Bearing outer ring temperature measuring and calculating method based on bearing oil return temperature
By establishing heat transfer and fluid mechanics models, calculating the outer ring temperature of the bearing based on the bearing oil return temperature and lubricating oil flow, the problems of temperature monitoring error and short slip ring life in the existing technology are solved, and the high-speed working conditions are realized accurate temperature measurement.
Patent Information
- Application Number
- CN202411391897.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-30
- Publication Date
- 2025-01-03
AI Technical Summary
The prior art is difficult to accurately monitor the bearing temperature of the inner and outer rings rotating simultaneously. The traditional method has large errors and the slip ring has a short life under high-speed operating conditions, making it unable to be suitable for long-term monitoring.
By establishing heat transfer and fluid mechanics models based on the bearing oil return temperature, combining the temperature of the stationary part and the flow of the lubricant, the lubricant temperature is reversed one by one, and the bearing outer ring temperature is calculated to improve the reliability and accuracy of measurement.
It realizes accurate measurement of the temperature of the outer ring of the bearing, reduces monitoring errors, and has no time limit for use under high-speed operating conditions. It is suitable for aircraft engines and other applications.
Smart Images
Figure CN119245866A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of bearing outer ring temperature measurement and calculation, and in particular to a bearing outer ring temperature measurement and calculation method based on bearing oil return temperature. Background Art
[0002] Oil lubrication is one of the rolling bearing lubrication methods. It has the advantages of sufficient lubrication and good heat dissipation, and is widely used in the lubrication of aircraft engine bearings. The circulating oil supply system required for oil lubrication usually consists of an oil tank, lubricating oil, oil pump, oil supply pipeline, bearing, oil return pipeline, etc. The test bearing temperature is an important parameter to characterize the operating state of the bearing, and is generally monitored by a temperature sensor in contact with the stationary ring of the bearing.
[0003] For bearings with inner and outer rings rotating at the same time, it is difficult for the temperature sensor to contact the bearing ring, and it is difficult to use the temperature sensor for direct monitoring. The current method is to indirectly characterize the temperature of the test bearing by monitoring the return oil temperature of the test bearing, but there is a gap between the return oil temperature and the bearing temperature, and this method has a large error. The second method is to use a slip ring as a dynamic shaft connection structure to monitor the bearing temperature, but the slip ring has a short life under high-speed conditions and cannot be used for long-term monitoring. Summary of the invention
[0004] The purpose of the present invention is to provide a bearing outer ring temperature measurement and calculation method based on the bearing return oil temperature, to derive the bearing rotating outer ring temperature based on the stationary part temperature and the lubricating oil flow rate, and to improve the reliability and accuracy of the bearing outer ring temperature measurement.
[0005] In order to achieve the above object, the technical solution adopted by the present invention is: a method for measuring and calculating the bearing outer ring temperature based on the bearing oil return temperature, comprising the following steps: Step 1: Install the test bearing on the test fixture for rotation test The test fixture comprises an inner ring test shaft, an outer ring test shaft and an oil sealing cover, a mounting seat is provided at the end of the inner ring test shaft, the inner ring of the test bearing is sleeved on the mounting seat, an inner locking nut is provided on the mounting seat to limit the inner ring of the test bearing, the inner hole at the end of the outer ring test shaft is sleeved on the outer ring of the test bearing, an outer locking nut is provided at the end of the outer ring test shaft to limit the outer ring of the test bearing, the test bearing and the mounting seat are both located in the cylindrical inner cavity of the oil sealing cover, the center holes on both sides of the oil sealing cover are respectively sealed and sleeved on the inner ring test shaft and the outer