A method for analyzing the cooling and lubrication effect of lubricating oil in aircraft engine thrust bearings

Abstract

The present invention belongs to the field of aerospace technology and provides a method for analyzing the cooling and lubricating effect of lubricating oil in thrust bearings of aircraft engines. Recognizing the current lack of a specialized quantitative analysis method for the cooling and lubricating effect of thrust bearings in China, the present invention proposes a comprehensive quantitative analysis method for the cooling and lubricating effect of thrust bearings based on two parameters: the bearing lubricating oil supply coefficient and the oil film coverage area ratio on the ball surface. This method specifically considers the impact of changes in the ball's position relative to the oil-slinging hole during rolling on the cooling and lubricating effect of the thrust bearing, as well as the impact of changes in the oil flow state at different speeds on the cooling and lubricating effect of the thrust bearing.

Description

Technical Field

[0001] The invention belongs to the field of aerospace technology, and in particular relates to a method for analyzing the cooling and lubricating effect of lubricating oil on a thrust bearing of an aero-engine. Background Art

[0002] The thrust bearings of advanced aircraft engines are subject to radial and axial loads, characterized by multi-directional forces and complex loads. To increase the contact angle and number of balls, thereby improving the ability to withstand axial loads, aircraft engines generally use ball bearings with a split inner ring and employ an under-ring oil supply method. This method involves injecting lubricating oil from a nozzle and then channeling it under the bearing's inner ring along a pre-defined oil flow path. Oil is then spun through oil holes in the split inner ring to the balls, thereby cooling and lubricating the balls. During operation, as the axial load on the ball bearing changes, the contact angle between the balls and the inner and outer rings of the bearing alters. Therefore, an oil film is required to adequately wrap the balls to ensure adequate cooling and lubrication under all operating conditions. Considering these requirements in simulation analysis and conducting a comprehensive, quantitative assessment of the cooling and lubrication effectiveness of thrust bearings is the analytical basis for optimizing lubricating oil systems. However, experimental methods are often used at home and abroad to conduct post-analysis of the lubricating and cooling effect of lubricating oil on thrust bearings, and there are few public documents that propose quantitative evaluation indicators for the lubricating and cooling effect of lubricating oil on thrust bearings. Therefore, the purpose of the present invention is to propose a method for analyzing the cooling and lubricating effect of lubricating oil on thrust bearings of aircraft engines to guide the design of lubricating oil systems under complex loads. Summary of the Invention

[0003] To solve the above technical problems, the present invention provides a method for analyzing the cooling and lubrication effect of lubricating oil in an aircraft engine thrust bearing to solve the problems in the prior art. The technical solution adopted by the present invention is:

[0004] A method for analyzing the cooling and lubrication effect of lubricating oil in an aircraft engine thrust bearing, comprising:

[0005] S101: Calculate various parameters of lubricating oil near the thrust bearing in the bearing cavity of the aircraft engine;

[0006] S102: extracting the bearing oil supply in the oil chamber and the oil-air ratio at each point near the ball surface under different ball relative oil-slinging hole positions and different operating speeds, and generating a data set;

[0007] S103: Based on the data set, a bearing lubricating oil supply coefficient m is proposed. A and ball surface oil film coverage ratio S A A comprehensive quantitative evaluation method for the cooling and lubrication effect of thrust bearings based on two parameters;

[0008] S104: Analyze the effect of the change in the position of the ball relative to the oil-slinging hole on the cooling and lubrication effect of the thrust bearing during the rolling process;

[0009] S105: Analyze the effect of the change in oil flow state at different speeds on the cooling and lubrication effect of the thrust bearing.

[0010] Furthermore, the lubricating oil supply amount of the bearing is the amount of lubricating oil supplied to the oil-slinging hole under the ring.

[0011] Furthermore, the bearing oil supply coefficient m A It is the ratio of the bearing oil supply to the total oil supply sprayed from the nozzle.

