scholarly journals A Robust Health Indicator for Rotating Machinery under Time-Varying Operating Conditions (July 2021)

IEEE Access ◽  
2022 ◽  
pp. 1-1
Author(s):  
Seokgoo Kim ◽  
Hyung Jun Park ◽  
Yun-Ho Seo ◽  
Joo-Ho Choi
Keyword(s):  
Rotating Machinery ◽  
Operating Conditions ◽  
Time Varying ◽  
Health Indicator

A Multiple Harmonic Open-Loop Controller for Hydro/Aerodynamic Force Measurements in Rotating Machinery Using Magnetic Bearings

2002 ◽  
Vol 124 (4) ◽  
pp. 827-834 ◽  
Author(s):  
D. O. Baun ◽  
E. H. Maslen ◽  
C. R. Knospe ◽  
R. D. Flack
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Open Loop ◽  
Rotating Machinery ◽  
Operating Conditions ◽  
Rotor Vibration ◽  
Aerodynamic Forces ◽  
Analog Input ◽  
Input And Output ◽  
The Time Domain

Inherent in the construction of many experimental apparatus designed to measure the hydro/aerodynamic forces of rotating machinery are features that contribute undesirable parasitic forces to the measured or test forces. Typically, these parasitic forces are due to seals, drive couplings, and hydraulic and/or inertial unbalance. To obtain accurate and sensitive measurement of the hydro/aerodynamic forces in these situations, it is necessary to subtract the parasitic forces from the test forces. In general, both the test forces and the parasitic forces will be dependent on the system operating conditions including the specific motion of the rotor. Therefore, to properly remove the parasitic forces the vibration orbits and operating conditions must be the same in tests for determining the hydro/aerodynamic forces and tests for determining the parasitic forces. This, in turn, necessitates a means by which the test rotor’s motion can be accurately controlled to an arbitrarily defined trajectory. Here in, an interrupt-driven multiple harmonic open-loop controller was developed and implemented on a laboratory centrifugal pump rotor supported in magnetic bearings (active load cells) for this purpose. This allowed the simultaneous control of subharmonic, synchronous, and superharmonic rotor vibration frequencies with each frequency independently forced to some user defined orbital path. The open-loop controller was implemented on a standard PC using commercially available analog input and output cards. All analog input and output functions, transformation of the position signals from the time domain to the frequency domain, and transformation of the open-loop control signals from the frequency domain to the time domain were performed in an interrupt service routine. Rotor vibration was attenuated to the noise floor, vibration amplitude ≈0.2 μm, or forced to a user specified orbital trajectory. Between the whirl frequencies of 14 and 2 times running speed, the orbit semi-major and semi-minor axis magnitudes were controlled to within 0.5% of the requested axis magnitudes. The ellipse angles and amplitude phase angles of the imposed orbits were within 0.3 deg and 1.0 deg, respectively, of their requested counterparts.

Using Sliding Mode Control to Adjust Drum Level of a Boiler Unit With Time Varying Parameters

2010 ◽  
Author(s):  
Hamed Moradi ◽  
Firooz Bakhtiari-Nejad ◽  
Majid Saffar-Avval ◽  
Aria Alasty
Keyword(s):  
Water Level ◽  
Transfer Functions ◽  
Sliding Mode ◽  
Operating Conditions ◽  
Model Parameters ◽  
Feed Water ◽  
Time Varying ◽  
Boiler Unit ◽  
Varying Parameters ◽  
Time Varying Parameters

Stable control of water level of drum is of great importance for economic operation of power plant steam generator systems. In this paper, a linear model of the boiler unit with time varying parameters is used for simulation. Two transfer functions between drum water level (output variable) and feed-water and steam mass rates (input variables) are considered. Variation of model parameters may be arisen from disturbances affecting water level of drum, model uncertainties and parameter mismatch due to the variant operating conditions. To achieve a perfect tracking of the desired drum water level, two sliding mode controllers are designed separately. Results show that the designed controllers result in bounded values of control signals, satisfying the actuators constraints.

scholarly journals Deep learning-based anomaly-onset aware remaining useful life estimation of bearings

2021 ◽  
Vol 7 ◽  
pp. e795
Author(s):  
Pooja Vinayak Kamat ◽  
Rekha Sugandhi ◽  
Satish Kumar
Keyword(s):  
Deep Learning ◽  
Anomaly Detection ◽  
Short Term Memory ◽  
Rotating Machinery ◽  
Remaining Useful Life ◽  
Operating Conditions ◽  
Learning Models ◽  
Vibration Data ◽  
Degradation Data ◽  
Useful Life

