Aero-engine vibration measurement sensor support frequency calculation method

Abstract

The application belongs to the technical field of aero-engines, and particularly relates to a frequency calculation method of an aero-engine vibration measurement sensor support, which calculates a mass change rate λ of the vibration measurement sensor support and the vibration measurement sensor; when the mass change rate λ is less than or equal to a set threshold, only the natural frequency of the vibration measurement sensor support is calculated; when the mass change rate λ is greater than the set threshold, if the vibration measurement sensor is a completely symmetrical structure, a single vibration measurement sensor simplified parameter model is established; if the vibration measurement sensor is a non-completely symmetrical structure, vibration measurement sensor simplified parameter models are respectively established for all possible installation directions, and each model contains mass and the mass center position under the corresponding installation direction; a three-dimensional analysis model of the vibration measurement sensor support is established, and boundary conditions are set; the simplified parameter model is coupled with the three-dimensional analysis model of the vibration measurement sensor support to form an overall calculation model; the natural frequency of the overall calculation model is calculated, and the application guarantees the accuracy of the whole machine vibration test.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of aero-engines, and particularly relates to a frequency calculation method for a vibration sensor support of an aero-engine. BACKGROUND

[0002] Whole machine vibration performance is an important indicator for measuring the working state of an aero-engine. Usually, multiple vibration sensors are arranged at engine force casing sections to monitor the vibration of key components such as the whole engine, rotor components, stator components, bearings and the like. Due to the extremely complex structure of the engine, which is composed of multiple components such as rotors and stators, multiple frequencies of vibration are generated during operation, which is a great test for whole machine vibration testing. In order to avoid the influence of resonance of the vibration sensor support due to its natural frequency on the whole machine vibration test during the whole engine speed process, the vibration sensor support frequency needs to be accurately calculated during the vibration sensor support structure design to ensure that the natural frequency does not affect the test results. Therefore, the factors affecting the vibration sensor support frequency need to be considered comprehensively, and the vibration sensor support frequency calculation method needs to be strictly regulated to guide the vibration sensor support structure design and avoid the distortion of vibration test and false alarm events caused by the vibration sensor support design problems.

[0003] Part of the theoretical and experimental research on the vibration sensor support frequency calculation is carried out, but there is still a lack of evaluation method research on the accurate calculation of the vibration sensor support frequency, which is obviously not conducive to the vibration sensor support design and vibration test.

[0004] For the engine whole machine vibration testing system, the vibration sensor is fixed on the engine through the vibration sensor support. Due to the influence of the mass of the vibration sensor, the vibration sensor support participates in vibration, the natural frequency of the combination body decreases accordingly, and with the gradual approach of the mass of the vibration sensor and the mass of the vibration sensor support, even exceeding the mass of the vibration sensor support, the natural frequency of the combination body will decrease exponentially. At the same time, due to the influence of the mass of the vibration sensor, the center of mass of the combination body is raised or changed in other ways, and when the vibration sensor is not a completely symmetrical structure, different installation directions will produce different center of mass positions, and multiple factors will affect the natural frequency of the combination body to different degrees. The existing calculation process and method do not consider the influence of the vibration sensor parameters, and there is no accurate and reliable method for frequency calculation, which leads to inaccurate vibration sensor support frequency calculation, which cannot effectively guide the vibration sensor support design, and is not conducive to the engine vibration test and fault diagnosis. SUMMARY

[0005] In order to solve the above problems, the present application provides a vibration sensor support frequency calculation method for an aero-engine, comprising:

[0006] Step 1: Obtain the mass m of the vibration sensor support z and the mass m of the vibration sensor c ;

[0007] Step 2: Calculate the mass change rate λ of the vibration sensor support and the vibration sensor;

[0008] When the mass change rate λ is less than or equal to a set threshold value, ignore the mass of the vibration sensor and only calculate the natural frequency of the vibration sensor support;

[0009] When the mass change rate λ is greater than the set threshold value, then perform Step 3;

[0010] Step 3: Determine the symmetry of the vibration sensor structure:

[0011] If the vibration sensor is a completely symmetric structure, then a simplified parameter model of a single vibration sensor is established, including the mass m c and the center of mass position of the vibration sensor