[0012] Furthermore, for the ball surface oil film coverage ratio S A :

[0013] When the oil-air ratio at a certain point on the ball surface is greater than 0.95, it is considered that there is an oil film there;

[0014] When the oil-air ratio is less than 0.95, it is considered that the lubricating oil on the bearing surface exists in the form of oil droplets;

[0015] The area occupied by the position on the ball surface where the oil-air ratio is greater than 0.95 is calculated as the oil film coverage area on the ball surface.

[0016] Furthermore, the step S104 includes:

[0017] The angle between the two lubricating holes is measured as θ, and the position where a certain ball is located just above the oil-slinging hole is defined as the initial position; a finite element model of the entire bearing cavity is established, and the CFD simulation method is used to calculate the bearing lubricating oil supply and the oil-air ratio of each point near the ball surface when a certain ball is located at the initial position, θ / n, 2θ / n, ... (n-1)θ / n (n = 1, 2, 3 ...) respectively; and the data is processed to calculate the bearing lubricating oil supply (m A,1 ,m A,2 ……m A,n ) and ball surface oil film coverage ratio (S A,1 , S A,2 ……S A,n );

[0018] Oil supply through bearings (m A,1 ,m A,2 ……m A,n ) and ball surface oil film coverage ratio (S A,1 , S A,2 ……S A,n ) are used to comprehensively and quantitatively evaluate the influence of the position change of the ball relative to the oil-slinging hole on the cooling and lubrication effect of the thrust bearing.

[0019] Furthermore, the step S105 includes:

[0020] A finite element model of the entire bearing cavity was established. CFD simulation was used to calculate the bearing oil supply and the oil-to-air ratio at various points near the ball surface, with the ball positioned at different positions relative to the oil-sling hole, from x% engine speed to 100% maximum operating speed. The data was then processed to calculate the bearing oil supply and the oil film coverage ratio at various speeds and positions relative to the oil-sling hole.

[0021] Calculate the mean and variance of the bearing oil supply coefficient at each operating speed;

[0022] The average value of the bearing lubricating oil supply coefficient at x% speed state is:

[0023]

[0024] The variance of the bearing lubricating oil supply coefficient at x% speed is:

[0025]

[0026] Calculate the mean and variance of the oil film coverage area ratio on the ball surface;

[0027] The average value of the oil film coverage area ratio of the ball surface at x% speed is:

[0028]

[0029] The variance of the oil film coverage area ratio on the ball surface at x% speed is:

[0030]

[0031] The comprehensive quantitative evaluation of the cooling and lubrication effect of the thrust bearing on the change of oil flow state at different speeds is achieved by measuring the average and variance of the bearing lubricating oil supply coefficient and the oil film coverage area ratio of the ball surface.

[0032] The present invention has the following beneficial effects:

[0033] (1) Based on the principle of lubricating oil cooling and lubrication, the present invention innovatively proposes a comprehensive quantitative evaluation parameter for the lubricating oil cooling and lubrication effect of an aircraft engine thrust bearing;

[0034] (2) The present invention analyzes the influence of the change in the position of the ball relative to the oil-swinging hole during the rolling process and the change in the oil flow state at different speeds, thus achieving a comprehensive consideration of the cooling and lubrication effect;

[0035] (3) The present invention can guide and optimize the design, shortening the design cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic flow chart of the present invention;

[0037] Figure 2 The present invention is based on the cooling and lubrication calculation results of the front thrust bearing of the high-pressure rotor of the F110 engine at the maximum operating speed when the ball is in different positions relative to the oil-slinging hole;

[0038] Figure 3 It is calculated based on the average and variance of the bearing oil supply at various operating speeds for the front thrust bearing of the high-pressure rotor of the F110 engine.

