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EN
Every change in the bottle geometry as well as every change of physical and rheological properties posesa risk of excessive gas entrainment during a filling process. To maintain satisfactory filling efficiencythere is a need to optimise this process with respect to all adverse phenomena which affect the fluidflow, such as spluttering on the bottom, air caverns formation and air entrainment with incoming liquid.This paper comprises numerical simulations of two filling methods. The first method involves dosingwith a pipe placed over the free liquid surface of a fully filled bottle. The second method covers fillingwith a pipe located near the bottom. Moreover, the influence of rheological properties and surfacetension values is considered. The comprehensive analysis of amount of entrained air represented byair volume fraction in dispensed liquid let the authors define the influence of filling speed on themechanism and amount of entrapped air.
EN
A novel three products hydrocyclone screen (TPHS) has been successfully developed; it consists of a cylindrical screen embedded in a conventional hydrocyclone (CH). In the new liquid cyclone, the combination of centrifugal classification and screening was employed for particle separation based on size. The aim of this study is to investigate the flow behaviour in TPHS using numerical simulation and experimental validation. A computational fluid dynamics simulation with a 4.35 million grid scheme and linear pressure–strain RSM generated the economic and grid-independence solution, which agreed well with the experiments of particle image velocimetry and water split. The velocity vector profile reveals that TPHS represented similar flow patterns to CH, wherein in addition to the outer downward swirl flow, inner upward swirl flow, central down-flow, second circulatory flow, and mantle, a particular fluid flow named screen underflow was created in TPHS owing to the presence of a cylindrical screen. The velocity distribution demonstrates that in TPHS, relative to CH, with the increase in radius, the lower tangential and higher radial velocity first increased to a peak and subsequently decreased, while the axial velocity primarily reduced to zero, increased in the opposite direction, and finally decreased rapidly to zero again. In addition, a disadvantageous flow, namely, screen backflow, was generated in TPHS, wherein the farther away the flow is from the feed inlet, the earlier this flow behaviour occurred. However, the rational scheme of aperture size and screen length can completely remove the screen backflow in TPHS.
PL
Na tle innych obiektów pływających jacht żaglowy wyróżnia się m.in. tym, że choć jest zaprojektowany jako pojazd poruszający się w pozycji wyprostowanej, to jednak znaczną część czasu żegluje w przechyle. Dlatego tak ważne jest poznanie zachodzących wtedy zjawisk, zwłaszcza związanych z oporem hydrodynamicznym. W artykule zaprezentowano porównanie oparte na weryfikacji wybranej, przybliżonej metody oszacowania zmian oporu całkowitego gołego kadłuba w wyniku jego przechylania się, polegającej na sprawdzeniu wykonanym metodą numeryczną (CFD) i eksperymentalną (przez badania modelowe). Obliczenia uproszczone oparto na metodach opracowanych w ramach serii Delft (The Delft Systematic Yacht Hull Series, DSYHS). W artykule przedstawiono wyniki oszacowań dla wybranego jachtu żaglowego.
EN
Unlike other floating structures yachts sail in heel most of their life, however, resistance in design process is estimated in upright condition. Thus, it is crucial to investigate into phenomena related to change of hull resistance due to heel. This article presents assessment of influence of yacht’s heel on bare hull resistance using approximate method. Results were compared to towing tank experiments and numerical computation (CFD). Calculations were performed using formulae developed based on The Delft Systematic Yacht Hull Series. Article presents results of analysis for specific sailing yacht.
4
Content available remote Badanie transportu masy i charakterystyki mieszania w przepływie segmentowym
PL
Zbadano transport masy w przepływie segmentowym generowanym w mikroreaktorze typu T o średnicy wewnętrznej 3 mm. Przebieg reakcji śledzono dzięki zmianie barwy błękitu bromotymolowego podczas neutralizacji wodnego roztworu wodorotlenku sodu kwasem octowym. Analiza fotografii pozwoliła zaobserwować niejednolitość w rozkładzie stężeń oraz wykazała zależność długości segmentów obu faz od objętościowego natężenia przepływu. Obecność stref martwych o słabym mieszaniu udało się potwierdzić z wykorzystaniem technik CFD (computational fluid dynamics). Przedstawiono drogę transportu masy wewnątrz segmentów z wykorzystaniem mapy wektorowej prędkości w przekroju poprzecznym segmentu. Wykazano również zależność pomiędzy szybkością reakcji a wartością dyssypacji energii, która może stanowić podstawę do szacowania szybkości wymiany masy w mikroreaktorach.
