A multi-profile segmented integral calibration based tip displacement measurement method

Abstract

The present application belongs to the field of cantilever beam structure bending deformation measurement in material mechanics, and particularly relates to a kind of propeller tip displacement measurement method based on multi-section segmented integral calibration.S1, n section is selected on the target blade Paste strain gauge, the i-th section is defined as Zi, wherein the first section is the root section Z1;S2, from section Z1 Start the calibration of the propeller tip flapping displacement, along the span direction to each section Zi in turn is carried out cumulative calibration, and the flapping strain response of section Zi is obtained i The transformation coefficient Ki of the propeller tip displacement mapped therewith;S3, the propeller tip flapping displacement L is obtained by the one-dimensional matrix [ε1, ε2, …, ε n ] of the flapping strain response of the n section and the one-dimensional matrix [K1, K2, …, K n ] of the transformation coefficient of the propeller tip displacement corresponding to the section.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of cantilever beam structure bending deformation measurement in material mechanics, and particularly relates to a propeller tip displacement measurement method based on multi-section segmented integral calibration. BACKGROUND

[0002] The propeller tip flapping displacement measurement method of a helicopter rotor blade under distributed aerodynamic load loading can be used for monitoring the tip spacing of a hingeless rigid multi-rotor. For a hingeless rigid rotor, the tip flapping displacement is completely affected by the aerodynamic load and does not exist the non-strain response tip displacement generated by the free movement of the flapping hinge in the articulated rotor. Therefore, the tip flapping displacement of the hingeless rigid rotor can be characterized by the aerodynamic flapping load of the blade.

[0003] However, the flapping strain response of each section on the blade can only map the bending moment load and cannot be one-to-one mapped with the tip displacement. The application provides a multi-section segmented integral calibration method based on the flapping displacement of the blade to obtain the accurate conversion relationship between the flapping displacement of the blade and the multi-section strain response of the blade. SUMMARY

[0004] The technical problem solved by the application: The technical scheme of the application is aimed at the problem that the multi-section strain response of the blade and the tip flapping displacement are not simply linearly mapped in the background technology. The application provides a multi-section segmented integral calibration method for measuring the tip displacement, which can accurately measure the conversion relationship between the tip flapping displacement and the multi-section strain response by calibrating the distributed flapping load of the rotor / airfoil blade.

[0005] The technical scheme of the application:

[0006] A multi-section segmented integral calibration method for measuring the tip displacement, the method comprising:

[0007] S1, selecting n sections on the target blade and pasting strain gauges, the i-th section is defined as Zi, wherein the first section is the root section Z1;

[0008] S2, starting from the section Z1, calibrating the tip flapping displacement, and sequentially calibrating each section Zi along the span to obtain the flapping strain response of the section Zi i and the transformation coefficient Ki of the mapped tip displacement;

[0009] S3, the tip flapping displacement L is obtained by the one-dimensional matrix [ε1, ε2,..., ε n ] of the flapping strain response of the n sections and the one-dimensional matrix [K1, K2,..., K n ] of the tip displacement transformation coefficient corresponding to the section.

[0010] Further, the completed flap with strain gage pasted is installed on the calibration bench, the flap is in cantilever state, the root chord line is horizontal, and the root angle of attack of the flap in the total pitch state is 0°. A displacement sensor or a camera is arranged at the tip of the flap to measure the flap tip displacement.

[0011] Further, S2, specifically:

[0012] Calibration is started from the root Z1 section, the flap load is applied at the Z2 section, and the conversion coefficient K1 of the flap tip displacement L1 and the flap strain response ε1 at the Z1 section is measured, K1=L1 / ε1.

[0013] Further, S2, specifically:

[0014] The flap load is applied at the Z3 section, and the flap tip displacement L2 and the flap strain responses ε 21 、ε 22 at the Z1 and Z2 sections are measured.

[0015] The flap tip displacement L2 is composed of the flap tip displacement L 21 mapped by the flap strain response ε 21 at the Z1 section and the flap tip displacement L 22 mapped by the flap strain response ε 22 at the Z2 section. Therefore, according to the change relationship between the strain response at the Z1 section and the flap tip displacement, the change relationship K2 between the flap strain response at the Z2 section and the flap tip displacement is expressed as K2=(L2-K1×ε 21 ) / ε 22 .

[0016] Further, S2, specifically:

[0017] When calibrating the strain displacement conversion coefficient at the Zi section, the flap load is applied at the Zi+1 section, and the flap tip displacement L i and the flap strain responses ε i1 、ε i2 、......、ε ii at the Z1 to Zi sections are measured.

