Nonlinear Dynamic Behavior of a Flexible Shaft Supported by Smart Hydrostatic Squeeze Film Dampers

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
A. Bouzidane ◽  
M. Thomas
Keyword(s):  
Electric Field ◽  
Dynamic Behavior ◽  
Nonlinear Model ◽  
Nonlinear Dynamic ◽  
Electrorheological Fluid ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
Flexible Shaft ◽  
Squeeze Film Dampers ◽  
Nonlinear Dynamic Behavior

The aim of this research is to study the nonlinear dynamic behavior of a flexible shaft supported by smart hydrostatic squeeze film dampers, which are filled with a negative electrorheological fluid (NERF). A nonlinear model of the hydrostatic squeeze film damper has been developed in order to study the effect of the electrorheological fluid on the dynamic behavior of a flexible shaft. The results obtained are discussed and compared with the linear model, which is restricted to only small vibrations around the equilibrium position. A new smart hydrostatic squeeze film damper is proposed to reduce the transient response of the shaft and transmitted forces by applying an electric field to the NER fluid, which results in modifying its viscosity. The results show that it is possible to effectively monitor the electric field and the viscosity of the fluid inside the hydrostatic squeeze film dampers (HSFD) for a better control of flexible shaft vibration and bearing transmitted forces.

Nonlinear Dynamic Study on Effects of Rub-Impact Caused by Oil-Rupture in a Multi-Shafts Turbine With a Squeeze Film Damper

2014 ◽  
Author(s):  
T. N. Shiau ◽  
C. R. Wang ◽  
D. S. Liu ◽  
W. C. Hsu ◽  
T. H. Young
Keyword(s):  
Dynamic Behavior ◽  
Nonlinear Dynamic ◽  
Equations Of Motion ◽  
Rotor System ◽  
Squeeze Film ◽  
Speed Ratio ◽  
Frequency Spectra ◽  
Squeeze Film Damper ◽  
Assumed Mode Method ◽  
Nonlinear Dynamic Behavior

An investigation is carried out the analysis of nonlinear dynamic behavior on effects of rub-impact caused by oil-rupture in a multi-shafts turbine system with a squeeze film damper. Main components of a multi-shafts turbine system includes an outer shaft, an inner shaft, an impeller shaft, ball bearings and a squeeze film damper. In the squeeze film damper, oil forces can be derived from the short bearing approximation and cavitated film assumption. The system equations of motion are formulated by the global assumed mode method (GAMM) and Lagrange’s approach. The nonlinear behavior of a multi-shafts turbine system which includes the trajectories in time domain, frequency spectra, Poincaré maps, and bifurcation diagrams are investigated. Numerical results show that large vibration amplitude is observed in steady state at rotating speed ratio adjacent to the first natural frequency when there is no squeeze film damper. The nonlinear dynamic behavior of a multi-shafts turbine system goes in its way into aperiodic motion due to oil-rupture and it is unlike the usual way (1T = >2T = >4T = >8T etc) as compared to one shaft rotor system. The typical routes of bifurcation to aperiodic motion are observed in a multi-shafts turbine rotor system and they suddenly turn into aperiodic motion from the periodic motion without any transition. Consequently, the increasing of geometric or oil parameters such as clearance or lubricant viscosity will improve the performance of SFD bearing.

Nonlinear Dynamic Behavior of Turbocharger Rotor-Bearing Systems With Hydrodynamic Oil Film and Squeeze Film Damper in Series: Prediction and Experiment

2010 ◽  
Vol 5 (4) ◽  
Author(s):  
K. Gjika ◽  
L. San Andrés ◽  
G. D. Larue
Keyword(s):  
Dynamic Behavior ◽  
Nonlinear Dynamic ◽  
High Performance ◽  
Squeeze Film ◽  
Inlet Temperature ◽  
Squeeze Film Damper ◽  
Feed Pressure ◽  
Nonlinear Dynamic Behavior ◽  
In Series ◽  
Bearing System