ring test shaft, an oil injection hole is provided in the oil sealing cover, the nozzle of the oil injection hole is located on the oil inlet side wall of the oil sealing cover, the nozzle of the oil injection hole can spray lubricating oil toward the oil collecting cavity between the mounting seat and the inner ring test shaft, an oil return port is provided at the bottom end of the oil sealing cover, and an oil collecting nut is screwed on the oil return port; The test bearing is subjected to a rotation test by relative rotation of the inner ring test shaft and the outer ring test shaft. Lubricating oil is delivered to the test bearing through the oil injection hole and recovered through the oil collecting nut. The temperature sensor and flow sensor set at the corresponding measuring point are used to measure the internal oil return temperature t of the oil collecting nut in real time. 1 , the outer wall temperature of the oil collecting nut t B1 , the outer wall temperature of the oil seal cover t B2 and return oil flow q; Step 2: Calculate the oil return temperature t at the oil receiving nut inlet 2 Calculate the return oil flow velocity u 1 for: In formula (1), d 1 is the inner diameter of the oil collecting nut; Calculate the flow Reynolds number R e1 for: In formula (2), v is the kinematic viscosity; If R e1 <2300, the flow is considered as laminar flow and the inlet section length L is calculated. t1 for: L t1 =0.05R e1 Pr formula (3); In formulas (3) and (4), Pr is the Prandtl number, μ is the viscosity of the lubricating oil, and c p is the specific heat at constant pressure, λ is the thermal conductivity; Then the radial distance L between the oil collecting nut inlet and the internal oil return temperature measuring point is 1 The length of the inlet section L t1 For comparison, If L t1 <L 1 , select the Nusselt number Nu 1 is 3.66; If L t1 >L 1 , calculate the Nusselt number Nu 1 for: In formula (5), η f is the dynamic viscosity of the flow core area, η w is the wall dynamic viscosity; The surface heat transfer coefficient is calculated as h 1 =(λ / d 1 )Nu 1Formula (6); If R e1 >2300, the flow is considered turbulent and the inlet section length L is calculated. t1 for: L t1 =60d 1 Formula (7); Then the radial distance L between the oil collecting nut inlet and the internal oil return temperature measuring point is 1 The length of the inlet section L t1 For comparison, If L t1 <L 1 , calculate the surface heat transfer coefficient h 1 for: In formula (8), k is the heat transfer coefficient; If L t1 >L 1 , calculate the Nusselt number Nu 1 for: f 1 =(1.82lgRe 1 -1.64) -2 Formula (10); Calculate the surface heat transfer coefficient h 1 for: h 1 =(λ / d 1 )Nu 1 Formula (11); In formula (9), c t1 is the temperature correction factor; The heat flow is calculated as: Φ 1 =h 1 A 1 Δt=h 1 A 1 ((t 1 +t 2 ) / 2-t B1 ) Formula (12); A 1 =πL 1 d 1 Formula (13); The heat flux density is calculated as: q 1 =Φ 1 / A 1 Formula (14); Calculate the oil return temperature t at the oil receiving nut inlet 2 for: In formula (15), h B1 is the surface heat transfer coefficient between the outer wall of the tube and the airflow outside the tube, h B1 =10W / (m 2 .K); By solving equations (11)-(15), we can obtain t 2 The value of Step 3: Calculate the oil inlet wall temperature t of the oil seal cover at the same radial position as the oil collecting nut inlet 3 Calculate the flow Reynolds number R e2 for: u 2 =0.7u 1 Formula (18); In formula (17), L 2 It is the axial distance between the oil inlet side wall of the oil seal cover and the center line of the oil collecting nut; Calculate the Nusselt number Nu 2 for: The local surface heat transfer coefficient is calculated as: Calculate the average surface heat transfer coefficient h 2 for: The heat flow is calculated as: Φ 2 =h 2 A 2 Δt=h 2 A 2 ((t 2 +t 3 ) / 2-t B2 ) Formula (21); The heat flux density is calculated as: q 2 =Φ 2 / A 2 Formula (22); In formula (22), A 2 is the lower wall area of the oil seal cover; Calculate the oil inlet side wall temperature t of the oil seal cover at the same radial position as the oil collecting nut inlet 3 for: In formula (23), h B2 is the surface heat transfer coefficient between the outer wall of the oil seal cover and the external airflow, h B2 =27W / (m2 .K); By solving equations (20)-(23), we can obtain t 3 The value of Step 4: Calculate the oil inlet side wall temperature t of the oil seal cover at the same radial position as the test bearing pitch circle 4 Calculate the flow Reynolds number R e3 for: u 3 =1.5u 2 Formula (26); In formula (25), L 3 The minimum distance between the test bearing pitch circle and the oil collecting