An ACF rotor trailing edge flap and its aerodynamic load stiffness test method

Abstract

The present application provides an ACF rotor trailing edge flap and its aerodynamic load stiffness test method, the method comprising: step 1: performing a displacement test on a rhombus piezoelectric actuator in a clamped-free state to obtain a voltage signal Δsg free (pk‑pk) and the output displacement of the driver output #imgabs0#Step 2: Perform output force and displacement tests on the diamond piezoelectric actuator in the clamped-clamped state to obtain the output displacement of the driver output #imgabs1# and the output force of the driver #imgabs2#. Calculate the blocking force of the driver #imgabs3#Step 3: Perform a stacked strain voltage test on the diamond piezoelectric actuator in the clamped-clamped state to obtain the voltage signal Δsg of the strain sensor block (pk‑pk); Step 4: Test the ACF rotor blades in a non-rotating state and calculate the spring load stiffness k of the drive unit flap ; Step 5: Test the ACF rotor blades in the rotating state to obtain the external load stiffness k of the driver load ; Step 6: According to the spring external load stiffness k of the driving device flap and the actuator external load stiffness k load , calculate the aerodynamic external load stiffness k of the trailing edge flap in the rotor rotating state aero .

Description

Technical Field

[0001] The invention belongs to the field of rotor test and testing, and in particular relates to an ACF rotor trailing edge flap and an aerodynamic load stiffness testing method thereof. Background Art

[0002] The calculation of rotor loads has always been a key focus of rotor dynamics research. Due to the complexity of the aerodynamic characteristics of rotor blades, errors in rotor load calculations are generally large. Current engineering practices primarily test the flapping, shimmying, and torsional bending moments of a specific blade section by attaching strain gauges to the blades. For ACF rotors, the aerodynamic loads of the trailing edge flaps are a key input to ACF blade design. The gap between the trailing edge flap and the main blade complicates the aerodynamics near the flaps, making the aerodynamics near the flaps more complex. Consequently, the reliability of the aerodynamic loads calculated using numerical simulations is low.

[0003] Because the trailing edge flap is located at the trailing edge of the blade, its small size and light weight make it impossible to directly measure its aerodynamic external loads while the blade is rotating. Furthermore, due to the limited space within the blade box and the need for high-precision servo control of the trailing edge flap, it is also difficult to insert a force sensor between the trailing edge flap and the actuator to measure the actuator output force. No method for measuring the aerodynamic torque and aerodynamic load stiffness of trailing edge flaps has been found in the published literature. Summary of the Invention

[0004] The present application provides an ACF rotor trailing edge flap and its aerodynamic load stiffness testing method. Through tests such as a rhombus piezoelectric actuator, a rhombus piezoelectric actuator + trailing edge flap drive device, and an ACF rotor rotation test, the aerodynamic load stiffness of the trailing edge flap of the ACF rotor in the rotating state is obtained through testing and analysis. The aerodynamic load stiffness can be used to guide the correction of the calculation results of the numerical simulation model and can be used to guide the improved design of the ACF rotor blades.

[0005] In a first aspect, the present application provides a method for testing the aerodynamic load stiffness of an ACF rotor trailing edge flap, the method comprising:

[0006] Step 1: Perform displacement test on the diamond piezoelectric actuator in the clamped-free state to obtain the peak-to-peak value Δsg of the voltage signal free (pk-pk) and the peak-to-peak value of the output displacement at the driver output

[0007] Step 2: Test the output force and displacement of the diamond piezoelectric actuator and force sensor in the clamped-clamped state to obtain the peak-to-peak value of the output displacement at the output end of the driver. Get the output force f1 of the driver load (pk-pk), the blocking force f1 of the diamond piezoelectric actuator is obtained by calculation block (pk-pk);

[0008] Step 3: Perform a stack strain voltage test on the diamond piezoelectric actuator in the clamped-clamped state to obtain the peak-to-peak value Δsg of the voltage signal of the strain sensor attached to the piezoelectric stack of the diamond piezoelectric actuator. block (pk-pk);

