In-situ dynamic balance method of aero-engine fan rotor

Abstract

The invention discloses an in-situ dynamic balance method of an aero-engine fan rotor, which is characterized by comprising the following steps of: A, calculating a vibration phase by using an in-situ dynamic balance algorithm; B, realizing in-situ dynamic balance of the fan rotor through a trial mass method or an influence coefficient method after obtaining the vibration size and the phase; the speed measurement assembly used in the process of realizing the in-situ dynamic balance of the fan rotor adopts a speed measurement assembly with short teeth. According to the method, the accurate unbalance amount and phase are obtained through the speed measuring gear and the in-situ dynamic balance algorithm, and compared with the prior art that the engine needs to be disassembled and reassembled for balance, the method is easy to implement, accurate in calculation and small in consumed working hours and resources, has huge economic benefits and can be used for in-situ dynamic balance of other engines of similar structures.

Description

Technical Field

[0001] The invention relates to the field of aircraft engine maintenance, in particular to an in-situ dynamic balancing method for an aircraft engine fan rotor. Background Art

[0002] The aircraft engine is the heart of the aircraft. The time it can work stably and reliably determines the safety and combat readiness of the aircraft. After a service life cycle, the engine is returned to the factory for repair and test run. Due to assembly and balancing factors, some engines still have fan rotor vibration or vibration exceeding the standard under high engine speed conditions. Conventional means cannot locate and accurately and quickly eliminate vibration faults. The only way is to disassemble, reassemble and balance the engine and then conduct test run verification. This method consumes a lot of manpower and time costs, and the vibration after reassembly and balancing may not be qualified.

[0003] Regarding the fan rotor vibration failure that occurs during the test run of aircraft engines, especially small and medium bypass ratio engines with air intake casings, the fan rotor front end is provided with an air intake casing and the internal space is limited. The in-situ dynamic balancing method of the fan rotor is not considered to reduce the vibration during the design, which brings difficulties to the elimination of the vibration. For example, the solution disclosed in the patent with the patent number "CN113357201A" realizes the rapid local balancing of the fan rotor and the low-pressure turbine rotor by designing a local balancing structure that can not decompose the air intake casing and the turbine rear casing. However, for the engines that have been finalized and put into use, it is impossible to modify the engine structure to achieve local balancing. For example, the solution disclosed in the patent with the patent number "CN103217255B" arranges a high-toothed speed measuring sound wheel at the two fulcrums of the fan, and installs a balancing block on the oil distribution ring balancing hole inside the journal. However, it is still necessary to improve the engine structure to achieve local balancing, and it is impossible to achieve the balance of the finalized engine. The literature {Wu Yuandong, Lou Jinwei, Fan Shunchang, et al. Study on the local balancing test of a certain type of engine fan rotor [J] Aero Engines} adopts the three-circle method for local balancing, and installs a balancing weight on the oil separator plate for testing. This requires many test runs, and the diameter of the balancing weight surface is too small, so a large-mass balancing weight needs to be installed, and the oil separator plate must be improved and designed. It still cannot be well used on the finalized engine.

[0004] Therefore, there is an urgent need for a method for eliminating fan rotor vibration during engine test runs that can be convenient, reduce modification, and be quickly applied and finalized. Summary of the invention

[0005] The object of the present invention is to provide an in-situ dynamic balancing method for an aircraft engine fan rotor, so as to realize rapid elimination of fan rotor faults during the aircraft engine test run.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions: An in-situ dynamic balancing method for an aircraft engine fan rotor, characterized in that it comprises the following steps: A. calculating the vibration phase using an in-situ dynamic balancing algorithm; B. achieving the in-situ dynamic balancing of the fan rotor by a test weight method or an influence coefficient method after obtaining the vibration magnitude and phase; The speed measuring component used in the process of achieving in-situ dynamic balancing of the fan rotor adopts a speed measuring component with short teeth.

[0007] There is no need to improve the engine structure. Just install a processed and assembled speed measuring component with low teeth to quickly obtain the imbalance size and circumferential phase of the fan rotor vibration through a test run, thereby realizing the rapid elimination of fan rotor faults during the aircraft engine test run.

