A matrix transfer function analysis applied to the active feedback control system of a divertor tokamak

1987 ◽  
Vol 27 (2) ◽  
pp. 299-312 ◽  
Author(s):  
M. Kikuchi ◽  
H. Ninomiya ◽  
R. Yoshino ◽  
S. Seki
Keyword(s):  
Control System ◽  
Feedback Control ◽  
Transfer Function ◽  
Function Analysis ◽  
Feedback Control System ◽  
Matrix Transfer Function ◽  
Transfer Function Analysis ◽  
Divertor Tokamak ◽  
Active Feedback ◽  
Active Feedback Control

scholarly journals Sound Transmission Comparisons of Active Elastic Wave Metamaterial Immersed in External Mean Flow

2021 ◽  
Author(s):  
Zhi-Hua He ◽  
Yi-Ze Wang ◽  
Yue-Sheng Wang
Keyword(s):  
Control System ◽  
Feedback Control ◽  
Elastic Wave ◽  
Sound Transmission ◽  
Feedback Control System ◽  
Mean Flow ◽  
Transmission Properties ◽  
Active Feedback ◽  
Active Feedback Control ◽  
Equivalent Method

AbstractUsing the active feedback control system on the elastic wave metamaterial, this research concentrates on the sound transmission with the dynamic effective model. The metamaterial is subjected to an incident pressure and immersed in the external mean flow. The elastic wave metamaterial consists of double plates and the upper and lower four-link mechanisms are attached inside. The vertical resonator is attached by the active feedback control system and connected with two four-link mechanisms. Based on the dynamic equivalent method, the metamaterial is equivalent as a single-layer plate by the dynamic effective parameter. With the coupling between the fluid and structure, the expression of the sound transmission loss (STL) is derived. This research shows the influence of effective mass density on sound transmission properties, and the STL in both modes can be tuned by the acceleration and displacement feedback constants. In addition, the dynamic response and the STL are also changed obviously by different values of structural damping, incident angle (i.e., the elevation and azimuth angles) and Mach number of the external fluid with the mean flow property. The results for sound transmission by two methods are compared, i.e., the virtual work principle for double plates and the dynamic equivalent method corresponding to a single one. This paper is expected to be helpful for understanding the sound transmission properties of both pure single- and double-plate models.

Active feedback control of elastic wave metamaterials

2017 ◽  
Vol 28 (15) ◽  
pp. 2110-2116 ◽  
Author(s):  
Yi-Ze Wang ◽  
Feng-Ming Li ◽  
Yue-Sheng Wang
Keyword(s):  
Control System ◽  
Feedback Control ◽  
Elastic Wave ◽  
Effective Mass ◽  
Stop Band ◽  
Acoustic Properties ◽  
System Stability ◽  
Negative Effective Mass ◽  
Active Feedback ◽  
Active Feedback Control

As an important extension of periodic structures and phononic crystals, elastic wave/acoustic metamaterials can show negative effective parameters for special frequency regions. Although the active control method is widely applied to the vibration isolation and elastic wave propagation, little attention has been paid on changing elastic wave/acoustic properties of metamaterials. In this work, a new kind of elastic wave metamaterials combined with the automatic control system is presented. Propagation behaviors of the elastic wave are discussed. To demonstrate the effect of the active feedback control, the stop band properties, tunable negative effective mass and control system stability are considered. The results show that the negative acceleration feedback control can enhance the frequency region that creates the negative effective mass. Moreover, the stability of this periodic structure can be achieved.

Sub-Scale Demonstration of the Active Feedback Control of Gas-Turbine Combustion Instabilities

2000 ◽  
Vol 122 (2) ◽  
pp. 262-268 ◽  
Author(s):  
Stanley S. Sattinger ◽  
Yedidia Neumeier ◽  
Aharon Nabi ◽  
Ben T. Zinn ◽  
David J. Amos ◽  
...  
Keyword(s):  
Control System ◽  
Feedback Control ◽  
Gas Turbine ◽  
Active Control ◽  
Combustion Instabilities ◽  
Engine Operation ◽  
Turbine Engine ◽  
Control Approach ◽  
Active Feedback ◽  
Active Feedback Control

Described are sub-scale tests that successfully demonstrate active feedback control as a means of suppressing damaging combustion oscillations in natural-gas-fueled, lean-premix combustors. The control approach is to damp the oscillations by suitably modulating an auxiliary flow of fuel injected near the flame. The control system incorporates state observer software that can ascertain the frequency, amplitude, and phase of the dominant modes of combustion oscillation, and a sub-scale fuel flow modulator that responds to frequencies well above 1 kHz. The demonstration was conducted on a test combustor that could sustain acoustically coupled combustion instabilities at preheat and pressurization conditions approaching those of gas-turbine engine operation. With the control system inactive, two separate instabilities occurred with combined amplitudes of pressure oscillations exceeding 70 kPa (10 psi). The active control system produced four-fold overall reduction in these amplitudes. With the exception of an explainable control response limitation at one frequency, this reduction represented a major milestone in the implementation of active control. [S0742-4795(00)00702-X]

Feedback Control of Karman Vortex Shedding

1996 ◽  
Vol 63 (3) ◽  
pp. 828-835 ◽  
Author(s):  
M. D. Gunzburger ◽  
H. C. Lee
Keyword(s):  
Feedback Control ◽  
Computational Study ◽  
Lift Coefficient ◽  
Pressure Measurements ◽  
Feedback Control System ◽  
Flow Around A Cylinder ◽  
Active Feedback ◽  
Karman Vortex ◽  
Active Feedback Control ◽  
Simple Feedback

A computational study of the feedback control of the magnitude of the lift in flow around a cylinder is presented. The uncontrolled flow exhibits an unsymmetric Karman vortex street and a periodic lift coefficient. The size of the oscillations in the lift is reduced through an active feedback control system. The control used is the injection and suction of fluid through orifices on the cylinder; the amount of fluid injected or sucked is determined, through a simple feedback law, from pressure measurements at stations along the surface of the cylinder. The results of some computational experiments are given; these indicate that the simple feedback law used is effective in reducing the size of the oscillations in the lift.

scholarly journals Sub-Scale Demonstration of the Active Feedback Control of Gas-Turbine Combustion Instabilities

1998 ◽  
Author(s):  
Stanley S. Sattinger ◽  
Yedidia Neumeier ◽  
Aharon Nabi ◽  
Ben T. Zinn ◽  
David J. Amos ◽  
...  
Keyword(s):  
Control System ◽  
Feedback Control ◽  
Gas Turbine ◽  
Active Control ◽  
Combustion Instabilities ◽  
Engine Operation ◽  
Turbine Engine ◽  
Control Approach ◽  
Active Feedback ◽  
Active Feedback Control

Described are sub-scale tests that successfully demonstrate active feedback control as a means of suppressing damaging combustion oscillations in natural-gas-fueled, lean-premix combustors. The control approach is to damp the oscillations by suitably modulating an auxiliary flow of fuel injected near the flame. The control system incorporates state observer software that can ascertain the frequency, amplitude, and phase of the dominant modes of combustion oscillation, and a sub-scale fuel flow modulator that responds to frequencies well above 1 kHz. The demonstration was conducted on a test combustor that could sustain acoustically coupled combustion instabilities at preheat and pressurization conditions approaching those of gas-turbine engine operation. With the control system inactive, two separate instabilities occurred with combined amplitudes of pressure oscillations exceeding 70 kPa (10 psi). The active control system produced four-fold overall reduction in these amplitudes. With the exception of an explainable control response limitation at one frequency, this reduction represented a major milestone in the implementation of active control.

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