[0009] Step 4: Test the ACF rotor blades in a non-rotating state and calculate the spring stiffness k of the trailing edge flap drive unit. flap ;

[0010] Step 5: Test the ACF rotor blade in a rotating state to obtain the external load stiffness k of the diamond piezoelectric actuator load ;

[0011] Step 6: According to the spring load stiffness k of the trailing edge flap drive device flap and the external load stiffness k of the rhombus piezoelectric actuator load , calculate the aerodynamic external load stiffness k of the trailing edge flap under the current rotor rotation state aero .

[0012] Specifically, step 1 includes:

[0013] Continuously excite the diamond piezoelectric actuator, select the test signal in the stable response section, and obtain the peak-to-peak value Δsg of the voltage signal of the strain sensor attached to the piezoelectric stack of the diamond piezoelectric actuator free (pk-pk), get the peak-to-peak value of the output displacement at the output of the driver

[0014] Specifically, step 2 includes:

[0015] The blocking force of the diamond piezoelectric actuator is calculated using the following formula:

[0016]

[0017] Specifically, step 4 includes:

[0018] Step 41: Continue to excite the diamond-shaped piezoelectric actuator until the trailing edge flap responds stably, and select a signal with a relatively large flapping angular velocity of the trailing edge flap;

[0019] Step 42: Peak-to-Peak Flap Angle of the Diamond-Shaped Piezoelectric Actuator Peak-to-peak value of the piezoelectric stack strain sensor signal Driver output displacement peak-to-peak

[0020] Step 43: According to and Use the following formula to calculate the driver output force f1non (pk-pk):

[0021]

[0022] Step 44: Output force f1 according to the driver non (pk-pk) and output displacement peak-to-peak Using the formula Calculate the stiffness k of the mechanical external load of the spring properties in the trailing edge flap drive relative to the actuator output displacement flap .

[0023] Specifically, step 5 includes:

[0024] Step 51: After the diamond-shaped piezoelectric actuator is continuously excited until the response is stable, a section of the sinusoidal signal with a relatively large flapping angular velocity is selected for analysis based on the angle signal of the trailing edge flap;

[0025] Step 52: Get the peak-to-peak flap angle Peak-to-peak value of the piezoelectric stack strain sensor signal and the peak-to-peak value of the driver output displacement

[0026] Step 53: According to and The peak-to-peak value f1 of the driver output force of a sine signal selected in the current state is calculated using the following formula: rot (pk-pk):

[0027]

[0028] Step 54: The peak-to-peak value f1 of the driver output force of a sine signal selected according to the current state rot (pk-pk), using the formula The external load stiffness k of the diamond piezoelectric actuator is calculated load .

[0029] Specifically, step 6 includes:

[0030] Step 61: Calculate the moment of inertia of the trailing edge flap k J , where J is the moment of inertia of the trailing edge flap, and r is the lever arm of the actuator driving the trailing edge flap to deflect;

[0031] Step 62: The mechanical spring load stiffness in the flap device remains unchanged, and the stiffness k of the spring external load of the trailing edge flap drive device is calculated. flap , external load stiffness k of diamond piezoelectric actuator load and the trailing edge flap moment of inertia stiffness k J , using the formula k aero =kload -k flap -k J , calculate the aerodynamic external load stiffness of the trailing edge flap under the current rotor rotation state.

[0032] Specifically, step 61 includes:

[0033] Using the formula Calculate the moment of inertia stiffness k of the trailing edge flap J , where J is the moment of inertia of the trailing edge flap, and r is the lever arm of the actuator driving the trailing edge flap to deflect.

[0034] Specifically, the method is applied to an ACF rotor trailing edge flap. The ACF rotor trailing edge flap is provided with a rhombus piezoelectric actuator for driving the trailing edge flap device; a strain gauge is attached to the piezoelectric stack of the rhombus piezoelectric actuator for measuring the deformation of the stack; and the trailing edge flap is provided with an angle sensor for measuring the flapping angle of the flap.