[0008] As a further preferred embodiment of the present invention, the weight test method specifically includes the following steps: b11, when the engine is monitored to have a large or excessive vibration of the fan rotor during the test run, the engine fairing cap and the original speed measuring assembly are removed, and replaced with a speed measuring assembly with short teeth for in-situ dynamic balancing, and the positions corresponding to the short teeth are marked on the fan blades with a marker pen, and the assembly of the fairing cap is restored; b12, an initial test run is performed, vibration and speed key phase data are measured, and the initial vibration magnitude and phase are obtained through the in-situ dynamic balancing algorithm; b13, the engine repairman card is checked to see whether there is a balance screw quality on the primary disk of the fan rotor, and if so, the balance screws are removed. Record the mass of the balancing screws and their positions relative to the marks on the fan blades; if there are no balancing screws, disassemble the air intake casing, install the balancing screws on the first-level fan disk, restore the installation of the air intake casing, and record the mass of the installed balancing screws and their positions relative to the marks on the fan blades; b14, perform a test run with added weight or removed counterweights, measure the vibration and speed key phase data, and use the in-situ dynamic balancing algorithm to obtain the vibration size and phase of the added weight or removed counterweights; use the in-situ dynamic balancing algorithm to calculate the influence relationship between the counterweight and the vibration, that is, the influence coefficient; then use the local balancing algorithm to calculate the size of the balancing screws required to reduce the initial vibration and the relative to the mark b15. Check the engine repairman card to see if there are balancing screws on the fan rotor primary disk. If yes, convert the balancing screw position into a phase relative to the fan blade mark position, and compare whether the phase difference between these balancing screws and the balancing screws in step b14 is 180°±30°; if yes, remove these balancing screws and record the mass of these balancing screws and their position relative to the mark on the fan blade; if not, disassemble the intake casing, install the balancing screws in step b14, and restore the assembly; b16. Perform a verification test, measure the vibration and speed key phase data, and check whether the fan rotor vibration is qualified. If If the vibration is qualified, it indicates that the influence coefficient of the above-mentioned trial weight method is available, and the influence coefficient can be calculated and updated by adding trial weight or taking counterweight and verifying the test data, so as to complete the in-situ dynamic balancing of the fan rotor. If the vibration is unqualified, the influence coefficient and the size and phase of the balancing screws required to reduce the initial vibration can be recalculated by adding trial weight or taking counterweight and verifying the test data. When installing new balancing screws, the balancing screws installed in b15 need to be removed until the in-situ dynamic balancing of the fan rotor is completed; b17, after completing the in-situ dynamic balancing of the fan rotor, separate the fairing cap and the speed measuring assembly with short teeth, install the original speed measuring assembly, and restore the assembly of the fairing cap.

[0009] The trial weight method first installs a speed measuring assembly with short teeth to measure the vibration and speed key phase data of the fan rotor in the initial state; then removes or installs a balancing weight on the fan rotor as a test weight, and conducts a test run with the test weight added (or the weight removed), and measures the vibration and speed key phase data of the fan rotor after the test weight is added (or the weight is removed); the in-situ dynamic balancing algorithm is used to calculate and process the two test run data to obtain the influence relationship between the weight and the vibration, which is called the influence coefficient. Based on the influence coefficient, the size and phase of the balancing screws required to reduce the initial vibration can be calculated; installing or removing balancing screws of corresponding size and phase can reduce the fan rotor vibration.

