Effect of Aspect Ratio and Semi Cone Angle on the Stability Behaviour of a Conical Hydrodynamic Journal Bearing

2017 ◽  
Author(s):  
Ajay Kumar Gangrade ◽  
Vikas M. Phalle ◽  
S.S. Mantha
Keyword(s):  
Aspect Ratio ◽  
Journal Bearing ◽  
Cone Angle ◽  
Stability Behaviour ◽  
Hydrodynamic Journal Bearing ◽  
The Stability

Investigation of sustainability of lubricated journal bearing under relevant design parameters

2018 ◽  
Vol 70 (4) ◽  
pp. 789-804 ◽  
Author(s):  
M.M. Shahin ◽  
Mohammad Asaduzzaman Chowdhury ◽  
Md. Arefin Kowser ◽  
Uttam Kumar Debnath ◽  
M.H. Monir
Keyword(s):  
Aspect Ratio ◽  
Elastic Strain ◽  
Journal Bearing ◽  
Design Parameters ◽  
Content Type ◽  
Computational Fluid Dynamics Cfd ◽  
Stress Formation ◽  
Bearing Design ◽  
The Stability ◽  
Bearing Friction

Purpose The purposes of the present study are to ensure higher sustainability of journal bearings under different applied loads and to observe bearing performances such as elastic strain, total deformation and stress formation. Design/methodology/approach A journal bearing test rig was used to determine the effect of the applied load on the bearing friction, film thickness, lubricant film pressure, etc. A steady-state analysis was performed to obtain the bearing performance. Findings An efficient aspect ratio (L/D) range was obtained to increase the durability or the stability of the bearing while the bearing is in the working condition by using SAE 5W-30 oil. The results from the study were compared with previous studies in which different types of oil and water, such as Newtonian fluid (NF), magnetorheological fluid (MRF) and nonmagnetorheological fluid (NMRF), were used as the lubricant. To ensure a preferable aspect ratio range (0.25-0.50), a computational fluid dynamics (CFD) analysis was conducted by ANSYS; the results show a lower elastic strain and deformation within the preferable aspect ratio (0.25-0.50) rather than a higher aspect ratio using the SAE 5W-30 oil. Originality/value It is expected that the findings of this study will contribute to the improvement of the bearing design and the bearing lubricating system.

Stability Analysis of a Hydrodynamic Journal Bearing With Rotating Herringbone Grooves

2003 ◽  
Vol 125 (2) ◽  
pp. 291-300 ◽  
Author(s):  
G. H. Jang ◽  
J. W. Yoon
Keyword(s):  
Journal Bearing ◽  
Equations Of Motion ◽  
Fourier Series Expansion ◽  
Algebraic Equations ◽  
High Rotational Speed ◽  
Dynamic Coefficients ◽  
Stiffness Coefficients ◽  
Hydrodynamic Journal Bearing ◽  
The Stability ◽  
Herringbone Grooves

This paper presents an analytical method to investigate the stability of a hydrodynamic journal bearing with rotating herringbone grooves. The dynamic coefficients of the hydrodynamic journal bearing are calculated using the FEM and the perturbation method. The linear equations of motion can be represented as a parametrically excited system because the dynamic coefficients have time-varying components due to the rotating grooves, even in the steady state. Their solution can be assumed as a Fourier series expansion so that the equations of motion can be rewritten as simultaneous algebraic equations with respect to the Fourier coefficients. Then, stability can be determined by solving Hill’s infinite determinant of these algebraic equations. The validity of this research is proved by the comparison of the stability chart with the time response of the whirl radius obtained from the equations of motion. This research shows that the instability of the hydrodynamic journal bearing with rotating herringbone grooves increases with increasing eccentricity and with decreasing groove number, which play the major roles in increasing the average and variation of stiffness coefficients, respectively. It also shows that a high rotational speed is another source of instability by increasing the stiffness coefficients without changing the damping coefficients.

Linear stability analysis of finite hydrodynamic journal bearing under turbulent lubrication with coupled-stress fluid

2016 ◽  
Vol 68 (3) ◽  
pp. 386-391 ◽  
Author(s):  
Abhishek Ghosh ◽  
Sisir Kumar Guha
Keyword(s):  
Stability Analysis ◽  
Newtonian Fluid ◽  
High Speed ◽  
Journal Bearing ◽  
Slenderness Ratio ◽  
Linear Perturbation ◽  
Content Type ◽  
Hydrodynamic Journal Bearing ◽  
The Stability ◽  
Coupled Stress

