Method for judging damping ratio influence factors of multi-contact-surface combined rotor assembly

Abstract

The invention discloses a multi-contact-surface combined rotor assembly damping ratio influence factor determination method, which comprises the following steps: simplifying a rotor assembly, extracting key contact surfaces of the rotor assembly, establishing a rotor assembly simplified structure model, and determining control factors in a damping ratio measurement test. By controlling and changing the size of the contact force of one contact surface or changing the material characteristics of the contact surface, a damping ratio test result is obtained by mutual verification of a single sensor hammering attenuation method and a frequency excitation attenuation method, and then key factors influencing and controlling the damping ratio of the rotor assembly in the form are judged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rotor assembly, in particular to a method for determining influencing factors of damping ratio of multi-contact-surface combined rotor assembly. BACKGROUND

[0002] Rotor assembly is one of the key components of liquid rocket engine turbine pump, single-disk turbine rotor assembly is widely used in the field of turbine pump and gas turbine, etc. The single-disk turbine rotor assembly has small volume and light weight, but due to the inherent properties of structural design, the damping ratio of the single-disk turbine rotor assembly is very small, and it needs to be combined with the shaft to form a combined rotor assembly through special design, so as to improve the damping ratio of the rotor assembly by the friction surface between the various parts of the rotor, thereby improving the stability and robustness of the rotor assembly during operation.

[0003] The prior art basically regards the rotor assembly as a whole unit when studying the rotor damping ratio, and the proportion of the damping ratio between the various parts in the total damping ratio is unknown. SUMMARY

[0004] The technical problem solved by the present application is to overcome the shortcomings of the prior art and provide a method for determining influencing factors of damping ratio of multi-contact-surface combined rotor assembly, so as to obtain the contribution degree of different contact surfaces of the multi-contact-surface combined rotor assembly to the damping ratio and determine the key influencing factors of controlling the damping ratio of the multi-contact-surface combined rotor assembly.

[0005] The technical solution of the present application is a method for determining influencing factors of damping ratio of multi-contact-surface combined rotor assembly, comprising:

[0006] Extract the key contact surface of the rotor assembly and establish a simplified structure model of the rotor assembly; the simplified structure model comprises a shaft test piece, a turbine disk test piece, bolts, damping sheets and nuts; the shaft test piece and the turbine disk test piece are coaxially installed, one end of the shaft test piece and the turbine disk test piece is provided with an axial hole, the protruding part at the center of the turbine disk test piece is inserted into the axial hole, the edge of the end part of the shaft test piece is fixedly connected with the turbine disk test piece through a plurality of bolts and nuts, and the damping sheet is arranged on the contact surface between the edge and the turbine disk test piece;

[0007] Determine the control factors in the damping ratio measurement test; including: factor 1: clearance fit or interference fit with different interference amounts between the axial hole of the shaft test piece and the protruding part of the turbine disk test piece; factor 2: clearance fit or interference fit with different interference amounts between the bolts and the shaft test piece and the turbine disk test piece; factor 3: the fitting degree of the contact plane between the edge of the end part of the shaft test piece and the turbine disk test piece; factor 4: the damping ratio of the damping sheet;

[0008] Keeping other factors constant, under a certain factor, change the value of that factor and carry out damping ratio measurement tests one by one; each damping ratio measurement test corresponds to a value of that factor, and the damping ratio of the rotor assembly under that factor value condition is obtained; repeat the above process to obtain the damping ratio range of the rotor assembly corresponding to each factor.

[0009] By comparing and analyzing the damping ratio ranges of rotor components corresponding to each factor, the factors most sensitive to the rotor components are identified.

[0010] Furthermore, when conducting the damping ratio measurement test, if factor 1 is changed, the interference between shaft test piece 1 and turbine disk test piece 2 is controlled by adjusting the diameter of the shaft hole of the shaft test piece; if factor 2 is changed, the interference between the bolt and the shaft test piece and the turbine disk test piece is controlled by adjusting the bolt rod diameter; if factor 3 is changed, the degree of contact between the end edge of the shaft test piece and the contact plane of the turbine disk test piece is controlled by adjusting the tightening torque of the nut; if factor 4 is changed, the damping ratio of the damping plate is controlled by adjusting the material of the damping plate.

