A fast evaluation method for the stability frequency design of a helicopter rotor-fuselage coupling

Abstract

The application belongs to the technical field of helicopter dynamics design, and discloses a kind of fast evaluation method of helicopter rotor body coupling stability frequency design, based on the change relation of rotor system characteristic frequency and body modal frequency with rotor speed, resonance center speed and speed stability margin are obtained, to carry out the fast evaluation of rotor body coupling stability, and according to the result of fast evaluation, whether the speed stability margin meets the design requirement is determined, to carry out the optimization design of rotor system characteristic frequency and body modal frequency, which can ensure that the rotor body coupling stability meets the design requirement in the early stage of design. The application avoids the problem of rotor body coupling stability, can carry out frequency design more accurately in each stage of type design, and has high universality and engineering application value.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of helicopter dynamics design, and particularly relates to a fast evaluation method for rotor-airframe coupling stability frequency design of a helicopter. BACKGROUND

[0002] If the rotor of a helicopter is a ball flexible hub, i.e. the design is a soft type of flapping, the rotor-airframe coupling stability problem may exist. The coupling of the rotor system and the helicopter may cause the vibration to continue, amplify and even diverge, which has a significant impact on the vibration of the helicopter. The essence of the rotor-airframe coupling stability problem is that the rotor flapping back type frequency is coupled with the airframe mode of the hub center in the rotation plane, and the two systems excite each other, when the damping of the system is insufficient, the rotor flapping motion and the motion of the airframe on the landing gear are intensified, i.e. the ground resonance problem. After the helicopter in ground operation is disturbed by the outside world, the rotor blades vibrate according to the back type mode, and the unbalanced rotation centrifugal force excites the vibration of the airframe on the landing gear; the hub center, as a point on the airframe, vibrates with the airframe, but it is also the connection point of the rotor system foundation, and the vibration of the hub center, as the foundation excitation, forms the foundation excitation to the rotor motion in the rotation plane, which affects (intensifies or weakens) the vibration of the original blades. If the vibration characteristics of the two vibration systems satisfy a certain relationship: the centrifugal excitation force generated by the rotor system flapping is the same as or close to the natural vibration frequency of the airframe on the landing gear, and the vibration mode corresponding to the natural frequency can make the hub center vibrate in the rotation plane, and the damping of the blade damping device and the landing gear system is smaller than the work done by the excitation force on the system in a vibration cycle, then the flapping motion of the blade and the vibration of the airframe on the landing gear will intensify each other, vicious cycle, and the amplitude can be large enough to damage the helicopter within a few seconds.

[0003] The internal condition for the occurrence of the rotor-airframe coupling stability problem is that the damping of the blade damping device and the landing gear system is large enough, or the centrifugal excitation force generated by the rotor system flapping is far away from the vibration frequency of the airframe on the landing gear, so that the vibration excited by the two vibration systems due to external disturbance will weaken each other until disappear, and the ground resonance problem will not occur.

[0004] Therefore, at the initial design stage, the reasonable configuration of the mutual relationship between the rotor system flapping back type mode and the airframe mode is the key link to avoid the occurrence of the rotor-airframe coupling stability problem.

[0005] The traditional method is to calculate the ground resonance stability curve by using the overall parameters and the landing gear preliminary performance parameters in the early design stage, and the relatively intuitive optimization design link is lacked; in the engineering design stage, the hub center dynamic characteristic test of the rotor is carried out by using the test prototype to obtain the modal parameters of the machine body on the landing gear, and then the ground resonance stability curve is calculated, and since the prototype has been completed, the optimization design has a long cycle and high cost.

[0006] The application is a fast evaluation method for the rotor-machine body coupling stability frequency design of a certain helicopter, carries out the rotor-machine body coupling stability design, and the test verification shows that the precision of the method meets the engineering needs. The method has high engineering value in the rotor-machine body coupling stability analysis, stability problem investigation and stability control plan of a new machine. SUMMARY

[0007] The application proposes a fast evaluation method for the rotor-machine body coupling stability frequency design of a helicopter, obtains the resonance center speed and the speed stability margin based on the change relationship of the rotor system characteristic frequency and the machine body modal frequency with the rotor speed, carries out the fast evaluation of the rotor-machine body coupling stability, and determines whether the speed stability margin meets the design requirements according to the fast evaluation result, so as to carry out the optimization design of the rotor system characteristic frequency and the machine body modal frequency, and ensure that the rotor-machine body coupling stability meets the design requirements in the early design stage.

