Minimum Dwell Times for the Stability of Switched Systems with Multiple Stable Operating Points

2018 ◽  
Author(s):  
William St. Pierre ◽  
Jonathan W. Kimball
Keyword(s):  
Switched Systems ◽  
Stable Operating ◽  
The Stability ◽  
Operating Points

An Investigation of the Stability Enhancement of a Centrifugal Compressor Stage Using a Porous Throat Diffuser

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Lee Galloway ◽  
Stephen Spence ◽  
Sung In Kim ◽  
Daniel Rusch ◽  
Klemens Vogel ◽  
...  
Keyword(s):  
Centrifugal Compressor ◽  
Compressor Stage ◽  
Vaned Diffuser ◽  
Flow Rates ◽  
Stall Inception ◽  
Centrifugal Compressor Stage ◽  
Operating Range ◽  
Stable Operating ◽  
The Stability ◽  
Circumferential Pressure

The stable operating range of a centrifugal compressor stage of an engine turbocharger is limited at low mass flow rates by aerodynamic instabilities which can lead to the onset of rotating stall or surge. There have been many techniques employed to increase the stable operating range of centrifugal compressor stages. The literature demonstrates that there are various possibilities for adding special treatments to the nominal diffuser vane geometry, or including injection or bleed flows to modify the diffuser flow field in order to influence diffuser stability. One such treatment is the porous throat diffuser (PTD). Although the benefits of this technique have been proven in the existing literature, a comprehensive understanding of how this technique operates is not yet available. This paper uses experimental measurements from a high pressure ratio (PR) compressor stage to acquire a sound understanding of the flow features within the vaned diffuser which affect the stability of the overall compression system and investigate the stabilizing mechanism of the porous throat diffuser. The nonuniform circumferential pressure imposed by the asymmetric volute is experimentally and numerically examined to understand if this provides a preferential location for stall inception in the diffuser. The following hypothesis is confirmed: linking of the diffuser throats via the side cavity equalizes the diffuser throat pressure, thus creating a more homogeneous circumferential pressure distribution, which delays stall inception to lower flow rates. The results of the porous throat diffuser configuration are compared to a standard vaned diffuser compressor stage in terms of overall compressor performance parameters, circumferential pressure nonuniformity at various locations through the compressor stage and diffuser subcomponent analysis. The diffuser inlet region was found to be the element most influenced by the porous throat diffuser, and the stability limit is mainly governed by this element.

scholarly journals Stability Analysis for Autonomous Dynamical Switched Systems through Nonconventional Lyapunov Functions

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
V. Nosov ◽  
J. A. Meda-Campaña ◽  
J. C. Gomez-Mancilla ◽  
J. O. Escobedo-Alva ◽  
R. G. Hernández-García
Keyword(s):  
Stability Analysis ◽  
Finite Number ◽  
Switched Systems ◽  
Lyapunov Functions ◽  
Switched System ◽  
Linear Functions ◽  
Asymptotically Stable ◽  
Multiple Lyapunov Functions ◽  
Stability Theorems ◽  
The Stability

The stability of autonomous dynamical switched systems is analyzed by means of multiple Lyapunov functions. The stability theorems given in this paper have finite number of conditions to check. It is shown that linear functions can be used as Lyapunov functions. An example of an exponentially asymptotically stable switched system formed by four unstable systems is also given.

Experimental Analysis of Biogas Combustion With Different Foam Materials in a Porous Media Burner

2019 ◽  
Author(s):  
Sangjukta Devi ◽  
Niranjan Sahoo ◽  
P. Muthukumar
Keyword(s):  
Porous Media ◽  
Energy Efficient ◽  
Combustion Zone ◽  
Load Range ◽  
Preheat Zone ◽  
Power Intensity ◽  
Stable Operating ◽  
Operating Limits ◽  
The Stability ◽  
Porous Media Burner

