Correlations for heat generation and outer ring temperature of high speed and highly loaded ball bearings in an aero-engine

2006 ◽  
Vol 10 (7) ◽  
pp. 611-617 ◽  
Author(s):  
Michael Flouros
Keyword(s):  
Heat Generation ◽  
High Speed ◽  
Outer Ring ◽  
Ball Bearings ◽  
Aero Engine ◽  
Highly Loaded

Active Outer Ring Cooling of High-Loaded and High-Speed Ball Bearings

2013 ◽  
Vol 135 (8) ◽  
Author(s):  
Michael Flouros ◽  
Markus Hirschmann ◽  
Francois Cottier ◽  
Peter Gloeckner ◽  
Klaus Dullenkopf
Keyword(s):  
Heat Generation ◽  
High Speed ◽  
High Rate ◽  
Outer Ring ◽  
Excessive Pressure ◽  
Pressure Losses ◽  
Aero Engine ◽  
Design Characteristics ◽  
Materials Used ◽  
Critical Limits

Bearings for aero engine applications are subjected to a high thermal impact because of the elevated speeds and loads. The high rate of heat generation in the bearing cannot be sustained by the materials used and, in the absence of lubrication, will fail within seconds. For this reason, aero engine bearings have to be lubricated and cooled by a continuous oil stream. The heat that is generated in the bearings through friction is transferred into the oil. Oil itself has limited capabilities and can only remove heat as long as its temperature does not reach critical limits. When the critical limits have been reached or even exceeded, the oil will suffer chemical decomposition (coking) with loss of its properties and subsequently cause a detrimental impact on the rotating machinery. Oil is normally transferred into the bearings through holes in the inner ring, thus taking advantage of the centrifugal forces due to the rotation. On its way through the bearing, the oil continuously removes heat from the inner ring, the rolling elements, and the bearing cage until it reaches the outer ring. Since the oil has already been heated up, its capability to remove heat from the outer ring is considerably reduced. The idea to provide the bearing with an “unlimited” quantity of oil to ensure proper cooling cannot be considered, since an increase in the oil quantity leads to higher parasitic losses (churning) in the bearing chamber and increased requirements on the engine's lubrication system in terms of storage, scavenging, cooling, weight, etc., not mentioning the power needed to accomplish all these. In this sense, the authors have developed a method that would enable active cooling of the outer ring. Similar to fins, which are used for cooling electronic devices, a spiral groove engraved in the outer ring material would function as a fin body with oil instead of air as the cooling medium. The number of “threads” and the size of the groove design characteristics were optimized in a way that enhanced heat transfer is achieved without excessive pressure losses. An experimental setup was created for this reason, and a 167.5-mm pitch circle diameter (PCD) ball bearing was investigated. The bearing was tested with and without the outer ring cooling. A reduction of 50% of the lubricant flow through the inner ring associated with a 30% decrease in heat generation was achieved.

Active Outer Ring Cooling of High Loaded and High Speed Ball Bearings

2012 ◽  
Author(s):  
Michael Flouros ◽  
Markus Hirschmann ◽  
Francois Cottier ◽  
Peter Gloeckner ◽  
Klaus Dullenkopf
Keyword(s):  
Heat Generation ◽  
High Speed ◽  
High Rate ◽  
Outer Ring ◽  
Excessive Pressure ◽  
Pressure Losses ◽  
Aero Engine ◽  
Design Characteristics ◽  
Materials Used ◽  
Critical Limits

Bearings for aero engine applications are subjected to a high thermal impact because of the elevated speeds and loads. The high rate of heat generation in the bearing cannot be sustained by the materials used and in the absence of lubrication will fail within seconds. For this reason aero engine bearings have to be lubricated and cooled by a continuous oil stream. The heat which is generated in the bearings through friction is transferred into the oil. Oil itself has not unlimited capabilities and can only remove heat as long as its temperature does not reach critical limits. When the critical limits have been reached or even exceeded the oil will suffer chemical decomposition (coking) with loss of its properties and subsequently causing a detrimental impact on the rotating machinery. Oil is normally transferred into the bearings through holes in the inner ring thus taking advantage of the centrifugal forces due to the rotation. In its way through the bearing the oil continuously removes heat from the inner ring, the rolling elements and the bearing cage until it reaches the outer ring. Since the oil has already been heated up its capability to remove heat from the outer ring is considerably reduced. The idea to provide the bearing with an “unlimited” quantity of oil to ensure proper cooling cannot be considered since an increase in the oil quantity leads to higher parasitic losses (churning) in the bearing chamber and increased requirements on the engine’s lubrication system in terms of storage, scavenging, cooling, weight, etc, not mentioning the power needed to accomplish all these. In this sense, the authors have developed a method which would enable active cooling of the outer ring. Similar to fins which are used for cooling electronic devices, a spiral groove engraved in the outer ring material would function as a fin body with oil instead of air as the cooling medium. The number of “threads” and the size of the groove design characteristics were optimized in a way that enhanced heat transfer is achieved without excessive pressure losses. An experimental set up was created for this reason and a 167.5mm PCD (Pitch Circle Diameter) ball bearing was investigated. The bearing was tested with and without the outer ring cooling. A reduction of 50% of the lubricant flow through the inner ring associated with a 30% decrease in heat generation was achieved.

