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1

Numerical investigation on the vibration reduction of rotating shaft using different groove shapes of tilt bearing

Abbood Ahmed Imad, Abdulla Fadhel Abbas

Diagnostyka

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2023

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Vol. 24, No. 3

art. no. 2023304

EN

Vibration control is very important for high-speed rotors. Oil film damping is considered an effective vibration-damping method, especially for long shafts in gas turbines, ships, and other high-speed rotating equipment. The existing groove in the internal surface of the tilt bearing increases the amount of oil that flows through the bearing; this is more effective in suppressing the vibration of the rotor system carried by the plain bearing. In order to suppress the vibration of the rotor system, which is supported by sliding bearings, a different groove-shaped oil flow (GSOF) is studied and analysed in this paper. A different shape of grooves in bearings was set up and measured to study the vibration-damping effect of the flow oil shape with GSOF. ANSYS software presents significant benefits to engage Fluent for oil flow with Transient structural for vibration measurements. This paper uses these terms to perform the simulation numerically to explore the groove-shaped damper's damping effect under the rotor system. The study identified three enhancements of vibration and settling time. First, the circular groove showed a 35.71% reduction in amplitude and 10% increase in stilling time; the next one is the circular groove which reduced the amplitude by 42.85% and the settling time by 0%. The third modification was the inclined groove which reduced the amplitude by 42.85% and the settling time by 12%. The last one was the triple-inclined groove, which reduced the amplitude and settling time by 57.14% and 20%, respectively.

2

Numerical analysis of a velocity distribution of a fluid flow inside a reversing chamber

Judt W., Bartoszewicz J.

Journal of KONES

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2018

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Vol. 25, No. 3

247--251

EN

Axisymmetric stream, which is directed into an obstacle, is an important type of a fluid flow for technical applications in a large amount of thermal and flow devices. The article presents a case wherein stream of a fluid is directed into a flat surface and changes the direction of a flow by an angle equal to 90°. After that, the free stream is changing a character of a flow into impinging stream. The article presents a methodology of numerical calculations preparation in ANSYS Fluent environment for a velocity distribution of an airflow inside a reversing chamber. Numerical calculations were prepared for a three-dimensional model as an unsteady simulation with Delayed Detached Eddy Simulation model of turbulence. A stream of an air, which was analysed inside a reversing chamber, was not initially swirled. Obtained results of realized calculations were compared with experimental analysis and numerical calculations, which was realized in a different environment by co-author. Model of reversing chamber, which was implemented into numerical analysis has the same dimensions as used in experimental research. Obtained results show areas of intense flow turbulence inside reversing chamber. Prepared numerical calculations agreed with experimental results of research and allowed to designate areas of stream core and impinging stream inside modelled chamber.

3

Numerical analysis of a heat transfer in economizer dedicated for 250 KW power solid fuel heating boiler

Judt W., Bartoszewicz J.

Journal of KONES

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2018

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Vol. 25, No. 2

164--168

EN

Heating boilers, which are combusting solid fuels, are a very popular heating device in Poland. Heating boilers for solid fuels with nominal power equal to 250-300 kW reach a high level of waste heat. Polish companies produced a significant amount of heating boilers with that level of heating power, which are being exploited all the time in smaller companies and housing associations. A temperature of exhaust gases in the outlet of the heating boiler can be equal to 270-300ºC. It means that it is possible to recover some part of the waste heat. It can be realizable in an external heat exchanger. The article contains a methodology of a heat transfer process calculation for this type of heat exchangers. Estimated waste heat, which can be recovered from this installation, is equal to 25 kW. Additional heat exchanger implementation into a plant can increase an efficiency of solid fuel combustion process for a 10 percent. Construction of a heat exchanger was calculated during analytical calculations. After that, analytical calculations were verified in numerical calculations. Numerical analysis of a heat exchanger model was realized in the ANSYS Fluent environment. During calculations, a shell-and-tube heat exchanger construction was analysed. Authors of the article analysed a real temperature distribution for exhaust gases located on a shell side and for a water, which are located on a tube side of the economizer. Numerical calculations allowed to model conditions of economizer steady state work for a whole volume of this construction.

4

Analysis of possibilities of increasing a turbulence by throttled axisymmetric stream for a fluid flow inside closed duct

Judt W., Bartoszewicz J.

