A decoupling patch method for oscillatory load test of a helicopter main blade airfoil section

Abstract

The application provides a decoupling patch method for a helicopter main blade airfoil section oscillation load test, which comprises the following steps: obtaining a profile position of the oscillation load measurement; sticking a strain gauge on the upper surface of the main blade at a distance from the leading edge of the main blade; sticking a strain gauge on the lower surface of the main blade at a distance from the leading edge of the main blade; sticking a strain gauge on the lower surface of the main blade at a distance from the trailing edge of the main blade; measuring the vertical distance from the strain gauge to the chord line of the main blade; selecting a proper position on the upper surface of the trailing edge of the main blade so that the distance from the position to the chord line is obtained; sticking a strain gauge at the position as the center; sticking a strain gauge on the left and right of the strain gauge; then measuring the strain gauge flapping response output; and determining whether the decoupling is successful. The application provides a decoupling patch method for a helicopter main blade airfoil section oscillation load measurement, which is used for decoupling patching of a helicopter main blade airfoil section oscillation load measurement, provides patching guidance for helicopter main blade airfoil section oscillation load measurement test modification, and improves the comprehensive performance of helicopter main blade load test patching modification.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of helicopter flight test load test patch modification, and particularly relates to a decoupling patch method for helicopter main rotor blade airfoil section flutter load test. BACKGROUND

[0002] The helicopter has the characteristics of vertical take-off and landing and strong maneuverability, and is extremely suitable for flight working conditions such as low altitude, low speed and fixed point operation. At present, the helicopter has been widely used in ground reconnaissance / attack, surprise landing, weapon delivery, short-distance transportation of logistics support guarantee, medical rescue, disaster relief and lifesaving, geological exploration, equipment hoisting and forest protection and fire extinguishing. The main rotor system is the only source of lift of the helicopter and is one of the most important system components of the helicopter. In the flight state, the flapping motion, flutter motion and torsional motion of the main rotor blade are important forms of representation of the motion characteristics of the main rotor system. Therefore, in the process of developing the helicopter, the main rotor blade flapping, flutter and torsional load under various real working conditions must be obtained through flight test, which is used for helicopter rotor system dynamics analysis, strength design and life evaluation.

[0003] The helicopter main rotor blade load measurement is a key test technology for helicopter load test flight, and how to quickly complete the patching, decoupling and calibration of the main rotor blade test piece is particularly important for helicopter main rotor system flight load test. At present, the main rotor blade airfoil section flutter measurement decoupling work is mainly completed by sticking a large number of strain gauges on the main rotor blade in a uniform manner, and the appropriate strain gauge sticking position is determined by decoupling measurement selection. However, this method needs to stick a large number of strain gauges, occupies human resources and has low comprehensive efficiency. SUMMARY

[0004] In order to solve the problems of needing to stick a large number of strain gauges, occupying human resources and low comprehensive efficiency in decoupling patching in the related art, the application provides a main rotor blade airfoil section flutter load measurement decoupling patching method for helicopter main rotor blade airfoil section flutter load measurement decoupling patching, provides patching guidance for helicopter main rotor blade airfoil section flutter load measurement test modification, and improves the comprehensive efficiency of helicopter main rotor blade load test patch modification. The technical solution is as follows:

[0005] In the first aspect, a main rotor blade airfoil section flutter load test decoupling patching method is provided, and the method comprises the following steps:

[0006] Step 1: According to the helicopter main rotor blade airfoil section flutter measurement requirement, the profile position of the flutter load measurement is obtained;

[0007] Step 2: Stick a strain gauge R1 on the upper surface of the main rotor blade at a certain distance from the leading edge of the main rotor blade;

[0008] Step three: paste a strain gauge R2 on the lower surface of the main blade at a certain distance from the leading edge of the main blade;

[0009] Step four: paste a strain gauge R3 on the lower surface of the main blade at a certain distance from the trailing edge of the main blade;

[0010] Step five: measure the vertical distances L1, L2, L3 from the strain gauges R1, R2, R3 to the chord line of the main blade of the helicopter, respectively, from the profile of the oscillation measurement surface of the main blade of the helicopter in the digital model, and the chord line of the main blade of the helicopter is the line connecting the frontmost end of the leading edge and the rearmost end of the trailing edge of the main blade of the helicopter;