An improved model on forecasting temperature rise of high-speed angular contact ball bearings considering structural constraints

2018 ◽  
Vol 70 (1) ◽  
pp. 15-22 ◽  
Author(s):  
De-xing Zheng ◽  
Weifang Chen ◽  
Miaomiao Li
Keyword(s):  
Heat Generation ◽  
Temperature Rise ◽  
High Speed ◽  
Structural Constraints ◽  
Ball Bearings ◽  
Content Type ◽  
Grid Model ◽  
Simulation Results ◽  
Operation Parameters ◽  
Improved Model

Purpose Thermal performances are key factors impacting the operation of angular contact ball bearings. Heat generation and transfer about angular contact ball bearings, however, have not been addressed thoroughly. So far, most researchers only considered the convection effect between bearing housings and air, whereas the cooling/lubrication operation parameters and configuration effect were not taken into account when analyzing the thermal behaviors of bearings. This paper aims to analyze the structural constraints of high-speed spindle, structural features of bearing, heat conduction and convection to study the heat generation and transfer of high-speed angular contact ball bearings. Design/methodology/approach Based on the generalized Ohm’s law, the thermal grid model of angular contact ball bearing of high-speed spindle was first established. Next Gauss–Seidel method was used to solve the equations group by Matlab, and the nodes temperature was calculated. Finally, the bearing temperature rise was tested, and the comparative analysis was made with the simulation results. Findings The results indicate that the simulation results of bearing temperature rise for the proposed model are in better agreement with the test values. So, the thermal grid model established is verified. Originality/value This paper shows an improved model on forecasting temperature rise of high-speed angular contact ball bearings. In modeling, the cooling/lubrication operation parameters and structural constraints are integrated. As a result, the bearing temperature variation can be forecasted more accurately, which may be beneficial to improve bearing operating accuracy and bearing service life.

The Nature of Slip in High-Speed Axially Loaded Ball Bearings

1986 ◽  
Vol 200 (5) ◽  
pp. 359-365 ◽  
Author(s):  
J Dominy
Keyword(s):  
Heat Generation ◽  
High Speed ◽  
Numerical Technique ◽  
Experimental Results ◽  
Ball Bearings ◽  
Roller Bearings ◽  
Axially Loaded

This paper develops a simplified numerical technique for the analysis of heat generation and cage slip in high-speed axially loaded ball bearings. The model compares well with experimental results and has shown the characteristic slip behaviour associated with ball bearings. It has been possible to use the model to investigate the nature and causes of slip in lightly loaded ball bearings and it has been shown that the mechanism is primarily dependent upon the spin power, which falls rapidly as slip sets in. The characteristics of slip in ball bearings are shown to be quite different to those in roller bearings.

scholarly journals Study on the Thermal Performance and Temperature Distribution of Ball Bearings in the Traction Motor of a High-Speed EMU

2020 ◽  
Vol 10 (12) ◽  
pp. 4373
Author(s):  
Yu Wang ◽  
Junci Cao ◽  
Qingbin Tong ◽  
Guoping An ◽  
Ruifang Liu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Heat Generation ◽  
Thermal Performance ◽  
High Speed ◽  
Convection Heat Transfer ◽  
Ball Bearings ◽  
Convection Heat ◽  
Rolling Bearings ◽  
Traction Motors

The transient thermal performance of rolling bearings affects the mechanical performance and system safety of traction motors. Most of the traditional empirical formulas used in temperature analysis have been simplified and cannot be completely applied to the calculation of heat generation and convection heat transfer coefficients. Based on the comparative analysis of finite element transient temperature and experimental data, this paper proposes a correction method of mathematical model and derives an accurate calculation formula for the heat generation and lubricant convection heat transfer coefficient of ball bearings applicable for the non-driving end in the traction motor of a high-speed EMU (Electric Multiple Unit). The accuracy of the results has been verified by durability experiment data. In addition, with changes in speed, radial load and other factors taken into account, we have analyzed the influence of these time-varying factors on ball bearing temperature, as well as the temperature distribution law of each component in a grease-lubricated bearing, in a bid to lay a foundation for follow-up research on the heat transfer laws of traction motors and rolling bearings.

