scholarly journals Operating Behavior of Sliding Planet Gear Bearings for Wind Turbine Gearbox Applications—Part I: Basic Relations

Lubricants ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 97
Author(s):  
Thomas Hagemann ◽  
Huanhuan Ding ◽  
Esther Radtke ◽  
Hubert Schwarze
Keyword(s):  
Wind Turbine ◽  
Local Maximum ◽  
Axial Direction ◽  
Operating Conditions ◽  
Design Parameters ◽  
Radial Clearance ◽  
Wind Turbine Gearbox ◽  
Local Loads ◽  
Gear Mesh ◽  
Planet Gear

The application of sliding planet gear bearings in wind turbine gearboxes has become more common in recent years. Assuming practically applied helix angles, the gear mesh of the planet stage causes high force and moment loads for these bearings involving high local loads at the bearing edges. Specific operating behavior and suitable design measures to cope with these challenging conditions are studied in detail based on a thermo-hydrodynamic (THD) bearing model. Radial clearance and axial crowning are identified as important design parameters to reduce maximum pressures occurring at the bearing edges. Furthermore, results indicate that a distinct analysis of the gear mesh load distribution is required to characterize bearing operating behavior at part-load. Here, operating conditions as critical as the ones reached at nominal load might occur. Wear phenomena can improve the shape of the gap in the circumferential as well as in axial direction incorporating a significant reduction of local maximum pressures. The complexity of the combination of these aspects and the additionally expected impact of structure deformation gives an insight into the challenges in the design processes of sliding planet gear bearings for wind turbine gearbox applications.

scholarly journals Operating Behavior of Sliding Planet Gear Bearings for Wind Turbine Gearbox Applications—Part II: Impact of Structure Deformation

Lubricants ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 98
Author(s):  
Thomas Hagemann ◽  
Huanhuan Ding ◽  
Esther Radtke ◽  
Hubert Schwarze
Keyword(s):  
Wind Turbine ◽  
Peak Load ◽  
Planetary Gear ◽  
Operating Conditions ◽  
Wind Turbine Gearbox ◽  
Structure Deformation ◽  
Drive Trains ◽  
Planet Gear ◽  
The Impact ◽  
Bearing Analysis

The use of planetary gear stages intends to increase power density in drive trains of rotating machinery. Due to lightweight requirements on this type of machine elements, structures are comparably flexible while mechanical loads are high. This study investigates the impact of structure deformation on sliding planet gear bearings applied in the planetary stages of wind turbine gearboxes with helical gears. It focuses on three main objectives: (i) development of a procedure for the time-efficient thermo-elasto-hydrodynamic (TEHD) analysis of sliding planet gear bearing; (ii) understanding of the specific deformation characteristics of this application; (iii) investigation of the planet gear bearing’s modified operating behavior, caused by the deformation of the sliding surfaces. Generally, results indicate an improvement of predicted operating conditions by consideration of structure deformation in the bearing analysis for this application. Peak load in the bearing decreases because the loaded proportion of the sliding surface increases. Moreover, tendencies of single design measures, determined for rigid geometries, keep valid but exhibit significantly different magnitudes under consideration of structure deformation. Results show that consideration of structure flexibility is essential for sliding planet gear bearing analysis if quantitative assertions on load distributions, wear phenomena, and interaction of the bearing with other components are required.

Estimation of Wind Turbine Gearbox Loads for Online Fatigue Monitoring Using Inverse Methods

2021 ◽  
Author(s):  
Felix C. Mehlan ◽  
Amir R. Nejad ◽  
Zhen Gao
Keyword(s):  
Wind Turbine ◽  
Fatigue Damage ◽  
Wind Turbine Gearbox ◽  
Local Loads ◽  
Vibration Data ◽  
Novel Approach ◽  
Torque Measurements ◽  
Continuous Estimation ◽  
Dynamic States

Abstract In this article a novel approach for the estimation of wind turbine gearbox loads with the purpose of online fatigue damage monitoring is presented. The proposed method employs a Digital Twin framework and aims at continuous estimation of the dynamic states based on CMS vibration data and generator torque measurements from SCADA data. With knowledge of the dynamic states local loads at gearbox bearings are easily determined and fatigue models are be applied to track the accumulation of fatigue damage. A case study using simulation measurements from a high-fidelity gearbox model is conducted to evaluate the proposed method. Estimated loads at the considered IMS and HSS bearings show moderate to high correlation (R = 0.50–0.96) to measurements, as lower frequency internal dynamics are not fully captured. The estimated fatigue damage differs by 5–15 % from measurements.

