Active Control Algorithms for the Control of Rotor Vibrations Using HSFDs

2000 ◽  
Author(s):  
A. El-Shafei
Keyword(s):  
Active Control ◽  
Gain Scheduling ◽  
Rotating Machinery ◽  
Squeeze Film ◽  
Control Algorithms ◽  
Critical Stage ◽  
Squeeze Film Damper ◽  
Active Vibration

The Hybrid Squeeze Film Damper (HSFD) has proven itself to be an effective controlling device of vibration in rotating machinery. The critical stage in the development of the HSFD as an active vibration suppressant, is the development of the control algorithms for active control of rotor vibrations. This paper summarizes, evaluates and compares the control algorithms for HSFD supported rotors. Quantitative as well as qualitative measures of the effectiveness of the control algorithms are presented. The study includes the PID-type controllers, LQR, gain scheduling, adaptive and bang-bang controllers. The adaptive, gain scheduling and nonlinear proportional controllers, have proved to be quite effective in the active control of HSFD supported rotors, with impressive results.

Active Control Algorithms for the Control of Rotor Vibrations Using Hybrid Squeeze Film Dampers

2002 ◽  
Vol 124 (3) ◽  
pp. 598-607 ◽  
Author(s):  
A. El-Shafei
Keyword(s):  
Active Control ◽  
Gain Scheduling ◽  
Rotating Machinery ◽  
Squeeze Film ◽  
Control Algorithms ◽  
Critical Stage ◽  
Squeeze Film Damper ◽  
Squeeze Film Dampers ◽  
Active Vibration

The hybrid squeeze film damper (HSFD) has proven itself to be an effective controlling device of vibration in rotating machinery. The critical stage in the development of the HSFD as an active vibration suppressant, is the development of the control algorithms for active control of rotor vibrations. This paper summarizes, evaluates, and compares the control algorithms for HSFD-supported rotors. Quantitative as well as qualitative measures of the effectiveness of the control algorithms are presented. The study includes the PID-type controllers, LQR, gain scheduling, adaptive and bang-bang controllers. The adaptive, gain scheduling, and nonlinear proportional controllers have proved to be quite effective in the active control of HSFD supported rotors, with impressive results.

Frequency Shaped Semi-Active Control for Magnetorheological Fluid-Based Vibration Control Systems

2013 ◽  
Author(s):  
Young-Tai Choi ◽  
Norman M. Wereley ◽  
Gregory J. Hiemenz
Keyword(s):  
Vibration Control ◽  
Control Systems ◽  
Active Control ◽  
Control Algorithm ◽  
Active Vibration Control ◽  
Control Algorithms ◽  
Model Parameters ◽  
Mr Fluid ◽  
Control Current ◽  
Active Vibration

Novel semi-active vibration controllers are developed in this study for magnetorheological (MR) fluid-based vibration control systems, including: (1) a band-pass frequency shaped semi-active control algorithm, (2) a narrow-band frequency shaped semi-active control algorithm. These semi-active vibration control algorithms designed without resorting to the implementation of an active vibration control algorithms upon which is superposed the energy dissipation constraint. These new Frequency Shaped Semi-active Control (FSSC) algorithms require neither an accurate damper (or actuator) model, nor system identification of damper model parameters for determining control current input. In the design procedure for the FSSC algorithms, the semi-active MR damper is not treated as an active force producing actuator, but rather is treated in the design process as a semi-active dissipative device. The control signal from the FSSC algorithms is a control current, and not a control force as is typically done for active controllers. In this study, two FSSC algorithms are formulated and performance of each is assessed via simulation. Performance of the FSSC vibration controllers is evaluated using a single-degree-of-freedom (DOF) MR fluid-based engine mount system. To better understand the control characteristics and advantages of the two FSSC algorithms, the vibration mitigation performance of a semi-active skyhook control algorithm, which is the classical semi-active controller used in base excitation problems, is compared to the two FSSC algorithms.

Subharmonic and Chaotic Motions of a Hybrid Squeeze-Film Damper-Mounted Rigid Rotor With Active Control

2002 ◽  
Vol 124 (2) ◽  
pp. 198-208 ◽  
Author(s):  
Chieh-Li Chen ◽  
Her-Terng Yau ◽  
Yunhua Li
Keyword(s):  
Lyapunov Exponent ◽  
Active Control ◽  
Chaotic Motion ◽  
Numerical Results ◽  
Operating Conditions ◽  
Squeeze Film ◽  
Speed Ratio ◽  
Maximum Lyapunov Exponent ◽  
Rigid Rotor ◽  
Squeeze Film Damper

The hybrid squeeze-film damper bearing with active control is proposed in this paper. The pressure distribution and the dynamics of a rigid rotor supported by such bearing are studied. A PD (proportional-plus-derivative) controller is used to stabilize the rotor-bearing system. Numerical results show that, due to the nonlinear factors of oil film force, the trajectory of the rotor demonstrates a complex dynamics with rotational speed ratio s. Poincare´ maps, bifurcation diagrams, and power spectra are used to analyze the behavior of the rotor trajectory in the horizontal and vertical directions under different operating conditions. The maximum Lyapunov exponent and fractal dimension concepts are used to determine if the system is in a state of chaotic motion. Numerical results show that the maximum Lyapunov exponent of this system is positive and the dimension of the rotor trajectory is fractal at the nondimensional speed ratio s=3.0, which indicate that the rotor trajectory is chaotic under such operation condition. In order to avoid the nonsynchronous chaotic vibrations, an increased proportional gain is applied to control this system. It is shown that the rotor trajectory will leave chaotic motion to periodic motion in the steady state under control action.