nut inlet; Calculate the Nusselt number Nu 3 for: The local surface heat transfer coefficient is calculated as: Calculate the average surface heat transfer coefficient h 3 for: The heat flow is calculated as: Φ 3 =h 3 A 3 Δt=h 3 A 3 ((t 3 +t 4 ) / 2-t B2 ) Formula (29); In formula (30), r 1 is the radius of the inner cavity of the oil seal, r 2 is the radius of the center hole on the oil inlet side of the oil seal cover; The heat flux density is calculated as: q 3 =Φ 3 / A 3 Formula (31); Calculate the oil inlet side wall temperature t of the oil seal cover at the same radial position as the test bearing pitch circle 4 for: In formula (32), h B3 is the heat transfer coefficient between the outer wall of the oil seal and the external airflow, h B3 =27W / (m 2 .K); By solving equations (28)-(32), we can obtain t 4 The value of Step 5: Calculate the temperature t of the test bearing pitch circle position on the oil inlet side of the oil seal cover 5 In formula (32), L 4 L is the minimum distance between the outer ring of the test bearing and the oil inlet side wall of the oil seal cover. 5 is the axial length of the test bearing outer ring; Step 6: Calculate the outer ring temperature t of the test bearing 6 Calculate the flow Reynolds number R e4 for: u 4 =12u 3 Formula (35); In formula (34), d 2 is the inner diameter of the outer ring of the test bearing; Considering the flow as turbulent, calculate the inlet section length L t2 for: L t2 =60d 2 Formula (36); Then the axial length L of the outer ring of the test bearing 5 The length of the inlet section L t2 For comparison, If L t2 <L 5 , calculate the surface heat transfer coefficient h 4 for: If L t2 >L 5 , calculate the Nusselt number Nu 4 for: f 2 =(1.82lgRe 4 -1.64) -2 Formula (39); Calculate the surface heat transfer coefficient h 4 for: h 4 =(λ / d 2 )Nu 4 Formula (42); In formula (38), c t2 is the temperature correction factor; The heat flow is calculated as: Φ4 =h 4 A 4 Δt=h 4 A 4 (t 5 -(t 6 / 2)) Formula (41); A 4 =πL 5 d 2 Formula (42); The heat flux density is calculated as: q 4 =Φ 4 / A 4 Formula (43); The test bearing outer ring temperature is
[0013] Compared with the prior art, the invention has the following beneficial effects: according to the characteristics of lubricating oil flow, the invention divides the flow process into several stages, establishes heat transfer and fluid mechanics models for each stage, and reversely infers the lubricating oil temperature of the previous stage based on the return oil temperature of the test bearing. According to the flow characteristics of lubricating oil inside the bearing, a convective heat transfer model is established to derive the outer ring temperature of the test bearing. The invention derives the difficult-to-measure rotating outer ring temperature of the bearing based on the relatively easy-to-measure stationary part temperature and lubricating oil flow rate, which can more accurately reflect the temperature change of the test bearing than monitoring the return oil temperature, and is of great significance to improving the reliability and accuracy of the bearing outer ring temperature measurement.
[0014] The traditional method of using slip rings as a moving shaft connection structure to monitor bearing temperature has a short life of the slip ring under high-speed conditions and cannot be used for long-term monitoring. The present invention has no time limit under high-speed conditions and is more advantageous in applications such as aircraft engines. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 It is the structural schematic diagram of the test tooling; Figure 2 is a schematic diagram of the measurement point location; Figure 3 Schematic diagram of parameters for temperature measurement calculation process.
[0015] Markings in the figure: 1. Inner ring test shaft, 2. Outer ring test shaft, 3. Mounting seat, 4. Test bearing, 5. Inner locking nut, 6. Outer locking nut, 7. Oil sealing cover, 8. Oil injection hole, 9. Oil collecting nut.
[0015] t 1 , oil return temperature inside the oil collecting nut, t B1 , the outer wall temperature of the oil collecting nut, t B2, the outer wall temperature of the oil seal cover, t 2 , oil return temperature at the oil receiving nut inlet, t 3 , the temperature of the oil inlet side wall of the oil seal cover at the same radial position as the oil collecting nut inlet, t 4 , the temperature of the oil inlet side wall of the oil seal cover at the same radial position as the test bearing pitch circle, t 5 , the temperature of the test bearing pitch circle position on the oil inlet side of the oil seal, t 6 , test the bearing outer ring temperature.