[0011] Step six: select a suitable position on the upper surface of the trailing edge of the main blade of the helicopter such that the distance L4 from the chord line is L1+L3-L2, and paste a strain gauge R5 at the center of the position;

[0012] Step seven: paste a strain gauge R4 and a strain gauge R6 at a certain distance to the left and right of the strain gauge R5, respectively;

[0013] Step eight: install the main blade of the helicopter on the calibration platform, and measure the flap response outputs ΔR1, ΔR2, ΔR3, ΔR4, ΔR5, ΔR6 of the strain gauges R1, R2, R3, R4, R5, R6 under flap loading on the profile;

[0014] Step nine: under the same flap loading, calculate the strain relationships of ΔR1, ΔR2, ΔR3, ΔR4, ΔR5, ΔR6 such that ΔR=ΔR1+ΔR3-ΔR2-ΔRC,

[0015] wherein ΔRC is ΔR4, ΔR5, ΔR6, and three ΔRs are obtained in the step nine;

[0016] Step ten: when one of the ΔRs is less than ±100 micro-strains, it is determined that the decoupling is successful.

[0017] Further, the method further comprises:

[0018] Step eleven: when the three ΔRs are not less than ±100 micro-strains, according to the true value of each ΔR, a strain gauge RX is additionally pasted for supplementary decoupling; steps eight, nine, and ten are repeated, and if the ΔR corresponding to the strain gauge RX is less than ±100 micro-strains, the decoupling is successful.

[0019] Further, the method further comprises:

[0020] Step twelve: if the added RX still cannot make the ΔR corresponding thereto less than ±100 micro-strains, the strain gauge pasting rule in step eleven is continued to be followed, and the strain gauge is continued to be pasted until the decoupling is successful.

[0021] The present application carries out graphical processing on the main blade airfoil section of the helicopter, and the connecting line of the blade leading edge and trailing edge is approximated as the rigidity center surface of the blade. The strain response of different patch positions on the blade surface is approximately proportional to the distance from the rigidity center surface. Through the method, the theoretical decoupling patch position can be provided for the blade flutter measurement patch. Compared with the traditional method, the number of strain patches can be greatly reduced, the strain patch material cost is reduced, the human resources are saved, and the work efficiency of the helicopter main blade load patch test modification is effectively improved.

[0022] In the step eleven, the rule for supplementally pasting the strain patch is that when ΔR is greater than 100 micro-strain, RX is pasted at a certain distance from the strain patch R6 towards the trailing edge of the main blade; and when ΔR is less than -100 micro-strain, RX is pasted at a certain distance from the strain patch R4 towards the leading edge of the main blade.

[0023] In the step two, the distance between the strain patch pasting position and the ironed edge is 20-40 mm.

[0024] In the step three, the distance between the strain patch pasting position and the ironed edge is 20-40 mm.

[0025] In the step four, the distance between the strain patch pasting position and the trailing edge of the main blade is 40-60 mm.

[0026] In the step seven, a strain patch R4 is pasted at the left 20-30 mm of the strain patch R5; and a strain patch R6 is pasted at the right 20-30 mm of the strain patch R5.

[0027] In the step eleven, when the strain patch RX is pasted, the flap loading response R4, R5, R6 of the strain patches R4, R5, R6 and the distance L from the strain patches R4, R5, R6 to the trailing edge of the main blade are subjected to second-order polynomial fitting as the theoretical value of the flap response of the supplementally pasted strain patch, so as to determine the compensation strain patch pasting position.

[0028] The present application has at least the following beneficial effects:

[0029] The present application can be used as a guide for the decoupling patch work of the main blade flutter measurement of the helicopter flight test. Compared with the traditional method, the number of strain patches can be greatly reduced, the strain patch material cost is reduced, the human resources are saved, and the work efficiency of the helicopter main blade load patch test modification is effectively improved. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 It is a schematic diagram of the blade airfoil section and patch position of the present application. DETAILED DESCRIPTION

[0031] The application will be further described in detail below with specific embodiments and drawings.

[0032] The application will be further described in detail below with specific embodiments and drawings.

