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Model-based initial residual unbalance identification for rotating machines in one and two planes using an iterative inverse approach

Bastakoti Satish, Choudhury Tuhin, Viitala Risto, Kurvinen Emil, Sopanen Jussi

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 6

art. no. e139790

EN

To achieve acceptable dynamical behavior for large rotating machines operating at subcritical speeds, the balancing quality check at the planned service speed in the installation location is often demanded for machines such as turbo-generators or high-speed machines. While most studies investigate the balancing quality at critical speeds, only a few studies have investigated this aspect using numerical methods at operational speed. This study proposes a novel, model-based method for inversely estimating initial residual unbalance in one and two planes after initial grade balancing for large flexible rotors operating at the service speeds. The method utilizes vibration measurements from two planes in any single direction, combined with a finite element model of the rotor to inversely determine the residual unbalance in one and two planes. This method can be practically used to determine the initial and residual unbalance after the balancing process, and further it can be used for condition-based monitoring of the unbalance state of the rotor.

2

The visualization of shaft vibration using the algorithm of phase-amplitude data interpolation

Piątkowski J.

Journal of Applied Mathematics and Computational Mechanics

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2016

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Vol. 15, nr 1

137--148

EN

In many cases of observations of phenomena and physical processes we use data measured in multidimensional spaces. However, in practice, for the economic or technical reasons, we cannot obtain equally numerous data sets for all dimensions. In this case we can say that we are trying to assess or classify this process by using a few parts of its projection. For processing and computing of an input data a different solutions of interpolation and/or approximation are often used. But data, which have phase-amplitude nature, should be treated in a specific way. The lack of proper interpretation of phase shifts in many cases can result in obtaining the significant distortions of an analyzed process image. In this paper the algorithm of phase-amplitude interpolation is presented. This algorithm has been used for creating the contours charts, as projections of rotating shaft vibrations, in transient operating conditions of the machine.

3

Vlianie gidrostaticeskoj zestkosti uplotnitel'nyh kolec na sobstvennye kolebania rotornoj sistemy

Nikiforov A.

Zeszyty Naukowe Politechniki Świętokrzyskiej. Nauki Techniczne

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2008

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Z. 10, Vol. 1

55-62

EN

Natural oscillations of system "flexible rotor - liquid film - sealing ring" on base of finite element model are researched. The hydrostatic stiffness effect on natural (partial) frequencies and mode shapes for rotor and ring is discussed. Simulation veracity is confirmed by analytical calculation of natural frequencies for researched system.

4

Rationale for mu-synthesis control of flexible rotor-magnetic bearing systems

Sawicki J. T.

Acta Mechanica et Automatica

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2008

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Vol. 2, no. 2

67-74

EN

The emergence of sophisticated formal control synthesis tools provokes important questions for any prospective user: why learn to use these new tools, what will they offer me? In synthesis of magnetic bearing controllers, it turns out that the range of stabilizing controllers is often quite narrow so that the difference between a poor controller and an “optimal” one may be small. Hence, the product of formal control synthesis tools often looks and performs much like what a reasonably clever control engineer would produce by hand. This paper demonstrates that the real value of these tools lies in a) generation of a performance benchmark which can be used to firmly establish the best performance relative to a specification and b) change of design parameter space to one which is relatively easy to maintain and represents a durable investment from an engineering process view.

5

Dynamics of the Flexible Rotor with an Additional Active Magnetic Bearing

Kozanecka D.

Machine Dynamics Problems

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2001

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Vol. 25, No. 2

39-48

EN

Search for new solutions of bearing systems in modern rotary machines that have to satisfy special performance demands has resulted in intereset in rotor active magnetic suspension systems. The application of active magnetic bearings (AMB) as a system of the shaft suspension gives supplementary, unparalleled in classical solutions, diagnostic capabilities. There are, however, also high requirements concerned with the control system of the shaft position. The overall goal of an AMB controller is to stabilise the plant and to reach the optimal technical performance. To achieve these goals, AMB systems have to be optimisied in an overall mechatronics design approach. This leads to a new concept for control systems and actuators. In rotor dynamics, the characteristics of bearings exert a decisive influence on modes of vibrations and critical frequencies of the rotating shaft. This paper presents an idea of programming a level of vibrations in the operating range of the rotating system of the flexible rotor (including critical speeds) by using an additional digitally controlled magnetic bearing. This cuases a qualitative change in the dynamic properties of the system. Some experimental investigations and numerical simulations of flexible rotor dynamics carried out on the test stand with an additional digitally controlled magnetic bearing are discussed. The experimental characteristic curves of the start-up and shut-down have confirmed possibilities of the programmable modeling of dynamics of the shaft line, and - in prospect - of the designed machine that includes a magnetic bearing.

PL

Poszukiwania nowych rozwiązań łożyskowania w konstrukcjach nowoczesnych maszyn wirnikowych, którym stawia się specjalne wymagania eksploatacyjne spowodowały zainteresowanie systemami aktywnego magnetycznego zawieszenia wirników. Zastosowanie aktywnego magnetycznego systemu podparcia wirnika maszyny daje nieporównywalne z klasycznym rozwiązaniem łożyskowania możliwości diagnostyczne. W dynamice wirników właściwości łożysk mają decydujący wpływ na postacie drgań oraz częstości krytyczne układu wirującego maszyny. W pracy przedstawiono koncepcję programowania poziomu drgań w zakresie pracy systemu wirującego giętkiego wirnika przy zastosowaniu dodatkowego, sterowanego cyfrowo łożyska magnetycznego. Stwarza to możliwość jakościowej zmiany właściwości dynamicznych systemu wirującego maszyny. Wykonane zostały obliczenia numeryczne, które zweryfikowano eksperymentalnie na stanowisku badawczym. Wyniki badań eksperymentalnych krzywych rozruchu i wybiegu systemu wirującego giętkiego wirnika potwierdziły możliwość programowego modelowania dynamiki lini wału, a w perspektywie projektowanej maszyny, która w swojej strukturze zawiera sterowane cyfrowo łożysko magnetyczne.