[0018] The flap tip displacement L i is composed of the flap tip displacements L i1 、L i2 、......、L ii mapped by the flap strain responses at the Z1 to Zi sections, i.e., the flap tip displacement L i1 mapped by the strain ε i1 at the Z1 section is L i1 =K1*ε i2Mapped tip displacement L i2 =K2*ε i2 , and so on, Zi-1 section strain ε i(i-1) Mapped tip displacement L i(i-1) =K i-1 *ε i(i-1) ;

[0019] The conversion coefficient Ki between the flapping strain response of the Zi section and its mapped blade tip displacement is expressed as

[0020] Furthermore, S2 is specifically:

[0021] When calibrating the strain-displacement conversion coefficient of the nth section, a flapping load is applied at any position between the Zn section and the blade tip section, and the flapping strain ε of the Z1 to Zn section is measured. n1 , ε n2 、......、ε nn The flapping displacement of the blade tip section is L n ;

[0022] The blade tip flapping displacement L n The blade tip flapping displacement L is mapped by the flapping strain from Z1 to Zn section n1 , L n2 、......、L nn Composition, that is, Z1 section strain ε i1 Mapped tip displacement L n1 =K1*ε n1 、Z2 section strain ε n2 Mapped tip displacement L n2 =K2*ε n2 , and so on, Zn-1 profile strain ε n(n-1) Mapped tip displacement L n(n-1) =K n-1 *ε n(n-1) ;

[0023] The conversion coefficient Kn of the Zn profile flapping strain response and its mapped blade tip displacement is expressed as

[0024] Furthermore, S3 is specifically:

[0025] The blade tip flapping displacement L is represented by a one-dimensional matrix of flapping strain responses [ε1, ε2, ..., ε n ] and the one-dimensional matrix of the tip displacement transformation coefficients relative to the profile [K1, K2, ..., K n ] is obtained by the dot product, L=K1×ε1+K2×ε2+...+K n ×ε n .

[0026] Further, the flapwise loading in S2 adopts five-stage load loading.

[0027] The present application proposes a method of calibration from the root and segmented loading, which can clearly calibrate the strain deflection from the root to the blade tip, solves the problem of accurate measurement of the blade tip flapwise displacement, and can also be used for measurement of other strains. The method of the present application has been verified by hovering and wind tunnel test of a 4-meter-diameter bearingless model rotor, and the maximum dynamic measurement range of the blade tip flapwise displacement reaches 86mm. The accuracy comparison is performed between the maximum orientation of the flapwise displacement and the image recognition of the blade tip displacement, and the deviation is not more than 2mm. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The segmented integral calibration principle for the present application. DETAILED DESCRIPTION

[0029] The technical solutions of the present application will be described in detail below with reference to the drawings.

[0030] The present application provides a blade tip displacement measurement method based on multi-section segmented integral calibration, as shown in the formula (1). Figure 1 As shown in the formula (1), n strain gauges are pasted on the target blade, and the i-th section is defined as Zi, wherein the first section is the root section Z1. The blade tip flapwise displacement is calibrated from the section Z1, and each section Zi is sequentially calibrated along the spanwise direction.

[0031] Further, the blade with the pasted flapwise strain gauges is installed on the calibration bench, the blade is in a cantilever beam state, and the root chord line is horizontal. The root angle of attack of the blade in the total distance state is controlled. A displacement sensor or a camera is arranged at the blade tip to measure the flapwise displacement of the blade tip

[0032] Further, the calibration is started from the root section Z1, the flapwise load is loaded at the section Z2, and the transformation relationship K1 of the flapwise strain response ε1 of the section Z1 and the blade tip flapwise displacement L1 is measured, i.e. K1=L1 / ε1.

[0033] Further, the flapwise load is loaded at the section Z3, and the flapwise strain responses ε 21 and ε 22 of the sections Z1 and Z2 are measured, and the blade tip flapwise displacement L2 is obtained. The present application considers that the blade tip flapwise displacement L2 is the blade tip flapwise displacement L 21 mapped by the flapwise strain response ε 21 of the section Z1 and the blade tip flapwise displacement L 22 mapped by the flapwise strain response ε 22Therefore, combined with the variation relationship between the strain response of the Z1 section and the blade tip flapping displacement in the previous step, the variation relationship K2 between the strain response of the Z2 section and the blade tip flapping displacement can be expressed as K2 = (L2-K1×ε 21 ) / ε 22 ;

[0034] Furthermore, when calibrating the strain / displacement conversion coefficient of the Zi section, a flapping load is applied to the Zi+1 section, and the flapping strain ε from the Z1 to Zi section is measured. i1 , ε i2 、......、ε ii The flapping displacement of the blade tip section is L i The present invention considers that the blade tip flapping displacement L i The blade tip flapping displacement L is mapped by the flapping strain from Z1 to Zi section i1 , L i2 、......、L ii Composition, that is, Z1 section strain ε i1 Mapped tip displacement L i1 =K1*ε i1 、Z2 section strain ε i2 Mapped tip displacement L i2 =K2*ε i2 , and so on, Zi-1 section strain ε i(i-1) Mapped tip displacement L i(i-1) =K i-1 *ε i(i-1) Therefore, the transformation relationship Ki between the flapping strain response of the Zi profile and its mapped blade tip displacement can be expressed as

