Rotation speed signal generation and measurement method with keyphasor function based on tip timing

Abstract

This application belongs to the field of aeroengines, and particularly relates to a method for generating and measuring a rotational speed signal with a keyphasor function based on tip timing. One of the engine blades is made non-reflective, and the remaining Nr−1 blades are made reflective; the sensor receives the reflected light signals when the reflective blades pass by the sensor, converts the reflected light signals into pulse signals, and outputs the pulse signals; the time difference Δt between adjacent pulse signals is obtained; based on the fact that the time difference Δt0 between the pulse signals of the two reflective blades on both sides of the non-reflective blade is greater than the time difference between the pulse signals of two adjacent reflective blades, the positions of the pulse signals Δt0 of the two reflective blades on both sides of the non-reflective blade are judged, and a rotational speed signal with a keyphasor function is output based on the positions of Δt0.

Description

Technical Field

[0001] This application belongs to the field of aero-engines, and particularly relates to a method for generating and measuring rotational speed signals with a keyphasor function based on tip-timing. Background Art

[0002] Vibration testing, pulsating pressure testing, dynamic stress testing, and non-contact rotor component vibration testing of aero-engines are important indicators for evaluating the stable operation safety of aero-engines. The aero-engine monitoring system monitors the engine vibration, structural component vibration, pressure pulsation, and rotational speed of the rotor through sensors installed at multiple parts of the engine. The three elements of a dynamic signal are amplitude, frequency, and phase, and the three together constitute all the characteristics of the signal.

[0003] Currently, during the vibration monitoring of aero-engines, the vibration amplitude and frequency characteristics of the rotor are generally monitored, ignoring the important information of the phase, and losing 33% of the information to some extent. Common causes of engine vibration faults include excessive rotor unbalance, rotor misalignment, rubbing, local resonance, oil accumulation in the rotor cavity, rotor thermal bending, etc. Most of these vibration fault frequency domain characteristics are extremely similar, and they cannot be effectively identified only through spectral characteristics, but there are obvious differences in the phase characteristics. Therefore, the physical meaning reflected by the vibration phase characteristics is significant, especially in the field of enriching the aero-engine vibration fault diagnosis methods.

[0004] According to statistics, rotor unbalance faults of aero-engines account for more than 80% of the vibration faults. Domestic aero-engines mostly use low-speed process balancing methods to control the dynamic unbalance of the rotor in order to suppress the vibration response during the whole-machine test. Most rotors can achieve the purpose of vibration control through this method, but there are still some rotors with excessive dynamic unbalance during the whole-machine test, resulting in a large vibration response of the whole machine. Therefore, it is necessary to adopt the local balancing method to suppress the rotor vibration response as a subsequent supplementary means to the process balancing. During the local balancing process using the influence coefficient method, vibration phase testing is a necessary task and cannot be lacking. The prerequisite for vibration phase testing is the acquisition of a stable rotational speed signal with a keyphasor function. Designing a reasonable rotational speed signal acquisition method with a keyphasor function has important engineering significance.

[0005] In related aero-engine tests such as pulsating pressure testing and non-contact blade vibration testing, to define the rotor blades in a high-speed rotating state, quickly locate the fault position, and analyze the vibration phase continuity between the rotating blades, a rotational speed signal keyphasor reference that is stationary relative to the rotating shaft is required. Designing a reasonable rotational speed signal acquisition method with a keyphasor function has important engineering significance.

[0006] At present, there are mainly two methods for testing the vibration phase of aero-engines. One is to install a magnetic steel sensor on the rotor component. During the rotation of the rotor, the electrical pulse signal generated by the stator component induction coil is used as the key phase reference (as shown in Figure 1 ). It is necessary to install a sensor and an induction coil on the rotor, and a magnetic induction sensor on the adjacent stator. Each time the aero-engine rotates one week, a speed pulse signal is generated. The position of this pulse signal represents the initial position of the rotating shaft every time it rotates one week. The initial position is determined by the physical position of the speed magnetic steel sensor installed on the rotating shaft. The other is to design a "high tooth" or "low tooth" at the speed measurement gear of the engine rotor. When the test gear rotates with the engine rotating shaft, the teeth on the speed measurement gear sequentially rotate and sweep across the eddy current sensor. Since the voltage signal amplitudes generated by the "high tooth" or "low tooth" are different from those of the unmodified ordinary teeth, the speed signal with key phase function is obtained by identifying the voltage amplitude difference and counting the number of signals generated by the speed measurement teeth (as shown in Figure 2 ). The initial pulse signals obtained by both methods need to be further demodulated by the signal conditioner at the back end.

