A bearing life-based fulcrum damper oil film gap selection method

Abstract

The application provides a fulcrum damper oil film gap selection method based on bearing life, comprising the following steps: S1, calculating bearing load based on engine bearing life; S2, establishing an engine bearing-damper-rotor system dynamics model to calculate the maximum eccentricity e of the bearing; S3, calculating the damper oil film gap value c according to the maximum eccentricity e of the bearing by using the formula c=e / ε, wherein ε is a dimensionless parameter. The application associates the selection of the oil film gap with the bearing life, so that the selected oil film gap can meet the design requirements of the bearing life, thereby avoiding irreversible damage such as blade rubbing and even rotor support collapse on the bearing.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of aero-engines and gas turbines, and relates to a pivot damper design technology, in particular to a pivot damper oil film gap selection method based on bearing life. BACKGROUND

[0002] The pivot damper is a common vibration reduction structure in high-performance rotating machinery such as aero-engines, which changes the stiffness and damping parameters of the pivot position to improve the dynamic characteristics of the rotor system, achieve vibration reduction, reduce the transmission force of the support, and further improve the bearing life and durability.

[0003] The main part of the pivot damper is an oil film outer ring and an oil film journal, and an oil film gap is formed between the two. When the rotor appears lateral vibration, the oil film journal produces planar motion and extrudes the oil film, thereby playing a role in vibration reduction. The parameter affecting the damping effect of the damper mainly depends on the oil film gap c.

[0004] At present, the damping parameter is generally selected by experience, and the oil film gap c is mostly selected by using the gap design experience value, that is, 2c / D (2 times the oil film radius gap / journal diameter), and the selected value is about 1.0‰-5.0‰. However, for the pivot damper design of high-temperature and high-speed rotors, it is impossible to guarantee the design requirements of bearing life by relying on experience to determine the oil film gap c, which will cause irreversible damage to the bearing, such as blade rubbing, and even the risk of rotor support collapse. SUMMARY

[0005] The purpose of the present application is to design a pivot damper oil film gap selection method based on bearing life, which correlates the selection of the oil film gap with the bearing life, so as to ensure that the selected oil film gap can meet the design requirements of bearing life, thereby avoiding irreversible damage to the bearing, such as blade rubbing and even rotor support collapse.

[0006] The technical scheme for achieving the purpose of the application is as follows: a pivot damper oil film gap selection method based on bearing life, comprising the following steps:

[0007] S1, calculating the bearing load based on the engine bearing life;

[0008] S2, establishing a system dynamics model of the engine bearing-damper-rotor, and calculating the maximum eccentricity e at the bearing;

[0009] S3, calculating the damper oil film gap value c according to the maximum eccentricity e of the bearing, and ε is a dimensionless parameter.

[0010] Further, the method for calculating the bearing load based on the bearing life comprises:

[0011] S101. Determine the engine bearing life based on the engine bearing type;

[0012] S102. Establish the relationship equation between bearing load and engine bearing life, engine speed, and basic load, link engine bearing life with rotor system dynamic design, and calculate bearing load.

[0013] Furthermore, in step S102, the relational equation is:

[0014] bearing load F b Formula 1 is:

[0015] Bearing design life L h Formula 2 is:

[0016] Equivalent dynamic load P r Formula 3 is:

[0017]

[0018] Among them, F b For bearing load; n np P is the equivalent speed of the bearing; r For equivalent dynamic load; C r For dynamic basic rated load; L h The bearing design life is represented by T; the total operating time of the bearing under all operating conditions is represented by n. j τ is the rotational speed of the bearing under the j-th operating condition; oj P represents the bearing operating time under a single operating condition. rj The equivalent dynamic load under a single working condition; j is 1 to n; X is the radial dynamic load coefficient; L h The bearing's design life.

[0019] Furthermore, a system dynamic model of the engine bearing-damper-rotor is established, and a method for calculating the maximum eccentricity at the bearing is developed, including:

[0020] S201. Establish the dynamic equations of the rotor-support system and calculate the vibration amplitude of the support.

[0021] S202. Establish the relationship equation between the maximum eccentricity at the engine bearing and the bearing load, the allowable unbalance of the rotor, and the vibration amplitude, and calculate the maximum eccentricity at the bearing.