Development of High-Loaded, Low-Speed Spiroid Gearboxes

2000 ◽  
Author(s):  
V. I. Goldfarb ◽  
V. M. Spiridonov ◽  
N. S. Golubkov
Keyword(s):  
High Reliability ◽  
Operating Conditions ◽  
Design Parameters ◽  
Angular Range ◽  
Operating Modes ◽  
Gear Design ◽  
Gear Mesh ◽  
Numerical Studies ◽  
High Durability ◽  
Spiroid Gear

Abstract Actuator rotation sometimes is required to transmit considerable torques at low speeds in a limited angular range. Such operating conditions are typical, for example, for the rotational drives of gas pipeline stop valves. These conditions are made worse by increased torques requried at the initial instant of motion when the torque is 1.3 to 1.5 times greater than the nominal torque, and by the range of operating temperatures of −60°C to +50°C. A number of gearboxes with a spiroid gear mesh were developed to satisfy these conditions for different torques (i.e. for different standard stop valves), with the steel spiroid pair case-hardened to 60–62 hardness Rc. A set of numerical studies had been conducted in order to choose gear design parameters and other elements of the gearbox. Experimental research performed using special testing rigs for definite operating modes showed high reliability and wear resistance of the drives developed and their high durability compared to known ones which is of great importance for given application domain.

The Effect of Operational Parameters on Vibration Signals of Wind Turbine Gearboxes

2019 ◽  
Author(s):  
Sofia Koukoura ◽  
Eric Bechhoefer ◽  
James Carroll ◽  
Alasdair McDonald
Keyword(s):  
Wind Turbine ◽  
Operating Conditions ◽  
Operating Costs ◽  
Normal Operation ◽  
Operational Parameters ◽  
Wind Turbine Gearbox ◽  
Vibration Signals ◽  
Gearbox Vibration ◽  
Maintenance Decisions ◽  
Yaw Angle

Abstract Vibration signals are widely used in wind turbine drivetrain condition monitoring with the aim of fault detection, optimization of maintenance actions and therefore reduction of operating costs. Signals are most commonly sampled by accelerometers at high frequency for a few seconds. The behavior of these signals varies significantly, even within the same turbine and depends on different parameters. The aim of this paper is to explore the effect of operational and environmental conditions on the vibration signals of wind turbine gearboxes. Parameters such as speed, power and yaw angle are taken into account and the change in vibration signals is examined. The study includes examples from real wind turbines of both normal operation and operation with known gearbox faults. The effects of varying operating conditions are removed using kalman filtering as a state observer. The findings of this paper will aid in understanding wind turbine gearbox vibration signals, making more informed decisions in the presence of faults and improving maintenance decisions.

scholarly journals The Enhancement of Weak Bearing Fault Signatures by Stochastic Resonance with a Novel Potential Function

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6348
Author(s):  
Chao Zhang ◽  
Haoran Duan ◽  
Yu Xue ◽  
Biao Zhang ◽  
Bin Fan ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Stochastic Resonance ◽  
Operating Conditions ◽  
Detection Accuracy ◽  
Wind Turbine Gearbox ◽  
Resonance Model ◽  
Function Type ◽  
Vibration Signals ◽  
Fourier Decomposition ◽  
Bearing Fault