[0012] If the vibration sensor is a non-completely symmetric structure, then a simplified parameter model of the vibration sensor is established for all possible installation directions, and each model includes the mass m c and the center of mass position of the vibration sensor in the corresponding installation direction;

[0013] Step 4: Establish a three-dimensional analysis model of the vibration sensor support and set boundary conditions;

[0014] Step 5: Couple the simplified parameter model of Step 3 with the three-dimensional analysis model of the vibration sensor support to form an overall calculation model;

[0015] Step 6: Calculate the natural frequency of the overall calculation model;

[0016] Step 7: Ensure that the natural frequency of the vibration sensor support or the natural frequency of the overall calculation model does not fall within the excitation frequency range within the engine operating speed range. Preferably, the determination of the non-completely symmetric structure in Step 3 is based on the fact that the line connecting the center of mass of the vibration sensor and the centroid of the installation surface is not parallel to the vertical line.

[0017] Preferably, the boundary conditions in Step 4 are set according to the actual fixed position and manner of the vibration sensor support on the aero-engine.

[0018] Preferably, the calculation formula of the mass change rate λ is:

[0019] λ = m c / m z × 100%.

[0020] Preferably, the set threshold value is 9.3%.

[0021] The application considers the geometric features of the vibration sensor, i.e. whether it is a completely symmetrical structure, the installation direction, identifies the mass center position of the vibration sensor, establishes one or more simplified parameter models of the vibration sensor including the mass and the mass center position, establishes a coupling relationship between the simplified parameter model and a three-dimensional analysis model of the vibration sensor support, carries out frequency calculation and analysis of the vibration sensor support under different conditions, and obtains comprehensive and accurate frequency calculation results of the vibration sensor support. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a flow chart of the frequency calculation method of the vibration sensor support of the aero-engine according to a preferred embodiment of the application. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the application clearer, the technical scheme of the embodiments of the application will be described in more detail below in combination with the drawings of the embodiments of the application. In the drawings, the same or similar reference signs represent the same or similar elements or elements with the same or similar functions throughout. The described embodiments are part of the embodiments of the application, not all of the embodiments of the application. The embodiments described below by referring to the drawings are exemplary and are intended to explain the application, and cannot be understood as a limitation of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application. The embodiments of the application will be described in detail below in combination with the drawings.

[0024] As shown in Figure 1 , the application provides a frequency calculation method of a vibration sensor support of an aero-engine, comprising:

[0025] Step 1: obtaining the mass m z of the vibration sensor support and the mass m c of the vibration sensor;

[0026] Step 2: calculating the mass variation rate λ of the vibration sensor support and the vibration sensor;

[0027] When the mass variation rate λ is less than or equal to a set threshold value, the influence of the vibration sensor mass is ignored, and only the natural frequency of the vibration sensor support is calculated;

[0028] When the mass variation rate λ is greater than the set threshold value, step 3 is performed;

[0029] Step 3: judging the symmetry of the vibration sensor structure: the judgment basis for the non-completely symmetrical structure is that the connecting line between the mass center of the vibration sensor and the shape center of the installation surface is not parallel to the plumb line.

[0030] If the vibration sensor is a fully symmetrical structure, a single vibration sensor simplified parameter model is established, including the vibration sensor mass m c and the center of mass position;

[0031] If the vibration sensor is a non-fully symmetrical structure, a vibration sensor simplified parameter model is established for all possible installation directions, and each model includes the vibration sensor mass m c and the center of mass position under the corresponding installation direction;

[0032] Step 4: Establish a three-dimensional analysis model of the vibration sensor support, and set boundary conditions;

[0033] Step 5: Coupling the simplified parameter model of step 3 with the three-dimensional analysis model of the vibration sensor support to form an overall calculation model;

[0034] Step 6: Calculate the natural frequency of the overall calculation model.

[0035] Step 7: Ensure that the natural frequency of the vibration sensor support or the natural frequency of the overall calculation model does not fall within the excitation frequency range within the engine operating speed range.

[0036] Preferably, in step 4, the boundary conditions are set according to the actual fixed position and manner of the vibration sensor support on the aero-engine.

[0037] Preferably, the calculation formula of the mass variation rate λ is:

[0038] λ=m c / m z ×100%.

[0039] Preferably, the set threshold value is 9.3%.