[0015] d 1 , Inner diameter of the oil collecting nut, d 2 , Inner diameter of the test bearing outer ring, r 1 , the radius of the inner cavity of the oil seal, r 2 , the radius of the center hole on the oil inlet side of the oil seal cover.
[0015] L 1 , radial distance between the oil collecting nut inlet and the internal oil return temperature measuring point, L 2 , the axial distance between the oil inlet side wall of the oil seal cover and the center line of the oil collecting nut, L 3 , the minimum distance between the test bearing pitch circle and the oil collecting nut inlet, L 4 , the minimum distance between the outer ring of the test bearing and the oil inlet side wall of the oil seal cover, L 5 , test the axial length of the bearing outer ring. DETAILED DESCRIPTION
[0016] A method for measuring and calculating the bearing outer ring temperature based on the bearing oil return temperature comprises the following steps: Step 1: Install the test bearing on the test fixture for rotation test The test tool of this embodiment is as follows Figure 1 As shown, it includes an inner ring test shaft, an outer ring test shaft and an oil sealing cover, a mounting seat is provided at the end of the inner ring test shaft, the inner ring of the test bearing is sleeved on the mounting seat, an inner locking nut is provided on the mounting seat to limit the inner ring of the test bearing, the inner hole at the end of the outer ring test shaft is sleeved on the outer ring of the test bearing, and an outer locking nut is provided at the end of the outer ring test shaft to limit the outer ring of the test bearing, the test bearing and the mounting seat are both located in the cylindrical inner cavity of the oil sealing cover, the center holes on both sides of the oil sealing cover are respectively sealed on the inner ring test shaft and the outer ring test shaft, an oil spray hole is opened in the oil sealing cover, the nozzle of the oil spray hole is located on the oil inlet side wall of the oil sealing cover, the nozzle of the oil spray hole can spray lubricating oil toward the oil collecting cavity between the mounting seat and the inner ring test shaft, and an oil return port is opened at the bottom end of the oil sealing cover, and an oil collecting nut is screwed on the oil return port.
[0017] The test bearing is subjected to a rotation test by relative rotation of the inner ring test shaft and the outer ring test shaft. Lubricating oil is delivered to the test bearing through the oil injection hole and recovered through the oil collecting nut. The temperature sensor and flow sensor set at the corresponding measuring point are used to measure the internal oil return temperature t of the oil collecting nut in real time. 1 , the outer wall temperature of the oil collecting nut t B1 , the outer wall temperature of the oil seal cover t B2 And return oil flow q.
[0018] Step 2: Calculate the oil return temperature t at the oil receiving nut inlet 2 Calculate the return oil flow velocity u 1 for: In formula (1), d 1 is the inner diameter of the oil collecting nut; Calculate the flow Reynolds number R e1 for: In formula (2), v is the kinematic viscosity; If R e1 <2300, the flow is considered as laminar flow and the inlet section length L is calculated. t1 for: L t1 =0.05R e1 Pr formula (3); In formulas (3) and (4), Pr is the Prandtl number, μ is the viscosity of the lubricating oil, and c p is the specific heat at constant pressure, λ is the thermal conductivity; Then the radial distance L between the oil collecting nut inlet and the internal oil return temperature measuring point is 1 The length of the inlet section L t1 For comparison, If L t1 <L 1 , select the Nusselt number Nu 1 is 3.66; If L t1 >L 1 , calculate the Nusselt number Nu 1 for: In formula (5), η f is the dynamic viscosity of the flow core area, η w is the wall dynamic viscosity; The surface heat transfer coefficient is calculated as h 1 =(λ / d 1)Nu 1 Formula (6); If R e1 >2300, the flow is considered turbulent and the inlet section length L is calculated. t1 for: L t1 =60d 1 Formula (7); Then the radial distance L between the oil collecting nut inlet and the internal oil return temperature measuring point is 1 The length of the inlet section L t1 For comparison, If L t1 <L 1 , calculate the surface heat transfer coefficient h 1 for: In formula (8), k is the heat transfer coefficient; If L t1 >L 1 , calculate the Nusselt number Nu 1 for: f 1 =(1.82lgRe 1 -1.64) -2 Formula (10); Calculate the surface heat transfer coefficient h 1 for: h 1 =(λ / d 1 )Nu 1 Formula (11); In formula (9), c t1 is the temperature correction factor; The heat flow is calculated as: Φ 1 =h 1 A 1 Δt=h 1 A 1 ((t 1 +t 2 ) / 2-t B1 ) Formula (12); A 1 =πL 1 d 1 Formula (13); The heat flux density is calculated as: q 1 =Φ 1 / A 1 Formula (14); Calculate the oil return temperature t at the oil receiving nut inlet 2for: In formula (15), h B1 is the surface heat transfer coefficient between the outer wall of the tube and the airflow outside the tube, h B1 =10W / (m 2 .K); By solving equations (11)-(15), we can obtain t 2 The numerical value of .