[0010] As a further preference of the present invention, the influence coefficient method specifically includes the following steps: b21. When the engine is tested and the fan rotor vibration is detected to be large or exceeds the standard, the engine fairing cap and the original speed measuring assembly are removed, and replaced with a speed measuring assembly with short teeth for in-situ dynamic balancing, and the corresponding positions of the short teeth are marked on the fan blades with a marker pen, and the assembly of the fairing cap is restored; b22. An initial test run is carried out to measure the vibration and speed key phase data, and the initial vibration magnitude and phase are obtained through the in-situ dynamic balancing algorithm, and the known influence coefficient is used to calculate the size and phase of the balancing screws required to reduce the initial vibration; b23. Check the engine repairman card to see if there are balancing screws on the primary disk of the fan rotor. If there are, convert the position of the balancing screws into a phase relative to the marked position of the fan blade, and compare whether the phase difference between these balancing screws and the balancing screws in step b22 is 180°±30°; if satisfied, these balancing screws can be removed. Screws, and record the mass of these balancing screws and their position relative to the marks on the fan blades; if not satisfied, disassemble the air intake casing, install the balancing screws in step b22, and restore the assembly; b24, conduct a verification test, measure the vibration and speed key phase data, and check whether the fan rotor vibration is qualified. If the vibration is qualified, it indicates that the influence coefficient is available, and the test weight or counterweight and verification test data can be used again to calculate and update the influence coefficient to complete the in-situ dynamic balancing of the fan rotor. If the vibration is unqualified, add the test weight or take the counterweight and verification test data again to recalculate the influence coefficient and the size and phase of the balancing screws required to reduce the initial vibration. When installing new balancing screws, remove the balancing screws installed in step b23 until the in-situ dynamic balancing of the fan rotor is completed; b25. After completing the in-situ dynamic balancing of the fan rotor, separate the fairing cap and the speed measuring assembly with short teeth, install the original speed measuring assembly, and restore the assembly of the fairing cap.

[0011] The influence coefficient method first needs to know the influence coefficient of the engine, or the influence coefficient has been obtained through the test weight method before it can be used. Next, install the speed measuring component with short teeth to measure the fan rotor vibration and speed key phase data in the initial state; secondly, calculate the initial vibration size and phase through the in-situ dynamic balancing algorithm, and combine the known influence coefficient to calculate the size and phase of the balancing screws required to reduce the initial vibration; install or remove the balancing screws of the corresponding size and phase to reduce the fan rotor vibration. Compared with the test weight method, one test run can be reduced.

[0012] As a further preferred embodiment of the present invention, the processing method of the speed measuring assembly with short teeth is as follows: a speed measuring gear with short teeth is processed, and then the speed measuring gear with short teeth and other parts are assembled into a speed measuring assembly with short teeth as a speed key phase meter.

[0013] As a further preferred embodiment of the present invention, the speed measuring gear with short teeth has one of its teeth machined to be 0.3 mm to 0.5 mm lower than the remaining teeth.

[0014] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: 1. There is no need to improve the engine structure. Just install a processed and assembled speed measuring component with short teeth to quickly obtain the imbalance size and circumferential phase of the fan rotor vibration through a test run.

[0015] 2. By pre-setting the balancing screws on the primary disk of the fan rotor, the unbalance amount can be quickly changed by removing the balancing screws during the test, avoiding the waste of resources caused by disassembling the air intake casing due to adding test weights.

[0016] 3. For engines with balancing screws on the first-stage fan disk and fan rotor vibration during the test run, this method can be used to calculate whether the existing balancing screws meet the requirements for reducing vibration. If they meet the requirements, the balancing screws can be directly removed to reduce the fan rotor vibration. If they do not meet the requirements, the size and phase information of the balancing screws can be provided to quickly eliminate the vibration. The air intake casing can be directly disassembled, the balancing screws can be installed and the assembly can be restored, which can save a lot of time and labor costs for disassembling, reassembling and balancing the engine.

[0017] 4. This application is applicable to other similar aircraft engines, gas turbines, etc., which have high-pressure and low-pressure rotors that vibrate during test runs and operation, and to perform in-situ dynamic balancing work at high speeds. It does not require changes to the engine structure, is fast, accurate, simple, has a wide range of applications, and is easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the fan rotor in-situ dynamic balancing structure.

[0019] Figure 2 This is a schematic diagram of the structure of a speed measuring gear with short teeth. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0024] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0025] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the invention is usually placed when in use, or the positions or positional relationships commonly understood by those skilled in the art, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0026] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. Specific embodiment 1: Figure 1 , Figure 2 A method for in-situ dynamic balancing of an aircraft engine fan rotor is shown, comprising the following steps: A. calculating the vibration phase using an in-situ dynamic balancing algorithm; B. achieving in-situ dynamic balancing of the fan rotor by a test weight method or an influence coefficient method after obtaining the vibration magnitude and phase; The speed measuring component used in the process of achieving in-situ dynamic balancing of the fan rotor adopts a speed measuring component with short teeth.

