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Wyświetlanie 1-15 z 23
Tytuł:
Analysis of abnormal vibrations of crude oil efflux pumps using Ansys
Autorzy:
Wang, Tianqi
Xie, Lei
Yu, Hongsheng
Wei, Xiuliang
Dong, Pengmin
Zhao, Tianyi
Powiązania:
https://bibliotekanauki.pl/articles/2200858.pdf
Data publikacji:
2023
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
abnormal vibrations
internal flow field
Ansys
Opis:
In this study, abnormal vibrations of 1 pump fluid in a crude oil efflux station in the Changqing Oilfield was investigated. Kinetic simulation was applied to flow fields in the crude oil efflux pump using Ansys to determine trends of the impeller static pressure, speed, total pressure, wall pressure of the impeller, outlet pressure and pressure on the pump shell and to identify the reasons behind the abnormal vibrations. The results indicated that the axial vibration amplitude of the pump could be reduced from 1.3mm down to 0.68mm if the operation parameters of the external control oil pump were set as 2500-2550r/min and 325-335m3/h, respectively.
Źródło:
Journal of Theoretical and Applied Mechanics; 2023, 61, 1; 23--36
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical simulations of gap flow above rotating disk
Autorzy:
Wasilczuk, F.
Flaszyński, P.
Doerffer, P.
Powiązania:
https://bibliotekanauki.pl/articles/1938643.pdf
Data publikacji:
2015
Wydawca:
Politechnika Gdańska
Tematy:
computational fluid dynamics CFD
internal flow
flow control
Opis:
A rotating disk can be considered a basic configuration for the investigations of the impact of various conditions on the flow through the clearance between the shrouded turbine blade and the casing. Numerical calculations using Fine/Turbo Numeca were conducted to examine the influence of the rotational velocity and the pressure difference across the disk on the flow conditions, especially the mass flow through the clearance. The results were validated using the experimental data. Moreover, the flow field was investigated to reveal the vortices induced in the flow. The calculations showed a significant drop of the mass flow with a rise of the rotation velocity. Additionally, the vortex created upstream of the disk at higher rotation velocities was observed. The phenomenon of separation at the edge of the disk was investigated.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2015, 19, 2; 89-100
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Qualitative comparison of 2D and 3D computation of flow field in the cone shaped turbine nozzle
Autorzy:
Puzyrewski, R.
Flaszyński, P.
Powiązania:
https://bibliotekanauki.pl/articles/1953945.pdf
Data publikacji:
2000
Wydawca:
Politechnika Gdańska
Tematy:
internal flow
turbomachinery
turbine nozzle
numerical methods
Opis:
The paper presents a qualitative comparison of 2D and 3D computation of the flow field in a cone shaped turbine nozzle. The calculation yields a surface, S/sub 2/, for a given conical stream surface S/sub 1/. The S/sub 2/ stream surface represents the curvature of blading passages. This formulation is typical for the inverse problem. Based on a surface it is possible to design the shape of the blade. Results of 3D computation by means of FLUENT have been presented and compared with assumptions in the 2D model.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2000, 4, 2; 179-191
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The rectangular two-phase closed thermosyphon: A case study of two-phase internal flow patterns behaviour for heat performance
Autorzy:
Chompookham, Teerapat
Sichamnan, Surachet
Bhuwakietkumjohn, Nipon
Parametthanuwat, Thanya
Powiązania:
https://bibliotekanauki.pl/articles/240618.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
internal flow
flow pattern
rectangular two-phase closed thermosyphon
Opis:
This research explored different types of two-phase flow patterns that influenced heat transfer rate by assessing rectangular two-phase closed thermosyphon (RTPCT) made from glass with the sides of equal length of 25.2 mm, aspect ratio 5 and 20, evaporation temperature of 50, 70, and 90°C, working substance addition rate of 50% by volume of evaporator, and water inlet temperature at condensation of 20°C. Upon testing with aspect ratios 5, three flow patterns emerged which were: bubble flow, slug flow and churn flow respectively. As per the aspect ratio 20, four flow patterns were discovered which were: bubble flow, slug flow, churn flow and annular flow, respectively. Aspect ratio 5 pertains characteristic which resulted in a shorter evaporation rate of the RTPCT than that of the aspect ratio 20, thus, a shorter flow distance from the evaporator section to heat releaser was observed. Therefore, flow patterns at aspect ratio 5 exhibited a faster flow velocity than that of the aspect ratio 20. Furthermore, changes of flow pattern to the one that is important for heat transfer rate can be easily achieved. Churn flow was the most important type of the flow for heat transfer, followed by slug flow. Moreover, with aspect ratio 20, annular flow was the most important flow for the heat transfer, followed by churn flow, respectively. Throughout the test, average heat flux as obtained from the aspect ratio 5 were 1.51 and 0.74 kW/m2 which were higher than those of the aspect ratio 20. The highest heat flux at the operating temperature of the evaporator section was 90°C, which was equivalent to 2.60 and 1.52 kW/m2, respectively.
Źródło:
Archives of Thermodynamics; 2020, 41, 3; 223-254
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical analysis of internal flow phenomena in a multi-blade centrifugal fan
Autorzy:
Wang, J.
Ou, Y.
Wu, K.