Abstract The existing biogas Conventional Burners (CBs) are less energy efficient and are designed for rich fuel combustion. Porous Media Burner (PMB), working on the principle of combustion in porous media offer several advantages including high thermal efficiency, low emissions, high power intensity, etc. In this work, a study on the effect of porous material on the thermal behaviour of a biogas operated PMB is presented. A state-of-the-art PMB working in the thermal load range of 5 to 10 kW has been developed, which can be used for both industrial and domestic purposes. It is a two section burner composed of a combustion zone and a preheat zone. Keeping the material of the preheat zone unchanged (Al2O3 ceramic), the burner is tested with two different materials in the combustion zone (SiC and ZrO2 foams). Experimental investigation has been done to analyze the stability criteria and study the temperature distribution in the PMB. This includes the identification of the stable operating limits (flashback and blow off) and measurement of temperature profiles in axial and radial direction. These assessments confirm that SiC is a better choice over ZrO2 for lean biogas combustion in PMB.

Stability and controllability of switched systems

2013 ◽  
Vol 61 (3) ◽  
pp. 547-555 ◽  
Author(s):  
J. Klamka ◽  
A. Czornik ◽  
M. Niezabitowski
Keyword(s):  
Stability Analysis ◽  
Asymptotic Stability ◽  
Linear Systems ◽  
Switched Systems ◽  
Sufficient Conditions ◽  
Switched Linear Systems ◽  
Arbitrary Switching ◽  
Mathematical Problems ◽  
The Stability ◽  
Necessary And Sufficient

Abstract The study of properties of switched and hybrid systems gives rise to a number of interesting and challenging mathematical problems. This paper aims to briefly survey recent results on stability and controllability of switched linear systems. First, the stability analysis for switched systems is reviewed. We focus on the stability analysis for switched linear systems under arbitrary switching, and we highlight necessary and sufficient conditions for asymptotic stability. After that, we review the controllability results.

Design of PSO Based PI Controller for Wind Turbine Systems

2013 ◽  
Vol 483 ◽  
pp. 529-532
Author(s):  
Jau Woei Perng ◽  
Guan Yan Chen ◽  
Der Min Tsay ◽  
Jao Hwa Kuang ◽  
Bor Jeng Lin ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Operating Parameter ◽  
Pso Algorithm ◽  
Turbine Generator ◽  
Optimal Operating ◽  
Wind Turbine Generator ◽  
Artificial Learning ◽  
Control Stability ◽  
The Stability ◽  
Operating Points

This paper implements a strategy to obtain the proportional-integral (PI) optimal operating point and find the description of the stability regions in the parameters space. In order to do this, the particle swarm optimization (PSO) algorithm has been used in this study. The intelligent algorithm which is artificial learning mechanism could find optimal operating points and generates the function of the best operating parameter in the PI control stability region. Then the graphical method can provide boundaries of the PI type controller space for close-loop wind turbine generator (WTG) systems. The proposed techniques are presented by using simulation results to the WTG model.

Journal Orbits and Their Stability for Rigid Unbalanced Rotors

1995 ◽  
Vol 117 (4) ◽  
pp. 709-716 ◽  
Author(s):  
Renato Brancati ◽  
Ernesto Rocca ◽  
Michele Russo ◽  
Riccardo Russo
Keyword(s):  
Orbital Motion ◽  
Journal Bearings ◽  
Stability Parameter ◽  
Parameter Plane ◽  
Linear Motion ◽  
Motion Equations ◽  
Unbalanced Rotor ◽  
Stable Operating ◽  
The Stability ◽  
Rotor Bearings

With reference to a rigid symmetrical unbalanced rotor on lubricated journal bearings and adopting the short bearing theory, synchronous orbits and orbits with a 1/2 component described by the journal are determined as approximated solutions of the system of non-linear motion equations. The method also makes it possible to evaluate the stability of the above solutions and thus of the journal orbital motion. For different values of dimensionless unbalance of the rotor, examples of orbits thus obtained are given and, in the modified Sommerfeld number-stability parameter plane, the stability areas of the solutions are identified, in particular, the area of stability of the small synchronous orbits corresponding to the stable operating condition of the rotor-bearings system.

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