EN
The mass transport in the segmented flow generated in a T-type microreactor (internal diam. 3 mm) was monitored by changing the color of the bromothymol blue during neutralizing NaOH with AcOH. A heterogeneity in the distribution of concns. and a relationship between the length of segments and volumetric flow rate were obsd. The presence of dead zones with poor mixing was confirmed by using computational flow dynamics techniques. The relationship between the reaction rate and the energy dissipation was also shown.
PL
W artykule przedstawiono wyniki symulacji modelu składającego się odcinka rurociągu, w którym płynie gaz ziemny pod ciśnieniem, a ruch płynu zakłócony jest elementem pomiarowym typu annubar. Celem jest wykazanie czy przepływ gazu ziemnego pod wysokim ciśnieniem może uszkodzić element wykonawczy przepływomierza. Dzięki zastosowaniu komputerowej mechaniki płynów (ang. Computational Fluid Dynamics) zasymulowany został realny przepływ gazu ziemnego przez rurę z elementem pomiarowym. Uzyskane wyniki pozwalają wnioskować, że przepływ gazu może powodować uszkodzenie elementu pomiarowego wskutek powstania zmiennej w czasie reakcji aerodynamicznej. Dzięki wynikom symulacji zaproponowane zostało wstępne rozwiązanie problemu. Rozwiązanie rozważanego problemu jest istotne, ponieważ może przyczynić się do osiągnięcia większej niezawodności elementów pomiarowych.
EN
The article presents the results of a model simulation comprising a pipeline section with natural gas flowing under pressure, and the fluid movement is disrupted with a measurement element of annubar type. The goal is to determine whether the flow of gas under high pressure can damage the operating element of a flowmeter. Thanks to the use of CFD (Computational Fluid Dynamics), the real flow of natural gas through a pipeline with a measurement element was simulated. The results obtained make it possible to claim that the flow of gas can damage the operating element due to an aerodynamic reaction variable in time. As a result of the simulation, a preliminary solution has been suggested. The solution of the problem is important, since it can lead to obtaining greater reliability of measurement elements.
EN
The aim of this paper was to demonstrate the feasibility of using a Computational Fluid Dynamics tool for the design of a novel Proton Exchange Membrane Fuel Cell and to investigate the performance of serpentine micro-channel flow fields. A three-dimensional steady state model consisting of momentum, heat, species and charge conservation equations in combination with electrochemical equations has been developed. The design of the PEMFC involved electrolyte membrane, anode and cathode catalyst layers, anode and cathode gas diffusion layers, two collectors and serpentine micro-channels of air and fuel. The distributions of mass fraction, temperature, pressure drop and gas flows through the PEMFC were studied. The current density was predicted in a wide scope of voltage. The current density – voltage curve and power characteristic of the analysed PEMFC design were obtained. A validation study showed that the developed model was able to assess the PEMFC performance.
EN
The paper addresses the issues of quantification and understanding of Solid Oxide Fuel Cells (SOFC) based on numerical modelling carried out under four European, EU, research projects from the 7FP within the Fuel Cell and Hydrogen Joint Undertaking, FCH JU, activities. It is a short review of the main projects’ achievements. The goal was to develop numerical analyses at a single cell and stack level. This information was integrated into a system model that was capable of predicting fuel cell phenomena and their effect on the system behaviour. Numerical results were analysed and favourably compared to experimental results obtained from the project partners. At the single SOFC level, a static model of the SOFC cell was developed to calculate output voltage and current density as functions of fuel utilisation, operational pressure and temperature. At the stack level, by improving fuel cell configuration inside the stack and optimising the operation conditions, thermal stresses were decreased and the lifetime of fuel cell systems increased. At the system level, different layouts have been evaluated at the steady-state and by dynamic simulations. Results showed that increasing the operation temperature and pressure improves the overall performance, while changes of the inlet gas compositions improve fuel cell performance.
8
Content available Air flow analysis around the autogyro fuselage
EN
The paper presents the results of the simulation of the air flow around the gyroplane without the influence of the rotor and pusher propellers. Three-dimensional calculations were performed using ANSYS Fluent software. Based on the calculations, the values of the drag force and the lift force on each component of the rotorcraft were determined. Based on the results obtained, the effect of angle of attack on the aerodynamic forces was obtained.
PL
W pracy przedstawiono wyniki symulacji opływu modelu wiatrakowca bez wpływu wirnika nośnego oraz śmigła pchającego. Trójwymiarowe obliczenia wykonano za pomocą programu ANSYS Fluent. Na podstawie przeprowadzonych obliczeń wyznaczono wartości siły oporu oraz siły nośnej działające na poszczególne części składowe statku powietrznego. W oparciu o uzyskane wyniki otrzymano wpływ kąta natarcia na siły aerodynamiczne.