Purpose Several researchers have observed that to satisfy modern day’s need, it is essential to enhance the characteristics of journal bearing, which is used in numerous applications. Moreover, the use of Newtonian fluid as a lubricant is diminishing day by day, and the use of Non-Newtonian fluids is coming more into picture. Furthermore, if turbo-machinery applications are taken into account, then it can be seen that journal bearings are used for high speed applications as well. Thus, neglecting turbulent conditions may lead to erroneous results. Hence, this paper aims to present focuses on studying the stability characteristics of finite hydrodynamic journal bearing under turbulent coupled-stress lubrication. Design/methodology/approach First, the governing equation relevant to the problem is generated. Then, the dynamic analysis is carried out by linear perturbation technique, leading to three perturbed equations, which are again discretized by finite difference method. Finally, these discretized equations are solved with the help of Gauss-Seidel Iteration technique with successive over relaxation scheme. Consequently, the film response coefficients and the stability parameters are evaluated at different parametric conditions. Findings It has been concluded from the study that with increase in value of the coupled-stress parameter, the stability of the journal may increase. Whereas, with increase in Reynolds number, the stability of the journal decreases. On the other hand, stability increases with increasing values of slenderness ratio. Originality/value Researches have been performed to study the dynamic characteristics of journal bearing with non-Newtonian fluid as the lubricant. But in the class of non-Newtonian lubricants, the use of coupled-stress fluid has not yet been properly investigated. So, an attempt has been made to perform the stability analysis of bearings with coupled-stress fluid as the advanced lubricant.

Morton Effect Induced Synchronous Instability in Mid-Span Rotor–Bearing Systems, Part 2: Models and Simulations

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
Zenglin Guo ◽  
Gordon Kirk
Keyword(s):  
Journal Bearing ◽  
Negative Impact ◽  
System Stability ◽  
Stability Performance ◽  
Fluid Film Bearings ◽  
Morton Effect ◽  
Thermal Bending ◽  
Hydrodynamic Journal Bearing ◽  
The Stability ◽  
Thermal Imbalance

The mechanism of the Morton Effect induced synchronous instability has been discussed in Part 1, using an assumption of isotropic linear bearings. The second part of the current study will now focus on the more realistic systems, mid-span rotors supported by the hydrodynamic journal bearings. First, the models to calculate the thermal bending of the shaft and the temperature distribution across the journal surface are established. This can be used to calculate the equivalent thermal imbalance. The calculations of the temperature difference and its equivalent thermal imbalance using hydrodynamic plain journal bearing models are conducted and discussed with the comparison to the analytical results obtained in Part 1. It shows that the thermal imbalance induced by the Morton Effect may increase to the level of the mechanical imbalance and then its influence on the system stability should be included. The suggested thermal bending model also partially explains that the mid-span rotors are less liable to be influenced by the Morton Effect induced instability than are the overhung configurations, because of the restraining effect between two supports. Finally, a symmetric mid-span rotor - hydrodynamic journal bearing system is calculated to show its stability performance. The results show the inclusion of the Morton Effect may lead to an unstable operation of the system. Considering the existence of the oil film self-induced vibration due to the dynamic characteristics of fluid film bearings, the Morton Effect may make a further negative impact on the stability of the system. The simulation results of the unbalance response show that the Morton Effect changes the shapes of the whirling orbits and makes them no longer the standard elliptical orbits around the static equilibriums.

Effect of journal cylindricity error with saddle or drum distribution on the performance of hydrodynamic journal bearing systems

2019 ◽  
Vol 234 (7) ◽  
pp. 1092-1105
Author(s):  
Bing Li ◽  
Dejian Zhou ◽  
Peter Ogrodnik ◽  
Wubin Xu
Keyword(s):  
Journal Bearing ◽  
System Stability ◽  
Analysis Method ◽  
Shape Distribution ◽  
Hydrodynamic Journal Bearing ◽  
The Stability ◽  
Cylindricity Error ◽  
Saddle Shape ◽  
Fourier Model ◽  
Bearing System

The present study investigates the effect of cylindricity error on the performance of hydrodynamic journal bearing systems. Two types of cylindricity errors of the journal, namely the drum shape distribution cylindricity error (DCE) and the saddle shape distribution cylindricity error (SCE), are considered. The Legendre–Fourier model is used to characterize the profile of each journal. Based on the nonlinear analysis method, the dynamic characteristics and stability of hydrodynamic journal bearing systems are analyzed. The results indicate that cylindricity error affects the system stability, and the effect is related to the type and level of the error. DCE used with a certain range of operating speed and load is not harmful and is even beneficial to the stability of hydrodynamic journal bearing systems; conversely, SCE decreases the system stability. When the Sommerfeld number is between 0.02 and 0.05, cylindricity errors have a minimal effect on the system stability. Additionally, the results indicate that the effect of cylindricity error on the bearing system is more significant than that of roundness error.