[0033] The application can provide a reference for the position of the oscillation load measurement decoupling patch of the main blade airfoil section with theoretical support, reduce the number of strain patches, save manpower and material resources, and greatly improve the work efficiency of the helicopter main blade airfoil section load test modification patch.

[0034] Referring to Figure 1 The application provides a helicopter main blade airfoil section oscillation load test decoupling patch method, comprising the following steps:

[0035] Step one: according to the oscillation measurement requirements of the helicopter main blade airfoil section, the profile position of the oscillation load measurement is obtained.

[0036] Step two: a strain patch R1 is pasted on the upper surface of the main blade at a certain distance from the leading edge of the main blade.

[0037] Step three: a strain patch R2 is pasted on the lower surface of the main blade at a certain distance from the leading edge of the main blade.

[0038] Step four: a strain patch R3 is pasted on the lower surface of the main blade at a certain distance from the trailing edge of the main blade.

[0039] Step five: the profile of the helicopter main blade oscillation measurement surface is cut from the digital model, and the vertical distances L1, L2, and L3 of the strain patches R1, R2, and R3 to the chord line (usually the line connecting the frontmost end of the leading edge of the main blade and the rearmost end of the trailing edge) are measured, and the specific measurement positions are as shown in Figure 1

[0040] Step six: a suitable position is selected on the upper surface of the trailing edge of the main blade, so that the distance L4 of the point to the chord line is L1+L3-L2 (formula 1), and a strain patch R5 is pasted at the center of the position.

[0041] Step seven: a strain patch R4 and a strain patch R6 are pasted at a certain distance to the left and right of the strain patch R5 respectively; the distance between the strain patches R4, R6 and the center position of the strain patch R5 is 20-30mm.

[0042] ​Step eight: install the main rotor blade on the calibration platform, and apply a flap load on the profile, and measure the flap response output AR1, AR2, AR3, AR4, AR5, AR6 of the strain gauges R1, R2, R3, R4, R5, R6;

[0043] Step nine: under the same flap load, calculate the strain relationship of AR1, AR2, AR3, AR4, AR5, AR6, so that AR = AR1 + AR3 - AR2 - ARC (formula 2), wherein ARC is AR4, AR5, AR6.

[0044] Step ten: when AR is less than ±100 micro-strain, it is determined that the decoupling is successful.

[0045] In another embodiment, the method of the present application can include the following steps in addition to the above-mentioned steps one to ten:

[0046] Step eleven: if AR4, AR5, AR6 cannot make AR less than ±100 micro-strain when substituted into formula 2, according to the true value of AR, a strain gauge RX is additionally pasted for supplementary decoupling (supplementary pasting strain gauge rule: when AR is greater than 100 micro-strain, RX can be pasted at a certain distance from strain gauge R6 towards the trailing edge of the main rotor blade. When AR is less than -100 micro-strain, RX can be pasted at a certain distance from strain gauge R4 towards the leading edge of the main rotor blade). Repeat steps eight, nine, and ten, and if AR is less than ±100 micro-strain, the decoupling is successful.

[0047] In step eleven, when selecting the pasting position of strain gauge RX, the flap load response AR4, AR5, AR6 of strain gauges R4, R5, R6 and the distance L (defined as shown in Figure 1 ) from each strain gauge (R4, R5, R6) to the trailing edge of the main rotor blade can be substituted into AR(L) = aL 2 +bL+c to calculate a, b, c, and the L value corresponding to AR(L) = 0 is taken as the pasting position of the supplementary pasting strain gauge RX.

[0048] Step twelve: if the added RX still cannot make AR less than ±100 micro-strain, continue to paste the strain gauge according to the supplementary pasting strain gauge rule described in step eleven until the decoupling is successful.

[0049] For example, the present application provides a method for testing and decoupling the oscillation load of a helicopter main rotor blade airfoil section, comprising the following steps:

[0050] Step one: according to the oscillation measurement requirements of the helicopter main rotor blade airfoil section, obtain the profile position for oscillation load measurement;

[0051] Step two: as shown in Figure 1As shown, a strain gauge R1 is pasted on the main blade upper surface at a distance from the main blade leading edge iron edge.

[0052] Step three: as shown in the figure, Figure 1 A strain gauge R2 is pasted on the main blade lower surface at a distance from the main blade leading edge iron edge.