[0008] The technical scheme of the application is implemented as follows:

[0009] In a first aspect, the application discloses a fast evaluation method for the rotor-machine body coupling stability frequency design of a helicopter, which includes the following steps:

[0010] Step 1: obtaining the parameters of the rotor system;

[0011] Step 2: calculating the flapping back type frequency of the rotor system under different rotor speeds by using the above parameters;

[0012] Step 3: calculating the four kinds of modal frequencies of the machine body on the landing gear by using the full machine model;

[0013] Step 4: drawing the speed-frequency graph, including: drawing the curve of the flapping back type frequency changing with the rotor speed, drawing the curves of the four kinds of machine body modal frequencies changing with the rotor speed respectively, drawing the vertical line corresponding to the rated speed of the rotor, and drawing the vertical line corresponding to the speed stability margin requirement;

[0014] Step 5: determining the resonance center, that is, the intersection point of the flapping back type frequency curve and the four machine body modal frequency curves;

[0015] Step 6: judge whether the resonance center falls in the range of the vertical line of the speed stability margin, if not, the evaluation is qualified;

[0016] Step 7: if yes, the evaluation is unqualified, frequency optimization design is needed, and steps 1-6 are repeated until the design requirements are met.

[0017] As a further scheme of the application: the parameters of the rotor system include rotor rated speed, mass moment of inertia of a blade, moment of inertia of a blade, elastic line stiffness of the hydraulic pendulum damper, distance from the hub center to the pendulum hinge, distance from the pendulum hinge to the pendulum damper.

[0018] As a further scheme of the application: the step 2 specifically includes the following steps:

[0019] Step 21: convert the elastic line stiffness of the hydraulic pendulum damper of the rotor system into the pendulum angle stiffness, and the specific calculation formula is as follows:

[0020] ;

[0021] wherein, represents the pendulum angle stiffness, ; represents the elastic line stiffness of the hydraulic pendulum damper, ; represents the distance from the pendulum hinge to the pendulum damper, ;

[0022] Step 22: according to the above pendulum angle stiffness and other rotor system parameters, the rotor system pendulum retrograde frequency at different rotor speeds is calculated, and the specific calculation formula is as follows:

[0023] ;

[0024] wherein, represents the first-order pendulum retrograde frequency, ; represents the distance from the hub center to the pendulum hinge, ; represents the mass moment of inertia of a blade around the pendulum hinge, ; represents the moment of inertia of a blade around the pendulum hinge, ; represents the rotor speed frequency, ; the specific calculation formula is as follows:

[0025] ;

[0026] wherein, represents the rotor speed, .

[0027] As a further scheme of the present application, the step 3 is specifically: calculating the modal of the machine body on the landing gear according to the full-maneuver characteristic model, to obtain the frequency of the machine body on the landing gear, including the heading first-order frequency, the lateral first-order frequency, the heading second-order frequency and the lateral second-order frequency.

[0028] As a further scheme of the present application, the judging whether the design requirement is met can also be:

[0029] According to the frequency-rotation speed diagram obtained in the step 4, the resonance center rotation speed is obtained;

[0030] The rotation speed stability margin is calculated through the resonance center rotation speed, and the specific calculation formula is as follows:

[0031] ;

[0032] Wherein, represents the rotation speed stability margin; represents the resonance center rotation speed, ; represents the rated rotation speed of the rotor, ;

[0033] The rotation speed stability margin is judged whether it meets the requirement, and the judging condition is as follows:

[0034] When the rotation speed stability margin is greater than 15%, the design requirement is met, and the evaluation is ended;

[0035] When the rotation speed stability margin is less than or equal to 15%, the design requirement is not met, and the frequency optimization design needs to be performed.

