Wyniki wyszukiwania - BazTech

1

Failure analysis of a high-speed induction machine driven by a SiC-inverter and operating on a common shaft with a high-speed generator

Breńkacz Łukasz, Bagiński Paweł, Adamowicz Marek, Giziewski Sebastian

Eksploatacja i Niezawodność

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2022

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Vol. 24, no. 1

177--185

EN

Due to ongoing research work, a prototype test rig for testing high speed motors/generators has been developed. Its design is quite unique as the two high speed machines share a single shaft with no support bearings between them. A very high maximum operating speed, up to 80,000 rpm, was required. Because of the need to minimise vibration during operation at very high rotational speeds, rolling bearings were used. To eliminate the influence of higher harmonics of supply voltage and current on the formation of torque oscillations on the shaft and excessive losses in the form of heat, a voltage source inverter with high switching silicon carbide (SiC) power transistors characterizing high precision of the output voltage generation with a fundamental harmonic frequency of several kilohertz has been used. During the first start-ups, it turned out that the system was not stable, and a failure occurred. The paper presents the consequences that may arise when a machine operating at a speed of about 70,000 rpm fails. The article contains pictures of a generator failure that occurred at a high rotational speed.

2

Comparable analysis of PID controller settings in order to ensure reliable operation of active foil bearings

Witanowski Łukasz, Breńkacz Łukasz, Szewczuk-Krypa Natalia, Dorosińska-Komor Marta, Puchalski Bartosz

Eksploatacja i Niezawodność

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2022

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Vol. 24, no. 2

377--385

EN

In comparison to the traditional solutions, active bearings offer great operating flexibility, ensure better operating conditions over a wider range of rotational speeds and are safe to use. In order to ensure optimum bearing performance a bearing control system is used that adapts different geometries during device operation. The selection of optimal controller parameters requires the use of modern optimization methods that make it possible to quickly achieve the assumed parameters. This article presents the method that has been employed to select the parameters of a proportional integral derivative (PID) controller, in which both stochastic algorithms and hybrid methods have been compared. The results show that all of the used algorithms were able to reach the global optimum but only the hybrid algorithm was repeatable in all runs within a low value of the standard deviation. The best solution will be proposed in the future to control an active foil bearing. Analysing of this paper would help to prevent failures of active foil bearing used in the designed rotating machine.

3

Transient simulation of a squeeze film damped turbocharger rotor under consideration of fluid inertia and cavitation

Drapatow Thomas, Alber Oliver, Woschke Elmar

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 6

art. no. e139201

EN

Squeeze film dampers (SFDs) are commonly used in turbomachinery in order to introduce external damping, thereby reducing rotor vibrations and acoustic emissions. Since SFDs are of similar geometry as hydrodynamic bearings, the REYNOLDS equation of lubrication can be utilised to predict their dynamic behaviour. However, under certain operating conditions, SFDs can experience significant fluid inertia effects, which are neglected in the usual REYNOLDS analysis. An algorithm for the prediction of these effects on the pressure build up inside a finite-length SFD is therefore presented. For this purpose, the REYNOLDS equation is extended with a first-order perturbation in the fluid velocities to account for the local and convective inertia terms of the NAVIER-STOKES equations. Cavitation is taken into account by means of a mass conserving two-phase model. The resulting equation is then discretized using the finite volume method and solved with an LU factorization. The developed algorithm is capable of calculating the pressure field, and thereby the damping force, inside an SFD for arbitrary operating points in a time-efficient manner. It is therefore suited for integration into transient simulations of turbo machinery without the need for bearing force coefficient maps, which are usually restricted to circular centralized orbits. The capabilities of the method are demonstrated on a transient run-up simulation of a turbocharger rotor with two semi-floating bearings. It can be shown that the consideration of fluid inertia effects introduces a significant shift of the pressure field inside the SFDs, and therefore the resulting damper force vector, at high oil temperatures and high rotational speeds. The effect of fluid inertia on the kinematic behaviour of the whole system on the other hand is rather limited for the examined rotor.