Current trends for advanced automotive engines focusing on downsizing, better fuel efficiency, and lower emissions have led to several changes in turbocharger bearing system design and technology. Automotive turbochargers run faster and use engine oils with very low viscosity under high oil inlet temperature and low feed pressure. The development of high performing bearing systems, marrying innovation with reliability, is a persistent challenge. This paper shows progress on the nonlinear dynamic behavior modeling of the rotor-radial bearing system (RBS) incorporating two oil films in series: a hydrodynamic one with a squeeze film damper commonly used in turbochargers. The developed fluid bearing code predicts bearing rotational speed (in the case of fully floating design), operating inner and outer bearing film clearances, effective oil viscosity, taking into account its shear effect, and hydrostatic load. A rotordynamics code uses this input to predict the nonlinear lateral dynamic response of the rotor-bearing system. The model predictions are validated with test data acquired on a high speed turbocharger RBS of a 6.0 mm journal diameter running up to 250,000 rpm (maximum speed), 5W30 oil type, 150°C oil inlet temperature, and 4 bar oil feed pressure. The tests are conducted at a rotordynamics technology laboratory using a high performance data acquisition system. Turbochargers with four combinations of inner and outer RBS clearances are tested. Prediction and measured synchronous response and total motion are in good agreement. Both demonstrate the nonlinear character of the RBS behavior, including several subsynchronous frequency components across the operating speed range. The nonlinear predictive model aids the development of high performance and optimized turbocharger RBS with faster development cycle times and increased reliability.

Nonlinear Dynamic Behavior of Turbocharger Rotor-Bearing Systems With Hydrodynamic Oil Film and Squeeze Film Damper in Series: Prediction and Experiment

2007 ◽  
Author(s):  
Kostandin Gjika ◽  
Chris Groves ◽  
Luis San Andre´s ◽  
Gerald D. LaRue
Keyword(s):  
Dynamic Behavior ◽  
Nonlinear Dynamic ◽  
High Performance ◽  
Squeeze Film ◽  
Inlet Temperature ◽  
Squeeze Film Damper ◽  
Feed Pressure ◽  
Nonlinear Dynamic Behavior ◽  
In Series ◽  
Bearing System

Current trends for advanced automotive engines focusing on downsizing, better fuel efficiency and lower emissions have led to several changes in turbocharger bearing systems design and technology. Automotive turbochargers run faster and use engine oils with very low viscosity under high oil inlet temperature and low feed pressure. The development of high performing bearing systems, marrying innovation with reliability, is a persistent challenge. This paper shows progress on the nonlinear dynamic behavior modeling of rotor-radial bearing system (RBS) incorporating two oil films in series: a hydrodynamic one with a squeeze film damper commonly used in turbochargers. The developed fluid bearing code predicts bearing rotational speed (in case of fully floating design), operating inner and outer bearing film clearances, effective oil viscosity taking into account its shear effect, and hydrostatic load. A rotordynamics code uses this input to predict the nonlinear lateral dynamic response of the rotor-bearing system. The model predictions are validated with test data acquired on a high speed turbocharger RBS of 6.0 mm journal diameter running up to 250,000 rpm (maximum speed), 5W30 oil type, 150 °C oil inlet temperature, and 4 bar oil feed pressure. The tests are conducted at a rotordynamics technology laboratory using a high performance data acquisition system. Turbochargers with four combinations of inner and outer RBS clearances are tested. Prediction and measured synchronous response and total motion are in good agreement. Both demonstrate the nonlinear character of RBS behavior including several subsynchronous frequencies components across the operating speed range. The non linear predictive model aids the development of high performance and optimized turbocharger RBS with faster development cycle times and increased reliability.

scholarly journals Nonlinear Model and Dynamic Behavior of Photovoltaic Grid-Connected Inverter

