scholarly journals Effects of linear modification on the performance of finite length journal bearings

2021 ◽  
Vol 1067 (1) ◽  
pp. 012108
Author(s):  
H A Al-Mosawy ◽  
H U Jamali ◽  
M H Tolephih
2001 ◽  
Vol 13 (4) ◽  
pp. 329-340 ◽  
Author(s):  
V. D'Agostino ◽  
D. Guida ◽  
A. Ruggiero ◽  
A. Senatore

1965 ◽  
Vol 87 (1) ◽  
pp. 185-192 ◽  
Author(s):  
H. S. Cheng ◽  
C. H. T. Pan

This paper extends the method of Cheng and Trumpler [5] to study stability of plain cylindrical gas journal bearings of finite length. Both equilibrium and stability results have been obtained.


2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Yaser Bastani ◽  
Marcio de Queiroz

A new method for determining a closed-form expression for the hydrodynamic forces in finite-length plain journal bearings is introduced. The method is based on applying correction functions to the force models of the infinitely long (IL) or infinitely short (IS) bearing approximation. The correction functions are derived by modeling the ratio between the forces from the numerical integration of the two-dimensional Reynolds equation and the forces from either the IL or IS bearing approximation. Low-order polynomial models, dependent on the eccentricity ratio and aspect ratio, are used for the correction functions. A comparative computational study is presented for the steady-state behavior of the bearing system under static and unbalance loads. The results show the proposed models outperforming the standard limiting approximations as well as a model based on the finite-length impedance method.


Author(s):  
Mohammad Miraskari ◽  
Farzad Hemmati ◽  
MY Alqaradawi ◽  
Mohamed S Gadala

Dynamic coefficients of a finite length journal bearing are numerically calculated under laminar and turbulent regimes based on Ng–Pan–Elrod and Constantinescu models. Linear stability charts of a flexible rotor supported on laminar and turbulent journal bearings are found by calculating the threshold speed of instability associated to the start of instable oil whirl phenomenon. Local journal trajectories of the rotor-bearing system were found at different operating conditions solely based on the calculated dynamic coefficients in laminar and turbulent flow. Results show no difference between laminar and turbulent models at low loading while significant change of the size of the stable region was observed by increasing the Reynolds number in turbulent models. Stable margins based on the laminar flow at relatively low Sommerfeld numbers [Formula: see text] were shown to fall inside the unstable region and hence rendering the laminar stability curves obsolete at high Reynolds numbers. Ng-Pan turbulent model was found to be generally more conservative and hence is recommended for rotor-bearing design.


2015 ◽  
Vol 32 (1) ◽  
pp. 101-111 ◽  
Author(s):  
M. Besanjideh ◽  
S. A. Gandjalikhan Nassab

ABSTRACTThe journal bearings which are designed for heavy-duty operations could experience different lubricant density due to high bearing loads. In the present work, hydrodynamic behaviour of finite length journal bearings under laminar and isoviscous flow with variable density are investigated. For this purpose, three-dimensional continuity and momentum equations along with a proper density-pressure relation are solved numerically, using CFD technique. Also, an appropriate cavitation model based on mass conservation is involved in the computation. Because of complex geometry of journal bearing, a conformal mapping is employed to generate an orthogonal grid and the governing equations are transformed in the computational domain. Since the degree of oil compressibility can be depended to the type of lubricant, typical mineral and synthetic oils treatments are modelled, separately. Results indicate that the oil compressibility effect leads to increasing load carrying capacity such that this increase is slightly more for the synthetic oil.


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