4

Rotor dynamics - four open questions

Kiciński Jan

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 6

art. no. e139791

EN

Despite many years of development in the field of rotor dynamics, many issues still need to be resolved. This is due to the fact that turbomachines, even those with low output power, have a very complex design. The author of this article would like to signal these issues in the form of several questions, to which there are no precise answers. The questions are as follows: How can we build a coherent dynamic model of a turbomachine whose some subsystems have non-linear characteristics? How can we consider the so-called prehistory in our analysis, namely, the relation between future dynamic states and previous ones? Is heuristic modelling the future of rotor dynamics? What phenomena may occur when the stability limit of the system is exceeded? The attempt to find answers to these questions constitutes the subject of this article. There are obviously more similar questions, which encourage researchers from all over the world to further their research.

5

Quasi-analytical solutions for the whirling motion of multi-stepped rotors with arbitrarily distributed mass unbalance running in anisotropic linear bearings

Klanner Michael, Prem Marcel S., Ellermann Katrin

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 6

art. no. e138999

EN

Vibration in rotating machinery leads to a series of undesired effects, e.g. noise, reduced service life or even machine failure. Even though there are many sources of vibrations in a rotating machine, the most common one is mass unbalance. Therefore, a detailed knowledge of the system behavior due to mass unbalance is crucial in the design phase of a rotor-bearing system. The modelling of the rotor and mass unbalance as a lumped system is a widely used approach to calculate the whirling motion of a rotor-bearing system. A more accurate representation of the real system can be found by a continuous model, especially if the mass unbalance is not constant and arbitrarily oriented in space. Therefore, a quasi-analytical method called Numerical Assembly Technique is extended in this paper, which allows for an efficient and accurate simulation of the unbalance response of a rotor-bearing system. The rotor shaft is modelled by the Rayleigh beam theory including rotatory inertia and gyroscopic effects. Rigid discs can be mounted onto the rotor and the bearings are modeled by linear translational/rotational springs/dampers, including cross-coupling effects. The effect of a constant axial force or torque on the system response is also examined in the simulation.

6

Balancing of a linear elastic rotor-bearing system with arbitrarily distributed unbalance using the Numerical Assembly Technique

Quinz Georg, Prem Marcel S., Klanner Michael, Ellermann Katrin

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 6

art. no. e138237

EN

In this paper, a new application of the Numerical Assembly Technique is presented for the balancing of linear elastic rotor-bearing systems with a stepped shaft and arbitrarily distributed mass unbalance. The method improves existing balancing techniques by combining the advantages of modal balancing with the fast calculation of an efficient numerical method. The rotating stepped circular shaft is modelled according to the Rayleigh beam theory. The Numerical Assembly Technique is used to calculate the steady-state harmonic response, eigenvalues and the associated mode shapes of the rotor. The displacements of a simulation are compared to measured displacements of the rotor-bearing system to calculate the generalized unbalance for each eigenvalue. The generalized unbalances are modified according to modal theory to calculate orthogonal correction masses. In this manner, a rotor-bearing system is balanced using a single measurement of the displacement at one position on the rotor for every critical speed. Three numerical examples are used to show the accuracy and the balancing success of the proposed method.

7

Application of the Teager-Kaiser energy operator in diagnostics of a hydrodynamic bearing

Blaut Jędrzej, Breńkacz Łukasz

Eksploatacja i Niezawodność

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2020

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Vol. 22, no. 4

757--765

EN

The paper presents the use of the Teager-Kaiser energy operator (TKEO) to evaluate the state of rotor unbalance. The method was developed in 1990 by Kaiser and involves a simple calculation of signal energy. It has been used before in diagnostics, e.g. during the evaluation of instability of hydrodynamic bearings and as a diagnostic symptom of gearbox damage. This paper is the first to present the use of the Teager-Kaiser method to evaluate the rotor unbalance in hydrodynamic bearings.