[0035] Furthermore, when calibrating the strain / displacement conversion coefficient of the nth section, flapping loading is performed at any position between the Zn section and the blade tip section, and the flapping strain ε of the Z1 to Zn section is measured. n1 , ε n2 、......、ε nn The flapping displacement of the blade tip section is L n The present invention considers that the blade tip flapping displacement L n The blade tip flapping displacement L is mapped by the flapping strain from Z1 to Zn section n1 , L n2 、......、L nn Composition, that is, Z1 section strain ε i1 Mapped tip displacement L n1 =K1*ε n1 、Z2 section strain ε n2 Mapped tip displacement L n2 =K2*ε n2Similarly, the Zn-1 profile strain ε n(n-1) The mapped tip displacement L n(n-1) = K n-1 * ε n(n-1) Therefore, the transformation relationship Kn between the Zn profile heave strain response and its mapped tip displacement can be expressed as

[0036] Further, the tip heave displacement L is obtained by the dot product of the one-dimensional matrix of the heave strain response [ε1, ε2,.... ε n ] of n profiles and the one-dimensional matrix of the profile transformation coefficients relative to the tip displacement [K1, K2,.... K n ], L = K1 x ε1 + K2 x ε2 +... + K n x ε n .

Claims

1. A method for measuring displacement of a tip of a blade based on multi-profile segmented integration calibration, characterized by, The method comprises: S1, selecting n profile strain gauges on the target blade, the i-th profile is defined as Zi, wherein the first profile is the root profile Z1; S2, from the profile Z1 starting tip oscillation displacement calibration, along the span to each profile Z1 in turn for cumulative calibration, get Z1 profile oscillation strain response The transformation coefficient K of the tip displacement mapped thereto i ; S3, a one-dimensional matrix of tip-paddle oscillation displacement L responses to the n-sectioned oscillation strain a one-dimensional matrix of tip displacement transformation coefficients corresponding to the sections is obtained.

2. The method of claim 1, wherein, The blade with completed edgewise strain gauge pasting is installed on a calibration bench, the blade is in a cantilever beam state, the root clamp of the blade is rotated so that the included angle between the root chord line and the horizontal line is 0°, the root angle of attack of the blade in the total pitch state is controlled, and a displacement sensor or a camera is arranged at the blade tip to measure the edgewise displacement of the blade tip.

3. The method of claim 2, wherein, S2, specifically: Calibration starts from root section Z1 profile, with flapwise load applied at Z2 profile, measuring flapwise strain response at Z1 profile with the tip flapwise displacement the transformation coefficient K1, .

4. The method of claim 2, wherein, S2, specifically: The flapwise loading was applied at Z3 section, and the flapwise strain responses of Z1 and Z2 sections were measured with the tip flapwise displacement ; the tip-pitch displacement is mapped from the Z1 profile tip-pitch displacement the tip-pitch displacement and the Z2 profile tip-pitch displacement the tip-pitch displacement compositions, therefore, according to the change relationship of the Z1 profile tip-pitch displacement and the Z2 profile tip-pitch displacement K2 is expressed as .

5. The method of claim 2, wherein, S2, specifically: When calibrating the strain-displacement transformation coefficient of the Zi profile, the flapwise load is applied on the Zi+1 profile, and the flapwise strain of the Z1 to Zi profiles is measured The flapwise displacement of the tip profile is ; the tip-pitch displacement is the tip-pitch displacement mapped by the tip-pitch strain of the profile Zi , i.e. the tip-pitch strain of the profile Z1 mapped by the tip-pitch displacement of the profile Z1 , the tip-pitch strain of the profile Z2 mapped by the tip-pitch displacement of the profile Z2 , and so on, the tip-pitch strain of the profile Zi-1 mapped by the tip-pitch displacement of the profile Zi-1 ; Zi profile flapwise strain response and its mapped transformation coefficient K of tip displacement i is represented as .

6. The method of claim 2, wherein, S2, specifically: When calibrating the strain-displacement conversion coefficient of the nth profile, the flapwise load is applied at any position between the Zn profile and the tip profile, and the flapwise strain of the Z1 to Zn profiles is measured The flapwise displacement of the tip profile is ; the tip-pitch displacement is the tip-pitch displacement mapped from the tip-pitch strain of the profile Z1 to Zn , i.e. the tip-pitch strain of the profile Z1 mapped to the tip-pitch displacement , the tip-pitch strain of the profile Z2 mapped to the tip-pitch displacement , and so on, the tip-pitch strain of the profile Zn-1 mapped to the tip-pitch displacement ; Zn profile flapping strain response and its mapped transformation coefficient K of the tip displacement of the paddle n is represented as .

7. The method of claim 2, wherein the method is a multi-profile segmented integration tip displacement measurement method. S3, specifically: L, the tip heave displacement, is obtained by the dot product of a one-dimensional matrix of heave strain responses comprising n sections a one-dimensional matrix of tip displacement transformation coefficients with respect to the section .​ 8. A multi-profile segmented integration calibration based tip displacement measurement method according to any one of claims 2-6, characterized in that, The edgewise loading in S2 adopts five-stage load loading.

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