[0035] In a second aspect, the present application provides an ACF rotor trailing edge flap, which is implemented using the above-mentioned ACF rotor trailing edge flap aerodynamic load stiffness testing method.

[0036] The present invention proposes a method for testing the aerodynamic load stiffness of a trailing edge flap. Specifically, the method comprises: determining the relationship between the actuator output force, the piezoelectric stack strain voltage, and the trailing edge flap angle in a rhombus piezoelectric actuator + trailing edge flap drive device through displacement testing under clamped-free boundary conditions, output displacement and output force testing of a rhombus piezoelectric actuator + force sensor under clamped-clamped boundary conditions, and voltage testing of the piezoelectric stack strain gauge of the rhombus piezoelectric actuator under clamped-clamped boundary conditions. The stiffness of the trailing edge flap mechanical structure is then determined by testing under non-rotating ACF rotor conditions. The test data is then analyzed in an ACF rotation test to determine the actuator's external load stiffness and flap's flapping moment of inertia stiffness, ultimately yielding the aerodynamic load stiffness. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic flow chart of an ACF rotor trailing edge flap aerodynamic load stiffness test method provided in this application. DETAILED DESCRIPTION

[0038] The present application provides a method for testing the aerodynamic load stiffness of an ACF rotor trailing edge flap. The method is applied to the ACF rotor trailing edge flap. A diamond-shaped piezoelectric actuator is provided on the ACF rotor trailing edge flap for driving the trailing edge flap device; a strain gauge is attached to the piezoelectric stack of the diamond-shaped piezoelectric actuator for measuring the deformation of the stack; and an angle sensor is provided on the trailing edge flap for measuring the flapping angle.

[0039] like Figure 1 As shown, in order to test and estimate the external load stiffness caused by the aerodynamic load of the trailing edge flap in the rotating state, the present application provides an ACF rotor trailing edge flap aerodynamic load stiffness test method, the method comprising:

[0040] Step 1: Perform displacement test on the diamond piezoelectric actuator in the clamped-free state to obtain the peak-to-peak value Δsg of the voltage signal free (pk-pk) and the peak-to-peak value of the output displacement at the driver output

[0041] Specifically, step 1 includes:

[0042] Continuously excite the diamond piezoelectric actuator, select the test signal in the stable response section, and obtain the peak-to-peak value Δsg of the voltage signal of the strain sensor attached to the piezoelectric stack of the diamond piezoelectric actuator free (pk-pk), get the peak-to-peak value of the output displacement at the output of the driver

[0043] In practical applications, one end of the diamond piezoelectric actuator is clamped and the other end is free. A 1Hz quasi-static sinusoidal voltage signal is applied. The excitation signal is as follows:

[0044] u(t)=Asin(2πt)

[0045] In the above formula, u(t) represents the excitation voltage signal that changes with time, and A is the amplitude of the sinusoidal signal.

[0046] Step 2: Test the output force and displacement of the diamond piezoelectric actuator and force sensor in the clamped-clamped state to obtain the peak-to-peak value of the output displacement at the output end of the driver. Get the output force f1 of the driver load (pk-pk), the blocking force f1 of the diamond piezoelectric actuator is obtained by calculation block (pk-pk);

[0047] Specifically, step 2 includes: calculating the blocking force of the diamond piezoelectric actuator using the following formula:

[0048]

[0049] Connect one end of the diamond piezoelectric actuator to the force sensor, then fix the two ends of the diamond piezoelectric actuator + force sensor, apply the same 1Hz quasi-static sinusoidal voltage signal as in step 1, and continue to excite until the response is stable. Select the test signal in the stable response section to obtain the peak-to-peak value of the output displacement of the driver output end. Get the output force f1 of the driver load (pk-pk).

[0050] Considering the diamond piezoelectric actuator as a spring, the blocking force of the diamond piezoelectric actuator (the output force of the driver when the excitation voltage is applied under the condition that both ends of the driver are fixed) is obtained according to the test results of steps 1 and 2.