PL

W artykule przedstawiono zastosowanie operatora energetycznego Teagera-Kaisera (TKEO) do oceny stanu niewyważenia wirnika. Metoda ta opracowana została w 1990 roku przez Kaisera i polega na prostym obliczeniu energii sygnału. Wykorzystywana była już wcześniej w diagnostyce np. przy ocenie niestabilności łożysk hydrodynamicznych oraz jako symptom diagnostyczny uszkodzenia przekładni. W artykule tym po raz pierwszy przedstawiono możliwość wykorzystania metody Teagera-Kaisera do oceny niewyważenia wirnika pracującego na łożyskach hydrodynamicznych.

8

Modelling of a rotor with gyroscopic coupling in a rotating reference frame using Ansys and Matlab

Kozioł Mateusz

Vibrations in Physical Systems

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2019

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Vol. 30, nr 2

art. no. 2019220

EN

The work presents a method that expands Ansys capabilities and allows for studying the dynamics of rotors with significant gyroscopic coupling in reference to rotating coordinates. The analyses of rotors in the rotating reference frame are less common, and in FEM software some limitations in such cases can be observed. There are specialised rotors for which the use of a non-inertial reference frame is inevitable. The current work proposes a solution. In the presented method, Ansys is used to generate and export systems matrices so that the manual creation of an FE model is unnecessary. The rest of the operations are realised in Matlab. A simple numerical example is presented to clarify all the steps and a more complex example concludes the paper.

9

Experimental investigation of rotor vibration by using full spectra from shaft mounted piezoelectric patches

Kozioł Mateusz, Cupiał Piotr

Vibrations in Physical Systems

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2019

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Vol. 30, nr 2

art. no. 2019203

EN

The work considers the applicability of signals coming from rotor-mounted sensors in machine diagnostics. In the experiments, such sensors were implemented by piezoelectric patches bonded to the surface of a shaft. The laboratory stand also included more common sensors: laser sensors that measured the displacement of the central disc, as well as accelerometers mounted on the supports. The signals measured are analysed using the so-called full FFT method and the spectra are compared. The results show that the signals from piezoelectric sensors can be processed so that their spectral content is similar to typical spectra obtained using stator-mounted sensors.

10

Anomaly of rotor dynamics in ultra-light helicopter – Robinson R22

Sobieszek Agnieszka

Journal of KONES

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2019

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Vol. 26, No. 4

235--239

EN

The article presents the analysis of anomaly of rotor dynamics in ultra-light helicopter - Robinson R22. Robinson R22 is two-seat, two-blade main rotor and single-engine helicopter, well known as simple and common used aircraft because of low price and high availability. At the same time, large number of accidents and strictly defined rules (recommended piloting technique) and weather condition for safe flight show disadvantages of Robinson R22. The reason for considering this topic is the analysis of different flight properties and helicopter behaviour as well as easy entering into dangerous flight manoeuvre. In the article different flight properties and loss of control during the pull-up, manoeuvre or vertical gusts of wind and mast bumping accidents were analysed. Analysis shows that problem may be caused by construction of three-hinged rotor hub, designed and patented by F. Robinson. Article presents model of rotor hub and review of main rotor and rotor hub construction in light helicopters. Because of number of accidents, caused by the unusual behaviour of Robinson R22, restrictive pilotage rules were introduced: prohibition of flight in certain weather conditions, the necessity of attending additional training conducted by trained instructors. To reduce the probability of an accident a special instruction for specific Robinson R22 properties was created. Moreover, the statistics of accidents resulting from loss of control and review of legal changes caused by Robinson R22 accidents are presented.

11

Experimental evaluation of the dynamic properties of an energy microturbine with defects in the rotating system

Żywica Grzegorz, Kaczmarczyk Tomasz Z.

Eksploatacja i Niezawodność

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2019

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Vol. 21, no. 4

670--678

EN

Today’s energy systems increasingly use various types of microturbines to produce electricity. A specific feature of such machines is a high-speed rotor, whose rotational speed can be higher than 100,000 rpm. Failure-free operation of highspeed microturbine rotors requires both special design and high precision during the manufacturing process. What is more, proper procedures must be followed during run-up and coast-down phases; and also, dedicated diagnostic systems have to be used. This article discusses the experimental research conducted on a 2.5 kW vapour microturbine that operated in a prototypical combined heat and power plant. A series of measurements was carried out to evaluate the dynamic performance of the machine during normal operation. After the appearance of certain defects in the rotating system, it was necessary to perform a new series of measurements in order to assess the dynamic properties of the machine. The measurements results obtained in the form of vibration velocity spectrums made it possible to define diagnostic symptoms corresponding to particular defects. Similar diagnostic symptoms can occur during the operation of this class of turbomachines.