[0022] Furthermore, the dynamic equation of the rotor-support system, Formula 4, is as follows:

[0023]

[0024] Where, m r For disk quality; kr is the disc stiffness; x r is the x-direction disc response; x b is the x-direction support response; y r is the y-direction disc response; y b is the y-direction support response; k b is the support stiffness; c b is the support damping; ω is the rotor speed; t is time; β is the phase;

[0025] Solving formula 4, the formula 5 of the support vibration amplitude is obtained as follows:

[0026] R = |R1| = { [R2] 2 + [R3] 2} -1 / 2 meω 2 ,

[0027] Wherein, R1 is

[0028] R2 is

[0029] R3 is

[0030] Based on formula 3, formula 5, the relationship between bearing load and unbalance is calculated, and the relationship formula 6 is obtained as follows:

[0031] Wherein, N is the rated speed; U max is the allowable unbalance of the rotor, R is the vibration amplitude of the disc, and e is the maximum eccentricity of the bearing.

[0032] Further, the value range of ε is 0-0.4.

[0033] Further, the value of ε is 0.4.

[0034] Compared with the prior art, the beneficial effects of the present application are that: the support point damper oil film gap selection method based on bearing life designed by the present application takes the load borne by the bearing as the design input, takes the bearing-damper-rotor system dynamics analysis model as the bridge, takes the relationship among the bearing load, the rotor unbalance force load, the rotor response and the bearing eccentricity as the tool, determines the damper parameter input eccentricity, and finally determines the support point damper oil film gap value.

[0035] The support point damper oil film gap selected by the method of the present application is subjected to rotor dynamics characteristic comparison test under the conditions of no oil filling and oil filling of the damper, and the result shows that the damper vibration reduction effect is ≮90%, and the bearing life test is carried out on the designed damper, and the requirement of 3000H bearing life is met. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings in the following description are only the technical solutions of the present application for more clearly illustrating the technical solutions of the embodiments of the present application or the prior art, and for those skilled in the art, other drawings can also be obtained without creative effort on the basis of these drawings.

[0037] Figure 1 The flow chart of the bearing life-based fulcrum damper oil film gap selection method in the specific embodiment. Specific Embodiment

[0038] The advantages and characteristics of the present application will be more apparent with the description. However, these embodiments are only exemplary and do not constitute any limitation on the scope of the present application. Those skilled in the art should understand that the details and forms of the technical solutions of the present application can be modified or replaced without departing from the spirit and scope of the present application, and such modifications and replacements all fall within the protection scope of the present application.

[0039] In the description of the present embodiment, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0040] In addition, the terms "first", "second", "third" and the like are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" and the like can explicitly or implicitly include one or more features. In the description of the present application, unless otherwise specified, the meaning of "multiple" is two or more.

[0041] The present specific embodiment provides a bearing life-based fulcrum damper oil film gap selection method, as shown in Figure 1 The bearing life-based fulcrum damper oil film gap selection method includes the following steps:

[0042] S1, based on the engine bearing life, calculating the bearing load;

[0043] S2, establishing a system dynamics model of the engine bearing-damper-rotor, and calculating the maximum eccentricity e at the bearing;

[0044] S3. Based on the maximum eccentricity e of the bearing, use the formula c = e / ε, where ε is a dimensionless parameter, to calculate the damper oil film clearance value c.

[0045] In one embodiment, a method for calculating bearing load using bearing life includes:

[0046] S101. Determine the engine bearing life based on the engine bearing type;

[0047] S102. Establish the relationship equation between bearing load and engine bearing life, engine speed, and basic load, link engine bearing life with rotor system dynamic design, and calculate bearing load.

[0048] Furthermore, in step S102, the relational equation is:

[0049] bearing load F b Formula 1 is:

[0050] Bearing design life L h Formula 2 is:

[0051] Equivalent dynamic load P r Formula 3 is:

[0052]

[0053] Among them, F b For bearing load; n np P is the equivalent speed of the bearing; r For equivalent dynamic load; C r For dynamic basic rated load; L h The bearing design life is given by T, where T is the total bearing operating time under all operating conditions; n j τ is the rotational speed of the bearing under the j-th operating condition; oj P represents the bearing operating time under a single operating condition. rj The equivalent dynamic load under a single working condition; j is 1 to n; X is the radial dynamic load coefficient; L h The bearing's design life.

[0054] In one embodiment, a method for establishing a system dynamics model of an engine bearing-damper-rotor and calculating the maximum eccentricity at the bearing includes:

[0055] S201. Establish the dynamic equations of the rotor-support system and calculate the vibration amplitude of the support.

[0056] S202. Establish the relationship equation between the maximum eccentricity at the engine bearing and the bearing load, the allowable unbalance of the rotor, and the vibration amplitude, and calculate the maximum eccentricity at the bearing.