[0036] As a further scheme of the present application, the frequency optimization design specifically includes the following steps:

[0037] Step 71: one or several of the parameters of the rotor system hydraulic pendulum damper pendulum elastic line stiffness, pendulum hinge to pendulum damper distance, hub center to pendulum hinge distance, mass moment of inertia and rotational inertia of the blade around the pendulum hinge are optimized and designed, to change the rotor system pendulum retrograde frequency;

[0038] Step 72: the parameters of the improved landing gear stiffness and the machine body elastic stiffness are optimized and designed, to change the machine body modal frequency.

[0039] In the second aspect, the present application discloses an electronic device, which comprises a processor and a memory storing a computer program, and when the processor runs the computer program, the steps of the above rapid evaluation method are executed.

[0040] In a third aspect, the present application discloses a computer storage medium, which stores a computer program, and the computer program is executed by a processor to perform the steps of the rapid evaluation method.

[0041] The present application has the following advantages:

[0042] 1. The present application is used in the early stage of helicopter design, and the rotor parameters and the body modal frequency parameters obtained by simulation calculation are used as inputs to quickly evaluate the resonance center of the rotor ground resonance retreat frequency and the body modal frequency from the perspective of frequency design, so as to obtain the ground resonance speed margin. In order to ensure the safety of helicopter ground test and flight, the possibility of ground resonance can be excluded by the frequency design analysis method in the early stage of design, so as to effectively guide the design, determine the limit value of the adjustable parameters of the rotor parameters and the body frequency, and exclude the possibility of ground resonance in the early stage of design.

[0043] 2. The present application finds out the influence parameters of the mutual coupling of the rotor system and the body structure, and describes the mechanism, key factors and effective solutions of mutual coupling, so as to effectively guide the design. The previous type generally can only estimate the rotor-body coupling ground resonance retreat frequency after a series of tests such as hub center dynamic characteristic test and landing gear static compression characteristic test, which has a long time period and high cost, and leads to difficulty in changing the design or taking stability control measures. Compared with the traditional method, the design method proposed by the present application can quickly and accurately predict the rotor-body coupling ground resonance retreat frequency in the early stage of design, the input parameter operation is also more simple and easy to operate, and the actual situation can be more truly simulated to form a rapid evaluation analysis method for helicopter rotor-body coupling calculation, which has high engineering value in ground resonance, tail rotor tail beam coupling stability and other design work. Mastering the rotor-body coupling stability in the early stage of type development and formulating a stability control plan are of great significance to ensure the flight safety of the helicopter. The evaluation method formed by the present application realizes the purpose of avoiding the risk of rotor-body coupling stability in each research and development stage of the type.

[0044] 3. The related application examples show that the frequency design method meeting the engineering precision requirement can be obtained according to the scheme of the present application, the safety requirement of rotor-body coupling stability is ensured, an accurate and reliable calculation method is provided for the rotor-body coupling stability design, the frequency design can be more accurately carried out in each stage of type design, and the present application has high universality and engineering application value.

[0045] The present application will be further described in detail below in combination with the accompanying drawings of the embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 It is a flowchart of the rapid evaluation method for helicopter rotor-body coupling stability frequency design of the present application.

[0047] Figure 2 A rotating speed-frequency diagram before optimization for applying the fast evaluation method of the helicopter rotor body coupling stability frequency design of the application;

[0048] Figure 3 A rotating speed-frequency diagram after optimization for applying the fast evaluation method of the helicopter rotor body coupling stability frequency design of the application. DETAILED DESCRIPTION

[0049] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described below in a more detailed manner with reference to the accompanying drawings in the embodiments of the present application. Identical or similar numerals in the accompanying drawings represent identical or similar elements or elements with identical or similar functions throughout. The described embodiments are part of the embodiments of the present application, but not all the embodiments of the present application.

[0050] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present application, but cannot be understood as a limitation of the present application.

[0051] Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0052] The accompanying drawings will be described below in conjunction with the embodiments of the present application. Figures 1-3 The embodiments of the present application will be described in detail.