[0039] Figure 4 It is calculated based on the average and variance of the oil film coverage area ratio of the ball surface at various operating speeds for the front thrust bearing of the high-pressure rotor of the F110 engine. DETAILED DESCRIPTION

[0040] The following is a combination of the embodiments of the present invention Figure 1-Figure 4 , the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0041] In aircraft engines, thrust bearings are often subjected to multi-directional forces and harsh loads. Therefore, addressing the current lack of a dedicated quantitative analysis method for the cooling and lubrication effectiveness of thrust bearings in China, this paper proposes a comprehensive quantitative analysis method for the cooling and lubrication effectiveness of thrust bearings based on two parameters: the bearing oil supply coefficient and the oil film coverage ratio on the ball surface. This method specifically considers the impact of changes in the ball's position relative to the oil-slinging hole during rolling on the cooling and lubrication effectiveness of the thrust bearing, as well as the impact of changes in the oil flow state at different speeds on the cooling and lubrication effectiveness of the thrust bearing.

[0042] A method for analyzing the cooling and lubrication effect of lubricating oil in an aircraft engine thrust bearing, comprising:

[0043] S101: Based on CFD simulation methods, calculate various parameters of the lubricating oil near the thrust bearing in the bearing cavity of the aircraft engine;

[0044] S102: extracting the bearing oil supply in the oil chamber and the oil-air ratio at each point near the ball surface under different ball relative oil-slinging hole positions and different operating speeds, and generating a data set;

[0045] S103: Based on the data set, a bearing lubricating oil supply coefficient m is proposed. A and ball surface oil film coverage ratio S AA comprehensive quantitative evaluation method for the cooling and lubrication effect of thrust bearings based on two parameters;

[0046] S104: Focus on analyzing the influence of the change in the position of the ball relative to the oil-slinging hole during the rolling process on the cooling and lubrication effect of the thrust bearing;

[0047] S105: Focus on analyzing the impact of the change in oil flow state at different speeds on the cooling and lubrication effect of the thrust bearing.

[0048] Furthermore, after the lubricating oil is sprayed out from the nozzle, a part of it is transported to the bottom of the inner ring of the bearing according to the preset lubricating oil flow path, and flows through the oil-slinging hole under the action of centrifugal load, and the lubricating oil is thrown out to the ball position to cool the ball; the other part directly returns to the oil or leaks directly from the sealing position. Therefore, the bearing lubricating oil supply is defined as the amount of lubricating oil supplied to the oil-slinging hole under the ring.

[0049] Specifically, the bearing lubricating oil supply coefficient m A , define the bearing lubricating oil supply coefficient m A It is the ratio of the bearing oil supply to the total oil supply sprayed from the nozzle.

[0050] Specifically, for the oil film, the oil-gas ratio of each point near the ball surface is extracted. When the oil-gas ratio at a certain point on the ball surface is large (greater than 0.95), it is considered that there is an oil film here, which can cool and lubricate the bearing; when the oil-gas ratio is small (less than 0.95), it is considered that the lubricating oil on the bearing surface only exists in the form of oil droplets, and it is considered that the bearing cannot be cooled and lubricated here.

[0051] The area occupied by the position with the largest oil-gas ratio (greater than 0.95) on the ball surface is the oil film coverage area on the ball surface. Define the oil film coverage area ratio S on the ball surface A It is the ratio of the oil film coverage area on the ball surface to the entire ball surface area.

[0052] Furthermore, since the position of the ball relative to the oil-slinging hole is constantly changing during the operation of the engine, the ball is sometimes located just above the oil-slinging hole and sometimes far away from the oil-slinging hole. Therefore, it is necessary to consider the effect of the change in the position of the ball relative to the oil-slinging hole on the cooling and lubrication effect of the thrust bearing during the rolling process. The angle between the two oil holes is measured as θ, and the position where a certain ball is located just above the oil-slinging hole is defined as the initial position. A finite element model of the entire bearing cavity is established, and the CFD simulation method is used to calculate the bearing lubricating oil supply and the oil-gas ratio of each point near the ball surface when a certain ball is located at the initial position, θ / n, 2θ / n, ... (n-1)θ / n (n = 1, 2, 3 ...). After data processing, the bearing lubricating oil supply (m A,1 ,m A,2 ……m A,n) and ball surface oil film coverage ratio (S A,1 , S A,2 ……S A,n These two parameters can be used to achieve a comprehensive quantitative evaluation of the cooling and lubrication effect of the thrust bearing due to the change in the position of the ball relative to the oil-slinging hole.