[0053] Step four: as shown in the figure, Figure 1 A strain gauge R3 is pasted on the main blade lower surface at a distance from the main blade trailing edge.

[0054] Step five: the profile of the helicopter main blade oscillation measurement surface is cut from the digital model, and the vertical distances L1, L2, L3 of the strain gauges R1, R2, R3 to the chord line (usually the line connecting the frontmost end of the leading edge of the main blade of the helicopter and the last end of the trailing edge) are measured, and the specific measurement positions are shown in the figure, Figure 1

[0055] Step six: a suitable position is selected on the upper surface of the trailing edge of the main blade of the helicopter, so that the distance L4 of the point to the chord line is L1+L3-L2 (formula 1), and a strain gauge R5 is pasted at the center of the position;

[0056] Step seven: a strain gauge R4 and a strain gauge R6 are pasted at a certain distance left and right of the strain gauge R5; in the step seven, the distance between the strain gauges R4, R6 and the center position of the strain gauge R5 is 20mm.

[0057] Step eight: the main blade of the helicopter is installed on the calibration table, and the flap loading is carried out on the profile, and the flap response outputs AR1, AR2, AR3, AR4, AR5, AR6 of the strain gauges R1, R2, R3, R4, R5, R6 are measured.

[0058] Step nine: under the same flap loading condition, the strain relationship of AR1, AR2, AR3, AR4, AR5, AR6 is calculated, so that AR=AR1+AR3-AR2-ARc (formula 2), wherein ARc is the substitution of AR4, AR5, AR6.

[0059] Step ten: AR4, AR5, AR6 are substituted into formula 2, and the result is that the AR corresponding to AR4 is less than ±100 micro-strain, which is determined as decoupling success.

[0060] For another example, the application provides a helicopter main blade airfoil section oscillation load test decoupling patch method, comprising the following steps:

[0061] ​Step one: According to the oscillation measurement requirements of the main rotor blade airfoil section of the helicopter, the profile position of the oscillation load measurement is obtained;

[0062] Step two: As shown in the figure, a strain gauge R1 is pasted on the upper surface of the main rotor blade at a certain distance from the leading edge of the main rotor blade. Figure 1

[0063] Step three: As shown in the figure, a strain gauge R2 is pasted on the lower surface of the main rotor blade at a certain distance from the leading edge of the main rotor blade. Figure 1

[0064] Step four: As shown in the figure, a strain gauge R3 is pasted on the lower surface of the main rotor blade at a certain distance from the trailing edge of the main rotor blade. Figure 1

[0065] Step five: The profile of the oscillation measurement surface of the main rotor blade of the helicopter is cut from the digital model, and the vertical distances L1, L2, L3 of the strain gauges R1, R2, R3 to the chord line (usually the line connecting the frontmost end of the leading edge of the main rotor blade and the rearmost end of the trailing edge) are measured, as shown in the attached figure. Figure 1

[0066] Step six: A suitable position is selected on the upper surface of the trailing edge of the main rotor blade such that the distance L4 of this point to the chord line is L1+L3-L2 (Formula 1), and a strain gauge R5 is pasted at the center of this position.

[0067] Step seven: A strain gauge R4 and a strain gauge R6 are pasted at a certain distance to the left and right of the strain gauge R5, respectively, and the distance between the center positions of the strain gauges R4, R6 and R5 is 30mm.

[0068] Step eight: The main rotor blade of the helicopter is installed on the calibration platform, and the flap loading is performed on the profile, and the flap response outputs AR1, AR2, AR3, AR4, AR5, AR6 of the strain gauges R1, R2, R3, R4, R5, R6 are measured.

[0069] Step nine: Under the same flap loading condition, the strain relationship of AR1, AR2, AR3, AR4, AR5, AR6 is calculated, so that AR=AR1+AR3-AR2-ARC (Formula 2), where ARC is AR4, AR5, AR6.

[0070] ​​​​Step ten: ΔR4, ΔR5, ΔR6 are substituted into formula 2, none of them can make ΔR less than ±100 micro-strain, according to the real value of ΔR, a strain gauge RX is additionally pasted to make up the decoupling. Steps eight, nine and ten are repeated, if ΔR is less than ±100 micro-strain, the decoupling is successful.