[0028] There is no need to improve the engine structure. Just install a processed and assembled speed measuring component with low teeth to quickly obtain the imbalance size and circumferential phase of the fan rotor vibration through a test run, thereby realizing the rapid elimination of fan rotor faults during the aircraft engine test run. Specific embodiment 2: This embodiment further illustrates the weight test method on the basis of the specific embodiment 1, and the weight test method specifically includes the following steps: b11, when the engine is monitored to have a large or excessive vibration of the fan rotor during the test run, the engine fairing cap and the original speed measuring assembly are separated, and replaced with a speed measuring assembly with short teeth for in-situ dynamic balancing, and the corresponding position of the short teeth is marked on the fan blade with a marker pen, and the assembly of the fairing cap is restored; b12, an initial test run is performed, and the vibration and speed key phase data are measured, and the initial vibration magnitude and phase are obtained through the in-situ dynamic balancing algorithm; b13, the engine repairman card is checked to see whether there are balancing screws on the primary disk of the fan rotor Mass, if there are balancing screws, separate the balancing screws and record the mass of the balancing screws and their positions relative to the marks on the fan blades; if there are no balancing screws, disassemble the air intake casing, install the balancing screws on the first-level fan disk, restore the installation of the air intake casing, and record the mass of the installed balancing screws and their positions relative to the marks on the fan blades; b14, carry out a test weight or remove the counterweight for test driving, measure the vibration and speed key phase data, and obtain the vibration size and phase of the added test weight or removed counterweight through the in-situ dynamic balancing algorithm; use the in-situ dynamic balancing algorithm to calculate the influence relationship between the counterweight and the vibration, that is, the influence coefficient; then use the local balancing algorithm to calculate the balance required to reduce the initial vibration screw size and phase relative to the mark; b15. Check the engine repairman card to see if there are balancing screws on the fan rotor primary disk. If there are, convert the balancing screw position into a phase relative to the fan blade mark position, and compare whether the phase difference between these balancing screws and the balancing screws in step b14 is 180°±30°; if satisfied, remove these balancing screws and record the mass of these balancing screws and the position relative to the mark on the fan blade; if not satisfied, disassemble the intake casing, install the balancing screws in step b14, and restore the assembly; b16. Perform a verification test, measure the vibration and speed key phase data, and check whether the fan rotor vibration is normal. If the vibration is qualified, it means that the influence coefficient of the above-mentioned trial weight method is available, and the influence coefficient can be calculated and updated by adding trial weight or taking counterweight and verifying the test data, so as to complete the in-situ dynamic balancing of the fan rotor. If the vibration is unqualified, the influence coefficient and the size and phase of the balancing screws required to reduce the initial vibration can be recalculated. When installing new balancing screws, the balancing screws installed in b15 need to be removed until the in-situ dynamic balancing of the fan rotor is completed; b17. After completing the in-situ dynamic balancing of the fan rotor, remove the fairing cap and the speed measuring assembly with short teeth, install the original speed measuring assembly, and restore the assembly of the fairing cap.