As the critical parts of wind turbines, rolling bearings are prone to faults due to the extreme operating conditions. To avoid the influence of the faults on wind turbine performance and asset damages, many methods have been developed to monitor the health of bearings by accurately analyzing their vibration signals. Stochastic resonance (SR)-based signal enhancement is one of effective methods to extract the characteristic frequencies of weak fault signals. This paper constructs a new SR model, which is established based on the joint properties of both Power Function Type Single-Well and Woods-Saxon (PWS), and used to make fault frequency easy to detect. However, the collected vibration signals usually contain strong noise interference, which leads to poor effect when using the SR analysis method alone. Therefore, this paper combines the Fourier Decomposition Method (FDM) and SR to improve the detection accuracy of bearing fault signals feature. Here, the FDM is an alternative method of empirical mode decomposition (EMD), which is widely used in nonlinear signal analysis to eliminate the interference of low-frequency coupled signals. In this paper, a new stochastic resonance model (PWS) is constructed and combined with FDM to enhance the vibration signals of the input and output shaft of the wind turbine gearbox bearing, make the bearing fault signals can be easily detected. The results show that the combination of the two methods can detect the frequency of a bearing failure, thereby reminding maintenance personnel to urgently develop a maintenance plan.

Probabilistic Performance of Helical Compound Planetary System in Wind Turbine

2015 ◽  
Vol 10 (4) ◽  
Author(s):  
Fisseha M. Alemayehu ◽  
Stephen Ekwaro-Osire
Keyword(s):  
Wind Turbine ◽  
Multibody Systems ◽  
Planetary System ◽  
Design Parameters ◽  
Wind Turbine Gearbox ◽  
New Approach ◽  
Highly Nonlinear ◽  
Multibody Dynamic ◽  
Input Variables ◽  
Maintenance Process

The dynamics of contact, stress and failure analysis of multibody systems is highly nonlinear. Nowadays, several commercial and other analysis software dedicated for this purpose are available. However, these codes do not consider the uncertainty involved in loading, design, and assembly parameters. One of these systems with a combined high nonlinearity and uncertainty of parameters is the gearbox of wind turbines (WTs). Wind turbine gearboxes (WTG) are subjected to variable torsional and nontorsional loads. In addition, the manufacturing and assembly process of these devices results in uncertainty of the design parameters of the system. These gearboxes are reported to fail in their early life of operation, within three to seven years as opposed to the expected twenty years of operation. Their downtime and maintenance process is the most costly of any failure of subassembly of WTs. The objective of this work is to perform a probabilistic multibody dynamic analysis (PMBDA) of a helical compound planetary stage of a selected wind turbine gearbox that considers ten random variables: two loading (the rotor speed, generator side torque), and eight design parameters. The reliability or probabilities of failure of each gear and probabilistic sensitivities of the input variables toward two performance functions have been measured and conclusions have been drawn. The results revealed that PMBDA has demonstrated a new approach of gear system design beyond a traditional deterministic approach. The method demonstrated the components' reliability or probability of failure and sensitivity results that will be used as a tool for designers to make sound decisions.

Jumping Phenomenon in Journal Bearing

1991 ◽  
Author(s):  
Krystof Kryniski
Keyword(s):  
High Speed ◽  
Standard Procedure ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Theory And Practice ◽  
Fluid Film ◽  
Design Parameters ◽  
Radial Clearance ◽  
Rotor Systems ◽  
Rotating Machine

Abstract Due to their reliability and low maintenance costs over an extended service time, the journal bearings, also known as fluid-film bearings, are commonly incorporated in the super-critical rotor systems. Together with proven balancing methods, they allow rotating machine to pass smoothly through the various of critical speeds, both during start-ups and shut-downs. However, journal bearings need to be designed very carefully, as at some operating conditions (speed and load), they may introduce the undesired effects, such as unstable operations or sub-harmonic resonances. The standard procedure leading to the optimum fluid-film bearing design is based on the bearing capacity, defined by the Sommerfield number [1][2]. When Sommerfield number is determined, all design parameters, such as viscosity, radial clearance, diameter and rotation speed, etc. are matched to satisfy the engineering requirements specified. The procedure is considered to be completely reliable and is commonly used in turbo-machinery and high-speed compressor design. However, the significant divergences between theory and practice were observed with the increase of a bearing radial clearance [3].

