Dynamic Behaviour of Tilting-Pad Journal Bearings

1995 ◽  
Vol 209 (4) ◽  
pp. 275-285 ◽  
Author(s):  
S Pagano ◽  
E Rocca ◽  
M Russo ◽  
R Russo
Keyword(s):  
Dynamic Behaviour ◽  
Static Load ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Rigid Rotor ◽  
Tilting Pad ◽  
Non Linear ◽  
The Stability ◽  
Tilting Pad Journal Bearings

The dynamic behaviour of a rigid rotor on tilting-pad journal bearings system is analysed for balanced and unbalanced rotors. The study mainly regards a two-pad journal bearing symmetric with respect to the external static load. Both linear and non-linear behaviours have been analysed, with particular reference to the stability of the journal and pads equilibrium positions in the case of balanced or slightly unbalanced rotors, and to the stability of their synchronous motions in the case of considerable unbalance.

scholarly journals Instability Threshold of a Rigid Rotor-Tilting Pad Journal Bearings System

1997 ◽  
Vol 3 (3) ◽  
pp. 199-213 ◽  
Author(s):  
Stefano Pagano ◽  
Ernesto Rocca ◽  
Michele Russo ◽  
Riccardo Russo
Keyword(s):  
Differential Equations ◽  
Numerical Integration ◽  
Equations Of Motion ◽  
Journal Bearings ◽  
Stable Operation ◽  
Rigid Rotor ◽  
Tilting Pad ◽  
The Stability ◽  
Tilting Pad Journal Bearings ◽  
Rotor Axis

The stability of a rigid rotor supported on radial tilting pad journal bearings is analysed. This study has been tackled both for small unbalance values by linearising the equations of motion, and also in the case where, because of the high unbalance value, the rotor axis describes orbits with an amplitude such that the system's non-linearity cannot be ignored. In both cases the system's stable operation maps have been obtained and verified through numerical integration of the differential equations of motion.

scholarly journals Experimental Investigations on Tilting Pad Journal Bearings

1999 ◽  
Vol 5 (3) ◽  
pp. 181-191 ◽  
Author(s):  
Renato Brancati ◽  
Stefano Pagano ◽  
Ernesto Rocca ◽  
Michele Russo ◽  
Riccardo Russo
Keyword(s):  
Dynamic Behaviour ◽  
Experimental System ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Experimental Investigations ◽  
Rigid Rotor ◽  
Tilting Pad ◽  
Set Up ◽  
The University ◽  
Tilting Pad Journal Bearings

The results of a survey conducted on an experimental system consisting of a rigid rotor supported on two radial bearings each with five tilting pads is presented. In particular, the system was set up in order to assess the dynamic behaviour of the bearing in unusual operating conditions. The response of the bearing to different unbalance values was determined after acquiring and analysing the orbits described by the journal axis for assigned unbalance values in different operating conditions. Analysis of the results shows some particular operating features that were not entirely predicted by the theoretical model and which may give rise to malfunctions in the rotor-tilting pad bearings system. The tests were carried out in the rotor dynamics laboratory of the Dipartimento di Ingegneria Meccanica per l'Energetica at the University of Naples.

Numerical and experimental study on the dynamic bearing properties of a four-pad and eight-pad tilting pad journal bearings in a vertical rotor

2021 ◽  
pp. 1-24
Author(s):  
Gudeta Berhanu Benti ◽  
David Jose Rondon ◽  
Rolf Gustavsson ◽  
Jan-Olov Aidanpää
Keyword(s):  
Dynamic Properties ◽  
Mean Value ◽  
Journal Bearings ◽  
Navier Stokes ◽  
Rigid Rotor ◽  
Navier Stokes Equation ◽  
Vertical Rotor ◽  
Tilting Pad ◽  
Fifth Order ◽  
Tilting Pad Journal Bearings