Remaining Useful Life (RUL) estimation of rotating machinery based on their degradation data is vital for machine supervisors. Deep learning models are effective and popular methods for forecasting when rotating machinery such as bearings may malfunction and ultimately break down. During healthy functioning of the machinery, however, RUL is ill-defined. To address this issue, this study recommends using anomaly monitoring during both RUL estimator training and operation. Essential time-domain data is extracted from the raw bearing vibration data, and deep learning models are used to detect the onset of the anomaly. This further acts as a trigger for data-driven RUL estimation. The study employs an unsupervised clustering approach for anomaly trend analysis and a semi-supervised method for anomaly detection and RUL estimation. The novel combined deep learning-based anomaly-onset aware RUL estimation framework showed enhanced results on the benchmarked PRONOSTIA bearings dataset under non-varying operating conditions. The framework consisting of Autoencoder and Long Short Term Memory variants achieved an accuracy of over 90% in anomaly detection and RUL prediction. In the future, the framework can be deployed under varying operational situations using the transfer learning approach.

Computer simulation of the reliability of the heat exchange surface of the steam turbine condenser

2022 ◽  
pp. 1748006X2110672
Author(s):  
Krzysztof Bernard Łukaszewski
Keyword(s):  
Heat Exchange ◽  
Steam Turbine ◽  
Cooling Water ◽  
Operating Conditions ◽  
Time Varying ◽  
Turbine Condenser ◽  
Heat Exchange Surface ◽  
Steam Turbine Condenser ◽  
The Relationship ◽  
Exchange Surface

The aim of the article is to demonstrate the relationship between the adaptive regulation of the heat exchange surface to specific operating conditions of a steam turbine condenser and the reliability and availability of this surface in a specific period of time. The article exemplifies the relationship between the settings of the condenser heat exchange surface and the resulting changes in the reliability structures of this surface. The method of creating a mathematical model of reliability estimation, which is characterized by the variability of the reliability structures of the heat exchange surface in relation to specific operating conditions in a specific period of time, was indicated. Then, exemplary simulations of the adaptation of reliability structures of specific pipe systems constituting the condenser’s heat exchange surface to specific processes of operation of this condenser are presented. The simulations refer to the time-varying thermal loads of the condenser, the time-varying mean thickness of the sediments, and changes in the temperature of the cooling water at the point of its intake over time. The adaptation of certain reliability structures consists in the adaptation of specific systems of pipes through which the cooling water flows to the currently existing operating conditions of the condenser in order to maintain the desired reliability of the heat exchange surface for a specified time. This is done by enabling or disabling the flow of cooling water through a given number of pipes in specific systems under given operating conditions. On the basis of computer simulations, the reliability functions, and the availability functions of the subsystem under consideration were estimated.

Nonlinear dynamic analysis of a microsegment gear system with a time-varying base circle

2020 ◽  
Vol 44 (2) ◽  
pp. 279-293
Author(s):  
Kang Huang ◽  
Fengwei Xu ◽  
Yangshou Xiong ◽  
Meng Sang ◽  
Yong Yi
Keyword(s):  
Dynamic Analysis ◽  
Nonlinear Dynamic ◽  
High Speed ◽  
Operating Conditions ◽  
Gear System ◽  
Resonant Peak ◽  
Time Varying ◽  
Heavy Load ◽  
Involute Gear ◽  
Base Circle

A systematic dynamic analysis of a microsegment gear system with a time-varying base circle, time-varying mesh stiffness, and gear backlash is carried out in this paper. By discretizing the meshing process, a six degree-of-freedom nonlinear dynamic model of a microsegment gear pair is established. To study the dynamic response of the microsegment gear and involute gear under various operating conditions, the numerical integration method is adopted. The dynamic transmission error (DTE) of the two gears is analysed in terms of time history charts, phase diagrams, fast Fourier transformation spectra, and Poincaré maps. The effects of support damping and support stiffness on radial vibration are also investigated. Results reveal that, compared with the involute gear system, the microsegment gear system is more stable at the high-speed condition and has a smaller amplitude of DTE under medium-speed and heavy-load, high-speed, and heavy-load conditions. The support damping and support stiffness have great effects on the resonant peak in the radial direction of the microsegment gear. Both the proposed model and numerical results are expected to provide a useful source of reference for the dynamic design of the microsegment gear system.