[0019] Step 3: Calculate the oil inlet wall temperature t of the oil seal cover at the same radial position as the oil collecting nut inlet 3 Calculate the flow Reynolds number R e2 for: u 2 =0.7u 1 Formula (18); In formula (17), L 2 It is the axial distance between the oil inlet side wall of the oil seal cover and the center line of the oil collecting nut; Calculate the Nusselt number Nu 2 for: The local surface heat transfer coefficient is calculated as: Calculate the average surface heat transfer coefficient h 2 for: The heat flow is calculated as: Φ 2 =h 2 A 2 Δt=h 2 A 2 ((t 2 +t 3 ) / 2-t B2 ) Formula (21); The heat flux density is calculated as: q 2 =Φ 2 / A 2 Formula (22); In formula (22), A 2 is the lower wall area of the oil seal cover; Calculate the oil inlet side wall temperature t of the oil seal cover at the same radial position as the oil collecting nut inlet 3 for: In formula (23), h B2is the surface heat transfer coefficient between the outer wall of the oil seal cover and the external airflow, h B2 =27W / (m 2 .K); By solving equations (20)-(23), we can obtain t 3 The numerical value of .
[0020] Step 4: Calculate the oil inlet side wall temperature t of the oil seal cover at the same radial position as the test bearing pitch circle 4 Calculate the flow Reynolds number R e3 for: u 3 =1.5u 2 Formula (26); In formula (25), L 3 The minimum distance between the test bearing pitch circle and the oil collecting nut inlet; Calculate the Nusselt number Nu 3 for: The local surface heat transfer coefficient is calculated as: Calculate the average surface heat transfer coefficient h 3 for: The heat flow is calculated as: Φ 3 =h 3 A 3 Δt=h 3 A 3 ((t 3 +t 4 ) / 2-t B2 ) Formula (29); In formula (30), r 1 is the radius of the inner cavity of the oil seal, r 2 is the radius of the center hole on the oil inlet side of the oil seal cover; The heat flux density is calculated as: q 3 =Φ 3 / A 3 Formula (31); Calculate the oil inlet side wall temperature t of the oil seal cover at the same radial position as the test bearing pitch circle 4 for: In formula (32), h B3is the heat transfer coefficient between the outer wall of the oil seal and the external airflow, h B3 =27W / (m 2 .K); Solving equations (28)-(32) yields t 4 The numerical value of .
[0021] Step 5: Calculate the temperature t of the test bearing pitch circle position on the oil inlet side of the oil seal cover 5 In formula (32), L 4 L is the minimum distance between the outer ring of the test bearing and the oil inlet side wall of the oil seal cover. 5 is the axial length of the test bearing outer ring.