[0053] Embodiment 1

[0054] The present application discloses a fast evaluation method of helicopter rotor body coupling stability frequency design, which comprises the following steps:

[0055] Step 1: providing parameters of a rotor system; the parameters of the rotor system include rated rotating speed of the rotor, radius of the blade, mass moment of inertia of a piece of blade, rotational inertia of a piece of blade, elastic line stiffness of a hydraulic pendulum damper, distance from the hub center to the pendulum hinge, distance from the pendulum hinge to the pendulum damper.

[0056] Step 2: calculating characteristic frequency of the rotor; specifically comprising the following steps:

[0057] Step 21: converting the elastic line stiffness of the hydraulic pendulum damper of the rotor system into pendulum angle stiffness, and the specific calculation formula is as follows:

[0058] ;

[0059] wherein, represents the pendulum angle stiffness, ; represents the elastic line stiffness of the hydraulic pendulums, represents the distance from the pitch hinge to the pendulum,

[0060] Step 22: Calculate the rotor system whirling retrograde mode frequencies at different rotor speeds according to the whirling stiffness and other rotor system parameters, the specific calculation formula is as follows:

[0061] ;

[0062] wherein, represents the first order whirling retrograde mode frequency, ; represents the distance from the hub center to the whirling hinge, ; represents the mass moment of inertia of a blade around the whirling hinge, ; represents the moment of inertia of a blade around the whirling hinge, ; represents the rotor speed frequency, ; the specific calculation formula is as follows:

[0063] ;

[0064] wherein, represents the rotor speed, , is the measured value, the rotor speed frequency is positively correlated with the rotor speed , when the rotor speed takes different values, different rotor system whirling retrograde mode frequencies are calculated.

[0065] Step 3: Provide the body modal frequency; specifically:

[0066] According to the full machine dynamic characteristic model, the modal of the machine body on the landing gear is calculated to obtain the frequency of the machine body on the landing gear, including the heading first order frequency, the lateral first order frequency, the heading second order frequency, and the lateral second order frequency.

[0067] Step 4: Draw the speed-frequency graph; specifically including the following steps:

[0068] Step 41: Draw the curve of the whirling retrograde mode frequency changing with the rotor speed using the rotor whirling retrograde mode frequencies obtained in step 2;

[0069] Step 42: Draw the curve of the four body modal frequencies changing with the rotor speed using the four body modal frequencies of step 3;

[0070] ​​Step 43: Draw a vertical line corresponding to the rated rotor speed;

[0071] Step 44: Draw a vertical line corresponding to the rotor speed stability margin requirement.

[0072] Step 5: Determine the resonance center; specifically:

[0073] According to the frequency-rotor speed diagram obtained in step 4, the intersection point of the whirling back type frequency curve and the four airframe modal frequency curves is the resonance center.

[0074] Step 6: Determine the rotor speed stability margin; specifically including the following steps:

[0075] Step 61: According to the resonance center obtained in step 5, the rotor speed stability margin is calculated through the resonance center rotor speed, and the specific calculation formula is as follows:

[0076] ;

[0077] Where, represents the rotor speed stability margin; represents the resonance center rotor speed, ; represents the rated rotor speed, ;

[0078] Step 62: Determine whether the rotor speed stability margin meets the requirements, and the judgment condition is as follows:

[0079] When the rotor speed stability margin is greater than 15% (the rotor speed stability margin is a set value, set according to the specific design requirements), it meets the design requirements, and the evaluation is completed;

[0080] When the rotor speed stability margin is less than or equal to 15%, it does not meet the design requirements, and frequency optimization design is required.

[0081] Another understanding of the judgment condition: combined with the attached Figure 2 , any one of the four intersection points (resonance center) falls within the rotor speed stability margin range, which does not meet the design requirements; combined with the attached Figure 3 , all four intersection points (resonance center) fall outside the rotor speed stability margin range, which meets the design requirements.

[0082] Step 7: If it does not meet the requirements, perform frequency optimization design, repeat steps 1-6 until the rotor speed stability margin meets the design requirements.