2020 ◽  
Vol 10 (6) ◽  
pp. 2120 ◽  
Author(s):  
Zhi-Xian Liao ◽  
Dan Luo ◽  
Xiao-Shu Luo ◽  
Hai-Sheng Li ◽  
Qin-Qin Xiang ◽  
...  
Keyword(s):  
Bifurcation Diagram ◽  
Dynamic Behavior ◽  
Nonlinear Model ◽  
Nonlinear Dynamic ◽  
Optimization Design ◽  
Stable Operation ◽  
Control Parameters ◽  
Nonlinear Dynamic Behavior ◽  
Predictive Controller ◽  
Grid Connected Inverter

A photovoltaic grid-connected inverter is a strongly nonlinear system. A model predictive control method can improve control accuracy and dynamic performance. Methods to accurately model and optimize control parameters are key to ensuring the stable operation of a photovoltaic grid-connected inverter. Based on the nonlinear characteristics of photovoltaic arrays and switching devices, we established a nonlinear model of photovoltaic grid-connected inverters using the state space method and solved its model predictive controller. Then, using the phase diagram, folded diagram, and bifurcation diagram methods, we studied the nonlinear dynamic behavior under the influence of control parameters on both fast and slow scales. Finally, we investigated the methods of parameter selection based on the characteristics of nonlinear dynamic behavior. Our research shows that the predictive controller parameters are closely related to the bifurcation and chaos behaviors of the grid-connected photovoltaic inverter. The three-dimensional bifurcation diagram can be used to observe the periodic motion region of the control parameters. After selecting the optimization target, the bifurcation diagram can be used to guide the selection of control parameters for inverter design. The research results can be used to guide the modeling, stability analysis, and optimization design of photovoltaic grid-connected inverters.

Elastomer O-Rings as Centering Spring in Squeeze Film Dampers: Application to Turbochargers

2013 ◽  
Author(s):  
Saeid Dousti ◽  
Jason A. Kaplan ◽  
Feng He ◽  
Paul E. Allaire
Keyword(s):  
Dynamic Behavior ◽  
Analytical Model ◽  
Nonlinear Dynamic ◽  
Operating Conditions ◽  
Squeeze Film ◽  
Damping Capacity ◽  
Squeeze Film Dampers ◽  
Low Amplitude ◽  
Hysteresis Characteristics ◽  
Load Conditions

This study addresses the nonlinear dynamic behavior of O-ring seals as the centering spring in squeeze film dampers. An analytical model is developed to predict the restoring and hysteresis characteristics of elastomer O-rings and extends the existing models to non-axisymmetric load conditions. Also, the inclusion of axial seals increases the damping capacity of squeeze film dampers. O-rings forces are investigated for different sizes, installation preloads, and operating conditions and contrasted with squeeze film damper’s hydrodynamic forces. This model is incorporated in linear and time transient rotordynamic analyses of a vertical turbocharger. It is shown that the O-rings contribution in rotor response for low rotational speeds and low amplitude vibrations is dominant and can not be ignored.

Performance characteristics of a three-pad hydrostatic squeeze film damper compensated with new electrorheological valve restrictors

2016 ◽  
Vol 231 (7) ◽  
pp. 889-899 ◽  
Author(s):  
Asma Abed ◽  
Ahmed Bouzidane ◽  
Marc Thomas ◽  
Hamou Zahloul
Keyword(s):  
Numerical Analysis ◽  
Electric Field ◽  
Electrorheological Fluid ◽  
Performance Characteristics ◽  
Squeeze Film ◽  
Static And Dynamic Characteristics ◽  
Squeeze Film Damper ◽  
Hydrostatic Bearing ◽  
Force Transmissibility ◽  
Bearing Design

A numerical analysis is carried out in order to investigate the effect of the electric field on the performance characteristics of a three-pad hydrostatic squeeze film damper compensated with new electrorheological valve restrictors. The bearing design is composed of three identical hydrostatic bearing pads. Each hydrostatic bearing pad is fed with a negative electrorheological fluid through an electrorheological valve. The numerical analysis showed that the viscosity of a smart fluid inside to each electrorheological valve can be controlled by using an electric field in order to control the static and dynamic characteristics. The results presented in this study can be made more useful to control rotor vibrations and force transmissibility especially around the critical speeds.

Sign in / Sign up

Export Citation Format

Share Document