[0011] Furthermore, for a single damping ratio measurement test, two methods, the hammer impact attenuation method and the frequency excitation attenuation method, are used to obtain the rotor assembly damping ratio respectively. When the difference between the rotor assembly damping ratios measured by the hammer impact attenuation method and the frequency excitation attenuation method is less than a preset percentage, the result is considered accurate. Finally, the average value of the rotor assembly damping ratio obtained by the two measurement methods is taken.

[0012] Furthermore, the hammer impact attenuation method employs a single-sensor measurement approach, attaching only one accelerometer to the rotor assembly, striking different points to measure the attenuation response of the rotor assembly, fitting the attenuation curve to obtain the damping coefficient, and then obtaining the damping ratio.

[0013] Furthermore, the fitted attenuation curve equation is y=a+b*exp(-c*x), where y represents the vibration amplitude, x represents time, c is the damping coefficient of the rotor assembly, and a and b are the fitting coefficients of the attenuation curve.

[0014] Furthermore, the damping ratio is obtained by the formula ζ=c / (f0*2*π), where ζ is the damping ratio and f0 is the natural frequency of the rotor assembly.

[0015] Furthermore, the excitation attenuation method uses an exciter to excite the rotor assembly at a first-order frequency. After stabilization, the exciter is turned off, and the attenuation response of the rotor assembly is measured. The damping coefficient is obtained by fitting the attenuation curve, and then the damping ratio is obtained.

[0016] Furthermore, when exciting the rotor assembly, the rotor assembly is suspended vertically, and the exciter is placed directly below the turbine disk test piece.

[0017] Furthermore, the bolts and nuts are evenly distributed along the circumference.

[0018] The advantages of this invention compared to the prior art are:

[0019] (1) The present invention simplifies complex rotor components into rotor test pieces with relatively simple structure and simple control factors, which greatly reduces the processing cycle and processing cost of test products.

[0020] (2) Compared with the overall determination of the damping ratio of the rotor assembly, this invention provides a method for determining the influence of a certain factor on the damping ratio of a multi-contact surface combined rotor. A total of four possible factors affecting the damping ratio of the multi-contact surface combined rotor were extracted, and each factor was analyzed separately to obtain the factor that is most sensitive to the damping ratio.

[0021] (3) This invention employs a single-sensor measurement method for impact attenuation, i.e., an accelerometer is attached to the test piece, and impacts are performed at different points to measure the attenuation response of the test piece. The damping ratio is determined by fitting the attenuation curve of the results. Compared with the multi-sensor measurement method, the turbine disk has less added mass, and the measured mode shape, frequency, and damping ratio are closer to the actual product situation.

[0022] (4) The present invention uses two methods, hammer impact attenuation method and frequency excitation attenuation method, to verify each other for damping test, and the test results are more accurate. Attached Figure Description

[0023] Figure 1 This is a flowchart of the method of the present invention;

[0024] Figure 2 Front view of the multi-contact surface combined rotor test piece;

[0025] Figure 3 Rear view of the multi-contact surface combined rotor test piece;

[0026] Figure 4 Cross-sectional view of the multi-contact surface combined rotor test piece;

[0027] Figure 5 Test diagrams for the invention of multi-contact surface combined rotor hammer attenuation method and excitation attenuation method. Detailed Implementation

[0028] To better understand the technical solution of the present invention, the specific embodiments of the present invention are described below.

[0029] The method for determining the influencing factors of the damping ratio of multi-contact surface combined rotor assembly proposed in this invention, such as... Figure 1 As shown, it includes the following steps:

[0030] (1) Extract the key contact surfaces of the rotor assembly and establish a simplified structural model of the rotor assembly.

[0031] like Figures 2 to 4 As shown, the simplified structural model of the rotor assembly includes a shaft test piece 1, a turbine disk test piece 2, bolts 3, damping plates 4, and nuts 5. The shaft test piece 1 and turbine disk test piece 2 are coaxially mounted. The end of the shaft test piece 1 that connects to the turbine disk test piece 2 has a central hole. The protrusion at the center of the turbine disk test piece 2 is inserted into the central hole. The edge of the end of the shaft test piece 1 is fixedly connected to the turbine disk test piece 2 by several bolts 3 and nuts 5. The damping plates 4 are located on the contact surface between the edge and the turbine disk test piece 2. A suspension hole 5 is provided at the center of the top of the shaft test piece 1, and eight bolts 3 and nuts 6 are evenly arranged circumferentially.