[0083] The frequency optimization design specifically includes the following steps:

[0084] Step 71: one or several of the parameters of the rotor system hydraulic pendulum damper pendulum elastic line stiffness, pendulum hinge to pendulum damper distance, hub center to pendulum hinge distance, mass moment of inertia of the blade around the pendulum hinge and rotational inertia are optimized and designed, and the retreating frequency of the rotor system pendulum is changed;

[0085] Step 72: the parameters of the improved landing gear stiffness and the body elastic stiffness are optimized and designed, and the body modal frequency is changed.

[0086] Embodiment 2

[0087] In order to prove the applicability and effectiveness of the present application, the rotor body coupling stability frequency of a certain type of helicopter is designed by using the present application, and the effectiveness of the rapid evaluation method of the present application is proved.

[0088] The present application provides a rapid evaluation method for the design of the rotor body coupling stability frequency of a helicopter, and the steps are as follows: Figure 1 , and are as follows:

[0089] S1: providing the parameters of the rotor system of a certain type of helicopter

[0090] The parameters of the rotor system include the rated speed of the rotor , the radius r of the blade, the mass moment of inertia of a piece of blade around the pendulum hinge , the rotational inertia of a piece of blade , the pendulum elastic line stiffness of the hydraulic pendulum damper , the distance from the hub center to the pendulum hinge , the distance from the pendulum hinge to the pendulum damper and the like, and the example results are as follows:

[0091] Symbol Units Design Value Comments 1000 Rated operating speed 0.2 Hub center to edgewise hinge distance 0.15 Edgewise hinge to roll damper distance 8.0 Mass moment of inertia of blade about edgewise hinge 7.5 Moment of inertia of blade about edgewise hinge 1100 Roll damper edgewise spring rate

[0092] S2: calculating the characteristic frequency of the rotor

[0093] S21: converting the pendulum elastic line stiffness of the hydraulic pendulum damper of the rotor system into the pendulum angle stiffness, and the specific calculation formula is as follows:

[0094] ;

[0095] Wherein, represents the pendulum angle stiffness, ; represents the pendulum elastic line stiffness of the hydraulic pendulum damper, ; represents the distance from the pendulum hinge to the pendulum damper, ;

[0096] S22: according to the pendulum angle stiffness and other rotor system parameters, the rotor system whirling retrograde mode frequencies at different rotor speeds are calculated, and the specific calculation formula is as follows:

[0097] ;

[0098] wherein, represents the first-order whirling retrograde mode frequency, ; represents the distance from the hub center to the whirling hinge, ; represents the mass moment of inertia of a blade around the whirling hinge, ; represents the moment of inertia of a blade around the whirling hinge, ; represents the rotor speed frequency, ; the specific calculation formula is as follows:

[0099] ;

[0100] wherein, represents the rotor speed, , the rotor speed frequency is measured, and the rotor speed is positively correlated with the rotor speed . When the rotor speed takes different values, different rotor system whirling retrograde mode frequencies are calculated. In this embodiment, the rotor speed takes the value of 1000 .

[0101] S3: Provide the modal parameters of the body of a certain type of helicopter

[0102] According to the full-machine dynamic characteristic model, the modal of the body on the landing gear is calculated to obtain the frequency of the body of the type of helicopter on the landing gear; including the first-order frequency in the heading direction, the second-order frequency in the heading direction and the first-order frequency in the lateral direction, the second-order frequency in the lateral direction, and the results are as follows:

[0103] Mode name Lateral first order Yaw first order Lateral second order Yaw second order Frequency / Hz 5.62 6.03 6.30 7.24

[0104] S4: Draw the speed-frequency graph

[0105] S41: using the rotor whirling retrograde mode frequency obtained in S2, draw the curve of the whirling retrograde mode frequency changing with the rotor speed;

[0106] S42: using the body modal frequency of S3, draw the curve of the body modal frequency changing with the rotor speed;

[0107] S43: draw the vertical line corresponding to the rated rotor speed;

[0108] S44: Draw the vertical line corresponding to the speed stability margin requirement.

[0109] The speed-frequency diagram obtained is shown in Figure 2 .