PL

We współczesnych systemach energetycznych coraz częściej do wytwarzania energii elektrycznej stosowane są różnego typu mikroturbiny. Charakterystyczną cechą takich maszyn są wysokoobrotowe wirniki, których prędkości obrotowe mogą przekraczać nawet 100 000 obr/min. Praca wirnika w takich warunkach wymaga zastosowania specjalnych rozwiązań konstrukcyjnych i bardzo dużej precyzji wykonania, a podczas eksploatacji zachowania odpowiednich procedur przy rozruchu i odstawieniu, a także stosowania dedykowanych systemów diagnostycznych. W niniejszym artykule zostały omówione badania eksperymentalne mikroturbiny parowej o mocy 2,5 kW, pracującej w prototypowym układzie kogeneracyjnym. Wykonane pomiary obejmowały ocenę stanu dynamicznego podczas normalnej pracy maszyny oraz badania jej właściwości dynamicznych w obecności defektów układu wirującego. Uzyskane wyniki pomiarów, w postaci rozkładów częstotliwościowych drgań, pozwalają na zdefiniowanie symptomów diagnostycznych typowych dla różnych defektów, które mogą pojawić się podczas eksploatacji tej klasy maszyn wirnikowych.

12

Determination of parameters for a design of the stable electro-dynamic passive magnetic support of a high-speed flexible rotor

Szolc T., Falkowski F., Henzel M., Kurnyta-Mazurek P.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2019

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Vol. 67, nr 1

91--105

EN

Electro-dynamic passive magnetic bearings are now viewed as a feasible option when looking for support for high-speed rotors. Nevertheless, because of the skew-symmetrical visco-elastic properties of such bearings, they are prone to operational instability. In order to avoid this, the paper proposes the addition of external damping into the newly designed vibrating laboratory rotor-shaft system. This may be achieved by means of using simple passive dampers that would be found among the components of the electro-dynamic bearing housings along with magnetic dampers, which satisfy the operational principles of active magnetic bearings. Theoretical investigations are going to be conducted by means of a structural computer model of the rotor-shaft under construction, which will take into consideration its actual dimensions and material properties. The additional damping magnitudes required to stabilize the most sensitive lateral eigenmodes of the object under consideration have been determined by means of the Routh-Hurwitz stability criterion.

13

Zastosowanie TKEO w procesie automatycznego wyważania wirnika

Blaut Jędrzej, Rumin Rafał, Cieślik Jacek, Hyla Paweł, Szpytko Janusz

Autobusy : technika, eksploatacja, systemy transportowe

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2019

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R. 20, nr 1-2

161--166

PL

W artykule zaprezentowano przykład zastosowania Operatora Energetycznego Teagera-Kaisera w automatycznym wyważaniu wirnika. Operator Energetyczny Teagera-Kaisera jest metodą analizy sygnału, która pozwala w dla niektórych obiektów mechanicznych oszacować zmiany energii w ujęciu newtonowski za pomocą sygnału przemieszczenia. Wirniki są elementem konstrukcyjnym wykonującym obrót wokół osi. Tradycyjne wyważanie wirników polega na wprowadzaniu mas korekcyjnych, których celem jest zmniejszenie drgań i hałasu podczas pracy maszyn. Możliwe jest również nadążne wyważania rotorów. Może ono być realizowane przez system mas korekcyjnych o zmiennej odległości od osi obrotu. Zmiana odległości masy korekcyjnej od osi obrotu wpływa na zmianę bezwładności obiektu a tym samym zmniejsza niewyważenie. W zależności od konstrukcji urządzenia modernizacja może zakładać rozbudowę lub wymianę poszczególnych elementów. Poprawa pracy urządzenia wymaga selekcji elementów w zależności od całościowej ingerencji w pracę maszyny oraz wpływu na prace całego urządzenia. Przedstawiona autorska metoda sterowania automatycznego niewyważeniem z wykorzystaniem Operatora Energetycznego z doborem parametrów została wykonana na rzeczywistym stanowisku laboratoryjnym.