Abstract In this paper, the dynamics of tilting pad journal bearings with four and eight pads are studied and compared experimentally and numerically. The experiments are performed on a rigid vertical rotor supported by two identical bearings. Two sets of experiments are carried out under similar test setup. One set is performed on a rigid rotor with two four-pad bearings, while the other is on a rigid rotor with two eight-pad bearings. The dynamic properties of the two bearing types are compared with each other by studying the unbalance response of the system at different rotor speeds. Numerically, the test rig is modeled as a rigid rotor and the bearing coefficients are calculated based on Navier-Stokes equation. A nonlinear bearing model is developed and used in the steady state response simulation. The measured and simulated displacement and force orbits show similar patterns for both bearing types. Compared to the measurement, the simulated mean value and range (peak-to-peak amplitude) of the bearing force deviate with a maximum of 16 % and 38 %, respectively. It is concluded that, unlike the eight-pad TPJB, the four-pad TPJB excite the system at the third and fifth-order frequencies, which are due to the number of pads, and the amplitudes of these frequencies increase with the rotor speed.

Non-linear stability analysis of micropolar fluid lubricated journal bearings with turbulent effect

2019 ◽  
Vol 71 (1) ◽  
pp. 31-39
Author(s):  
Subrata Das ◽  
Sisir Kumar Guha
Keyword(s):  
Stability Analysis ◽  
Linear Stability ◽  
Micropolar Fluid ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Turbulent Regime ◽  
Content Type ◽  
Non Linear ◽  
The Stability ◽  
Bearing System

Purpose The purpose of this paper is to investigate the effect of turbulence on the stability characteristics of finite hydrodynamic journal bearing lubricated with micropolar fluid. Design/methodology/approach The non-dimensional transient Reynolds equation has been solved to obtain the non-dimensional pressure field which in turn used to obtain the load carrying capacity of the bearing. The second-order equations of motion applicable for journal bearing system have been solved using fourth-order Runge–Kutta method to obtain the stability characteristics. Findings It has been observed that turbulence has adverse effect on stability and the whirl ratio at laminar flow condition has the lowest value. Practical implications The paper provides the stability characteristics of the finite journal bearing lubricated with micropolar fluid operating in turbulent regime which is very common in practical applications. Originality/value Non-linear stability analysis of micropolar fluid lubricated journal bearing operating in turbulent regime has not been reported in literatures so far. This paper is an effort to address the problem of non-linear stability of journal bearings under micropolar lubrication with turbulent effect. The results obtained provide useful information for designing the journal bearing system for high speed applications.

Non-Linear Transient Stability Analysis of a Rigid Rotor Supported on Journal Bearings With Rectangular Dimples

2015 ◽  
Author(s):  
Ram Turaga
Keyword(s):  
Stability Analysis ◽  
Surface Texture ◽  
Transient Stability ◽  
Equations Of Motion ◽  
Journal Bearings ◽  
Pressure Curve ◽  
Rigid Rotor ◽  
Non Linear ◽  
The Stability ◽  
Transient Stability Analysis

The influence of deterministic surface texture on the sub-synchronous whirl stability of a rigid rotor has been studied. Non-linear transient stability analysis has been performed to study the stability of a rigid rotor supported on two symmetric journal bearings with a rectangular dimple of large aspect ratio. The surface texture parameters considered are dimple depth to minimum film thickness ratio and the location of the dimple on the bearing surface. Journal bearings of different Length to diameter ratios have been studied. The governing Reynolds equation for finite journal bearings with incompressible fluid has been solved using the Finite Element Method under isothermal conditions. The trajectories of the journal center have been obtained by solving the equations of motion of the journal center by the fourth-order Runge-Kutta method. When the dimple is located in the raising part of the pressure curve the positive rectangular dimple is seen to decrease the stability whereas the negative rectangular dimple is seen to improve the stability of the rigid rotor.

