Active axial vibration control of a shaft-bearing system excited by the dynamic thrust force

2022 ◽  
pp. 147509022110702
Author(s):  
Mingke Ren ◽  
Xiling Xie ◽  
Dequan Yang ◽  
Zhiyi Zhang
Keyword(s):  
Active Control ◽  
Adaptive Algorithm ◽  
Thrust Bearing ◽  
Thrust Force ◽  
Moving Average ◽  
Arma Model ◽  
Experimental System ◽  
Axial Vibration ◽  
Control Approach ◽  
Bearing System

The axial vibration of a shaft-bearing system induced by the thrust excitation is usually composed of multiple tones. To suppress the axial vibration of the shaft-bearing system, two inertial electro-magnetic actuators are mounted symmetrically at the thrust bearing and work in parallel to exert control forces. The control signal is generated by an adaptive algorithm with subband filtering, which aims to attenuate over a broadband the vibration of the thrust bearing and its foundation induced by the dynamic thrust force. To reduce computational complexity, the recursive computation is partly realized with the auto-regressive moving average (ARMA) model. The proposed active control approach is evaluated numerically at first with the dynamic model of the shaft-bearing system and then verified with an experimental system. It is demonstrated by the numerical and experimental results that the active control approach is able to suppress the multi-tone vibration of the thrust bearing and the foundation. Moreover, in comparison to the single-band adaptive feedback algorithm, the adaptive algorithm with subband filtering is more effective when the disturbance contains multiple tones.

Unsteady Thrust Force Loading of a Turbocharger Rotor During Engine Operation

2015 ◽  
Author(s):  
Bernhardt Lüddecke ◽  
Philipp Nitschke ◽  
Michael Dietrich ◽  
Dietmar Filsinger ◽  
Michael Bargende
Keyword(s):  
Thrust Bearing ◽  
Thrust Force ◽  
Combustion Engine ◽  
Operating Conditions ◽  
Turbine Stage ◽  
Force Modeling ◽  
Thrust Load ◽  
Bearing System ◽  
Engine Cycle ◽  
Bearing Friction

The bearing system of a turbocharger has to keep the rotor in the specified position and thus has to withstand the rotor forces that result from turbocharger operation. Hence, its components need to be designed in consideration of the bearing loads that have to be expected. The applied bearing system design also has significant influence on the overall efficiency of the turbocharger and impacts the performance of the combustion engine. It has to ideally fulfil the trade-off between bearing friction and load capacity. For example, the achievable engine’s low end-torque is reduced, if the bearing system produces more friction losses than inherently unavoidable for safe and durable operation because a higher portion of available turbine power needs to be employed to compensate bearing losses instead of providing boost pressure. Moreover, also transient turbocharger rotor speed up can be compromised and hence the response of the turbocharged combustion engine to a load step becomes less performant than it could be. Besides the radial bearings, the thrust bearing is a component that needs certain attention. It can already contribute to approx. 30 percent of the overall bearing friction, even if no load is applied and this portion further increases under thrust load. It has to withstand the net thrust load of the rotor under all operating conditions resulting from the superimposed aerodynamic forces that the compressor and the turbine wheel produce. A challenge for the determination of the thrust forces appearing on engine is the non-steady loading under pulsating conditions. The thrust force will alternate with the pulse frequency over an engine cycle what is caused by both the engine exhaust gas pressure pulses on the turbine stage and — to a smaller amount — the non-steady compressor operation due to the reciprocating operation of the cylinders. The conducted experimental investigations on the axial rotor motion as well as the thrust force alternations under on-engine conditions employ a specially prepared compressor lock nut in combination with an eddy current sensor. The second derivative of this signal can be used to estimate the occurring thrust force changes. Moreover, a modified thrust bearing — equipped with strain gauges — was used to cross check the results from position measurement and thrust force modeling. All experimental results are compared with an analytical thrust force model that relies on the simultaneously measured, crank angle resolved pressure signals before and after the compressor and turbine stage. The results give insight into the axial turbocharger rotor oscillations occurring during an engine cycle for several engine operating points. Furthermore, they allow a judgment of the accuracy of thrust force modeling approaches that are based on measured pressures.

Unsteady Thrust Force Loading of a Turbocharger Rotor During Engine Operation

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Bernhardt Lüddecke ◽  
Philipp Nitschke ◽  
Michael Dietrich ◽  
Dietmar Filsinger ◽  
Michael Bargende
Keyword(s):  
Thrust Bearing ◽  
Thrust Force ◽  
Combustion Engine ◽  
Operating Conditions ◽  
Turbine Stage ◽  
Force Modeling ◽  
Thrust Load ◽  
Bearing System ◽  
Engine Cycle ◽  
Bearing Friction