EN

The article presents an example of application of the Teager-Kaiser Energy Operator in automatic rotor balancing. The Teager-Kaiser Energy Operator is a signal analysis method, which allows for some mechanical objects to estimate energy changes in Newtonian terms by means of a displacement signal. Rotors are a structural element that rotates around an axis. Traditional balancing of the rotors is based on the introduction of correction masses, the aim of which is to reduce vibrations and noise during machine operation. Traditional balancing of the rotors is also possible. It can be realized by a system of correction masses with variable distance from the axis of rotation. The change of the correction mass distance from the axis of rotation influences the change of inertia of the object and thus reduces the unbalance. Depending on the design of the device, the modernization may assume extension or replacement of individual elements. Improvement of the operation of the device requires selection of elements depending on the overall interference in the operation of the machine and the impact on the operation of the entire device. The presented original method of automatic unbalance control with the use of the Energy Operator with the selection of parameters has been performed on a real laboratory stand.

14

Numerical analysis of the rotor of a 30 kw ORC microturbine considering properties of aerodynamic gas bearings

Breńkacz Ł., Żywica G., Bogulicz M.

Mechanics and Mechanical Engineering

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2018

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Vol. 22, nr 2

425--435

EN

The paper focuses on the analysis of a 30 kW microturbine operating in the organic Rankine cycle (ORC) with a low-boiling working medium. The nominal speed of the rotor is 40,000 rpm. The investigated microturbine is an oil-free machine, which means that its bearings use the ORC working medium as a lubricant. We created a numerical model, which was used to assess the dynamic properties of the newly designed microturbine. The conducted analyses covered, inter alia, the optimization of some geometrical parameters of each bearing in order to cause the lubricating film to be created at a correspondingly low rotational speed as well as to obtain optimal dynamic properties of the system. The article provides a full dynamic picture of the rotor supported by two aerodynamic gas bearings. The included graphs demonstrate the vibration amplitude of the shaft as a function of the rotational speed as well as the results of the modal analysis in the form of natural vibration modes of the system and their corresponding natural frequencies.

15

Application concept of the active magnetic suspension technology in the aircraft engine

Kurnyta-Mazurek P., Kurnyta A., Pręgowska A., Kaźmierczak K., Frąś L.

Aviation Advances & Maintenance

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2018

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Vol. 41, Issue 1

161--176; 177--193

EN

The paper presents the results of work on control and monitoring systems of an active magnetic bearings for the aircraft engine. Mathematic model of the active homopolar electromechanical actuator with permanent magnets is expanded. Mathematical model of the test object is developed what allows to propose a control algorithm. The experimental verification of this theory was performed on the laboratory test stand. Moreover, special monitoring system is also designed. Presented comprehensive approach allows increasing reliability of the aircraft engines, as well as in wind turbines, electric drives and machine tools spindles.

PL

W artykule zaprezentowano wyniki badań w zakresie sterowania i monitorowania układu aktywnych łożysk magnetycznych w silniku lotniczym. W pierwszej części pracy przedstawiono model matematyczny homopolarnego aktywnego siłownika elektromechanicznego z magnesami trwałymi. Opracowany model matematyczny badanego obiektu umożliwił zaprojektowanie algorytmu sterowania, którego eksperymentalna weryfikacja została przeprowadzona na stanowisku badawczym. Dodatkowo, zaprojektowano również dedykowany system monitorowania. Przedstawione kompleksowe analizy pokazują możliwość zwiększenia niezawodności silników lotniczych, turbin wiatrowych, napędów elektrycznych oraz wrzecion obrabiarek poprzez zastosowanie aktywnych zawieszeń magnetycznych.