Experimental and Analytical Investigation of Hybrid Squeeze Film Dampers

1993 ◽  
Vol 115 (2) ◽  
pp. 353-359 ◽  
Author(s):  
A. El-Shafei
Keyword(s):  
High Speed ◽  
Extreme Case ◽  
Analytical Investigation ◽  
Rotating Machinery ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
Controlling Mechanism ◽  
Squeeze Film Dampers ◽  
Oil Flow ◽  
Hybrid Damper

A new concept for actively controlling high-speed rotating machinery is investigated both analyically and experimentally. The controlling mechanism consists of a hybrid squeeze film damper (patent pending) that can be adaptively controlled to change its characteristics according to the instructions of a controller. In an extreme case the hybrid damper can act as a long damper, which is shown to be effective in reducing the amplitude of vibration of rotating machinery. In the other extreme the hybrid damper acts as a short damper, which is shown to be effective in reducing the force transmitted to the support. In the long damper configuration the oil flow is circumferential, while in the short damper configuration the oil flow is predominantly axial. The hybrid damper is designed to operate in either the short or the long damper configuration by controlling the positions of two movable sealing rings. The hybrid damper was tested on a Bently Nevada Rotor Kit and it is shown experimentally that the long damper configuration is extremely efficient at controlling the amplitude of vibration and the short damper configuration reduces the force transmitted to the support.

scholarly journals Investigation about Electrorheological Squeeze Film Damper Applied to Active Control of Rotor Dynamic

1997 ◽  
Vol 3 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Benjamin Pecheux ◽  
Olivier Bonneau ◽  
Jean Frêne
Keyword(s):  
Active Control ◽  
Strong Electric Field ◽  
Solid Particles ◽  
Squeeze Film ◽  
Concentrated Suspensions ◽  
Rotating Shaft ◽  
Heavy Load ◽  
Squeeze Film Damper ◽  
Er Fluids ◽  
Er Fluid

Electrorheological (ER) fluids, discovered in 1947 by W. WINSLOW, are concentrated suspensions of solid particles in an oily base liquid. Exposed to a strong electric field, their resistance to flow increases very greatly and this change is progressive, reversible and occurs very rapidly. Nowadays, ER fluids, made of lithium salt and fluorosilicon got rid of their old abrasive characteristics and are able to provide a good interface between electronics and mechanical components. A bibliographical study on ER fluids and ER technology has been carried out. The aim of this study is adapting ER technology to Squeeze Film Damper. In order to provide an active control on a flexible rotating shaft so as to command the whole shaft/bearings device in case of high rotating speed or heavy load trouble. Results of numerical computation of a shaft bearing assembly with a Squeeze Film Damper using negative ER fluid are showed in order to see the possibility of avoiding critical speeds by natural frequency shifting. A technical study of ER Squeeze Film Damper design is also presented, taking into account ER fluid properties and ER technology requirements.

A Dynamic Analysis of a Dual Clearance Squeeze Film Damper

2010 ◽  
Author(s):  
L. Moraru ◽  
T. G. Keith ◽  
F. Dimofte ◽  
S. Cioc ◽  
N. Ene ◽  
...  
Keyword(s):  
High Speed ◽  
Reynolds Equation ◽  
Numerical Solutions ◽  
Rotating Machinery ◽  
Operating Conditions ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
Squeeze Film Dampers ◽  
Abnormal Operating Conditions ◽  
Oil Films

Squeeze film dampers (SFD) are devices utilized to control the shafts of high-speed rotating machinery. A dual squeeze film damper (DSFD) consists of two squeeze film bearings that are separated by a sleeve, which is released when the rotor experiences abnormal operating conditions. In this part of our study of DSFD we analyze the case when both the inner and the outer oil films are active. We present computed and measured unbalance responses of a shaft supported in DSFD. The oil forces which are utilized in the calculation of the unbalance response are obtained from numerical solutions of the Reynolds equation. A finite-difference algorithm is utilized for solving the pressure equation within the calculation of the dynamic response of the shaft.

scholarly journals Experimental and Analytical Investigation of Hybrid Squeeze Film Dampers

1991 ◽  
Author(s):  
A. El-Shafei
Keyword(s):  
High Speed ◽  
Extreme Case ◽  
Analytical Investigation ◽  
Rotating Machinery ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
Controlling Mechanism ◽  
Squeeze Film Dampers ◽  
Oil Flow ◽  
Hybrid Damper

A new concept for actively controlling high speed rotating machinery is investigated both analytically and experimentally. The controlling mechanism consists of a hybrid squeeze film damper (patent pending) that can be adaptively controlled to change its characteristics according to the instructions of a controller. In an extreme case the hybrid damper can act as a long damper which is shown to be effective in reducing the amplitude of vibration of rotating machinery. In the other extreme the hybrid damper acts as a short damper which is shown to be effective in reducing the force transmitted to the support. In the long damper configuration the oil flow is circumferential, while in the short damper configuration the oil flow is predominantly axial. The hybrid damper is designed to operate in either of the short or the long damper configurations by controlling the positions of two movable sealing rings. The hybrid damper was tested on a Bently Nevada Rotor Kit and it is shown experimentally that the long damper configuration is extremely efficient at controlling the amplitude of vibration and the short damper configuration reduces the force transmitted to the support.

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