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Furthermore, any parts of the present invention not described in detail are conventional techniques.

Claims

1. A calibration method for a helicopter main rotor blade dynamic balancing test bench, characterized in that, include: Static calibration and dynamic calibration, wherein static calibration includes: calibrating the length of the force measuring rod and the linear actuator, adjusting the zero position, and calibrating the pitch of the propeller hub at different positions; Dynamic calibration includes: calibrating the force sensor of the force measurement system; calibrating the direction of the force sensor based on the difference in torque measurement values ​​at 5 rpm and 430 rpm to eliminate the influence of centrifugal force on hinge torque measurement; calibrating the hub characteristics and standard blades; conducting a standard blade exchange test; calculating the hub characteristic values ​​and the standard blade characteristic values; calibrating the standard blades and accompanying blades; conducting a standard blade exchange test; and obtaining the hub correction value using the data from the exchange test.

2. The method according to claim 1, characterized in that, The specific steps for adjusting the zero value position are as follows: a. Adjust the periodic pitch to zero: Use a spirit level and quadrant to measure the pitch dial, and adjust the periodic pitch actuator to return the periodic pitch to zero. The measurement should be performed in two mutually perpendicular directions. b. Adjust the total pitch to zero.

3. The method according to claim 1, characterized in that, The specific pitch calibration of the propeller hub at different positions is as follows: a. Install horizontal supports under the three propeller hubs, and install the quadrant clamps on the propeller hubs. Use the quadrant to measure and adjust the horizontal supports so that the radial level of the propeller hubs is within 0°±5'. b. Position the force-measuring linkage of the yellow propeller hub to the left of the cycle, measure the angle of attack of the yellow propeller hub, and adjust the overall pitch to make the angle of attack 4°±5´. At this point, the overall pitch is 0°. c. Rotate the rotor head and measure the angle of attack at the forward, right, and rear cyclic positions. The angle of attack error at each measurement position shall not exceed ±5'. d. When the angle of attack error exceeds the standard, adjust the periodic pitch actuator to make it acceptable. e. Check the consistency of the total pitch and the three hubs. If they are consistent, proceed to the next step; if they are inconsistent, repeat steps a through e. f. While ensuring that the maximum angle of attack error of each propeller hub at different positions does not exceed 5', check the error between the three propeller hubs; the error between them should also not exceed 5'. g. Position the yellow propeller hub to the left during the period, and measure the angle of attack of the yellow propeller hub. h. Control the total pitch so that the measured total pitch value increases from 0° in 1° increments to 10°, and mark the accurate position of the pitch scale. i. Measure the angle of attack of the blue and red propeller hubs at 0° and 10°, with the error between the two and the yellow propeller hub not exceeding ±5'. j. If the angle of attack difference exceeds ±5', check whether the link length and the length of the linear actuator are within the standard range.

4. The method according to claim 1, characterized in that, The force sensor used to calibrate the force measurement system is specifically: a. Disconnect the lower connecting pin of the force-measuring linkage of the force-measuring system, and use a support block to suspend the force-measuring linkage. b. Zero the force measurement system. c. Suspend a standard weight on the force-measuring linkage, adjust the amplification factor of the force-measuring cabinet to make the side force sensor reading the standard value, and complete the calibration of the three force-measuring cabinets in sequence. d. Repeat 2-3 times until the fluctuation between the force sensor value and the standard value is less than 0.1 N·m.

5. The method according to claim 1, characterized in that, Based on the difference in torque measurements at 5 revolutions and 430 revolutions, the orientation of the force sensor was calibrated to eliminate the influence of centrifugal force on the hinge torque measurement. Specifically: a. Assume the periodic pitch is 1° in the previous period. b. Adjust the dynamic zero point at 5 revolutions. c. Remove the force-measuring linkage at 0 revolutions and record the static zero point. d. Measure the direct reading of the hinge torque at 5 revolutions. e. Measure the direct reading of the hinge torque at 430 rpm, and calculate the hinge torque difference ΔMNR between 430 rpm and 5 rpm. f. If ΔMNR exceeds ±0.5 N·m, depending on the magnitude of the deviation and experience, decide to change the orientation of one or two force sensors, approximately 45° each time. g. If the error still exceeds the tolerance, repeat steps b to f until the error is within tolerance.

6. The method according to claim 1, characterized in that, When calibrating the hub characteristics and standard blades, the calibration parameters are: forward cycle 1°, and rotational speed is the rated speed.

7. The method according to claim 1, characterized in that, During the original standard blade replacement test, the three original standard blades were numbered P1, P2, and P3. The three hubs were defined as J (yellow hub), B (blue hub), and R (red hub). The following test was conducted: a. Install the original standard blades in the following positions: install P1 on the yellow hub, P2 on the blue hub, and P3 on the red hub. b. Adjust the initial installation angles of the blue and red rotor hubs at a total pitch of 1° to balance the conicity. c. Measure the hinge torque and conic cone data every 2° from the total pitch of 1° to 9°. d. Install the original standard blades in the following positions: install P1 on the red hub, P2 on the yellow hub, and P3 on the blue hub. Repeat steps b and c. e. Install the original standard blades in the following positions: install P1 on the blue hub (B), install P2 on the red hub, and install P3 on the yellow hub. Repeat steps b and c.

