Minimizing Misalignment Effects in Finite Length Journal Bearings

Jamali, Hazim U.; Aljibori, Hakim S. Sultan; Senatore, Adolfo; AL-Dujaili, Zahraa A.; Jweeg, Muhsin J.; Abed, Azher M.; Abdullah, Oday I.

doi:10.3390/designs6050085

Cited by 5 publications

(11 citation statements)

References 29 publications

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“…The chamfered bearing is schematically illustrated in Figure 3. More detail about this modification can be found in the previous reference [12]. The gap in the circumferential direction resulted from the bearing chamfer, which is a function of z along the bearing length as [12]…”

Section: Profile Modification Of the Bearingmentioning

confidence: 99%

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Analysis of the Performance of Chamfered Finite-Length Journal Bearings under Dynamic Loads

et al. 2023

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Misalignment is one of the most common challenges that the normal operation of journal bearings faces. This type of problem may be the result of a wide range of reasons, such as bearing wear, shaft deformation, and errors related to the manufacturing and installation process. The main undesirable consequences of the misalignment, such as pressure rise and lubricant film reduction, are concentrated on the bearing edges. Therefore, chamfering the bearing edges reduces such misalignment-related drawbacks. This work presents a novel numerical solution to the problem of finite-length journal bearing considering edge chamfering. This solution involves the determination of the levels of lubricant layer thickness and pressure distribution in addition to the journal trajectory under impact load with the related stability limits. The finite difference method is used in this solution, and the equations of motion are also solved numerically using the Runge–Kutta method. The Results of this novel analysis show that chamfering the bearing edges increases the film thickness and reduces pressure spikes associated with the system operation under the case of 3D misalignment. Furthermore, the chamfered bearing shows a wide stability range under impact loads, where the normal bearing is unstable as the critical speed increases by 26.98%, which has positive consequences on the journal’s trajectory.

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Section: Profile Modification Of the Bearingmentioning

confidence: 99%

“…The effect of bearing profile was investigated by Liu et al [11] where the study was extended to consider the elasto-hydrodynamic regime in a journal bearing. Several studies proposed chamfering the bearing edges to reduce the misalignment effects without considering its impact on the system stability [5,12].…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Performance of Chamfered Finite-Length Journal Bearings under Dynamic Loads

et al. 2023

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“…The variation of the bearing profile shown previously in Figure 1c will change the gap between the shaft's surface and the bearing's inner surface, which is essentially used to compensate for the reduction in the gap due to misalignment. Detailed steps of this method were explained in [24].…”

Section: Governing Equations and The Mathematical Modelmentioning

confidence: 99%

“…Recently, Ren et al [23] used a numerical investigation to study the effects of profile parameters on the bearing performance, where the results showed that the quadratic profile improves the bearing performance significantly. Jamali et al [24,25] showed that the bearing performance can be improved by using a variable bearing profile. More recently, the misalignment problem in journal bearing has also been investigated by [26][27][28].…”

Section: Introductionmentioning

confidence: 99%

A New Geometrical Design to Overcome the Asymmetric Pressure Problem and the Resulting Response of Rotor-Bearing System to Unbalance Excitation

Jamali,

Aljibori,

Al-Tamimi

et al. 2023

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Improving the bearing design helps in reducing the negative consequences related to errors in installation, manufacturing, deflections under severe loading conditions, progressive wear of machine elements, and many other aspects. One of the methods of such a design improvement effort is changing the bearing profile along the bearing width to compensate for the reduction in the geometrical gap between the shaft and the bearing inner surface due to the aforementioned causes. Since in all rotating machinery, unbalance usually exists at some level, this paper deals with the response of this modified bearing to unbalanced excitation to evaluate the effectiveness of such geometrical design on the dynamic characteristics of the rotor-bearing system. The numerical solution is performed using the finite difference method by assuming Reynolds boundary conditions to determine the cavitation limits, and the 4th-order Range-Kutta method is used to determine the time responses resulting from the unbalance excitation. The time responses to this type of excitation show that the rotor-bearing with the improved geometrical design is more stable, particularly at high speeds. In addition, this modification leads to an improvement in the lubricant layer thickness and the reduction in the levels of the generated pressure between the surfaces despite the presence of large deviations from the perfectly aligned bearing system. Furthermore, the suggested geometrical design overcomes the problem of asymmetricity in the pressure field resulting from the shaft deviation to a large extent. The results of this work (the enhancement in the level of the film thickness and the improvement in the dynamic response of the system as well as the reduction of the maximum pressure value) extend the range of misalignment in which the rotor bearing systems can operate safely which represents a significant step in designing the rotor-bearing system.

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“…Some and Guha 25 reported that increasing degrees of misalignment results in higher steady-state pressure values in the film region, and up to a certain point, this pressure rises as a result of rising coupled-stress parameters of a doubled-layered porous journal bearing. Jamali et al 26 discussed the edge modification method in a finite-length journal bearing to minimize the effect of misalignment.…”

Section: Introductionmentioning

confidence: 99%

Performance analysis of journal bearing having surface waviness operating under misaligned condition

Bangotra,

Sharma,

Taufique

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part J:

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In this present study, the effect of surface waviness on the performance of journal bearing operating in misaligned conditions has been investigated. The journal’s misaligned conditions in the present analysis are taken about the circumferential, the axial, and both axes. For computing the pressure of lubricant inside the bearing, the finite element method has been applied to solve the Reynolds equation and thus static parameters are obtained. The static parameters, that is, load carrying capacity and coefficient of friction are evaluated at different waviness variables and are compared with misaligned journal bearing without surface waviness. It is observed that misalignment considered in both axes has the most severe effect on static performance parameters as compared to misalignment only in the circumferential or axial axis. With the increase in circumferential waviness number up to n = 5, the load-carrying capacity increases, and the coefficient of friction decreases under high eccentricity ratios. Change in waviness amplitude also impacts the bearing performance. Axial waviness always deteriorates the bearing performance. Combined waviness increases the load carrying capacity and decreases the coefficient of friction when circumferential waviness number n = 5 and axial waviness number m = 2. The highest performance enhancement ratio is attained at an eccentricity ratio of 0.8 with a circumferential waviness number n of 5, axial waviness number m of 2, and dimensionless waviness amplitude [Formula: see text] of 0.075.

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Minimizing Misalignment Effects in Finite Length Journal Bearings

Cited by 5 publications

References 29 publications

Analysis of the Performance of Chamfered Finite-Length Journal Bearings under Dynamic Loads

Analysis of the Performance of Chamfered Finite-Length Journal Bearings under Dynamic Loads

A New Geometrical Design to Overcome the Asymmetric Pressure Problem and the Resulting Response of Rotor-Bearing System to Unbalance Excitation

Performance analysis of journal bearing having surface waviness operating under misaligned condition

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