Effect of vibration on power loss of angular contact ball bearings

2019 ◽  
Vol 72 (5) ◽  
pp. 657-664
Author(s):  
De-Xing Zheng ◽  
W.F. Chen ◽  
Guanyun Xiao ◽  
Dateng Zheng
Keyword(s):  
Heat Generation ◽  
Power Loss ◽  
High Speed ◽  
Forecasting Model ◽  
Ball Bearings ◽  
Content Type ◽  
Additional Load ◽  
Vibration Effect ◽  
Bearing Loads ◽  
Experimental Values

Purpose This paper aims to devote to the experimental analysis and modeling on the heat generation of angular contact ball bearings under vibration. Design/methodology/approach The experiments about vibration effect on bearing temperature are implemented. To explore the causes of bearing temperature rise, the shaft-bearing system is first simplified to a forced vibration model to analyze the bearing loads in vibration. Next, the vibratory-induced additional load is proposed and the spin power loss of balls is re-derived under vibration. The vibration-induced heat is integrated into a novel forecasting model of bearing power loss. For validation, the muti-node model for angular contact ball bearings is referred to create the thermal network of spindle front bearing, and then the contrast and discussion is done. Findings The simulation and test results both indicate that more energy is expended and more heat is generated with vibration. And the further quantitative comparisons between simulation results and experimental values of bearing temperature demonstrate the rationality and availability of constructed model on bearing heat generation. Originality/value The vibration-induced additional load is proposed and modeled, and the novel forecasting model for heat generation for high-speed angular contact ball bearings with vibration is constructed and validated.

scholarly journals Mathematical Modelling and Transient Thermal Analysis of Coupler-Rocker Bearing

2018 ◽  
Vol 225 ◽  
pp. 04005
Author(s):  
Abdullah Jamil ◽  
Masri B. Baharom ◽  
Tamiru Alemu Lemma
Keyword(s):  
Thermal Analysis ◽  
Mathematical Modelling ◽  
Heat Generation ◽  
Relative Motion ◽  
High Speed ◽  
Sliding Friction ◽  
Ball Bearings ◽  
Fluid Films ◽  
High Productivity ◽  
Precision Machine Tools

Friction is the resisting force between two bodies having relative motion. These bodies can be solid surfaces, fluid films or elements sliding against each other. There are many devices used to overcome sliding friction which include wheels and bearings. Ball bearings are used in many high speed and high precision machine tools because of their high productivity. A Crank-Rocker four bar mechanism consists of 4 linkages and 4 nodes. These nodes perform complex motions especially the coupler-rocker joint. In order to reduce the friction between these relatively moving links, ball bearings can be introduced. The coupler-rocker bearing oscillates about some axis as well as the raceways have some relative motion. Heat generation rate is not known for bearings performing this type of complex motion. This paper describes the mathematical modelling and thermal analysis of coupler-rocker bearing. Heat generation in the bearing can be estimated using this model. This can be countered by having proper lubrication and speed of bearing.

Temperature Rise Prediction of Oil-Air Lubricated Angular Contact Ball Bearings Using Artificial Neural Network

2019 ◽  
Vol 12 (3) ◽  
pp. 248-261
Author(s):  
Baomin Wang ◽  
Xiao Chang
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Temperature Rise ◽  
High Speed ◽  
Ball Bearing ◽  
Influence Factors ◽  
Ball Bearings ◽  
Ann Model ◽  
Angular Contact Ball Bearing ◽  
Artificial Neural

Background: Angular contact ball bearing is an important component of many high-speed rotating mechanical systems. Oil-air lubrication makes it possible for angular contact ball bearing to operate at high speed. So the lubrication state of angular contact ball bearing directly affects the performance of the mechanical systems. However, as bearing rotation speed increases, the temperature rise is still the dominant limiting factor for improving the performance and service life of angular contact ball bearings. Therefore, it is very necessary to predict the temperature rise of angular contact ball bearings lubricated with oil-air. Objective: The purpose of this study is to provide an overview of temperature calculation of bearing from many studies and patents, and propose a new prediction method for temperature rise of angular contact ball bearing. Methods: Based on the artificial neural network and genetic algorithm, a new prediction methodology for bearings temperature rise was proposed which capitalizes on the notion that the temperature rise of oil-air lubricated angular contact ball bearing is generally coupling. The influence factors of temperature rise in high-speed angular contact ball bearings were analyzed through grey relational analysis, and the key influence factors are determined. Combined with Genetic Algorithm (GA), the Artificial Neural Network (ANN) model based on these key influence factors was built up, two groups of experimental data were used to train and validate the ANN model. Results: Compared with the ANN model, the ANN-GA model has shorter training time, higher accuracy and better stability, the output of ANN-GA model shows a good agreement with the experimental data, above 92% of bearing temperature rise under varying conditions can be predicted using the ANNGA model. Conclusion: A new method was proposed to predict the temperature rise of oil-air lubricated angular contact ball bearings based on the artificial neural network and genetic algorithm. The results show that the prediction model has good accuracy, stability and robustness.

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