EN
In this study n-heptane spray in supercritical environments was simulated using commercial CFD (Computational Fluid Dynamic) software AVL Fire. The numerical results were analyzed in terms of global spray parameter, and spray penetration. The results obtained were compared with experimental data available at Sandia National Laboratories. N-heptane spray simulations were performed in the same conditions as in the Sandia experiments. The goal of the study was to assess whether the Lagrangian approach performs well in engine relevant conditions in terms of spray global parameters. Not included in this assessment was the influence of supercritical mixing on liquid-gas interphase. The major element was the potential for practical application of the commercial CFD code in terms of properly representing global spray parameters and thus mixture formation in supercritical conditions, which is one of the core aspects in whole engine process simulation. The key part of the study was mesh optimization. Therefore, the influence of mesh density on both the accuracy of calculations and the calculation time was determined, taking into consideration detailed experimental data as initial conditions for the subsequent calculations. This served as a basis to select the optimal mesh with regard to both accuracy of the results obtained and time duration of the calculations. As a determinant of accuracy, the difference within a range of evaporated fuel stream was used. Using selected mesh the set of numerical calculations were performed and the results were compared with experimental ones taken from the literature. Several spray parameters were compared: spray tip penetration, temperature of the gaseous phase and mixture fraction in the gaseous phase. The numerical results were very consistent in respect of spray tip penetration. The other parameters were influenced by specific features of the Lagrangian approach. Nevertheless the results obtained showed that the Lagrangian approach may be used for engine relevant conditions.
10
Content available remote Instability issues in the server room cooling system
EN
Since 2009, the National Center for Nuclear Research in Poland has been constructing its own High Performance Computing (HPC) Centre under the name Świerk Computing Centre (CIŚ). Now, it is ready reaching its target - 1 PFLOPS - in December 2015. However at the early operation stage, one of its major problems was the unstable work of the HPC cluster cooling system, resulting in increased maintenance costs. The main aim of this work is to thoroughly investigate the origin of the problem and to find the best solution for it based on results from a Computational Fluid Dynamics (CFD) analysis. The constructors suspected that the oscillations in the flow domain are caused by thermal flow stratification, but something else was proved. In this paper, a wide range of cases will be analyzed, covering different work regimes of the installation as well as various geometry modifications. Finally, certain improvement to the current design will be suggested by the CFD Analysis Group.
EN
The paper presents an analysis of the influence of the fuel spray geometry on the combustion and emission characteristic of the marine 4-stroke Diesel engine. Presented analysis was prepared based on computational fluid dynamic model (CFD). Initial and boundary conditions of the model as well as data used to model validation were collected during the laboratory study. Calculations were conducted for two different fuel injectors with changed nozzle holes diameters, the number of nozzle holes and the angle between holes axis. The increase of the fuel nozzle holes diameter causes the decrease of the fuel spray tip penetration, but simultaneously the decrease of holes number causes that auto-ignition delay is not changed. The increase of the angle between holes axis from 150° to 158° causes fuel ingintion near cylinder head wall. Result of this is the increase of CO fraction. The deterioration of fuel combustion causes the decrease of NOx mass fraction in the cylinder also.
EN
The present study deals with modelling and validation of a planar Solid Oxide Fuel Cell (SOFC) design fuelled by gas mixture of partially pre-reformed methane. A 3D model was developed using the ANSYS Fluent Computational Fluid Dynamics (CFD) tool that was supported by an additional Fuel Cell Tools module. The governing equations for momentum, heat, gas species, ion and electron transport were implemented and coupled to kinetics describing the electrochemical and reforming reactions. In the model, the Water Gas Shift reaction in a porous anode layer was included. Electrochemical oxidation of hydrogen and carbon monoxide fuels were both considered. The developed model enabled to predict the distributions of temperature, current density and gas flow in the fuel cell.
EN
The paper presents a modelling procedure of the M-28 Bryza wing with extended flaps and Computational Fluid Dynamics (CFD) simulations results preformed in order to assess the performance of the investigated wing for various flap extension rates. The M-28 Bryza is a two-engine high-wing aircraft used in the Polish Air Force for short distance airlift of people and equipment. The aim of this work was to determine the aerodynamic characteristics of the investigated wing. The CFD simulations were performed in order to investigate the influence of flap extension on lift and drag coefficients at various angles of attack. In order to validate the results of two different commercial CFD packages were used. The findings are presented in the form of flow visualization and aerodynamic characteristics. The typical and non-standard extension rates were investigated for low, moderate and high angles of attack. The results correlated with the limitations specified in the aircraft manual. The outcome of the presented work confirmed the feasibility of the presented methodology for its use as a supportive tool for providing additional information about airplane performance in standard and non-standard conditions of flight such as landing with one engine working. The results of work might prove useful for M-28 Bryza pilots and maintenance personnel as well as for educational purposes.