[0110] S5: Determine the resonance center

[0111] According to the frequency-speed diagram obtained by S4, the intersection of the swing-back frequency curve and the body modal frequency curve is obtained, which is the resonance center. Its speed is 1078 .

[0112] S6: Determine the speed stability margin

[0113] S61: The resonance center speed is 1078 according to S5 , the speed stability margin is calculated to be 7.8%, and the specific calculation formula is as follows:

[0114] ;

[0115] in, Indicates the speed stability margin; represents the resonance center speed, ; Indicates the rated rotor speed, ;

[0116] S62: Determine whether the speed stability margin does not meet the design requirements. The judgment conditions are as follows:

[0117] When the speed stability margin is greater than 15%, the design requirements are met and the evaluation ends;

[0118] When the speed stability margin is less than or equal to 15%, it does not meet the design requirements and frequency optimization design is required.

[0119] S7: Frequency Optimized Design

[0120] S71: Optimize the design of the rotor system hydraulic damper shimmy elastic line stiffness and increase the rotor system hydraulic damper shimmy elastic line stiffness to 1200 ;

[0121] S72: Optimize the design of parameters such as the improved landing gear stiffness and airframe elastic stiffness, and increase the lowest-order airframe modal frequency (the lowest of the first-order and second-order heading frequencies and the first-order and second-order lateral frequencies) to 5.65 Hz.

[0122] S8: Conclusion

[0123] Repeat steps S1 to S6 until the speed stability margin after frequency optimization design meets the design requirements.

[0124] The frequency design rapid evaluation method obtained by the application has engineering requirement precision and can be applied to rapid evaluation of the helicopter rotor body coupling frequency design.

[0125] Embodiment 3

[0126] The application provides an electronic device, comprising a processor and a memory storing a computer program; in actual application, the number of processors can be one or more; the number of memories can be one or more. When the processor runs the computer program, the rapid evaluation method applied to the electronic device is realized.

[0127] The memory can be a volatile memory or a non-volatile memory, and can also include both volatile and non-volatile memories. The non-volatile memory can be a Read Only Memory (ROM), a Programmable Read-Only Memory (PROM), an Erasable Programmable Read-Only Memory (EPROM), an Electrically Erasable Programmable Read-Only Memory (EEPROM), a ferromagnetic random access memory (FRAM), a Flash memory, a magnetic surface memory, an optical disc, or a Compact Disc Read-Only Memory (CD-ROM). The magnetic surface memory can be a disk memory or a tape memory. The volatile memory can be a Random Access Memory (RAM) used as an external cache. By way of example and not limitation, many forms of RAM can be used, such as Static Random Access Memory (SRAM), Synchronous Static Random Access Memory (SSRAM), Dynamic Random Access Memory (DRAM), Synchronous Dynamic Random Access Memory (SDRAM), Double Data Rate Synchronous Dynamic Random Access Memory (DDR SDRAM), Enhanced Synchronous Dynamic Random Access Memory (ESDRAM), Sync Link Dynamic Random Access Memory (SLDRAM), and Direct Rambus Random Access Memory (DRRAM).

[0128] The memory of the present application is used to store various types of data to support the operation of the electronic device. Examples of these data include: any computer programs used to operate on the electronic device, such as operating systems and application programs; contact data; phonebook data; messages; pictures; videos; etc. Among them, the operating system contains various system programs, such as framework layer, core library layer, driver layer, etc., for implementing various basic services and processing hardware-based tasks. The application program can contain various application programs, such as media player (Media Player), browser (Browser), etc., for implementing various application services. Here, the program for implementing the method of the embodiment of the present application can be contained in the application program.

[0129] Embodiment 4

[0130] The present application also provides a computer storage medium, which stores a computer program, and the computer storage medium can be a ferromagnetic random access memory (FRAM), a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a flash memory, a magnetic surface memory, an optical disc, a compact disc read-only memory (CD-ROM), or the like. The computer storage medium can also be various devices including one or any combination of the above memories, such as a mobile phone, a computer, a tablet device, a personal digital assistant, etc. The computer program stored in the computer storage medium is run by a processor to implement the fast evaluation method applied to the above electronic device.