[0032] (2) Determine the control factors in the damping ratio measurement test

[0033] The control factors specifically include: Factor 1: the shaft test piece 1 shaft hole and the turbine disk test piece 2 protrusion are clearance fit or interference fit with different degrees of interference; Factor 2: the bolt 3 is clearance fit or interference fit with different degrees of interference between the shaft test piece 1 and the turbine disk test piece 2; Factor 3: the degree of contact between the end edge of the shaft test piece 1 and the contact plane of the turbine disk test piece 2; Factor 4: the damping ratio of the damping plate 4.

[0034] (3) Conduct damping ratio measurement tests

[0035] During the experiment, other factors were kept constant. Under a certain factor, the value of that factor was changed, and a damping ratio measurement experiment was carried out. For a factor value, a rotor assembly damping ratio was obtained. The above process was repeated to obtain the damping ratio range corresponding to each factor.

[0036] Specifically, before the experiment, refer to Figure 5 As shown, the test piece is vertically suspended by an elastic rope 7 and a lifting ring 8 through a suspension hole 5 on the shaft. The exciter 9 is located directly below the turbine disk test piece 2, and the vibration amplitude of the turbine disk is measured by an acceleration sensor 10.

[0037] When conducting the damping ratio measurement test, for factor 1, the interference between shaft test piece 1 and turbine disk test piece 2 is controlled by adjusting the diameter of the shaft hole of shaft test piece 1; for factor 2, the interference between bolt 3 and shaft test piece 1 and turbine disk test piece 2 is controlled by adjusting the diameter of bolt 3; for factor 3, the degree of contact between the end edge of shaft test piece 1 and turbine disk test piece 2 is controlled by adjusting the tightening torque of nut 6; for factor 4, the damping ratio of damping plate 4 is controlled by adjusting the material of damping plate 4.

[0038] For each damping ratio measurement test, two methods, the hammer impact attenuation method and the frequency excitation attenuation method, were used to verify each other; and the positions of the hammer impact point, accelerometer, exciter and laser vibrometer remained unchanged in each test.

[0039] The hammer-impact attenuation method employs a single-sensor measurement approach. Only one accelerometer is attached to the rotor assembly, and hammering is performed at different points to measure the attenuation response of the rotor assembly. The damping coefficient is obtained by fitting the attenuation curve, and subsequently, the damping ratio is calculated. The fitted attenuation curve equation is y = a + b * exp(-c * x), where y represents the vibration amplitude, x represents time, c is the damping coefficient of the rotor assembly, and a and b are the attenuation curve fitting coefficients. The damping ratio is obtained using the formula ζ = c / (f0 * 2 * π), where ζ is the damping ratio, and f0 is the natural frequency of the rotor assembly.

[0040] The vibration damping method involves obtaining the first-order frequency through frequency testing, then exciting the specimen at that frequency using a vibrator. After stabilization, the vibration response of the specimen is measured and then turned off to obtain the damping response. The damping coefficient is obtained by fitting the damping curve of the result, and the damping ratio of the structure can then be calculated.

[0041] If the difference between the results obtained by the hammer impact attenuation method and the frequency excitation attenuation method is less than 5%, the result is considered accurate, and the final result is the average of the two test results.

[0042] (4) Finally, by comparing and analyzing the damping ratio ranges corresponding to each element, the factors most sensitive to the multi-contact surface combined rotor assembly are identified.

[0043] It is understood that this invention has been described through embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of this invention. Furthermore, under the teachings of this invention, these features and embodiments can be modified to adapt to specific circumstances without departing from the spirit and scope of this invention. Therefore, this invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are considered part of this invention.

[0044] Within the scope of protection provided by the invention.