[0040] The set threshold value calculation method is:

[0041] The natural frequency of the vibration sensor support itself is represented as , k z is the stiffness of the vibration sensor support, and its theoretical calculation expression is:

[0042] (1)

[0043] In actual use, the vibration sensor is fixed on the vibration sensor support and almost merges with the vibration sensor support, resulting in an increase in the combined system vibration mass. At this time, the overall natural frequency of the vibration sensor support and the vibration sensor is represented as , and its theoretical calculation expression is:

[0044] (2)

[0045] The rate of change of frequency And the rate of change of mass The expression is as follows:

[0046] (3)

[0047] (4)

[0048] The arrangement can be obtained:

[0049] (5)

[0050] After considering the influence of the vibration sensor mass, the rate of change of the natural frequency of the vibration sensor support and the vibration sensor combination Should not be higher than 5%, then when the rate of change of mass Higher than 9.3%, the influence of the sensor mass on the calculation of the natural frequency of the vibration sensor support cannot be ignored.

[0051] The present application is aimed at the present situation that there is a lack of systematic and accurate vibration sensor support frequency calculation method and process in the design process of engine vibration sensor support. First, from the natural frequency calculation formula as the starting point, the influence of the vibration system vibration mass change rate on the vibration sensor support frequency change is determined. On the basis of controlling the rate of change of the natural frequency of the vibration sensor support and the sensor combination not to exceed 5%, the vibration mass change rate caused by the vibration sensor mass is given to measure whether the influence of the sensor mass needs to be considered. At the same time, the geometric structure characteristics of the sensor are considered, that is, whether it is a completely symmetrical structure, the installation direction, the mass center position of the sensor is identified, one or more vibration sensor simplified parameter models including mass and mass center position are established, the coupling relationship between the model and the three-dimensional analysis model of the vibration sensor support is established, and the frequency calculation analysis of the vibration sensor support under different conditions is carried out, so as to obtain comprehensive and accurate vibration sensor support frequency calculation results.

[0052] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any changes or replacements within the technical range disclosed in the present application can be easily thought of by those skilled in the art, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An aeroengine vibration sensor support frequency calculation method, characterized in that, Comprising: Step 1: Obtain the mass m of the vibration sensor support z and the mass m of the vibration sensor c ; Step 2: Calculate the mass change rate λ of the vibration sensor support and the vibration sensor; When the mass change rate λ is less than or equal to the set threshold, only the natural frequency of the vibration sensor support is calculated; When the mass change rate λ is greater than the set threshold, step 3 is performed; Step 3: Determine the symmetry of the vibration sensor structure: If the vibration measurement sensor is a fully symmetrical structure, a single vibration measurement sensor simplified parameter model is established, including the mass m c and the center of mass position; If the vibration measurement sensor is not a fully symmetrical structure, a simplified parameter model of the vibration measurement sensor is established for all possible installation directions, and each model includes the mass m c of the vibration measurement sensor and the mass center position under the corresponding installation direction. Step 4: Establish a three-dimensional analysis model of the vibration sensor support and set boundary conditions; Step 5: Coupling the simplified parameter model of step 3 with the three-dimensional analysis model of the vibration sensor support to form an overall calculation model; Step 6: Calculate the natural frequency of the overall calculation model.

2. The aeroengine vibration pickup sensor support frequency calculation method of claim 1, wherein, In step 3, the determination of the non-complete symmetric structure is based on that the line connecting the center of mass of the vibration sensor and the shape center of the mounting surface is not parallel to the plumb line.

3. The aeroengine vibration pickup sensor support frequency calculation method of claim 1, wherein, In step 4, the boundary conditions are set according to the actual fixed position and method of the vibration sensor support on the aero-engine.

4. The aeroengine vibration pickup sensor support frequency calculation method of claim 1, wherein, Further comprising step 7: Ensure that the natural frequency of the vibration sensor support or the natural frequency of the overall calculation model does not fall within the excitation frequency range within the engine operating speed range.

5. The aeroengine vibration pickup sensor support frequency calculation method of claim 1, wherein, The calculation formula of the mass change rate λ is: λ = m c / m z x 100%.

6. The aeroengine vibration pickup sensor support frequency calculation method of claim 1, wherein, The set threshold value is 9.3%.

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