The bearing system of a turbocharger has to keep the rotor in the specified position and thus has to withstand the rotor forces that result from turbocharger operation. Hence, its components need to be designed in consideration of the bearing loads that have to be expected. The applied bearing system design also has significant influence on the overall efficiency of the turbocharger and impacts the performance of the combustion engine. It has to ideally fulfill the trade-off between bearing friction and load capacity. For example, the achievable engine’s low end-torque is reduced, if the bearing system produces more friction losses than inherently unavoidable for safe and durable operation because a higher portion of available turbine power needs to be employed to compensate bearing losses instead of providing boost pressure. Moreover, also transient turbocharger rotor speed up can be compromised and hence the response of the turbocharged combustion engine to a load step becomes less performant than it could be. Besides the radial bearings, the thrust bearing is a component that needs certain attention. It can already contribute to approximately 30% of the overall bearing friction, even if no load is applied and this portion further increases under thrust load. It has to withstand the net thrust load of the rotor under all operating conditions resulting from the superimposed aerodynamic forces that the compressor and the turbine wheel produce. A challenge for the determination of the thrust forces appearing on engine is the nonsteady loading under pulsating conditions. The thrust force will alternate with the pulse frequency over an engine cycle, which is caused by both the engine exhaust gas pressure pulses on the turbine stage and—to a smaller amount—the nonsteady compressor operation due to the reciprocating operation of the cylinders. The conducted experimental investigations on the axial rotor motion as well as the thrust force alternations under on-engine conditions employ a specially prepared compressor lock nut in combination with an eddy-current sensor. The second derivative of this signal can be used to estimate the occurring thrust force changes. Moreover, a modified thrust bearing—equipped with strain gauges—was used to cross check the results from position measurement and thrust force modeling. All experimental results are compared with an analytical thrust force model that relies on the simultaneously measured, crank angle resolved pressure signals before and after the compressor and turbine stage. The results give insight into the axial turbocharger rotor oscillations occurring during an engine cycle for several engine operating points. Furthermore, they allow a judgment of the accuracy of thrust force modeling approaches that are based on measured pressures.

scholarly journals A Critical Review of Supersonic Flow Control for High-Speed Applications

2021 ◽  
Vol 11 (15) ◽  
pp. 6899
Author(s):  
Abdul Aabid ◽  
Sher Afghan Khan ◽  
Muneer Baig
Keyword(s):  
Supersonic Flow ◽  
Flow Control ◽  
Active Control ◽  
Critical Review ◽  
High Speed ◽  
Passive Control ◽  
Control Method ◽  
Sudden Expansion ◽  
Control Approach ◽  
Cost Efficient

In high-speed fluid dynamics, base pressure controls find many engineering applications, such as in the automobile and defense industries. Several studies have been reported on flow control with sudden expansion duct. Passive control was found to be more beneficial in the last four decades and is used in devices such as cavities, ribs, aerospikes, etc., but these need additional control mechanics and objects to control the flow. Therefore, in the last two decades, the active control method has been used via a microjet controller at the base region of the suddenly expanded duct of the convergent–divergent (CD) nozzle to control the flow, which was found to be a cost-efficient and energy-saving method. Hence, in this paper, a systemic literature review is conducted to investigate the research gap by reviewing the exhaustive work on the active control of high-speed aerodynamic flows from the nozzle as the major focus. Additionally, a basic idea about the nozzle and its configuration is discussed, and the passive control method for the control of flow, jet and noise are represented in order to investigate the existing contributions in supersonic speed applications. A critical review of the last two decades considering the challenges and limitations in this field is expressed. As a contribution, some major and minor gaps are introduced, and we plot the research trends in this field. As a result, this review can serve as guidance and an opportunity for scholars who want to use an active control approach via microjets for supersonic flow problems.

Numerical Analysis of a Coupled Porous Journal and Thrust Bearing System

2005 ◽  
Vol 127 (1) ◽  
pp. 120-129 ◽  
Author(s):  
Takuji Kobayashi ◽  
Hiroshi Yabe
Keyword(s):  
Thrust Bearing ◽  
Dynamic Performance ◽  
Internal Flow ◽  
Disk Drive ◽  
Rotating Shaft ◽  
Static And Dynamic Characteristics ◽  
Bottom Face ◽  
Magnetic Hard Disk ◽  
Bearing System ◽  
Porous Sleeve

A numerical model has been developed to analyze both static and dynamic characteristics of a coupled porous journal and thrust bearing system that is used to support a rotating shaft in a magnetic hard disk drive. The analyzed system is composed of a porous sleeve, a herringbone-grooved solid thrust plate and a flanged shaft, where the bottom end is closed to form a cantilever spindle. The inner surface and the bottom face of the porous sleeve operate as a herringbone-grooved journal and thrust bearing, respectively. The model is based on the narrow groove theory for the bearing oil film, and Darcy’s law for the internal flow in the porous sleeve. The pressure distribution, static equilibrium position of the shaft and dynamic coefficients are obtained under a given external axial load. There exists a window of permeability of the porous sleeve that presents significant advantage to prevent the creation of a sub-ambient condition and to maintain a large thrust bearing film thickness at the expense of some loss of dynamic performance.