[0045] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A method for determining the influencing factors of the damping ratio of a multi-contact surface combined rotor assembly, characterized in that, include: The key contact surfaces of the rotor assembly are extracted, and a simplified structural model of the rotor assembly is established. The simplified structural model includes a shaft test piece (1), a turbine disk test piece (2), bolts (3), damping plates (4), and nuts (6). The shaft test piece (1) and the turbine disk test piece (2) are coaxially installed. The end of the shaft test piece (1) that is connected to the turbine disk test piece (2) has a shaft hole. The protrusion in the center of the turbine disk test piece (2) is inserted into the shaft hole. The edge of the end of the shaft test piece (1) is fixedly connected to the turbine disk test piece (2) by several bolts (3) and nuts (6). The damping plate (4) is provided on the contact surface between the edge and the turbine disk test piece (2). The control factors in the damping ratio measurement test are determined, including: Factor 1: whether the shaft test piece (1) and the turbine disk test piece (2) protrusion are clearance fit or interference fit with different degrees of interference; Factor 2: whether the bolt (3) is clearance fit or interference fit with different degrees of interference between the shaft test piece (1) and the turbine disk test piece (2); Factor 3: the degree of contact between the end edge of the shaft test piece (1) and the contact plane of the turbine disk test piece (2); Factor 4: the damping ratio of the damping plate (4); Keeping other factors constant, under a certain factor, change the value of that factor and carry out damping ratio measurement tests one by one; each damping ratio measurement test corresponds to a value of that factor, and the damping ratio of the rotor assembly under that factor value condition is obtained; repeat the above process to obtain the damping ratio range of the rotor assembly corresponding to each factor. By comparing and analyzing the damping ratio ranges of rotor components corresponding to each factor, the factors most sensitive to the rotor components are identified.

2. The method for determining the influencing factors of the damping ratio of a multi-contact surface combined rotor assembly according to claim 1, characterized in that: When conducting a damping ratio measurement test, if factor 1 is changed, the interference between shaft test piece 1 and turbine disk test piece 2 is controlled by adjusting the diameter of the shaft hole of shaft test piece (1); if factor 2 is changed, the interference between bolt (3) and shaft test piece (1) and turbine disk test piece (2) is controlled by adjusting the rod diameter of bolt (3); if factor 3 is changed, the degree of contact between the end edge of shaft test piece (1) and turbine disk test piece (2) is controlled by adjusting the tightening torque of nut (6); if factor 4 is changed, the damping ratio of damping plate (4) is controlled by adjusting the material of damping plate (4).

3. The method for determining the influencing factors of the damping ratio of a multi-contact surface combined rotor assembly according to claim 1, characterized in that: For a single damping ratio measurement test, two methods, hammer impact attenuation method and frequency excitation attenuation method, are used to obtain the damping ratio of the rotor assembly. When the difference between the damping ratio of the rotor assembly measured by the hammer impact attenuation method and the frequency excitation attenuation method is less than a preset percentage, the result is considered accurate. Finally, the average value of the damping ratio of the rotor assembly obtained by the two measurement methods is taken.

4. The method for determining the influencing factors of the damping ratio of a multi-contact surface combined rotor assembly according to claim 3, characterized in that: The hammer-impact attenuation method uses a single-sensor measurement approach. Only one accelerometer is attached to the rotor assembly, and hammering is performed at different points to measure the attenuation response of the rotor assembly. The damping coefficient is obtained by fitting the attenuation curve, and then the damping ratio is obtained.

5. The method for determining the influencing factors of the damping ratio of a multi-contact surface combined rotor assembly according to claim 4, characterized in that: The fitted damping curve equation is y = a + b * exp(-c * x), where y represents the vibration amplitude, x represents time, c is the damping coefficient of the rotor assembly, and a and b are the damping curve fitting coefficients.

6. The method for determining the influencing factors of the damping ratio of a multi-contact surface combined rotor assembly according to claim 5, characterized in that: The damping ratio is obtained by the formula ζ=c / (f0*2*π), where ζ is the damping ratio and f0 is the natural frequency of the rotor assembly.

7. The method for determining the influencing factors of the damping ratio of a multi-contact surface combined rotor assembly according to claim 3, characterized in that: The excitation attenuation method uses an exciter to excite the rotor assembly at a first-order frequency. After stabilization, the exciter is turned off, and the attenuation response of the rotor assembly is measured. The damping coefficient is obtained by fitting the attenuation curve, and then the damping ratio is obtained.

8. The method for determining the influencing factors of the damping ratio of a multi-contact surface combined rotor assembly according to claim 1, characterized in that: When the rotor assembly is vibrated, the rotor assembly is suspended vertically and the vibrator (9) is placed below the turbine disk test piece (2).

9. The method for determining the influencing factors of the damping ratio of a multi-contact surface combined rotor assembly according to claim 1, characterized in that: Bolts (3) and nuts (6) are evenly distributed along the circumference.

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