16

Experimental investigation of ceramic ball bearings for microturbines

Bagiński P., Andrearczyk A., Żywica G.

Diagnostyka

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2017

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Vol. 18, No. 1

51--58

EN

This article presents the experimental research on ball bearings, which could be applied in vapour microturbines operating in CHP systems. The bearings are of three kinds, according to their constructional solution: 1. all-steel (all components are made of steel); 2. ceramic-steel-hybrid (ceramic balls, steel cage and races); 3. all-ceramic (the balls, as well as external and internal races, are made from ceramic silicon nitride - Si3N4, while the cage is made of PTFE). The test rig and the research method were discussed. In order to have a better picture of vibrations of the rotor-bearing system, we applied the bearing system with a flexible rotor. That option entailed some difficulties, however. In each case, both the analysis of the ball bearings' properties and of the impact of ceramic components on the dynamic performance of the rotor was carried out. The results of these analyses are presented in the following forms: displacement amplitudes of the rotor, colormap graphs of the type Order Spectrum Analysis and three-dimensional vibration trajectories. The bearings were analysed on the basis of colormap graphs, while the analysis of the rotating rotor was conducted using graphs depicting 3D vibration trajectories and displacement amplitudes at the disk location. As a result of all this work that we have mentioned, useful information on the possible application of tested bearings for vapour microturbines has been gained.

PL

W artykule przedstawiono opis badań trzech rodzajów łożysk kulkowych, które mogłyby być zastosowane w mikroturbinach parowych pracujących w układach kogeneracyjnych. Rodzaje badanych łożysk to: stalowe, hybrydowe (kulki ceramiczne, bieżnie stalowe, koszyk stalowy, ceramiczne gdzie elementy takie jak bieżnie wew. i zew. oraz kulki zostały wykonane z azotku krzemu (Si3N4) a koszyk z PTFE. Opisano budowę stanowiska badawczego i metodę badań. Aby drgania układu wirnik - łożyska były lepiej widoczne zastosowano wiotki wirnik, co sprawiało dodatkowe trudności podczas badań. W każdym z przypadków porównano właściwości badanych łożysk tocznych oraz wpływ elementów ceramicznych na dynamikę wirnika. Wyniki te przedstawiono w formie przebiegów, histogramów (Order Spectrum Analysis) i wykresów trajektorii drgań. Na podstawie map ekspozycji przeprowadzono analizę łożysk natomiast za pomocą przebiegów amplitudy przemieszczenia dysku i trajektorii 3D analizę wirującego wiotkiego wirnika. W rezultacie oceniono możliwość zastosowania badanych łożysk w mikroturbinach parowych.

17

Dynamic state assessment of the high-speed rotor based on a structural-flow model of a foil bearing

Żywica G., Bagiński P., Breńkacz Ł., Miąskowski W., Pietkiewicz P., Nalepa K.

Diagnostyka

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2017

|

Vol. 18, No. 1

95--102

EN

In the recent years, foil bearings have increasingly been used over a wide variety of different high-speed fluid-flow machinery. Since modern bearings of this type are the complex result of an assembly of several interdependent components, both their theoretical description and their modelling is very problematic. This article provides an analysis of the rotor supported by foil bearings conducted on the basis of an in-house developed numerical model. The model takes into account both structural and flow-related parameters, and makes it possible to determine the characteristics of a foil bearing under various operating conditions. The developed model allows analysing the dynamic performance of different foil bearings, taking into account the lubricating medium's properties as well as the geometry and characteristics of structural materials (top foil and bump foil). It gives an opportunity to shape the bearing freely so as to optimise its structure. An example of such an optimisation, which aims to minimise vibration of the rotor, was presented in the article.