[0053] Furthermore, since the engine speed ω is constantly changing during operation, the required lubricating oil quantity at different operating speeds is different, and the lubricating oil flow state is also constantly changing. Therefore, it is necessary to consider the impact of the changing lubricating oil flow state at different speeds on the cooling and lubrication of the thrust bearing. A finite element model of the entire bearing cavity was established, and CFD simulation was used to calculate the bearing lubricating oil supply quantity and the oil-to-air ratio at various points near the ball surface when the ball was located at different positions relative to the oil-slinging hole at the engine speed of 20%, 21%, x%, and all the way to 100% of the maximum operating speed. The data was then processed to calculate the bearing lubricating oil supply quantity and the oil film coverage area ratio at different speeds and different positions of the ball relative to the oil-slinging hole.

[0054] Since there are multiple data at a certain working speed, the average value of the bearing lubricating oil supply coefficient (E(m A,20％ ), E(m A,21％ )……E(m A,x％ )……E(m A,100％ )) and variance (D(m A,20％ ), D(m A,21％ )……D(m A,x％ )……D(m A,100％ ));

[0055] The average value of the bearing lubricating oil supply coefficient at x% speed is:

[0056]

[0057] The variance of the bearing lubricating oil supply coefficient at x% speed is:

[0058]

[0059] Calculate the average value of the oil film coverage area ratio of the ball surface (E(S A,20％ ), E(S A,21％ )……E(S A,x％ )……E(S A,100％ )) and variance (D(S A,20％ ), D(S A,21％ )……D(S A,x％ )……D(S A,100％ ));

[0060] The average value of the oil film coverage area ratio of the ball surface at x% speed is:

[0061]

[0062] The variance of the oil film coverage area ratio of the ball surface at x% speed is:

[0063]

[0064] The comprehensive quantitative evaluation of the cooling and lubrication effect of the thrust bearing on the change of oil flow state at different speeds can be achieved through the average and variance of the bearing lubricating oil supply coefficient and the oil film coverage area ratio of the ball surface.

[0065] A specific embodiment is given below:

[0066] Taking the high-pressure front thrust bearing of the F110 engine as the research object, a finite element model of the entire front bearing cavity was established based on the CFD simulation method. The flow and heat transfer of the sliding oil at the maximum operating speed were simulated and calculated when the thrust bearing ball was in different positions relative to the oil-slinging hole.

[0067] The angle between the two lubricating holes is defined as θ, and the position where ball No. 1 (the top ball) is located just above the oil-slinging hole is selected as the initial position. Let n = 5, that is, the bearing lubricating oil supply amount and the oil-air ratio of each point near the ball surface at the initial position, θ / 5 position, 2θ / 5 position, 3θ / 5 position, and 4θ / 5 position at the maximum operating speed are extracted. The data is processed to obtain the bearing lubricating oil supply coefficient (m A,1 ,m A,2 ……m A,5 ) and ball surface oil film coverage ratio (S A,1 , S A,2 ……S A,5 ) and make a line graph. The calculation results are as follows Figure 2 shown.

[0068] Secondly, based on the CFD simulation method, the bearing lubricating oil supply and the oil-air ratio at each point near the ball surface are calculated at 1% speed intervals from 20% speed to 100% maximum operating speed. The data are processed into the average and variance of the bearing lubricating oil supply and the oil film coverage area ratio of the ball surface at different positions of the ball relative to the oil-slinging hole at a specific operating speed. The average value of the bearing lubricating oil supply coefficient (E(m A,20％ ), E(m A,21％ )……E(m A,100％ ))、Variance(D(m A,20％ ), D(m A,21％ )……D(m A,100％)) and the average value of the oil film coverage area ratio of the ball surface at different working speeds (E(S A,20％ ), E(S A,21％ )……E(S A,100％ ))、Variance(D(S A,20％ ), D(S A,21％ )……D(S A,100％ )) is made into a broken line graph. This can achieve a comprehensive quantitative evaluation of the cooling and lubrication effects at different speeds. The calculation results are as follows: Figure 3 and Figure 4 The calculated results are consistent with the experience, which proves that this analysis method is reasonable.