[0051] Step 3: Perform a stack strain voltage test on the diamond piezoelectric actuator in the clamped-clamped state to obtain the peak-to-peak value Δsg of the voltage signal of the strain sensor attached to the piezoelectric stack of the diamond piezoelectric actuator. block (pk-pk);

[0052] In practical applications, the two ends of the diamond piezoelectric actuator are fixed, and a 1Hz quasi-static sinusoidal voltage signal is applied as in step 1. The excitation is continued until the response is stable. The test signal in the stable response section is selected to obtain the peak-to-peak value Δsg of the voltage signal of the strain sensor attached to the piezoelectric stack of the diamond piezoelectric actuator. block (pk-pk).

[0053] Step 4: Test the ACF rotor blades in a non-rotating state and calculate the spring stiffness k of the trailing edge flap drive unit. flap ;

[0054] Specifically, step 4 includes:

[0055] Step 41: Continue to excite the diamond-shaped piezoelectric actuator until the trailing edge flap responds stably, and select a signal with a relatively large flapping angular velocity of the trailing edge flap;

[0056] Step 42: Peak-to-Peak Flap Angle of the Diamond-Shaped Piezoelectric Actuator Peak-to-peak value of the piezoelectric stack strain sensor signal Driver output displacement peak-to-peak

[0057] Step 43: According to and Use the following formula to calculate the driver output force f1 non (pk-pk):

[0058]

[0059] Step 44: Output force f1 according to the driver non (pk-pk) and output displacement peak-to-peak Using the formula Calculate the stiffness k of the mechanical external load of the spring properties in the trailing edge flap drive relative to the actuator output displacement flap .

[0060] An ACF rotor blade containing a rhombus piezoelectric actuator and trailing-edge flap drive was mounted on a rotor test bench, not rotating, and subjected to a 1Hz quasi-static sinusoidal voltage signal. The external loads on the rhombus piezoelectric actuator primarily consisted of the elastic force of the centrifugal force plate and the friction of the flap bearing. Since the rotor was not rotating, the aerodynamic loads on the flap were negligible. Since the flap flapping frequency was 1Hz, the inertial force of the flap flapping was also negligible. Therefore, the external loads on the actuator in this state can be divided into two categories: spring force related to the actuator's output displacement, and friction force related to the speed of the actuator's output displacement. The load stiffness associated with the spring force is generally determined by the material's elastic modulus and torsional modulus, and remains constant whether the rotor is rotating or not. However, friction forces, such as those associated with the bearing, are speed-dependent and can be considered constant when the speed exceeds a certain threshold.

[0061] In summary, a 1Hz quasi-static sinusoidal voltage signal is applied as follows:

[0062] u(t)=Bsin(2πt)

[0063] Continue to excite until the trailing edge flap responds steadily, select the signal where the trailing edge flap flapping angular velocity is relatively large, that is, the friction force is almost unchanged, and obtain the peak-to-peak value of the flap flapping angle Peak-to-peak value of the piezoelectric stack strain sensor signal According to the calibration relationship between the trailing edge flap flap angle and the driver output displacement, the corresponding driver output displacement peak-to-peak value is obtained. Then the peak-to-peak value of the driver output force of a signal selected in the current state is obtained.

[0064] Step 5: Test the ACF rotor blade in a rotating state to obtain the external load stiffness k of the diamond piezoelectric actuator load ;

[0065] Specifically, step 5 includes:

[0066] Step 51: After the diamond-shaped piezoelectric actuator is continuously excited until the response is stable, a section of the sinusoidal signal with a relatively large flapping angular velocity is selected for analysis based on the angle signal of the trailing edge flap;

[0067] Step 52: Get the peak-to-peak flap angle Peak-to-peak value of the piezoelectric stack strain sensor signal and the peak-to-peak value of the driver output displacement

[0068] Step 53: According to and The peak-to-peak value f1 of the driver output force of a sine signal selected in the current state is calculated using the following formula: rot (pk-pk):

[0069]

[0070] Step 54: The peak-to-peak value f1 of the driver output force of a sine signal selected according to the current state rot (pk-pk), using the formula The external load stiffness k of the diamond piezoelectric actuator is calculated load .