[0071] The above only expresses the embodiments of the present application, the description is more specific and detailed, but it cannot be understood as the limitation of the patent scope. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, which all belong to the protection scope of the present application. In addition, the non-exhaustive part of the present application is the routine technology.

Claims

1. A decoupling patch method for testing the tumbling load of a helicopter main rotor blade airfoil section, characterized in that, The method includes: Step 1: According to the requirements for measuring the shimmy of the helicopter main rotor blade airfoil section, obtain the profile position for measuring the shimmy load; Step 2: Attach a strain gauge R1 to the upper surface of the main blade at a certain distance from the edge of the leading edge of the main blade; Step 3: Attach a strain gauge R2 to the lower surface of the main blade at a certain distance from the edge of the leading edge of the main blade's cladding. Step 4: Attach a strain gauge R3 to the lower surface of the main blade at a certain distance from the trailing edge of the blade; Step 5: Extract a cross-sectional view of the helicopter main rotor blade oscillation measurement surface from the digital model, and measure the vertical distances L1, L2, and L3 from the strain gauges R1, R2, and R3 to the chord line of the helicopter main rotor blade. The chord line of the helicopter main rotor blade is the line connecting the foremost leading edge and the last trailing edge of the helicopter main rotor blade. Step 6: Select a suitable position on the upper surface of the trailing edge of the helicopter main rotor blade such that the distance from the suitable position to the chord line is L4 = L1 + L3 - L2, and attach a strain gauge R5 with this position as the center. Step 7: Attach a strain gauge R4 and a strain gauge R6 at a certain distance to the left and right of strain gauge R5; Step 8: Install the helicopter main rotor blades on the calibration platform and apply flapping load to the cross-section. Measure the flapping response output of strain gauges R1, R2, R3, R4, R5, and R6. R1、 R2, R3, R4 R5 R6; Step 9: Under the same swing loading conditions, calculate R1、 R2, R3, R4 R5 The strain relationship of R6 makes R= R1+ R3- R2- RC, in, RC is R4 R5 R6, step nine yields three R; Step 10: When there is one If R is less than ±100 micro-strains, the decoupling can be considered successful.

2. The method according to claim 1, characterized in that, The method further includes: Step 11: When three When R is not less than ±100 micro-strains, according to each The true value of R is obtained by pasting a strain gauge RX to supplement decoupling; steps eight, nine, and ten are repeated. If the strain gauge RX corresponds to... If R is less than ±100 microstrains, then decoupling is successful.

3. The method according to claim 2, characterized in that, The method further includes: Step 12: If the added strain gauge RX still cannot achieve the corresponding If R is less than ±100 micro-strains, continue to add strain gauges according to the rules in step eleven until decoupling is successful.

4. The method according to claim 2, characterized in that, The rule for adding strain gauges in step eleven is: when When R is greater than 100 micro-strain, the strain gauge RX is attached to the strain gauge R6 at a certain distance from the trailing edge of the main blade; when When R is less than -100 micro-strain, attach strain gauge RX to strain gauge R4 at a certain distance from the leading edge of the main blade.

5. The method according to claim 1, characterized in that, In step two, the distance between the strain gauge attachment position and the edge of the cladding iron is 20-40mm.

6. The method according to claim 1, characterized in that, In step three, the distance between the strain gauge attachment position and the edge of the cladding iron is 20-40mm.

7. The method according to claim 1, characterized in that, In step four, the distance between the strain gauge attachment position and the trailing edge of the main blade is 40-60 mm.

8. The method according to claim 1, characterized in that, In step seven, a strain gauge R4 is attached 20-30 mm to the left of strain gauge R5; and a strain gauge R6 is attached 20-30 mm to the right of strain gauge R5.

9. The method according to claim 2, characterized in that, In step eleven, when selecting the mounting position of strain gauge RX, the flapping response of strain gauges R4, R5, and R6 is output. R4 R5 The distances L from strain gauges R6 to the trailing edge of the main blade are fitted with a second-order polynomial to obtain the theoretical values ​​for the flapping response of the supplementary strain gauges, thus determining the bonding position of the compensation strain gauges.

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