Detecting and Predicting Early Faults of Complex Rotating Machinery Based on Cyclostationary Time Series Model

2006 ◽  
Vol 128 (5) ◽  
pp. 666-671 ◽  
Author(s):  
Z. S. Chen ◽  
Y. M. Yang ◽  
Z. Hu ◽  
G. J. Shen
Keyword(s):  
Signal To Noise Ratio ◽  
Rotating Machinery ◽  
Ar Model ◽  
Model Parameters ◽  
Time Varying ◽  
Signal To Noise ◽  
Vibration Signals ◽  
Novel Method ◽  
Cyclostationary Signals ◽  
Gear Crack

Vibration signals of complex rotating machinery are often cyclostationary, so in this paper one novel method is proposed to detect and predict early faults based on the linear (almost) periodically time-varying autoregressive (LPTV-AR) model. At first the algorithms of identifying model parameters and order are presented using the higher-order cyclic-cumulant, which can suppress additive stationary noises and improve the signal to noise ratio (SNR). Then numerical simulations are done and the results indicate that this model is more effective for cyclostationary signals than the classical AR model. In the end the proposed method is used for detecting incipient gear crack fault in a helicopter gearbox. The results demonstrate that the approach can be used to detect and predict early faults of complex rotating machinery by the kurtosis of the residual signal.

Dynamics of Hypoid Gear Transmission With Nonlinear Time-Varying Mesh Characteristics

2003 ◽  
Vol 125 (2) ◽  
pp. 373-382 ◽  
Author(s):  
Yuping Cheng ◽  
Teik C. Lim
Keyword(s):  
Response Spectra ◽  
Transmission Error ◽  
Operating Conditions ◽  
Time Varying ◽  
Analysis Model ◽  
Tooth Contact Analysis ◽  
3 Dimensional ◽  
Resonant Modes ◽  
Loaded Tooth Contact Analysis ◽  
Backlash Nonlinearity

The coupled translation-rotation vibratory response of hypoid geared rotor system due to loaded transmission error excitation is studied by employing a generalized 3-dimensional dynamic model. The formulation includes the effects of backlash nonlinearity as well as time-dependent mesh position and line-of-action vectors. Its mesh coupling is derived from a quasi-static, 3-dimensional, loaded tooth contact analysis model that accounts for the precise gear geometry and profile modifications. The numerical simulations show significant tooth separation and occurrence of multi-jump phenomenon in the predicted response spectra under certain lightly loaded operating conditions. Also, resonant modes contributing to the response spectra are identified, and cases with super-harmonics are illustrated. The computational results are then analyzed to quantify the extent of non-linear and time-varying factors.

A Dual-Loop EGR Engine Air-Path Oxygen Concentration Model With Time-Varying Transport Delays

2013 ◽  
Author(s):  
Xiangrui Zeng ◽  
Junmin Wang
Keyword(s):  
Oxygen Concentration ◽  
Dynamic Models ◽  
Operating Conditions ◽  
High Fidelity ◽  
Exhaust Gas ◽  
Time Varying ◽  
Transport Delay ◽  
Engine Model ◽  
Gas Recirculation ◽  
Transient Operations

Dual-loop exhaust gas recirculation (EGR) systems can provide control authorities for adjusting the engine in-cylinder gas conditions. However, the transport delay in the EGR air-path makes some simple oxygen concentration dynamic models perform poorly under the transient operating conditions. In this paper, a dual-loop EGR air-path oxygen concentration model considering the time-varying transport delays is developed and a method to calculate the delay time based on the continuity of gas velocity is presented. Simulation validations using a high-fidelity GT-Power 1-D computational engine model show that the developed model can capture the oxygen concentration dynamics during both steady-state and transient operations.

Calculation and analysis of the loss and heat on damper bars in large tubular hydro-generator

2013 ◽  
Vol 62 (1) ◽  
pp. 43-54 ◽  
Author(s):  
Yong Liao ◽  
Zhen-Nan Fan ◽  
Li Han ◽  
Li-Dan Xie
Keyword(s):  
Electromagnetic Field ◽  
Temperature Field ◽  
Heat Conduction ◽  
Heat Dissipation ◽  
Operating Conditions ◽  
Fe Model ◽  
Time Varying ◽  
Rotor Core ◽  
Anisotropic Heat Conduction ◽  
Generator Design

Abstract In order to research the losses and heat of damper bars thoroughly, a multislice moving electromagnetic field-circuit coupling FE model of tubular hydro-generator and a 3D temperature field FE model of the rotor are built respectively. The factors such as rotor motion and non-linearity of the time-varying electromagnetic field, the stator slots skew, the anisotropic heat conduction of the rotor core lamination and different heat dissipation conditions on the windward and lee side of the poles are considered. Furthermore, according to the different operating conditions, different rotor structures and materials, compositive calculations about the losses and temperatures of the damper bars of a 36 MW generator are carried out, and the data are compared with the test. The results show that the computation precision is satisfied and the generator design is reasonable.

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