[0069] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various deformations, modifications, and substitutions made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A method for analyzing the cooling and lubrication effect of lubricating oil in an aircraft engine thrust bearing, characterized in that: include: S101: Calculate various parameters of lubricating oil near the thrust bearing in the bearing cavity of the aircraft engine; S102: extracting the bearing oil supply in the oil chamber and the oil-air ratio at each point near the ball surface under different ball relative oil-slinging hole positions and different operating speeds, and generating a data set; S103: Based on the data set, a bearing lubricating oil supply coefficient m is proposed. A and ball surface oil film coverage area ratio S A A comprehensive quantitative evaluation method for the cooling and lubrication effect of thrust bearings based on two parameters; S104: Analyze the effect of the change in the position of the ball relative to the oil-slinging hole on the cooling and lubrication effect of the thrust bearing during the rolling process; S105: Analyze the effect of the change in the oil flow state at different speeds on the cooling and lubrication effect of the thrust bearing; The step S104 includes: The angle between the two oil holes is measured as θ, and the position where a ball is just above the oil hole is defined as the initial position; a finite element model of the entire bearing cavity is established, and the CFD simulation method is used to calculate the initial position, The bearing lubricating oil supply at these n positions and the oil-air ratio at each point near the ball surface; and after data processing, the bearing lubricating oil supply m A,1 ,m A,2 ……m A,n and ball surface oil film coverage area ratio S A,1 , S A,2 ……S A,n ; Oil supply through bearings m A,1 ,m A,2 ……m A,n and ball surface oil film coverage area ratio S A,1 , S A,2 ……S A,n These two parameters are used to comprehensively and quantitatively evaluate the influence of the position change of the ball relative to the oil-slinging hole on the cooling and lubrication effect of the thrust bearing; The step S105 includes: A finite element model of the entire bearing cavity was established. CFD simulation was used to calculate the bearing oil supply and the oil-to-air ratio at various points near the ball surface, with the ball positioned at different positions relative to the oil-sling hole, from x% engine speed to 100% maximum operating speed. The data was then processed to calculate the bearing oil supply and the oil film coverage ratio at various speeds and positions relative to the oil-sling hole. Calculate the mean and variance of the bearing oil supply coefficient at each operating speed; The average value of the bearing lubricating oil supply coefficient at x% speed state is: The variance of the bearing lubricating oil supply coefficient at x% speed is: Calculate the mean and variance of the oil film coverage area ratio on the ball surface; The average value of the oil film coverage area ratio of the ball surface at x% speed is: The variance of the oil film coverage area ratio on the ball surface at x% speed is: The comprehensive quantitative evaluation of the cooling and lubrication effect of the thrust bearing on the change of oil flow state at different speeds is achieved by measuring the average and variance of the bearing lubricating oil supply coefficient and the oil film coverage area ratio of the ball surface.

2. The method for analyzing the cooling and lubrication effect of lubricating oil in an aircraft engine thrust bearing according to claim 1, characterized in that: The bearing lubricating oil supply is the amount of lubricating oil entering the oil-slinging hole under the ring.

3. The method for analyzing the cooling and lubricating effect of lubricating oil in an aircraft engine thrust bearing according to claim 1, characterized in that: Bearing lubricating oil supply coefficient m A It is the ratio of the bearing oil supply to the total oil supply sprayed from the nozzle.

4. The method for analyzing the cooling and lubricating effect of lubricating oil in an aircraft engine thrust bearing according to claim 1, characterized in that: For the ball surface oil film coverage area ratio S A : When the oil-air ratio at a certain point on the ball surface is greater than 0.95, it is considered that there is an oil film there; When the oil-air ratio is less than 0.95, it is considered that the lubricating oil on the bearing surface exists in the form of oil droplets; The area occupied by the position on the ball surface where the oil-air ratio is greater than 0.95 is calculated as the oil film coverage area on the ball surface.

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