Numerical Analysis of Static Characteristics of Herringbone Grooved Hydrodynamic Journal Bearing

2011 ◽  
Vol 105-107 ◽  
pp. 2259-2262
Author(s):  
Han Ting Zhu ◽  
Qian Ding
Keyword(s):  
Journal Bearing ◽  
Normal Pressure ◽  
Differential Method ◽  
Static Characteristics ◽  
Load Carrying ◽  
Significant Performance ◽  
Hydrodynamic Journal Bearing ◽  
The Stability ◽  
Spiral Angle ◽  
Selection Of

By means of the finite differential method, the Reynolds equation is solved and the static characteristics of herringbone grooved hydrodynamic journal bearing are numerically analyzed by presenting the circumferential and axial pressures. The influences of parameters such as the eccentricity, width-diameter ratio of bearing, spiral angle, depth and number of grooves, on the static characteristics of herringbone grooved bearing are discussed. The results indicate that the normal pressure of oil film and the load carrying capacity as well, of herringbone grooved bearing will decrease with the increase of groove number and depth. On the other hand, as the pressure distributes in wider area in the circumferential direction, the stability of bearing can be improved. In consideration of these two aspects, the optimal groove number is 8-12, and the selection of depth and screw angle of grooves should also be chosen carefully to obtain the significant performance of herringbone grooved bearing.

Effect of Tangential Torque on the Stability of Rotors Supported by Hydrodynamic Bearings

1992 ◽  
Author(s):  
Dong-Chul Han
Keyword(s):  
Free Vibration ◽  
Transient Response ◽  
Rotational Speed ◽  
Stability Region ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Shaft Flexibility ◽  
Hydrodynamic Journal Bearing ◽  
Bearing Loads ◽  
The Stability

The effect of tangential torque on the stability of a rotor supported by various hydrodynamic journal bearings is investigated by the free vibration and transient response analyses. It is shown that the stability region of the rotational speed is bounded by both upper and lower rotational speeds. The parametric study of this investigation has been carried out in terms of the dimensionless bearing characteristics, shaft flexibility and tangential torque. It is shown that the use of hydrodynamic journal bearing can eliminate the instability due to tangential torque except for the case of light bearing loads and high shaft flexibilities.

The effect of active control on stability characteristics of hydrodynamic journal bearings with an axial groove

2002 ◽  
Vol 216 (9) ◽  
pp. 939-946 ◽  
Author(s):  
B-H Rho ◽  
K-W Kim
Keyword(s):  
Active Control ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Linear Dynamic ◽  
Conventional Analysis ◽  
Theoretical Investigations ◽  
Rotor Bearing ◽  
Hydrodynamic Journal Bearing ◽  
The Stability ◽  
Bearing System

Results of theoretical investigations on stability characteristics of an actively controlled hydrodynamic journal bearing are presented. Proportional, derivative and integral controls are adopted for a hydrodynamic journal bearing with an axial groove. Furthermore, a cavitation algorithm, implementing the Jakobsson-Floberg-Olsson boundary condition, is adopted to predict cavitation regions in a fluid film more accurately than the conventional analysis, which uses the Reynolds condition. Using the bearing's linear dynamic coefficients, which are evaluated from the perturbation method, the stability characteristics of a rotor-bearing system are investigated using the Routh-Hurwitz criteria. It is shown that the instability threshold speed of a rotor-bearing system can be greatly increased and the unbalanced responses of the system can be markedly decreased by both proportional and derivative control of the bearing. Results show that active control of a hydrodynamic journal bearing can be adopted for stability improvement and reduction of the unbalanced whirl amplitude of a rotor-bearing system.

Morton Effect Induced Synchronous Instability in Mid-Span Rotor-Bearing Systems: Part 2—Models and Simulations

2010 ◽  
Author(s):  
Zenglin Guo ◽  
Gordon Kirk
Keyword(s):  
Journal Bearing ◽  
Negative Impact ◽  
System Stability ◽  
Stability Performance ◽  
Fluid Film Bearings ◽  
Morton Effect ◽  
Thermal Bending ◽  
Hydrodynamic Journal Bearing ◽  
The Stability ◽  
Thermal Imbalance

The mechanism of the Morton Effect induced synchronous instability has been discussed in Part 1, using an assumption of isotropic linear bearings. The second part of the current study will now focus on the more realistic systems, mid-span rotors supported by the hydrodynamic journal bearings. First, the models to calculate the thermal bending of the shaft and the temperature distribution across the journal surface are established. This can be used to calculate the equivalent thermal imbalance. The calculations of the temperature difference and its equivalent thermal imbalance using hydrodynamic plain journal bearing models are conducted and discussed with the comparison to the analytical results obtained in Part 1. It shows that the thermal imbalance induced by the Morton Effect may increase to the level of the mechanical imbalance and then its influence on the system stability should be included. The suggested thermal bending model also partially explain that the mid-span rotors are less liable to be influenced by the Morton Effect induced instability than are the overhung configurations, because of the restraining effect between two supports. Finally, a symmetric mid-span rotor–hydrodynamic journal bearing system is calculated to show its stability performance. The results show the inclusion of the Morton Effect may lead to an unstable operation of the system. Considering the existence of the oil film self-induced vibration due to the dynamic characteristics of fluid film bearings, the Morton Effect may make a further negative impact on the stability of the system. The simulation results of the unbalance response show that the Morton Effect changes the shapes of the whirling orbits and makes them no longer be the standard elliptical orbits around the static equilibriums.

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