[0030] The trial weight method first installs a speed measuring assembly with short teeth to measure the vibration and speed key phase data of the fan rotor in the initial state; then removes or installs a balancing weight on the fan rotor as a test weight, and conducts a test run with the test weight added (or the weight removed), and measures the vibration and speed key phase data of the fan rotor after the test weight is added (or the weight is removed); the in-situ dynamic balancing algorithm is used to calculate and process the two test run data to obtain the influence relationship between the weight and the vibration, which is called the influence coefficient. Based on the influence coefficient, the size and phase of the balancing screws required to reduce the initial vibration can be calculated; installing or removing balancing screws of corresponding size and phase can reduce the fan rotor vibration. Specific embodiment 3: This embodiment further illustrates the influence coefficient method on the basis of the specific embodiment 1, and the influence coefficient method specifically includes the following steps: b21, when the engine is tested and it is monitored that the fan rotor vibration is large or exceeds the standard, the engine fairing cap and the original speed measuring assembly are separated, and replaced with the speed measuring assembly with short teeth for in-situ dynamic balancing, and the corresponding position of the short teeth is marked on the fan blade with a marker, and the assembly of the fairing cap is restored; b22, an initial test run is carried out, and the vibration and speed key phase data are measured, and the initial vibration size and phase are obtained by the in-situ dynamic balancing algorithm, and the known influence coefficient is used to calculate the size and phase of the balancing screw required to reduce the initial vibration; b23, check the engine repairman card to see if there are balancing screws on the primary disk of the fan rotor, and if there are, convert the position of the balancing screws into a phase relative to the marked position of the fan blade, and compare whether the phase difference between these balancing screws and the balancing screws in step b22 is 180°±30°; if it meets If the requirements are met, remove the balancing screws and record the mass and position of the balancing screws relative to the marks on the fan blades. If the requirements are not met, disassemble the air intake casing, install the balancing screws in step b22, and restore the assembly. b24: perform a verification test, measure the vibration and speed key phase data, and check whether the fan rotor vibration is qualified. If the vibration is qualified, it indicates that the influence coefficient is available, and the influence coefficient can be calculated and updated by adding test weights or taking counterweights and verifying the test data to complete the in-situ dynamic balancing of the fan rotor. If the vibration is unqualified, add test weights or take counterweights and verifying the test data to recalculate the influence coefficient and the size and phase of the balancing screws required to reduce the initial vibration. When installing new balancing screws, remove the balancing screws installed in step b23 until the in-situ dynamic balancing of the fan rotor is completed. b25: after completing the in-situ dynamic balancing of the fan rotor, remove the fairing cap and the speed measuring assembly with short teeth, install the original speed measuring assembly, and restore the assembly of the fairing cap.

[0032] The influence coefficient method first needs to know the influence coefficient of the engine, or the influence coefficient has been obtained through the test weight method before it can be used. Next, install the speed measuring component with short teeth to measure the fan rotor vibration and speed key phase data in the initial state; secondly, calculate the initial vibration size and phase through the in-situ dynamic balancing algorithm, and combine the known influence coefficient to calculate the size and phase of the balancing screws required to reduce the initial vibration; install or remove the balancing screws of the corresponding size and phase to reduce the fan rotor vibration. Compared with the test weight method, one test run can be reduced. Specific embodiment 4: This embodiment further illustrates the speed measuring assembly with short teeth on the basis of the specific embodiment 1. The processing method of the speed measuring assembly with short teeth is as follows: a speed measuring gear with short teeth is processed, and then the speed measuring gear with short teeth and other parts are assembled into a speed measuring assembly with short teeth as a speed key phase meter. Specific embodiment 5: This embodiment further illustrates the speed measuring gear with short teeth on the basis of the specific embodiment 4. The speed measuring gear with short teeth is that one of the teeth is processed to be 0.3 mm to 0.5 mm lower than the other teeth.

[0035] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An in-situ dynamic balancing method for an aircraft engine fan rotor, characterized in that: The method comprises the following steps: A. calculating the vibration phase by using an in-situ dynamic balancing algorithm; B. realizing the in-situ dynamic balancing of the fan rotor by using a test weight method or an influence coefficient method after obtaining the vibration magnitude and phase; The speed measuring component used in the process of achieving in-situ dynamic balancing of the fan rotor adopts a speed measuring component with short teeth.

