A method for the experimental estimation of direct and cross-coupled dynamic coefficients of tilting-pad journal bearings of vertical hydro-generators

2021 ◽  
pp. 147592172110265
Author(s):  
Geraldo C Brito ◽  
Roberto D Machado ◽  
Anselmo C Neto ◽  
Leonardo Y Kimura
Keyword(s):  
Journal Bearing ◽  
Random Noise ◽  
Turbine Rotor ◽  
Journal Bearings ◽  
Order Model ◽  
Vibration Signals ◽  
Dynamic Coefficients ◽  
Tilting Pad ◽  
Bearing Vibration ◽  
Tilting Pad Journal Bearings

This article presents a method to experimentally estimate the direct and cross-coupled dynamic coefficients of tilting-pad journal bearings of vertical hydro-generators and other similar rotating machinery for damage detection purposes. Based on a simplified second-order model of a journal bearing in the state-space, the method employs only the usually monitored vibrations, the shaft radial relative, and the bearing radial absolute vibrations originated by the hydro-generator residual unbalance or by hydraulic excitations in the turbine rotor. This article shows that the method was successfully tested using the shaft and bearing vibration signals synthesized by a mathematical model of a 700 MW hydro-generator, even when these signals are contaminated with random noise. This article also shows the method’s performance when applied to real vibration signals acquired from the modeled hydro-generator. Finally, it discusses the possible measures to improve the method’s efficiency.

Effect of Uncertainties in the Estimation of Dynamic Coefficients on Tilting Pad Journal Bearings

2016 ◽  
Author(s):  
Rafael O. Ruiz ◽  
Sergio E. Diaz
Keyword(s):  
Surrogate Model ◽  
Journal Bearing ◽  
Deterministic Model ◽  
Journal Bearings ◽  
Kriging Interpolation ◽  
Manufacturing Tolerance ◽  
Dynamic Coefficients ◽  
Tilting Pad ◽  
Tilting Pad Journal Bearing ◽  
Tilting Pad Journal Bearings

It has been identified that small variations in the pad clearance and preload of a Tilting Pad Journal Bearing lead to important variations in their dynamic coefficients. Although this variation trend is already identified, a more robust statistical analysis is required in order to identify more general tendencies and quantify it. This work presents a framework that helps to identify the relation between the manufacturing tolerance of the bearing (reflected in the pad clearance and preload) and the expected variations on the dynamic coefficients. The procedure underlies the adoption of a surrogate model (based on Kriging interpolation) trained by any deterministic model available to predict dynamic coefficients. The pad clearance and preload are considered uncertain parameters defined by a proper probability density function. All statistical quantities are obtained using stochastic simulation, specifically adopting a Monte Carlo simulation employing the surrogate model. The framework is illustrated through the study of a five pad bearing.

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.

Theoretical and Experimental Analyses of Directly Lubricated Tilting-Pad Journal Bearings With Leading Edge Groove

2018 ◽  
Author(s):  
Thomas Hagemann ◽  
Hubert Schwarze
Keyword(s):  
Theoretical Model ◽  
Test Data ◽  
Journal Bearing ◽  
Leading Edge ◽  
Journal Bearings ◽  
Oil Supply ◽  
Tilting Pad ◽  
The Impact ◽  
Leg Design ◽  
Tilting Pad Journal Bearings

Flooded lubrication of tilting-pad journal bearings provides safe and robust operation for many applications due to a completely filled gap at the leading edge of each pad. While flooded conditions can be ensured by restrictive seals on the lateral bearing ends for any conventional bearing design, direct lubrication by leading edge grooves (LEG) placed on the pads represents an alternative to produce completely filled gaps at the entrance to the convergent lubricant film. Moreover, this design is flexible to apply different axial sealing baffles in order to influence the thermal equilibrium within the entire bearing. A theoretical model is presented that describes the specific influences of LEG design on the operating characteristics. First, in opposite to conventional tilting-pad journal bearing designs the LEG is a self-contained lube oil pocket which is generally connected to an outer annular oil supply channel. Consequently, each leading edge groove can feature a specific speed and load dependent effective pocket pressure and flow rate. As a consequence of this and the fact that the LEG is part of the pad, it directly influences its tilting angle. Secondly, the thermal inlet mixing model must consider the specific flow conditions depending on the main flow direction within the film as well as the one between outer annular channel and pocket. The novel LEG model is integrated into a comprehensive bearing code validated earlier for other bearing designs. The code is based on an extended Reynolds equation and a three-dimensional energy equation. The entire theoretical model is validated with test data from high performance journal bearing test rig for a four tilting-pad bearing in load between pivot orientation. The bearing is described by the following specifications: 0.5 nominal preload, 60% offset, 70° pad arc angle, 120 mm inner diameter, 72 mm pad length and 1.7 per mille relative bearing clearance. Measurements are conducted for rotational speeds between 4000 and 15000 rpm and specific bearing loads between 0.5 and 2.5 MPa. Within the investigated operating range good agreement between theoretical and experimental data is achieved if all boundary conditions are accurately considered. Additionally, the impact of single simplifications within the model are studied and evaluated. Finally, the test data is compared to results from the same test bearing with modified lubricant oil supply conditions in order to identify specific properties of LEG design. Here, the leading groove edge elements are replaced by conventional spray-bars. It is shown that an assessment of the comparison depends on the definition of reference conditions as the bearings require different oil flow rates for nominal operation due to their design.