[0131] Up to now, the purpose of the present application is achieved.

[0132] The above is only a preferred embodiment of the present application, and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for fast evaluation of the helicopter rotor mast coupling stability frequency design, characterized in that, The method comprises the following steps: Step 1: obtaining parameters of the rotor system; Step 2: calculating the rotor system's lagging frequency at different rotor speeds using the parameters, specifically as follows: Converting rotor system hydraulic pendulation elastomer line stiffness to pendulation angle stiffness : ； wherein, represents the pitch angle stiffness, ; represents the pitch elastic wire stiffness of the hydraulic pitch damper, ; represents the pitch hinge to pitch damper distance, ; According to the above described pitch stiffness and other rotor system parameters, the rotor system pitch back mode frequencies are calculated for different rotor speeds, in particular: ； wherein represents the first order lagging mode frequency, ; represents the distance from the hub center to the lagging hinge, ; represents the mass moment of inertia of a blade about the lagging hinge, ; represents the moment of inertia of a blade about the lagging hinge, ; represents the rotor speed frequency, , the specific calculation formula is: ; wherein, represents the rotor speed, ; Step 3: calculating four kinds of modal frequencies of the machine body on the landing gear using the full machine model; Step 4: drawing a rotor speed-frequency graph, including: drawing a curve of the lagging frequency changing with the rotor speed, drawing four curves of the machine body modal frequencies changing with the rotor speed respectively, drawing a vertical line corresponding to the rated rotor speed, and drawing a vertical line corresponding to the rotor speed stability margin requirement; Step 5: determining the resonance center, i.e. the intersection point of the lagging frequency curve and the four machine body modal frequency curves; Step 6: judging whether the resonance center falls within the range defined by the rotor speed stability margin vertical line, if not, the evaluation is qualified; Step 7: if so, the evaluation is unqualified, and frequency optimization design is required, and steps 1-6 are repeated until the design requirements are met.

2. The method of claim 1, wherein: The parameters of the rotor system include the rated rotor speed, the mass moment of inertia of a blade, the rotational inertia of a blade, the lagging elastic line stiffness of the hydraulic lag damper, the distance from the hub center to the lagging hinge, and the distance from the lagging hinge to the lag damper.

3. The method of claim 1, wherein: Step 3 specifically comprises: calculating the modal of the machine body on the landing gear according to the full machine dynamic characteristic model to obtain the frequency of the machine body on the landing gear, including the heading first-order frequency, the lateral first-order frequency, the heading second-order frequency, and the lateral second-order frequency.

4. The method of claim 1, wherein: The judgment of whether the design requirements are met can also be: According to the frequency-rotor speed graph obtained in step 4, the resonance center speed is obtained; The rotor speed stability margin is calculated through the resonance center speed, and the specific calculation formula is as follows: ； wherein, represents a rotational speed stability margin; represents a resonance center rotational speed, ; represents a rotor rated rotational speed, ; Judge whether the rotor speed stability margin meets the requirements, and the judgment condition is as follows: When the rotor speed stability margin is greater than 15%, the design requirements are met, and the evaluation is ended; When the rotor speed stability margin is less than or equal to 15%, the design requirements are not met, and frequency optimization design is required.

5. A method of rapid evaluation of the coupled stability frequency of a helicopter rotor mast according to claim 4, characterized in that, The frequency optimization design specifically comprises the following steps: Step 71: optimizing the design of the lagging elastic line stiffness of the rotor system hydraulic lag damper, the distance from the lagging hinge to the lag damper, the distance from the hub center to the lagging hinge, the mass moment of inertia of the blade around the lagging hinge, and the rotational inertia of the blade to change the rotor system's lagging frequency; Step 72: optimizing the design of the improved landing gear stiffness and machine body elastic stiffness parameters to change the machine body modal frequency.

6. An electronic device, comprising: It comprises: A processor and a memory storing a computer program, when the processor runs the computer program, the rapid evaluation method of any one of claims 1-5 is realized.

7. A computer storage medium, characterized in that A computer program is stored, and when the computer program is executed by a processor, the rapid evaluation method of any one of claims 1-5 is realized.

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