[0007] 1. Technical aspects

[0008] a) For the magnetic steel key phase testing technology installed on the rotating shaft, due to the small volume, poor magnetism, and strong brittleness of the magnetic steel itself, the electrical signal quality induced by the coil is weak. At the same time, affected by the vortex motion of the engine rotor itself, blind spots may occur when the stator coil is far from the pole of the magnetic steel, and the signal is further attenuated, making the back-end conditioning extremely difficult. The effective working time of the magnetic steel sensor is short, the requirements for the working environment are high, and it demagnetizes quickly when heated and cannot work for a long time. Because the cable diameter of the induction coil wound around the stator is very small, it often breaks due to improper installation and vibration fatigue factors during use, and the test success rate is low. Limited by the compact structure of the aero-engine, it is difficult to find enough positions to install the magnetic steel sensor transceiver component. Since installing a sensor on the rotating shaft requires drilling and grooving on the rotating shaft, which damages the rotor structure and reduces the service life of the structural component. The speed pulse generated by the magnetic steel sensor due to induction is affected by the dynamic performance of electromagnetic components, and the response speed is slow. Installing a sensor on the rotating shaft brings risks to the structural safety of the engine.

[0009] b) In the high and low tooth key phase testing technology, due to the influence of the rotor axial force and axial vibration, the speed measuring gear axially moves along with the engine rotating shaft. At different speeds and pneumatic working conditions, the voltage amplitude generated by the speed measuring gear and the eddy current sensor changes unpredictably. It is necessary to continuously change the appropriate threshold trigger voltage to locate the high and low tooth signals, and the test success rate is also relatively low. The axial movement causes the high tooth to rub against the probe of the speed sensor many times, which has an adverse impact on the working state of the hardware and the test results, and the test success rate is also relatively low. Limited by the dynamic characteristics of the eddy current sensor, the speed signal (sine) generated by the eddy current needs to be further conditioned, with a slow response speed. The key phase position has a large test error caused by the processing characteristics of the key phase threshold algorithm, the conditioning time lag characteristics, and the dynamic characteristics of the sensor. There is a speed fluctuation, resulting in a low test success rate.

[0010] 2. In terms of cost

[0011] Adopting the magnetic steel key phase testing technology requires a large number of structural modifications to the rotor and stator of the aeroengine, including: the rotor needs to be drilled at the labyrinth to ensure the installation of the magnetic steel, the stator parts need to be structurally cut to wind the magnetic induction coil, and at the same time, all stator parts along the lead wire path need to be drilled to ensure the lead wire. This damages the shaft structure near the sensor installation structure, resulting in the million-dollar shaft not being reusable or having a reduced service life. In short, the time cost and hardware loss cost of the structural modification are both large.

[0012] The high tooth key phase testing scheme brings the test safety risk of rubbing between the rotating and static parts, with a low test success rate, resulting in additional test and trial run costs due to repeated tests.

[0013] 3. In terms of efficiency

[0014] Existing speed testing schemes with key phase functions all require complex modifications to the rotor structure, and effective maintenance and modification of the modifications cannot be carried out in the assembled state. The processing time of the modified structure is long. When the test fails, only by decomposing the engine off the platform can the modification measures be reinstalled, resulting in low efficiency. Summary of the Invention

[0015] Aiming at the disadvantages of the existing test scheme, such as complex modification, long processing cycle, high cost of structural modification, and complex implementation of the test modification scheme. Combining the structural characteristics of the engine, avoiding structural modification on the rotating shaft and its vicinity, and obtaining the rotational speed signal of the aero-engine with keyphasor function by designing measures such as optical diffuse reflection structures (painting, gluing, frosting) at the tip of the rotor blades and installing fiber optic sensors on the engine casing. This scheme is only implemented at the tip of one blade of a certain stage of rotor blades, with a short modification cycle, small modification amount, the same processing method for high and low pressure blades, small modification to the rotor structure, no modification to the internal stator structure of the engine, and no safety risks. The processing cycle is short and the test scheme is easy to implement. Since the sensor is installed on the casing and can be disassembled, it can be installed and maintained on the test bench, saving test costs.