[0022] Step 6: Calculate the outer ring temperature t of the test bearing 6 Calculate the flow Reynolds number R e4 for: u 4 =12u 3 Formula (35); In formula (34), d 2 is the inner diameter of the outer ring of the test bearing; Considering the flow as turbulent, calculate the inlet section length L t2 for: L t2 =60d 2 Formula (36); Then the axial length L of the outer ring of the test bearing 5 The length of the inlet section L t2 For comparison, If L t2 <L 5 , calculate the surface heat transfer coefficient h 4 for: If L t2 >L 5 , calculate the Nusselt number Nu 4 for: f 2 =(1.82lgRe 4 -1.64) -2 Formula (39); Calculate the surface heat transfer coefficient h 4 for: h 4 =(λ / d 2 )Nu4 Formula (42); In formula (38), c t2 is the temperature correction factor; The heat flow is calculated as: Φ 4 =h 4 A 4 Δt=h 4 A 4 (t 5 -(t 6 / 2)) Formula (41); A 4 =πL 5 d 2 Formula (42); The heat flux density is calculated as: q 4 =Φ 4 / A 4 Formula (43); The test bearing outer ring temperature is
[0023] According to the characteristics of lubricating oil flow, the present invention divides its flow process into several stages, establishes heat transfer and fluid mechanics models for each stage, and reversely infers the lubricating oil temperature of the previous stage based on the return oil temperature of the test bearing. According to the flow characteristics of lubricating oil inside the bearing, a convective heat transfer model is established to derive the outer ring temperature of the test bearing. The present invention derives the difficult-to-measure rotating outer ring temperature of the bearing based on the relatively easy-to-measure stationary part temperature and lubricating oil flow rate. It can more accurately reflect the temperature change of the test bearing than monitoring the return oil temperature, and is of great significance to improving the reliability and accuracy of the bearing outer ring temperature measurement. In addition, the present invention has no time limit for use under high-speed conditions, and is more advantageous in applications such as aircraft engines.
Claims
1. A method for measuring and calculating the bearing outer ring temperature based on the bearing oil return temperature, characterized in that: The following steps are involved: Step 1: Install the test bearing on the test fixture for rotation test The test fixture comprises an inner ring test shaft, an outer ring test shaft and an oil sealing cover, a mounting seat is provided at the end of the inner ring test shaft, the inner ring of the test bearing is sleeved on the mounting seat, an inner locking nut is provided on the mounting seat to limit the inner ring of the test bearing, the inner hole at the end of the outer ring test shaft is sleeved on the outer ring of the test bearing, an outer locking nut is provided at the end of the outer ring test shaft to limit the outer ring of the test bearing, the test bearing and the mounting seat are both located in the cylindrical inner cavity of the oil sealing cover, the center holes on both sides of the oil sealing cover are respectively sealed and sleeved on the inner ring test shaft and the outer ring test shaft, an oil injection hole is provided in the oil sealing cover, the nozzle of the oil injection hole is located on the oil inlet side wall of the oil sealing cover, the nozzle of the oil injection hole can spray lubricating oil toward the oil collecting cavity between the mounting seat and the inner ring test shaft, an oil return port is provided at the bottom end of the oil sealing cover, and an oil collecting nut is screwed on the oil return port; The test bearing is subjected to a rotation experiment by relative rotation of the inner ring test shaft and the outer ring test shaft. Lubricating oil is delivered to the test bearing through the oil injection hole and recovered through the oil collecting nut. The temperature sensor and flow sensor set at the corresponding measuring point are used to measure the internal oil return temperature t1 of the oil collecting nut and the outer wall temperature t B1 , the outer wall temperature of the oil seal cover t B2 and return oil flow q; Step 2: Calculate the oil return temperature t2 at the oil receiving nut inlet Calculate the return oil flow velocity u1 as: In formula (1), d1 is the inner diameter of the oil collecting nut; Calculate the flow Reynolds number R e1 for: In formula (2), v is the kinematic viscosity; If R e1 <2300, the flow is considered as laminar flow and the inlet section length L is calculated. t1 for: L t1 =0.05R e1 Pr formula (3); In formulas (3) and (4), Pr is the Prandtl number, μ is the viscosity of the lubricating oil, and c p is the specific heat at constant pressure, λ is the thermal conductivity; Then the radial distance L1 between the oil collecting nut inlet and the internal oil return temperature measuring point and the inlet section length L