Analysis of the Oil Squeezing Power Losses of a Spur Gear Pair by Mean of CFD Simulations

2012 ◽  
Author(s):  
Franco Concli ◽  
Carlo Gorla
Keyword(s):  
High Efficiency ◽  
Fluid Dynamic ◽  
Axial Direction ◽  
Spur Gear ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Main Concern ◽  
Power Losses ◽  
Dynamic Simulations ◽  
Gear Mesh

Efficiency is becoming more and more a main concern in the design of power transmissions and the demand for high efficiency gearboxes is continuously increasing. Also the new restrictive euro standards for the reduction of pollutant emissions from light vehicles impose to improve the efficiency of the engines but also of the gear transmissions. For this reason the resources dedicated to this goal are continuously increasing. The first step to improve efficiency is to have appropriate models to compare different design solutions. Even if the efficiency of transmissions is quit high if compared to the efficiency of the engines and appropriate models to predict the power losses due to gear meshing, to bearings and to seals already exist, in order to have a further improvement, some aspects like the power losses related to the oil churning, oil squeezing and windage are still to be investigated. These losses rise from the interaction between the moving or rotating elements of the transmission and the lubricant. In previous papers [39, 40, 41 43, 44], the authors have investigated the churning losses of planetary speed reducers (in which there is a relative motion between the “planets + planet carrier” and the lubricant). This report is focused on the oil squeezing power losses. This kind of losses is associated with the pumping of the oil at the gear mesh, where there is a contraction of the volume between the mating gears due to the rotation of them and a consequent overpressure. This overpressure implies a fluid flow primarily in the axial direction and this, for viscous fluids, means additional power losses and a decrease of the efficiency. In this work this phenomena has been studied by means of some CFD (computational fluid dynamic) simulations with a VOF (volume of fluid) approach. The influence of some operating conditions like the rotational speed and the lubricant temperature have been studied. The results of this study have been included in a model to predict the efficiency of the whole transmission.

scholarly journals PISTON LUBRICATION IN RECIPROCATING COMPRESSORS

2001 ◽  
Vol 1 (1) ◽  
pp. 56
Author(s):  
A. T. Prata ◽  
J. R. S. Fernandes ◽  
F. Fagotti
Keyword(s):  
Hydrodynamic Force ◽  
Problem Formulation ◽  
Operating Conditions ◽  
Oscillatory Motion ◽  
Viscous Force ◽  
Design Parameters ◽  
Radial Clearance ◽  
Oil Viscosity ◽  
Time Step ◽  
Detailed Model

Piston dynamics plays a fundamental role in two critical processes related to fluid flow in reciprocating compressors. The first is the refrigerant leakage through the radial clearance, which may cause considerable loss in the pumping efficiency of the compressor. The second process is the viscous friction associated with the lubricant film in the radial clearance; certainly a significant factor in the compressor energy consumption. In the present contribution a numerical simulation of the piston movement inside the cylinder of a reciprocating compressor is performed. The compressor considered here is a small hermetic compressor employed in domestic refrigerators. For the problem formulation both the axial and the radial piston motion is considered. In operation, the piston moves up and down along the axis of the cylinder, but the radial oscillatory motion in the cylinder bore, despite being usually small, plays a very important role on the compressor performance and reliability. The compromise between sealing of the gas leakage through the piston-cylinder clearance and the friction losses requires a detailed analysis of the oscillatory motion for a good design. The forces acting on the piston are the hydrodynamic force due to the pressure build up in the oil film (lubrication effects), the force due to the connecting rod, the viscous force associated with the relative motion between the piston and oil, and the force exerted by the gas on the top of the piston. All corresponding moments are also included in the problem formulation of the piston dynamics, in order to determine the piston trajectory, velocity and acceleration at each time step. The hydrodynamic force is obtained from the integration of the pressure distribution on the piston skirt, which, in turn, is determined from a finite volume solution of the time dependent equation that governs the oil flow. A Newton-Raphson procedure was employed in solving the equations of the piston dynamics. The results explored the effects of some design parameters and operating conditions on the stability of the piston, its sealing performance and friction losses. Emphasis was placed on investigating the influence of the pin location, radial clearance and oil viscosity on the piston dynamics. The complexity of the piston movement in reciprocating compressors was demonstrated and the detailed model presented can be employed as an useful tool for engineering design.

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