[0071] In practical applications, when the ACF rotor is rotating, hovering, or in forward flight, an excitation voltage is applied to the trailing edge flaps to meet the requirements of vibration reduction, noise reduction, and other functions, such as a sinusoidal excitation voltage at the rotor frequency Nb / rev, as shown below:

[0072]

[0073] It should be noted that for the diamond piezoelectric actuator, the external load includes the spring load of the trailing edge flap mechanism, the aerodynamic load of the trailing edge flap, the friction load in the mechanism, and the non-negligible rotational inertia of the trailing edge flap. After the response stabilizes, according to the angle signal of the trailing edge flap, a section of the sinusoidal signal with a relatively large flapping angular velocity and almost constant friction is selected for analysis to obtain the peak-to-peak value of the flap flap angle. Peak-to-peak value of the piezoelectric stack strain sensor signal According to the calibration relationship between the trailing edge flap flap angle and the driver output displacement, the corresponding driver output displacement peak-to-peak value is obtained.

[0074] Step 6: According to the spring load stiffness k of the trailing edge flap drive device flap and the external load stiffness k of the rhombus piezoelectric actuator load , calculate the aerodynamic external load stiffness k of the trailing edge flap under the current rotor rotation state aero .

[0075] Specifically, step 6 includes:

[0076] Step 61: Using the formula Calculate the moment of inertia stiffness k of the trailing edge flap J , where J is the moment of inertia of the trailing edge flap, and r is the lever arm of the actuator driving the trailing edge flap to deflect;

[0077] Step 62: The mechanical spring load stiffness in the flap device remains unchanged, and the stiffness k of the spring external load of the trailing edge flap drive device is calculated. flap , external load stiffness k of diamond piezoelectric actuator load and the trailing edge flap moment of inertia stiffness k J , using the formula k aero =k load -k flap -kJ , calculate the aerodynamic external load stiffness of the trailing edge flap under the current rotor rotation state.

[0078] In addition, the present application provides an ACF rotor trailing edge flap, which is implemented using the above-mentioned ACF rotor trailing edge flap aerodynamic load stiffness testing method.

[0079] In summary, the present invention proposes a method for testing the aerodynamic load stiffness of the trailing edge flap. Through tests such as a rhombus piezoelectric actuator, a rhombus piezoelectric actuator + a trailing edge flap drive device, and an ACF rotor rotation test, the aerodynamic load stiffness of the trailing edge flap in the rotating state of the ACF rotor is tested and analyzed, which can be used to guide the correction of the calculation results of the numerical simulation model and can be used to guide the improved design of the ACF rotor blades.

Claims

1. A method for testing the aerodynamic load stiffness of an ACF rotor trailing edge flap, characterized in that: The method comprises: Step 1: Perform displacement test on the diamond piezoelectric actuator in the clamped-free state to obtain the peak-to-peak value Δsg of the voltage signal free (pk-pk) and the peak-to-peak value of the output displacement at the driver output Step 2: Test the output force and displacement of the diamond piezoelectric actuator and force sensor in the clamped-clamped state to obtain the peak-to-peak value of the output displacement at the output end of the driver. Get the output force f1 of the driver load (pk-pk), the blocking force f1 of the diamond piezoelectric actuator is obtained by calculation block (pk-pk); Step 3: Perform a stack strain voltage test on the diamond piezoelectric actuator in the clamped-clamped state to obtain the peak-to-peak value Δsg of the voltage signal of the strain sensor attached to the piezoelectric stack of the diamond piezoelectric actuator. block (pk-pk); Step 4: Test the ACF rotor blades in a non-rotating state and calculate the spring stiffness k of the trailing edge flap drive unit. flap ; Step 5: Test the ACF rotor blade in a rotating state to obtain the external load stiffness k of the diamond piezoelectric actuator load ; Step 6: According to the spring load stiffness k of the trailing edge flap drive device flap and the external load stiffness k of the rhombus piezoelectric actuator load , calculate the aerodynamic external load stiffness k of the trailing edge flap under the current rotor rotation state aero .