Journal of KONES

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2018

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Vol. 25, No. 1

185--190

EN

Fluid flow through the closed duct is a common phenomenon, which is used in many technical applications. A stream of a fluid is often disturbed by different shapes of elements, which have an effect for a flow and causes the growth of a turbulence. Turbulence rising causes an increase of heat transfer process and eliminates areas of flow stagnation in thermal devices. Article presents methodology and results of research about possibilities of turbulence increasing for a fluid flow inside a closed duct. Authors analysed capabilities of application of an internal stream of a fluid in the axis of the tested duct, in the inlet to analysed construction for mainstream turbulence expanding. An additional stream of a fluid was added into the model by internal, partially throttled pipe, which was clogged by special disc. Contact between the disc and internal pipe generated a small gap, where an additional stream of a fluid was directed. Numerical analysis of a level of turbulence for a fluid flow through analysed duct was realized in ANSYS Fluent environment, as an unsteady simulation with Delayed Detached Eddy Dissipation model of turbulence. Experimental research was realized with constant anemometry measurement method. Results of experimental and numerical analysis show, what part of a fluid inside duct disturbed mainstream of a flow.

5

Numerical Studies on a Three-dimensional Flow Field in Four-Roller Compact Spinning with a Guiding Device

Liu X., Xie C., Su X., Mei H.

Fibres & Textiles in Eastern Europe

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2013

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Vol. 21, no. 6 (102)

50--57

EN

Research on the flow field in the fibre-converging zone is always the emphasis and difficulty of compact spinning. Therefore in this work numerical studies on the three-dimensional flow field in four-roller compact spinning with a guiding device were carried out using Fluent software. First a three-dimensional physical model of the fibre-converging zone was obtained using AutoCAD software. Then numerical simulations of the three-dimensional flow field in four-roller compact spinning with and without a guiding device were presented, respectively, using Fluent software. It was shown that the negative pressure is chiefly concentrated near the air-suction flume, and the velocity reaches the maximum on the centre line. Comparing with the flow field in compact spinning without a guiding device, the effective range of negative pressure in four-roller compact spinning with a guiding device increases significantly and negative pressure use efficiency improves accordingly. Furthermore the optimal installation position of the guiding device was studied, and it was shown that the optimal installation position is closely related to the linear density of the spun yarn. Finally the theoretical results obtained were illustrated by experiments.

PL

Podstawową trudnością w przędzeniu kompaktowym jest analiza pola przepływu strumienia włókien, którą przeprowadzono korzystając ze specjalnego oprogramowania – Fluent Software. Wstępnie opracowano model fizyczny procesu korzystając z systemu AutoCAD. Wykazano, że podciśnienie jest głównie skoncentrowane w pobliżu kanałów zasysających i prędkość osiąga swoje maksimum w centrum układu. Wykazano korzyści z zastosowania układu czterorolkowego w porównaniu do układu klasycznego i optymalne pozycje rozmieszczenia ściśle uzależnione od masy liniowej produkowanej przędzy. Uzyskane obliczenia teoretyczne porównano z wynikami praktycznymi.

6

Zastosowanie numerycznej mechaniki płynów do analizy ograniczeń drogi wodnej

Jachowski J.

Logistyka

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2009

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nr 4

CD-CD

PL

W ostatnich latach przeprowadzone zostały liczne badania mające na celu identyfikacje sił hydrodynamicznych działających na manewrujący statek na akwenach portowych przystosowanych dla dużych statków. Niekorzystne zjawiska, które oddziałują na warunki eksploatacji statku na ograniczonej drodze wodnej odgrywają ważną rolę w projektowaniu akwenów i są przedmiotem wielu badań. W artykule zostanie omówione zagadnienie związane z zastosowaniem systemu obliczeniowego Fluent do analizy zjawisk zachodzących podczas ruchu statku na wodzie płytkiej takich jak wzrost przegłębienia, osiadania, powstanie prądu powrotnego oraz wzrost oporów kadłuba. Oszacowanie wielkości osiadania ma istotne znaczenie w wyznaczeniu wymaganej tolerancji między zanurzeniem statku, a głębokością akwenu. Określenie dokładnego związku między wielkością osiadania a prędkością umożliwi maksymalne wykorzystanie dopuszczalnego zanurzenia przy zachowaniu bezpieczeństwa eksploatacji statku.

EN

The problem of ship squat is one among the crucial factors affecting the navigation of ships in restricted waters. The squat can be estimated using either the empirical or analytical models. It may be evaluated by implementing the real scale tests or CFD technology as well. The results of calculations should be validated with the results obtained using the existing methods of squat identification. From the hydrodynamic phenomena point of view the main attention has been paid to hydrodynamic forces affecting the hull in shallow water