EN
With the constant growth of computer simulation significance in science and engineering, many new fields are gaining access to these powerful tools. One of these new disciplines is medicine. Human body provides many fascinating areas that could be researched from completely different angle and could gain all the benefits that computer simulation offers. For example blood flow in human arteries can be studied using Computational Fluid Dynamics. Researchers of cerebrovascular disorders can get an insight view on physical phenomena of blood flow and study risk factors of embolism or cerebral aneurysm. Main issue in using computer simulation in medical research is the complexity and uniqueness of geometry that needs to be handled. After all, human body is one of the most sophisticated engineering systems created by nature. In this paper, a workflow for creating a numerical mesh for CFD simulation purposes is shown. Application shown in the example focus on cerebral arteries blood flow simulation. Numerical mesh is generated based on CT scan of patient’s head, using freeware tools Slicer3D and AutoIt3 as well as commercial software ANSYS Fluent Meshing 15.0.
PL
Omówiono Computational Fluid Dynamics (CFD) w praktyce inżynierskiej jako integralną część postępu w całej inżynierii procesowej wędzenia z uwzględnieniem rozwoju technik i metod przeprowadzania obróbki wędzarniczej. Wykorzystanie narzędzi związanych z modelowaniem CFD pozwoliło na uzyskanie istotnych informacji dotyczących przeprowadzanego procesu wędzenia dla asortymentu o kształcie geometrycznym zbliżonym do szynki (myszka). Komora jednowózkowa stanowiła konstrukcję bazową dla rozwiązań proponowanej modyfikacji elementów zasilających (dysz), jak również geometrię modelu komputerowego samej konstrukcji komory pustej i z wsadem. Dyskretyzacja została wykonana w programie ANSYS Mechanical APDL 12.1 i na jej podstawie stworzono model o proponowanym rozwiązaniu konstrukcji dysz zasilających i rozprowadzających mieszaninę dymu wewnątrz komory wędzarniczej. Na podstawie modeli symulacyjnych i uzyskanych z nich wyników można jednoznacznie stwierdzić, że osiągnięto korzystniejsze warunki rozprowadzenia mieszaniny dymu w komorze wędzarniczej. Przeprowadzone w warunkach rzeczywistych badania z wykorzystaniem zmodyfikowanych dysz zasilających w porównaniu z klasycznym układem potwierdzają zależności uzyskane z symulacji.
EN
This paper elaborates upon the use of Computational Fluid Dynamics (CFD) tools in the engineering practice as an integral part of progress of the chemical engineering of smoke-drying taking into consideration the technical progress and smoke-drying methods. The use of tools connected to CDF modeling allowed collecting crucial information concerning the performed process of smoke-drying for the assortment geometrically shaped similarly to a piece of oval ham. A single truck chamber was a base construction for solutions of the suggested modification of the powering elements (nozzles) as well as for the computer model geometry of the construction of an empty chamber and a full chamber itself. Discretization has been made in the ANSYS Mechanical APDL 12.1 software and on this basis a model of the suggested solution for construction of power nozzles as well as nozzles spreading the smoke substance inside the smoking chamber has been prepared. On the basis of simulating models and received feedback we can unequivocally say, that more advantageous conditions of spreading the smoke substance in the smoking chamber had been found. The tests performed in the real conditions with the use of modified power nozzles in comparison to the classical arrangement confirm dependences obtained during simulation.
16
PL
W niniejszym artykule zostały zaprezentowane wyniki obliczeń numerycznych oddziaływania wiatru na przepływ powietrza w tunelach. Zagadnienie oddziaływania wiatru na przepływ powietrza w tunelach odgrywa istotną rolę przy projektowaniu wentylacji bytowej, systemów bezpieczeństwa pożarowego tuneli a w szczególności systemów wentylacji pożarowej oraz systemów detekcji pożaru. W przypadku nieuwzględnienia wiatru na etapie projektowania wyżej wymienionych systemów prawidłowe wykrycie pożaru oraz skuteczne funkcjonowanie systemu wentylacji pożarowej będą bardzo utrudnione, a w niektórych przypadkach nawet niemożliwe. Artykuł ten stanowi fragment prowadzonej przez autora pracy badawczej.
EN
In this paper there are presented results of the numerical analyses of the wind influence on flow field in tunnels. The results show that wind shall be considered during ventilation design process.
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