scholarly journals Forecasting and Modelling of Solar Radiation for Photovoltaic (PV) Systems

2021 ◽  
Author(s):  
Ines Sansa ◽  
Najiba Mrabet Bellaaj
Keyword(s):  
Time Series ◽  
Solar Radiation ◽  
Cloud Cover ◽  
Moving Average ◽  
Arma Model ◽  
Weather Conditions ◽  
Pv Systems ◽  
Auto Regressive ◽  
Micro Grid ◽  
One Year

Solar radiation is characterized by its fluctuation because it depends to different factors such as the day hour, the speed wind, the cloud cover and some other weather conditions. Certainly, this fluctuation can affect the PV power production and then its integration on the electrical micro grid. An accurate forecasting of solar radiation is so important to avoid these problems. In this chapter, the solar radiation is treated as time series and it is predicted using the Auto Regressive and Moving Average (ARMA) model. Based on the solar radiation forecasting results, the photovoltaic (PV) power is then forecasted. The choice of ARMA model has been carried out in order to exploit its own strength. This model is characterized by its flexibility and its ability to extract the useful statistical properties, for time series predictions, it is among the most used models. In this work, ARMA model is used to forecast the solar radiation one year in advance considering the weekly radiation averages. Simulation results have proven the effectiveness of ARMA model to forecast the small solar radiation fluctuations.

scholarly journals An Improved Deep Learning Algorithm for Risk Prediction of Corporate Internet Reporting

2020 ◽  
Vol 34 (4) ◽  
pp. 437-444
Author(s):  
Lingyan Ou ◽  
Ling Chen
Keyword(s):  
Deep Learning ◽  
Risk Prediction ◽  
Short Term Memory ◽  
Learning Algorithm ◽  
Moving Average ◽  
Arma Model ◽  
Evaluation Index System ◽  
Online Information ◽  
Deep Learning Algorithm ◽  
Research Findings

Corporate internet reporting (CIR) has such advantages as the strong timeliness, large amount, and wide coverage of financial information. However, the CIR, like any other online information, faces various risks. With the aid of the increasingly sophisticated artificial intelligence (AI) technology, this paper proposes an improved deep learning algorithm for the prediction of CIR risks, aiming to improve the accuracy of CIR risk prediction. After building a reasonable evaluation index system (EIS) for CIR risks, the data involved in risk rating and the prediction of risk transmission effect (RTE) were subject to structured feature extraction and time series construction. Next, a combinatory CIR risk prediction model was established by combining the autoregressive moving average (ARMA) model with long short-term memory (LSTM). The former is good at depicting linear series, and the latter excels in describing nonlinear series. Experimental results demonstrate the effectiveness of the ARMA-LSTM model. The research findings provide a good reference for applying AI technology in risk prediction of other areas.

scholarly journals Synchronization and Anti-Synchronization of Two Identical Hyperchaotic Systems Based on Active Backstepping Design

2011 ◽  
pp. 117-122
Author(s):  
Atefeh Saedian ◽  
Hassan Zarabadipoor
Keyword(s):  
Numerical Simulations ◽  
Active Control ◽  
Chaos Control ◽  
Control Method ◽  
Design Method ◽  
Backstepping Design ◽  
Backstepping Technique ◽  
Control Approach ◽  
Hyperchaotic Systems

This paper presents an active backstepping design method for synchronization and anti-synchronization of two identical hyperchaotic Chen systems. The proposed control method, combining backstepping design and active control approach, extends the application of backstepping technique in chaos control. Based on this method, different combinations of controllers can be designed to meet the needs of different applications. Numerical simulations are shown to verify the results.

Research on Reliability Assessment of Power System with Wind Farms

2012 ◽  
Vol 608-609 ◽  
pp. 588-591
Author(s):  
Wen Jiang ◽  
Ye Xia Cheng ◽  
Ye Jian Cheng
Keyword(s):  
Power System ◽  
Wind Farm ◽  
Sequential Monte Carlo ◽  
Moving Average ◽  
Reliability Assessment ◽  
Arma Model ◽  
Wind Farms ◽  
Test System ◽  
Wind Speeds ◽  
State Models

Due to randomness and fluctuation of wind speed, reliability of power system will be affected severely with increasing wind energy injected into power grid. In order to evaluate the effect on reliability of power system with wind farms, the author considers feature of time-sequential and self-correlation of wind speeds and builds an auto-regressive and moving average (ARMA) model to forecast wind speeds. Combining with state models of conventional generating units, transmission lines and transformers, a time-sequential Monte Carlo simulation reliability model is proposed to do reliability assessment of composite generation and transmission system with wind farm. IEEE-RTS test system is introduced to prove the proposed model. Analysis and comparison of results show that reliability can be improved clearly after integration of wind farm.

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