[0016] A method for testing the rotational speed signal of an aero-engine with keyphasor function based on the tip-timing principle is proposed. A rotational speed signal test system with keyphasor function is developed based on the Labview environment. The 6602 series test board is used to calculate the arrival time of the blades collected by the fiber optic sensor, identify the keyphasor signal that remains unchanged relative to the rotating shaft, and generate a rotational speed signal with keyphasor function. The fiber optic sensor has better dynamic performance than magnetic steel sensors and eddy current sensors, and directly generates the original signal through an optoelectronic converter, with one less signal conditioning link compared to the existing scheme, eliminating the rotational speed error caused by the signal conditioning link. Since the change in the distance between the rotor blade and the sensor is small, the signal amplitude is almost unchanged, which is better than the high and low tooth test scheme.

[0017] The specific scheme of this application includes: a method for generating and measuring a rotational speed signal with keyphasor function based on tip-timing:

[0018] Step S1: Make one of the engine blades non-reflective, and make the remaining N r -1 blades reflective;

[0019] Step S2: Receive the reflected light signal when the reflective blade passes by the sensor through the sensor, convert the reflected light signal into a pulse signal, and output the pulse signal;

[0020] Step S3: Obtain the time difference Δt between adjacent pulse signals;

[0021] Step S4: Based on the fact that the time difference Δt0 between the pulse signals of the two reflective blades on both sides of the non-reflective blade is greater than the time difference between the pulse signals of two adjacent reflective blades, determine the position of the pulse signal Δt0 of the two reflective blades on both sides of the non-reflective blade, and output a rotational speed signal with keyphasor function based on the position of Δt0.

[0022] Preferably, the position of the pulse signal Δt0 of the two reflective treatment blades on both sides of the blade without reflective treatment is judged in step S4. The specific judgment method is: obtaining the period T of the engine blade rotating one week, and based on Δt0 being greater than Judge the position of the pulse signal Δt0 of the two reflective treatment blades on both sides of the blade without reflective treatment.

[0023] Preferably, based on Δt0 being greater than Judge the position of the pulse signal Δt0 of the two reflective treatment blades on both sides of the blade without reflective treatment, specifically including based on Δt0 being greater than Judge the position of the pulse signal Δt0 of the two reflective treatment blades on both sides of the blade without reflective treatment, where a takes a value of 1.5 to 1.8.

[0024] Preferably, the engine blades are numbered and processed in sequence, and the (N r -1)th blade is subjected to non-reflective treatment.

[0025] Preferably, the sensor includes a multimode optical fiber and an optoelectronic converter. The multimode optical fiber includes 1 path of transmitted light and 6 paths of received reflected light. The transmitted light is provided by the optoelectronic converter, and the reflected light received by the multimode optical fiber is converted into a pulse signal by the optoelectronic converter.

[0026] Preferably, an NI-PXI, 6602 data acquisition card is used, and the pulse signal is digitally acquired using an 80M clock.

[0027] Preferably: the non-reflective treatment of the blade includes painting and frosting the blade.

[0028] Preferably, record the circumferential position of the N r blade, define the rotation angle of the N r blade as 0°, and the position of the generated rotational speed signal with key phase function is the 0° position of the N r blade.

[0029] Preferably, the position of Δt0 is specifically the rising edge of a pulse signal after Δt0.

[0030] Preferably, the non-reflective treatment of the blade is located at the blade tip position.

[0031] The advantages of this application include:

[0032] a) In terms of technology, the present invention proposes a solution for testing the rotational speed through an optical sensor. Compared with the existing testing solutions where the sensor is installed on the engine casing, which is equivalent to the outside of the engine, it has the advantages of simple structure installation, low structure modification cost, simple disassembly and assembly, and long working efficiency.

[0033] b) The present invention relates to a triggering method for rotational speed signals with keyphasor function. Compared with the existing magnetoelectric test scheme, the dynamic performance of the optical sensor is superior to the existing scheme, the modification amount of the engine rotor parts is small, the modification period is short, there is no need for internal wiring of the engine, and the cost of structural modification is low.