2. The in-situ dynamic balancing method for an aircraft engine fan rotor according to claim 1, characterized in that: The weight test method specifically includes the following steps: b11, when the engine is tested and it is monitored that the fan rotor vibrates greatly or exceeds the standard, the engine fairing cap and the original speed measuring assembly are removed, and replaced with a speed measuring assembly with short teeth for in-situ dynamic balancing, and the corresponding positions of the short teeth are marked on the fan blades with a marker, and the assembly of the fairing cap is restored; b12, an initial test run is carried out, and the vibration and speed key phase data are measured, and the initial vibration magnitude and phase are obtained through the in-situ dynamic balancing algorithm; b13, the engine repairman card is checked to see whether there is a balance screw quality on the primary disk of the fan rotor, and if so, some balance screws are removed, and the removed balance screws are recorded The mass and position relative to the mark on the fan blade; if there is no balancing screw, the air intake casing needs to be disassembled, and then the balancing screws are installed on the fan primary disk, and the installation of the air intake casing is restored, and the mass of the installed balancing screws and the position relative to the mark on the fan blade are recorded; b14, add test weight or remove counterweight for test running, measure the vibration and speed key phase data, and obtain the vibration size and phase of the added test weight or removed counterweight through the in-situ dynamic balancing algorithm; use the in-situ dynamic balancing algorithm to calculate the influence relationship between the counterweight and the vibration, that is, the influence coefficient; then use the local balancing algorithm to calculate the size of the balancing screw required to reduce the initial vibration and the phase relative to the mark; b 15. Check the engine repair card to see if there are balancing screws on the fan rotor primary disk. If there are, convert the balancing screw positions into phases relative to the fan blade mark positions, and compare whether the phase difference between these balancing screws and the balancing screws in step b14 is 180°±30°; if satisfied, remove these balancing screws and record the mass of these balancing screws and their positions relative to the marks on the fan blades; if not satisfied, disassemble the intake casing, install the balancing screws in step b14, and restore the assembly; b16. Perform a verification test, measure the vibration and speed key phase data, and check whether the fan rotor vibration is qualified. If the vibration is qualified, If it is not qualified, it indicates that the influence coefficient of the above-mentioned trial weight method is available, and the influence coefficient can be calculated and updated by adding trial weight or taking counterweight and verifying the test data, so as to complete the in-situ dynamic balancing of the fan rotor. If the vibration is unqualified, the influence coefficient and the size and phase of the balancing screws required to reduce the initial vibration can be recalculated by adding trial weight or taking counterweight and verifying the test data. When installing new balancing screws, the balancing screws installed in b15 need to be removed until the in-situ dynamic balancing of the fan rotor is completed; b17. After completing the in-situ dynamic balancing of the fan rotor, remove the fairing cap and the speed measuring assembly with short teeth, install the original speed measuring assembly, and restore the assembly of the fairing cap.

3. The in-situ dynamic balancing method for an aircraft engine fan rotor according to claim 1, characterized in that: The influence coefficient method specifically includes the following steps: b21. When the engine is tested and it is detected that the fan rotor vibration is large or exceeds the standard, the engine fairing cap and the original speed measuring assembly are separated and replaced with a speed measuring assembly with short teeth for in-situ dynamic balancing, and the corresponding positions of the short teeth are marked on the fan blades with a marker, and the assembly of the fairing cap is restored; b22. An initial test run is carried out to measure the vibration and speed key phase data, and the initial vibration magnitude and phase are obtained through the in-situ dynamic balancing algorithm, and the known influence coefficient is used to calculate the size and phase of the balancing screws required to reduce the initial vibration; b23. Check the engine repairman card to see if there are balancing screws on the primary disk of the fan rotor. If there are, convert the position of the balancing screws into a phase relative to the marked position of the fan blade, and compare whether the phase difference between these balancing screws and the balancing screws in step b22 is 180°±30°; if satisfied, these balancing screws can be removed and recorded. The mass of these balancing screws and their positions relative to the marks on the fan blades; if they are not satisfied, disassemble the air intake casing, install the balancing screws in step b22, and restore the assembly; b24, conduct a verification test, measure the vibration and speed key phase data, and check whether the fan rotor vibration is qualified. If the vibration is qualified, it indicates that the influence coefficient is available, and the influence coefficient can be calculated and updated by adding test weights or taking counterweights and verifying the test data again to complete the in-situ dynamic balancing of the fan rotor. If the vibration is not qualified, add test weights or take counterweights and verify the test data again to recalculate the influence coefficient and the size and phase of the balancing screws required to reduce the initial vibration. When installing new balancing screws, remove the balancing screws installed in step b23 until the in-situ dynamic balancing of the fan rotor is completed; b25, after completing the in-situ dynamic balancing of the fan rotor, separate the fairing cap and the speed measuring assembly with short teeth, install the original speed measuring assembly, and restore the assembly of the fairing cap.

4. The in-situ dynamic balancing method for an aircraft engine fan rotor according to claim 1, characterized in that: The processing method of the speed measuring assembly with short teeth is as follows: a speed measuring gear with short teeth is processed, and then the speed measuring gear with short teeth and other parts are assembled into a speed measuring assembly with short teeth as a speed key phase measuring device.

5. The in-situ dynamic balancing method for an aircraft engine fan rotor according to claim 4, characterized in that: The speed measuring gear with short teeth has one of its teeth machined to be 0.3 mm to 0.5 mm lower than the other teeth.

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