PL

Łożyska foliowe są w ostatnich latach coraz częściej stosowane w różnego rodzaju wysokoobrotowych maszynach wirnikowych. Ponieważ współczesne łożyska tego typu stanowią wynik połączenia kilku współzależnych części składowych, zarówno ich opis teoretyczny jak i ich modelowanie nastręcza wielu trudności. W artykule przedstawiono przykład analizy wirnika z łożyskami foliowymi, wykonanej w oparciu o własny model numeryczny. W modelu tym uwzględniono zarówno parametry przepływowe jak i strukturalne, co pozwoliło na wyznaczenie charakterystyk układu w zależności od warunków pracy. Opracowany model pozwala na analizę właściwości różnego typu łożysk foliowych z uwzględnieniem właściwości czynnika smarnego oraz geometrii i charakterystyk materiałów konstrukcyjnych (folii ślizgowej i nośnej). Daje to możliwość dowolnego kształtowania właściwości łożyska oraz optymalizacji. Przykład takiej optymalizacji, której celem była minimalizacja drgań wirnika, został przedstawiony w artykule.

18

Operational Modal Analysis for Crack Detection in Rotating Blades

Bednarz J.

Archives of Acoustics

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2017

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Vol. 42, No. 1

105--112

EN

Vibration analysis has found widespread application for condition monitoring in a variety of applications and industries. With the continual development of cheaper and more powerful processing hardware, such systems have developed from utilizing simple checks on amplitude to those based around sophisticated spectral analysis. The paper presents application of the model based diagnostic method for early detection of faults in rotating machinery. The proposed diagnostics system based on modal analysis methods (OMA and OMAX methods). In the paper the diagnostic system based on such modelling is presented. The proposed system was verified during research on a specialized test rig, which can generate vibration signals.

19

Analysis of the dynamics of microturbines bearings lubricated using conventional and unconventional agents

Kiciński J.

Transactions of the Institute of Fluid-Flow Machinery

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2016

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nr 131

3--16

EN

The paper presents the research results of the microturbines dynamics with power of a few to several hundred kW. These are combined heat and power (CHP) units (generating heat and electricity) for houses and for municipalities in the form of Autonomous Energy Regions (ARE). These are key technologies for energy sector with respect to the distributed generation and for small-scale eco-power engineering. The following examples will refer only to the several selected research projects coordinated by the Institute of the Fluid-Flow Machinery of the Polish Academy of Sciences in Gdańsk. The paper will focus on the dynamics of rotors and bearings lubricated by means of low boiling agents, i.e., by means of turbine working medium. Analysis of hydrodynamic instability phenomena, including the development of oil whirl and oil whip has also been carried out.

20

Wpływ temperatury na dynamikę układu wirnik – łożyska foliowe

Bagiński P., Żywica G.

Mechanik

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2016

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R. 89, nr 7

634--635

PL

Artykuł przedstawia badania wpływu wzrostu temperatury, w jakiej pracuje wirnik podparty na łożyskach foliowych, na dynamikę całego układu. Badania przeprowadzono na zbudowanym stanowisku badawczym z modułem do podnoszenia temperatury otoczenia wokół łożysk. Podczas badań zarejestrowano przebiegi czasowe drgań oraz przemieszczenia i temperaturę wewnątrz łożyska foliowego. Następnie podniesiono temperaturę w obrębie jednej podpory łożyskowej do ok. 160 °C. Ponownie zarejestrowano przebiegi czasowe i porównano je ze sobą. Po analizie otrzymanych wyników można było stwierdzić, że układ wykazywał dużą wrażliwość na zmianę warunków termicznych pracy wirnika. Wirnik zwiększał swoją średnicę, przez co zmniejszała się szczelina smarna w łożyskach. Mimo niekorzystnych warunków pracy wirnika można powiedzieć, że układ dalej pracował stabilnie.

EN

The article presented research of growth temperature effect at which the working rotor supported on the foil bearings on the dynamics of this system. Tests were carried out on the test rig constructed with the module to raise the ambient temperature around the bearings. During the study recorded time courses of vibration, displacement and temperature which were inside the foil bearing. Then, the temperature was raised within one of the bearing support to approx. 160°C. Time courses was again recorded and compare them. After analyzing the results could be noted that, the system was sensitive to the changing in temperature conditions of the rotor. Shaft increased diameter thus reduced the lubricating gap in bearings. Despite the unfavorable working conditions of the rotor could be said the system was further worked stably.