[0034] c) The digital acquisition system based on NI-PXI and the acquisition software in the Labview environment implemented by the present invention. The rotational speed signal generation algorithm can accurately locate the marker position, providing a solid foundation for the calculation accuracy and accuracy of the vibration phase. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the test scheme for installing a magnetic steel on the rotating shaft;

[0036] Figure 2 It is a test scheme diagram for the high and low teeth of the speed measurement gear and keyphasor test;

[0037] Figure 3 It is a timing diagram of the rotational speed of the rotating shaft magnetic steel keyphasor and the arrival time of the blade;

[0038] Figure 4 It is a sampling timing diagram of the unprocessed original signal;

[0039] Figure 5 It is a sampling timing diagram of the frequency-divided signal;

[0040] Figure 6 It is a collected result diagram of the processed tip timing;

[0041] Figure 7 It is a diagram of the rotational speed signal acquisition system with keyphasor function;

[0042] Figure 8 It is a flowchart of the rotational speed signal generation with keyphasor function;

[0043] Figure 9 Software operation interface. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] To make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings in the embodiments of this application. In the drawings, the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions throughout. The described embodiments are some but not all of the embodiments of this application. The embodiments described below by referring to the drawings are exemplary and are intended to explain this application and should not be construed as limiting this application. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the drawings.

[0045] 1 Rotational speed signal acquisition principle with keyphasor function based on tip timing

[0046] 1.1 Characteristics of rotational speed signals with keyphasor function and characteristics of rotating blade sampling signals of tip timing sampling principle

[0047] The full name of the present invention is rotational speed signal acquisition technology with keyphasor function based on tip timing principle. First, the rotational speed signals with keyphasor function and the tip timing signals without special treatment are studied, and the test scheme is as Figure 3 . Through the magnetic steel sensor installed on the rotor shaft, every time the rotor rotates one week, a rotational speed pulse is generated, which is the starting moment of this rotational speed cycle. Through the fiber optic sensor installed on the rotor casing of the aeroengine, every time a rotating blade passes by the fiber optic sensor, the reflected light is transmitted into the sensor, and a blade arrival moment pulse signal is generated through the optoelectronic transducer. The test results are as Figure 3 shown.

[0048] By analyzing the collected rotational speed signals and the pulse signals of blade arrival, it can be obtained that according to the characteristics of the rotor blades of the aeroengine, N r blades are evenly distributed in the circumferential direction. Let the pulse trigger moment generated by the rotational speed sensor be the starting moment of the current rotation of the rotor. The arrival moment of the reflected signal of the first collected blade is defined as TOA1 of the 1# blade, the arrival moment of the reflected signal of the second collected blade is defined as TOA2 of the 2# blade... The pulse of the last blade in the current cycle is defined as the arrival moment of the N r # blade According to the tip timing test principle, there must be rotational speed pulse signals brought by N r blades between every two rotational speed pulses with keyphasor function. Through the rotational speed acquisition system, the rotational speed arrival moment sequence {t 转速 (n)} can be obtained, where t 转速 (n) is the arrival moment of the rotational speed pulse when the rotor rotates the nth week. Here, there is a rotational speed period T

[0049]

[0050] The circumferential position angle of the i# blade and the absolute position of the magnetic steel sensor on the shaft is θ i :[[]]END]]

[0051]

[0052] Characteristics of rotational speed signals with keyphasor function

[0053] a) Every time the rotor rotates one week, a rotational speed pulse can be generated. The time difference between two adjacent rotational speed pulses is the rotational speed period T of the current cycle. Every time it rotates one week, N rReflect pulses from the blades and record the time of arrival (TOA). i (n);

[0054] b) Define the blade number of the rotor blade through the absolute position of the rotational speed sensor on the rotating shaft. Its position relative to the rotating shaft remains unchanged. The circumferential positions of all blades on the rotating shaft relative to the circumferential relative angle θ of the position of the magnetic steel rotational speed sensor i remain unchanged.

[0055] 1.2 Principle of generating and collecting rotational speed signals with keyphasor function based on tip timing

[0056] It can be seen from formula (1) that the rotational speed period T can be calculated through TOA i (n). By accumulating the time differences of N r adjacent blade pulses, the rotational speed period T can be obtained. That is, the time difference between the arrival time of the i# blade in the previous revolution and the current revolution is the rotational speed period T. Only using the blade reflection pulses of tip timing to generate rotational speed signals. Assuming there are 8 blades per week, the signal timing diagram of the rotational speed signal obtained with the rotational speed keyphasor function is as Figure 4 . By counting pulse frequency division, a rotational speed signal is generated every 8 blade pulses. This operation is called using the frequency division signal of blade pulses. The sampling result is as Figure 5 .