Experimental Study of Tilting-Pad Journal Bearings—Comparison With Theoretical Thermoelastohydrodynamic Results

1992 ◽  
Vol 114 (3) ◽  
pp. 579-587 ◽  
Author(s):  
Michel Fillon ◽  
Jean-Claude Bligoud ◽  
Jean Freˆne
Keyword(s):  
Experimental Study ◽  
Theoretical Model ◽  
Rotational Speed ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Operating Characteristics ◽  
Tilting Pad ◽  
Tilting Pad Journal Bearing ◽  
Tilting Pad Journal Bearings

Operating characteristics of four-shoe tilting-pad journal bearings of 100 mm diameter and 70 mm length are determined on an experimental device. The load, between pad configuration, varies from 0 to 10,000 N and the rotational speed is up to 4000 rpm. Forty thermocouples are used in order to measure bearing element temperatures (babbitt, shaft, housing and oil baths). The influence of operating conditions and preload ratio on bearing performances are studied. Comparison between theoretical and experimental results is presented. The theoretical model is also performed on a large tilting-pad journal bearing which was investigated experimentally by other authors.

Research on the Complete Dynamic Model of Tilting-Pad Journal Bearings Including Fluid Film Temperature Effect

2012 ◽  
Vol 157-158 ◽  
pp. 589-594
Author(s):  
Zhen Shan Zhang ◽  
Xu Dong Dai
Keyword(s):  
Journal Bearing ◽  
Dynamic Properties ◽  
Fluid Film ◽  
Effect Of Temperature ◽  
Rotor Systems ◽  
Dynamic Coefficients ◽  
Tilting Pad ◽  
Precise Prediction ◽  
Tilting Pad Journal Bearing ◽  
Tilting Pad Journal Bearings

Considering the coupling moving of shaft and pads, a theoretical model for calculating the complete dynamic coefficients (CDCs) of tilting-pad journal bearing (TPJB) is described in this paper. The model includes the influence of fluid film temperature. Based on this model, the effect of fluid film temperature on journal equilibrium position, pads inclinations, and complete dynamic coefficients is investigated for given load cases. The numerical results indicate that the effect of temperature is not neglected for the dynamic properties of TPJB. The solution will provide useful tool for precise prediction of dynamic behavior of the rotor systems supported by TPJB.

The Rolling-Pad Journal Bearing: A Promising Antiwhirl Configuration

1981 ◽  
Vol 23 (3) ◽  
pp. 131-141
Author(s):  
M. Malik ◽  
R. Sinhasan ◽  
D. V. Singh
Keyword(s):  
Journal Bearing ◽  
Dynamic Performance ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Performance Characteristics ◽  
Tilting Pad ◽  
The Comparative Study ◽  
Tilting Pad Journal Bearing ◽  
Tilting Pad Journal Bearings ◽  
Theoretical Performance

The rolling-pad journal bearing is a kinematic variation of the well-known tilting-pad journal bearing. In rolling-pad bearings, the pads, instead of tilting about fixed pivots, roll at their back surfaces on the inside surface of a common sleeve to accommodate changes in the operating conditions of the bearing. This paper presents a comparison of the theoretical performance characteristics of rolling-pad journal bearings with those of tilting-pad journal bearings. The comparative study indicates that the dynamic performance characteristics of the rolling-pad bearing configuration are superior to those of the tilting-pad bearing.

Thermal Deformation of Pads in Tilting 5-Pad Journal Bearing

2005 ◽  
Author(s):  
S. Strzelecki ◽  
L. Kusmierz ◽  
G. Poniewaz
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Oil Film ◽  
Tilting Pad ◽  
Drive Trains ◽  
Shaft Misalignment ◽  
Tilting Pad Journal Bearings ◽  
Turbine Drive ◽  
Oil Film Pressure

In high speed compressors and turbine drive trains, the tilting 5-pad journal bearings are applied. Tilting-pad journal bearings are good option because they have very good hydrodynamic stability at high speed and are less sensitive to load direction and shaft misalignment. The paper introduces thermo-elastic deformations of tilting 3-pad journal bearing with asymmetric support of pads and operating at the conditions of adiabatic oil film. The deformations of pads were obtained based on the oil film pressure and temperature distributions. Reynolds, energy, geometry and viscosity equations have been solved numerically on the assumption of aligned orientation of bearing and journal axis and at static equilibrium position of journal.

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