Stability Analysis of Two-Layered Finite Hydrodynamic Porous Journal Bearing Using Linear and Nonlinear Transient Method

2007 ◽  
Author(s):  
S. K. Kakoty ◽  
S. K. Laha ◽  
P. Mallik
Keyword(s):  
Journal Bearing ◽  
Journal Bearings ◽  
Operating Conditions ◽  
System Stability ◽  
Rigid Rotor ◽  
Transient Method ◽  
Porous Bearing ◽  
Nonlinear Transient ◽  
Linear And Nonlinear ◽  
The Stability

A theoretical analysis has been carried out to determine the stability of rigid rotor supported on two symmetrical finite two-layered porous oil journal bearings. The stability curves have been drawn for different eccentricity ratios and Sommerfeld numbers. The effect of bearing feeding parameter, L/D ratio on the stability is also investigated. This paper also deals with a theoretical investigation of stability using a non-linear transient method. This analysis gives the journal centre locus and from this the system stability can be determined. With the help of graphics, several trajectories of the journal centre have been obtained for different operating conditions. Finally a comparison between single-layered porous bearing and the two-layered porous bearing is presented here.

Development of an Active Control System for Rotating Machinery by Means of Tilting Pad Journal Bearings

2016 ◽  
Author(s):  
Steven Chatterton ◽  
Filippo Cangioli ◽  
Paolo Pennacchi ◽  
Andrea Vania ◽  
Phuoc Vinh Dang
Keyword(s):  
Control System ◽  
Journal Bearing ◽  
Sliding Mode ◽  
Resonance Condition ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Rotating Machines ◽  
Tilting Pad ◽  
Tilting Pad Journal Bearing ◽  
Tilting Pad Journal Bearings

The current design trend of rotating machines like turbo-generators, compressors, turbines, and pumps is focused on obtaining both high dynamic performances and high versatility of machines in different operating conditions. The first target is nowadays achieved by equipping machines with tilting pad journal bearings. For the second target, State-of-the-Art researches are focused on the development of active systems able to adapt the dynamic behavior of the machine to the external environment and new operating conditions. Typical causes of large vibration in rotating machines are faults, residual unbalance, resonance condition and instabilities. Aiming at vibration reduction, in recent years many studies are carried out to investigate different solutions; one of them is based on active tilting pad journal bearing. In this paper, the authors investigate, by simulations, the reduction of shaft vibration by controlling the motion of the pads of a tilting pad journal bearing. The basic idea is to balance the exciting force on the shaft with a suitable resulting force of the oil-film pressure distribution. In particular, a sliding mode controller has been considered and both angular rotation of the pads about the pivot and the radial motion of the pivot have been analyzed. Sliding mode control guarantees high robustness of the control system in real applications that can be characterized by a strong non-linear behavior. In the paper a general consideration about the bearing, the actuating methods and the control system have been provided. A numerical analysis of large size rotor equipped with active pads has been carried out in order to verify the effectiveness of the system in several conditions, even during the most critical operating phase, i.e. the lateral critical speed.

Numerical and experimental study on dynamic characteristics of tilting-pad journal bearings considering pivot stiffness in a vertical rotor system

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Fan Zhang ◽  
Peng Yin ◽  
Yuyang Liu ◽  
Jianmei Wang
Keyword(s):  
Dynamic Characteristics ◽  
Journal Bearings ◽  
Rotor System ◽  
Obvious Effect ◽  
Content Type ◽  
Vertical Rotor ◽  
Tilting Pad ◽  
Rotor Bearing ◽  
The Stability ◽  
Tilting Pad Journal Bearings

Purpose The purpose of this paper is to study the influence of pivot stiffness on the dynamic characteristics of tilting-pad journal bearings (TPJBs) and the stability of the bearing-rotor system. Design/methodology/approach A theoretical numerical model is established, and the influences of pivot stiffness on TPJBs and a bearing-rotor system are analyzed. Then, two kinds of pivot structures with different stiffness are designed and the vibration characteristics are tested on the vertical rotor bearing test bench. Findings The pivot stiffness has an obvious effect on the dynamic characteristics of the TPJBs and the stability of the bearing-rotor system. As a result of appropriate pivot stiffness, the critical speed and the vibration amplification factor can be reduced, the logarithmic decay rate and the stability of the rotor system can be effectively increased. While the journal whirl orbit is smoother and the rubbing is obviously reduced when the bearings have flexible pivots. Originality/value The influence of pivot stiffness on TPJBs and a vertical rotor-bearing system is studied by theoretical and experimental methods.

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