[0057] Compare Figure 4 、 Figure 5 's acquisition results. For the rotational speed signal obtained by frequency division of the 2# blade, its position relative to the magnetic steel signal remains unchanged. According to formula (1), the rotational speed period T obtained by the magnetic steel and frequency division is the same. However, since the first blade recorded by the frequency division operation is unknown, the blades triggering the frequency division rotational speed signals are inconsistent for different starting trips, and it cannot achieve the same effect as installing a sensor on the rotating shaft. That is, if the rotational speed signal obtained by frequency division of the 2# blade is used, the number of the 2# blade becomes 8# under the positioning of this rotational speed signal. Although it has the keyphasor function in the same test run, it cannot be used as the comparison keyphasor signal for different test runs.

[0058] On the basis of the frequency division operation, through hardware processing of the 7# blade, by painting and frosting the top of the 7# blade, the top of the 7# blade has diffuse reflection, and no effective light intensity can be reflected when the blade passes through the fiber optic sensor. At this time, the acquisition result of the blade is as Figure 6 shown. It can be seen from the result that the time difference between the pulses of the processed 6# and 8# blades is the time difference between the arrival times of the remaining adjacent blades. The time difference between all adjacent blade pulses Only the time difference between 6# and 8# Through logical judgment and pulse trigger setting, calculate the cumulative rotational speed period T every time 7 pulses are collected, and judge the time difference Δt between two blade pulses. When Yes, the rising edge pulse of the blade triggers the generation of a rotational speed divided-frequency pulse. The generation result is as follows Figure 6 , this judgment scheme can make the rotational speed signal be triggered by the 8# blade each time. Since the 8# blade will not change in the circumferential position. Therefore, the generated rotational speed signal has a key phase function, and the rotational speed signals with key phase functions for different driving trips are all triggered by the 8# blade. It can replace the magnetic steel positioning signal as the collection of rotational speed signals with key phase functions.

[0059] Generalize to N r blades per revolution of the rotor. Make the (N r -1)# blade non-reflective, so that when it passes by the fiber optic sensor on the casing, it does not reflect light and thus does not generate a corresponding voltage pulse signal on the photoelectric transducer. Through the PXI and 6602 acquisition boards, according to the rising edge trigger, the counter records the time difference Δt between the current trigger pulse and the previous pulse. Every time (N r -1) time differences Δt are collected, the rotational speed period T is calculated once, and the logical value of is judged. When it is true, the rising edge of the current pulse triggers the generation of a rotational speed pulse; when it is false, the next pulse is judged. Use this logic program and software and hardware processing to obtain a rotational speed signal with a key phase function.

[0060] 2 Hardware composition of the rotational speed signal generation and acquisition scheme for aero-engines with key phase functions

[0061] a. The flow chart of the test system for the rotational speed signal acquisition scheme of aero-engines with key phase functions is as follows Figure 7 , different from the existing test methods, the scheme of testing the low pressure on the speed measurement gear and the high pressure on the accessory casing, this method has the advantages of simple structural modification and universal high and low pressure test schemes. The hardware mainly includes:

[0062] Structural modification of the tested part: Design a sensor installation structure on the casing of the rotor blade to be tested, so that the light emitted by the fiber optic sensor installed on the casing is perpendicular to the top of the rotor blade. To reduce the rotational speed test error, select the trailing edge position of the blade for installation. In the assembled state, select the 1# blade among the N r blades in the circumferential direction, and determine the rotation direction of the rotor. Define the 2#, 3#... N r # blades in sequence along the rotation direction. Apply paint or glue that is non-reflective, heat-resistant enough, will not fall off, and has a thickness allowed by the gap at the position where the fiber optic light shines on the top of the (N r -1)# blade, and perform a matte non-reflective treatment. Record the circumferential position of the N r # blade, define it as 0°, and the position corresponding to the generated rotational speed pulse is the 0° position of the N r # blade.

[0063] b. Selection of fiber optic sensors and photoelectric converters: Fiber optic sensors use multimode optical fibers, with one channel for transmitting light and six channels for receiving reflected light. The transmitted light is provided by a photoelectric converter, and the received reflected light is converted into a pulse point signal by a photoelectric converter circuit. Compared with the existing rotational speed measurement methods of electromagnetic sensors such as eddy current sensors and magnets, fiber optic sensors have better dynamic characteristics, low ripple noise, and fast response speed. The fiber optic sensor installed on the casing can be replaced on the bench (without disassembling the engine), which is more maintainable.