t1 For comparison, if L t1 <L1, the Nusselt number Nu1 is selected as 3.66; If L t1 >L1, calculate the Nusselt number Nu1 as: In formula (5), η f is the dynamic viscosity of the flow core area, η w is the wall dynamic viscosity; The surface heat transfer coefficient is calculated as h1=(λ / d1)Nu1 Formula (6); If R e1 >2300, the flow is considered turbulent and the inlet section length L is calculated. t1 for: L t1 =60d1 Formula (7); Then the radial distance L1 between the oil collecting nut inlet and the internal oil return temperature measuring point and the inlet section length L t1 For comparison, if L t1 <L1, the calculated surface heat transfer coefficient h1 is: In formula (8), k is the heat transfer coefficient; If L t1 >L1, calculate the Nusselt number Nu1 as: f1=(1.82lgRe1-1.64) -2 Formula (10); The calculated surface heat transfer coefficient h1 is: h1=(λ / d1)Nu1 Formula (11); In formula (9), c t1 is the temperature correction factor; The heat flow is calculated as: Φ1 = h1A1Δt = h1A1((t1 + t2) / 2 - t B1 ) Equation (12); A1=πL1d1 Formula (13); The heat flux density is calculated as: q1=Φ1 / A1 Formula (14); Calculate the oil return temperature t2 at the oil receiving nut inlet: In formula (15), h B1 is the surface heat transfer coefficient between the outer wall of the tube and the airflow outside the tube, h B1 =10W / (m 2 .K); The value of t2 is obtained by solving equations (11)-(15); Step 3: Calculate the oil inlet wall temperature t3 of the oil seal cover at the same radial position as the oil collecting nut inlet. Calculate the flow Reynolds number R e2 for: u2=0.7u1Equation (18); In formula (17), L2 is the axial distance between the oil inlet side wall of the oil seal cover and the center line of the oil collecting nut; Calculate the Nusselt number Nu2 as: The local surface heat transfer coefficient is calculated as: The average surface heat transfer coefficient h2 is calculated as: The heat flow is calculated as: Φ2 = h2A2Δt = h2A2((t2 + t3) / 2 - t B2 ) Equation (21); The heat flux density is calculated as: q2=Φ2 / A2 Formula (22); In formula (22), A2 is the lower wall area of the oil seal cover; The temperature t3 of the oil inlet side wall of the oil seal cover at the same radial position as the oil collecting nut inlet is calculated as: In formula (23), h B2 is the surface heat transfer coefficient between the outer wall of the oil seal cover and the external airflow, h B2 =27W / (m 2 .K); The value of t3 is obtained by solving equations (20)-(23); Step 4: Calculate the oil inlet wall temperature t4 of the oil seal cover at the same radial position as the test bearing pitch circle to calculate the flow Reynolds number R e3 for: u3=1.5u2 Formula (26); In formula (25), L3 is the minimum distance between the test bearing pitch circle and the oil collecting nut inlet; Calculate the Nusselt number Nu3 as: The local surface heat transfer coefficient is calculated as: The average surface heat transfer coefficient h3 is calculated as: The heat flow is calculated as: Φ3 = h3A3Δt = h3A3((t3 + t4) / 2 - t B2 ) Equation (29); In formula (30), r1 is the radius of the inner cavity of the oil seal cover, and r2 is the radius of the central hole on the oil inlet side of the oil seal cover; The heat flux density is calculated as: q3=Φ3 / A3 Formula (31); The temperature t4 of the oil seal cover oil inlet side wall at the same radial position as the test bearing pitch circle is calculated as: In formula (32), h B3 is the heat transfer coefficient between the outer wall of the oil seal and the external airflow, h B3 =27W / (m 2 .K); The value of t4 is obtained by solving equations (28)-(32); Step 5: Calculate the temperature t5 of the test bearing pitch circle position facing the oil inlet side of the oil seal cover In formula (32), L4 is the minimum distance between the outer ring of the test bearing and the oil inlet side wall of the oil seal cover, and L5 is the axial length of the outer ring of the test bearing; Step 6: Calculate the outer ring temperature t6 of the test bearing Calculate the flow Reynolds number R e4 for: u4=12u3 Formula (35); In formula (34), d2 is the inner diameter of the outer ring of the test bearing; Considering the flow as turbulent, calculate the inlet section length L t2 for: L t2 =60d2 Formula (36); Then the axial length L5 of the outer ring of the test bearing and the length L of the inlet section t2 For comparison, if L t2 <L5, the calculated surface heat transfer coefficient h4 is: If L t2 >L5, calculate the Nusselt number Nu4 as: f2=(1.82lgRe4-1.64) -2 Formula (39); The calculated surface heat transfer coefficient h4 is: h4=(λ / d2)Nu4 Formula (42); In formula (38), c t2 is the temperature correction factor; The heat flow is calculated as: Φ4=h4A4Δt=h4A4(t5-(t6 / 2)) Formula (41); A4=πL5d2 Formula (42); The heat flux density is calculated as: q4=Φ4 / A4 Formula (43); The test bearing outer ring temperature is