8. The method according to claim 1, characterized in that, The calculation of the hub characteristic values ​​and the original standard blade characteristic values ​​is as follows: Let B2 represent the difference reading of the original standard blade P2 on the blue hub, and B and J represent the inherent characteristic values ​​of the blue and yellow hubs, respectively. The difference obtained after each blade swap is expressed as follows: First experiment: B2=(B+P2)-(J+P1)(1) R3=(R+P3)-(J+P1)(2) Second experiment: B3=(B+P3)-(J+P2)(3) R1=(R+P1)-(J+P2)(4) Third experiment: B1=(B+P1)-(J+P3)(5) R2=(R+P2)-(J+P3)(6) In the formula, B+P2 represents the actual value of blade P2 on the blue hub, J+P1 represents the actual value of blade P1 on the yellow hub, and the difference between the two is the difference reading of blade P2 on the blue hub relative to P1. The difference in characteristic values ​​between the blue and yellow propeller hubs is represented by (BJ), and the difference in characteristic values ​​between the red and yellow propeller hubs is represented by (RJ). By adding equations (1), (3), and (5), and by adding equations (2), (4), and (6), the propeller hub characteristic values ​​are obtained: (BJ)=(B1+B2+B3)÷3(7) (RJ)=(R1+R2+R3)÷3(8) The length of the rotor hub tie rod is corrected based on the obtained rotor hub characteristic value: Substitute the initial installation angle adjustment obtained from each test into equation (7) and equation (8) to obtain the zero position deviation of the blue rotor hub and red rotor hub relative to the yellow rotor hub, and use this value to correct the length of the blue rotor hub and red rotor tie rod. Let Ai represent the characteristic values ​​of the torque and taper of the i-th original standard blade, and let P1, P2, and P3 represent the values ​​of the three original standard blades themselves. The value of the interaction between these three original standard blades is obtained and defined as the characteristic value of the original standard blade, denoted by Ai. Ai = Pi - (P1 + P2 + P3) / 3 (9) In the formula, i = 1, 2, 3, representing three original standard blades. Adding equations (7) and (8) together, we get: R1+ B1=(R+P1)-(J+P2)+ (B+P1)-(J+P3), Simplifying, we get: {B1+R1-[(BJ)+(RJ)]} / 3=P1-(P1+P2+P3) / 3=A1. Let K = (BJ) + (RJ). Equation (9) can be transformed into: Ai=(Bi+Ri-K) / 3 (i=1, 2, 3) (10) Determine the average value Am of the reference blade characteristic values: the taper slope is represented by ΔEHθ, which is the difference between the taper height under large pitch and small pitch. The characteristic value of the original standard blade with EHθ closest to zero is taken as the average value of the original standard blade characteristic values.

9. The method according to claim 1, characterized in that, When calibrating the standard blade and accompanying blades, remove the original standard blade whose conicity slope characteristic value is closest to 0, and install the standard blade on the yellow hub. Install the other two original standard blades in the same position and condition as the removed original standard blade on the yellow hub. The calibration process is as follows: a. At rated speed, record the static zero point and adjust the dynamic zero point; b. Install the blades; c. With a total pitch of 1° and at the rated speed, adjust the installation angle of the standard blade so that its conic height is in the middle of the two original standard blades; d. Adjust the initial installation angle of the two original standard blades to achieve a balance in their conicity; e. Measure the conicity and torque values ​​for each pitch, determine and adjust the standard blades, and adjust the tolerance to half of the batch production test tolerance; f. If the tolerance requirements are met, the standard blade calibration is considered complete. The same method is used for the accompanying blades, following steps a to f. g. Read the initial installation angle of the standard blade and correct it using the batch production correction value of the initial installation angle.

10. The method according to claim 1, characterized in that, Conduct a standard blade exchange test, specifically as follows: a. After calibrating the standard blades, exchange the two original standard blades; b. Keeping the standard blade installation angle unchanged, adjust the initial installation angle of the blue and red blade hubs at 366 rpm and 1° total pitch to balance the conicity; c. Increasing the total pitch to 9° with a step size of 2°, and collecting conicity and torque data; The hub correction value is calculated using data from the exchange test, specifically as follows: Let the standard blade, balanced together with the two reference blades P1 and P2, be designated as Pm. The characteristic value of this blade should be the average of the characteristic values ​​of the reference blades. First experiment: The blade PI on the blue rotor hub arm is: Bi = (PI+B)-(S+J). The blade PJ on the red rotor hub arm: Rj = (PJ+R)-(S+J). Second experiment: The blade PJ:Bj = (PJ+B)-(S+J) on the blue hub support arm. The blade PI on the red rotor hub arm: Ri = (PI+R)-(S+J). Calculate the average value of the characteristic values ​​of the two reference blades: Am = -(AI + AJ) For the given blue propeller hub support arm, we get: Correction factor = (AI - Bi + AJ - Bj) / 2 = -(Am + Bi + Bj) / 2, Correction value = (Am + bi + bj) / 2 In the formula: Bi represents the measurement value of the reference blade P1 mounted on the blue hub. PI represents the intrinsic value of the reference blade P1 mounted on the blue hub. PJ represents the intrinsic value of the reference blade P2 mounted on the red hub. S represents the inherent value of the standard blade mounted on the yellow hub. Rj represents the measurement value of the P2 reference blade mounted on the red hub. R represents the inherent value of the red propeller hub itself.

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