[0064] c. Digital acquisition system and software: Using NI-PXI, 6602 digital acquisition card, using 80M clock to digitally acquire pulse electrical signals, it has a higher time resolution than the existing speed acquisition system and can obtain more accurate speed signals. After being processed by the speed signal acquisition software with key phase function, a speed signal with key phase function is generated and a corresponding N is generated every time the rotor rotates one circle. r #The speed pulse at the blade's circumferential 0° position is used by other acquisition devices.

[0065] 3. Aircraft engine speed signal acquisition software process with key phase function

[0066] The speed signal acquisition software is written based on the speed signal acquisition principle of the aircraft engine with key phase function based on blade tip timing. The software implementation flow chart is as follows Figure 8 , the operation interface is as follows Figure 9 Enter the number of blades and pulse time difference counting channel, and connect the signal cables according to the channel.

[0067] Step 1: Collect hardware information, including the number of rotor blades;

[0068] Step 2: Establish the speed cycle T of the rotor blade in the first cycle;

[0069] Step 3: Start from rising edge and judge logic Generate key phase speed pulse signal and execute it cyclically;

[0070] Step 4: Infinite loop, stop manually.

[0071] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for generating and measuring a rotational speed signal with a keyphasor function based on tip timing, characterized in that: Step S1: Treat one of the engine blades without reflection, and treat the remaining Nr - 1 blades with reflection. Step S2: Install a sensor on the casing so that the light emitted by the sensor is perpendicular to the engine blade and reflected back to the sensor. When the blade with reflection treatment passes by the sensor, the sensor receives the reflected light signal, converts the reflected light signal into a pulse signal, and outputs the pulse signal. Step S3: Obtain the time difference △t0 between adjacent pulse signals. Step S4: Based on the fact that the time difference △t0 between the pulse signals of the two blades with reflection treatment on both sides of the blade without reflection treatment is greater than the time difference between the pulse signals of two adjacent blades with reflection treatment, determine the position of the pulse signal △t0 of the two blades with reflection treatment on both sides of the blade without reflection treatment, and output a rotational speed signal with a keyphasor function based on the position of △t0. The specific method for determining the position of the pulse signal △t0 of the two blades with reflection treatment on both sides of the blade without reflection treatment in Step S4 is: Obtain the period T of one rotation of the engine blade, and determine the position of the pulse signal △t0 of the two blades with reflection treatment on both sides of the blade without reflection treatment based on △t0 being greater than T / Nr. The determination of the position of the pulse signal △t0 of the two blades with reflection treatment on both sides of the blade without reflection treatment based on △t0 being greater than T / Nr specifically includes determining the position of the pulse signal △t0 of the two blades with reflection treatment on both sides of the blade without reflection treatment based on △t0 being greater than (aT) / Nr, where a ranges from 1.5 to 1.

8. Number the engine blades in sequence, and treat the (Nr - 1)th blade without reflection. Record the circumferential position of the Nrth blade, define the rotation angle of the Nrth blade as 0°, and the position of the generated rotational speed signal with a keyphasor function is the 0° position of the Nrth blade.

2. The rotational speed signal generation and measurement method with keyphasor function based on tip timing according to claim 1, characterized in that The sensor includes a multimode optical fiber and an optoelectronic converter. The multimode optical fiber includes 1 path of transmitted light and 6 paths of received reflected light. The transmitted light is provided by the optoelectronic converter, and the reflected light received by the multimode optical fiber is converted into a pulse signal by the optoelectronic converter.

3. The rotational speed signal generation and measurement method with keyphasor function based on tip-timing according to claim 1, characterized in that, Use an NI - PXI, 6602 data acquisition card, and use an 80M clock to digitally acquire the pulse signal.

4. The rotational speed signal generation and measurement method with keyphasor function based on tip-timing according to claim 1, characterized in that: The non - reflection treatment of the blade includes painting and frosting the blade.

5. The rotational speed signal generation and measurement method with keyphasor function based on tip timing according to claim 1, characterized in that, The position of △t0 is specifically the rising edge of a pulse signal after △t0.

6. The method for generating and measuring rotational speed signals with keyphasor function based on tip-timing according to claim 4, wherein The non - reflection treatment of the blade is located at the tip of the blade.

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