2. The method according to claim 1, characterized in that Step 1 includes: Continuously excite the diamond piezoelectric actuator, select the test signal in the stable response section, and obtain the peak-to-peak value Δsg of the voltage signal of the strain sensor attached to the piezoelectric stack of the diamond piezoelectric actuator free (pk-pk), get the peak-to-peak value of the output displacement at the output of the driver 3. The method according to claim 1, characterized in that Step 2 includes: The blocking force of the diamond piezoelectric actuator is calculated using the following formula:

4. The method according to claim 1, wherein Step 4 includes: Step 41: Continue to excite the diamond-shaped piezoelectric actuator until the trailing edge flap responds stably, and select a signal with a relatively large flapping angular velocity of the trailing edge flap; Step 42: Peak-to-Peak Flap Angle of the Diamond-Shaped Piezoelectric Actuator Peak-to-peak value of the piezoelectric stack strain sensor signal Driver output displacement peak-to-peak Step 43: According to and Use the following formula to calculate the driver output force f1 non (pk-pk): Step 44: Output force f1 according to the driver non (pk-pk) and output displacement peak-to-peak Using the formula Calculate the stiffness k of the mechanical external load of the spring properties in the trailing edge flap drive relative to the actuator output displacement flap .

5. The method according to claim 1, wherein Step 5 includes: Step 51: After the diamond-shaped piezoelectric actuator is continuously excited until the response is stable, a section of the sinusoidal signal with a relatively large flapping angular velocity is selected for analysis based on the angle signal of the trailing edge flap; Step 52: Get the peak-to-peak flap angle Peak-to-peak value of the piezoelectric stack strain sensor signal and the peak-to-peak value of the driver output displacement Step 53: According to and The peak-to-peak value f1 of the driver output force of a sine signal selected in the current state is calculated using the following formula: rot (pk-pk): Step 54: The peak-to-peak value f1 of the driver output force of a sine signal selected according to the current state rot (pk-pk), using the formula The external load stiffness k of the diamond piezoelectric actuator is calculated load .

6. The method according to claim 1, wherein Step 6 includes: Step 61: Calculate the moment of inertia of the trailing edge flap k J , where J is the moment of inertia of the trailing edge flap, and r is the lever arm of the actuator driving the trailing edge flap to deflect; Step 62: The mechanical spring load stiffness in the flap device remains unchanged, and the stiffness k of the spring external load of the trailing edge flap drive device is calculated. flap , the external load stiffness k of the diamond piezoelectric actuator load and the trailing edge flap moment of inertia stiffness k J , using the formula k aero =k load -k flap -k J , calculate the aerodynamic external load stiffness of the trailing edge flap under the current rotor rotation state.

7. The method according to claim 6, characterized in that Step 61 specifically includes: Using the formula Calculate the moment of inertia stiffness k of the trailing edge flap J , where J is the moment of inertia of the trailing edge flap, and r is the lever arm of the actuator driving the trailing edge flap to deflect.

8. The method according to claim 1, characterized in that The method is applied to an ACF rotor trailing edge flap. The ACF rotor trailing edge flap is provided with a rhombus piezoelectric actuator for driving the trailing edge flap device; a strain gauge is attached to the piezoelectric stack of the rhombus piezoelectric actuator for measuring the deformation of the stack; and the trailing edge flap is provided with an angle sensor for measuring the flapping angle.

9. An ACF rotor trailing edge flap, characterized in that: The ACF rotor trailing edge flap is realized by using the ACF rotor trailing edge flap aerodynamic load stiffness testing method according to any one of claims 1 to 8.

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