[0057] Furthermore, the dynamic equation of the rotor-support system, Formula 4, is as follows:

[0058]

[0059] Where, m r For disk quality; k r For disk stiffness; x r For x-axis steering wheel response; x b The response at the support in the x-direction; y r For y-steering wheel response; y b The response at the support in the y-direction; k b c is the support stiffness. b ω is the support damping; ω is the rotor speed; t is time; β is the phase.

[0060] Solving for Equation 4, we obtain Equation 5 for the amplitude of the support vibration:

[0061] R = |R1| = {[R2]} 2 +[R3] 2} -1 / 2 meω 2 ,

[0062] Where R1 is

[0063] R2 is

[0064] R3 is

[0065] Based on formulas 3 and 5, the relationship between bearing load and unbalance is calculated, resulting in formula 6:

[0066] Where N is the rated speed; U max R is the allowable unbalance of the rotor, R is the vibration amplitude of the disc, and e is the maximum eccentricity of the bearing.

[0067] In one embodiment, according to bearing lubrication theory, as the eccentricity increases, the oil pressure and oil film stiffness also increase sharply. When ε > 0.4, it will exhibit strong nonlinearity. Therefore, in this specific embodiment, the value of ε is in the range of 0 to 0.4, and preferably, the value of ε is 0.4.

[0068] The maximum eccentricity e of the bearing can be calculated using formula 6. ε is chosen to be 0.4, and the oil film clearance value c of the damper can be calculated using the formula c = e / ε.

[0069] The method for selecting the oil film clearance of the pivot damper based on bearing life designed in this invention uses the load borne by the bearing as the design input, the dynamic analysis model of the bearing-damper-rotor system as the bridge, and the relationship between bearing load, rotor unbalanced force load, rotor response and bearing eccentricity as the tool to determine the damper parameter input eccentricity, and finally determine the oil film clearance value of the pivot damper.

[0070] Using the method of this invention, the oil film gap of the fulcrum damper was selected. A comparative test of rotor dynamic characteristics was conducted in the damper under oil-filled and oil-filled conditions. The results showed that the damper's vibration reduction effect was ≥90%. The bearing life test was conducted on the designed damper, and the bearing life requirement of 3000H was met.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0072] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for selecting the oil film clearance of a pivot damper based on bearing life, characterized in that, Includes the following steps: S1. Based on the engine bearing life, calculate the bearing load, including: S101. Determine the engine bearing life based on the engine bearing type; S102. Establish the relationship equation between bearing load and engine bearing life, engine speed, and basic load, associate engine bearing life with rotor system dynamic design, and calculate bearing load. S2. Establish a system dynamic model of engine bearing-damper-rotor and calculate the maximum eccentricity e at the bearing, including: establishing the dynamic equation of the rotor-support system and calculating the support vibration amplitude; establishing the relationship equation between the maximum eccentricity at the engine bearing and the bearing load, the allowable unbalance of the rotor, and the vibration amplitude, and calculating the maximum eccentricity at the bearing. Among them, bearing load Formula 1 is: ; Engine bearing life Formula 2 is: ; Equivalent dynamic load Formula 3 is: ； The dynamic equation of the rotor-support system, Formula 4, is as follows: ； in, For disk quality; For disk stiffness; For x-axis steering wheel response; The response at the support in the x-direction; for y Steering wheel response; for y Response at directional support; For support stiffness; ω is the support damping; t is the rotor speed; β is the time; β is the phase. Solving for Equation 4, we obtain Equation 5 for the amplitude of the support vibration: Where R1 is ; R2 is ; R3 is ; Based on formulas 3 and 5, the relationship between bearing load and unbalance is calculated, resulting in formula 6: ; in, For bearing load, N Rated speed; This refers to the allowable imbalance of the rotor. R denoted as , where is the vibration amplitude of the disc, and 'e' is the maximum eccentricity of the bearing. This refers to the equivalent rotational speed of the bearing. This is the equivalent dynamic load; For basic load; The bearing life is T, where T is the total bearing operating time under all operating conditions. Let J be the rotational speed of the bearing under the j-th operating condition; This refers to the bearing operating time under a single operating condition. The equivalent motion load under a single working condition; j is 1~n; X Radial dynamic load factor; S3. Based on the maximum eccentricity e of the bearing, use the formula c=e / ε, where ε is a dimensionless parameter, to calculate the damper oil film clearance value c.

2. The method for selecting the oil film gap of the pivot damper according to claim 1, characterized in that: The value of ε ranges from 0 to 0.

4.

3. The method for selecting the oil film gap of the pivot damper according to claim 2, characterized in that: The value of ε is 0.4.

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