Powiązania:
https://bibliotekanauki.pl/articles/1964163.pdf
Data publikacji:
2005
Wydawca:
Politechnika Gdańska
Tematy:
multi-blade centrifugal fan
internal flow field
CFD
Opis:
A three-dimensional, steady, incompressible, turbulent flow field inside a multi-blade centrifugal fan used in an air-conditioner has been analyzed numerically. Reynolds-averaged Navier-Stokes equations with the standard k-epsilon turbulence model have been discretized by the finite volume method. The calculation results have shown complex three-dimensional characteristics of the flow, especially in the blade passages near the shroud side. The results have revealed a boundary layer separating the flow from the leading edge on the blade suction surface, the flow's reversal from the high pressure region inside the volute to the low pressure region near the impeller inlet, the flow's recirculation near the shroud side, a jet-wake pattern at the rotor exit, pressure fluctuation on the blade surface, etc. Some of the numerical results agree well with previous experiment.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2005, 9, 2; 245-256
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical analysis of the tip vortex in an air-conditioners propeller fan
Autorzy:
Wang, J.
Wu, K.
Powiązania:
https://bibliotekanauki.pl/articles/1955218.pdf
Data publikacji:
2006
Wydawca:
Politechnika Gdańska
Tematy:
tip vortex
internal flow field
propeller fan
numerical simulation
Opis:
A steady, incompressible, turbulent flow field inside a propeller fan used in an air conditioner has been analyzed numerically using the single-equation Spalart-Allmaras turbulence model. It has been found that the formation of tip vortex starts from the blade tip's suction side at about one third of the axial chord's length aft of the rotor's leading edge. It is due to the rolling-up of the intense shear layer flow between the main axial flow and the suck-in inward flow caused by the large pressure difference between the pressure and the suction sides. The tip vortex passes through the blade passage in a curve reversed towards the direction of the blade's rotation. Its trace is partial to the tangential direction as it goes into the aft part of the blade passage covered by the shroud and, simultaneously, its trace in the radial direction is turned from the outward direction to the inward direction. The operating flow rates have an important effect on the axial position of the tip vor-tex's trace, while its effect on the radial position is negligible. At law flow rates, the vortex disappears at a location closer to the leading edge. The effect of the shroud's width on the tip vortex's trajectory is notable. For a fan with a wide shroud, the trace of the tip vortex moves upstream with a smaller radial influence region than that of a fan with a narrower shroud.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2006, 10, 2; 101-112
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Three-dimensional numerical analysis of internal flow phenomena in a diagonal rotor
Autorzy:
Bin, Y.
Keqi, W.
Powiązania:
https://bibliotekanauki.pl/articles/1955712.pdf
Data publikacji:
2004
Wydawca:
Politechnika Gdańska
Tematy:
diagonal rotor
numerical analysis
internal flow
tree-dimensional analysis
Opis:
A numerical analysis has been designed to study internal flow phenomena in a diagonal rotor. A calculated diagonal rotor was designed by a quasi-three-dimensional method. Its hub and casing walls were inclined 45o and 25o, respectively. The numerical simulation was based on the Navier-Stokes equations coupled with a k-ε turbulence model. We found that the rotor's wake was stronger near the hub and in the casing end wall region. The wake at a lower flow rate was stronger than that at a higher flow rate. Static pressure gradually increased from the hub to the casing along the height of a blade, on the rotor pressure surface and in the front 60% of the chord region of the suction surface. In the back 40% of the chord region of the suction surface, static pressure gradually decreased. A passage vortex formed in the stator flow passage and an 80% axial chord plane. It was located near the hub end-wall. The passage vortex developed into a large vortex centered near the midspan at a 99% axial chord plane of the stator. The casing wall boundary layer downstream of the rotor occupied approximately 10% of the flow passage. Along the height of a blade, the meridian velocity gradually increased upstream of rotor and decreased downstream. The calculated aerodynamic characteristic curve, the meridian velocity distribution upstream and downstream of the rotor, and the streamline distribution on the meridian surface were consistent with experimental results and design data. Our findings proved that the present numerical method is reliable and practicable. It can be used to design and analyze swept diagonal rotors in order to improve their surging and rotation stall state. The present results also provide comparative data for the design of highly-loaded swept diagonal rotors in future studies.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2004, 8, 1; 27-40
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hydraulic development of a centrifugal pump impeller using the agile turbomachinery design system
Autorzy:
Denus, K.
Osborne, C.
Powiązania:
https://bibliotekanauki.pl/articles/1986764.pdf
Data publikacji:
2002
Wydawca:
Politechnika Gdańska
Tematy:
impeller design
CFD analysis
turbomachinery design optimization
internal flow analysis
Opis:
The impeller of an existing industrial pump (with both geometry and performance known) was analyzed and redesigned using an integrated, design/analysis, turbomachinery geometry modeling and flow simulation system. The purpose of the redesign was to achieve improved impeller performance (at the duty point). Fluid dynamics and geometry modeling parts of the design/analysis system were systematically applied: a) to analyse the existing impeller (impeller A), which was designed using conventional (routine in industry) hydraulic layout procedures, and b) to develop a new impeller (impeller B), using a coupled, multilevel 1D-Q3D-3D for the design and optimization. This paper discusses the features and advantages of the integrated design system, in which the coupled CAD/CFD approach is fully implemented. The analysis results are presented for impellers A and B, with the latter demonstrating a predicted increased efficiency and smaller size. Comparisons of the CFD results for both impellers reveal internal flow features that explain the improved impeller B performance levels.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2002, 6, 1; 79-100
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modification of the Rigid Finite Element Method in Modeling Dynamics of Lines and Risers
Modyfikacja metody sztywnych elementów skończonych w modelowaniu dynamiki lin i riserów
Autorzy:
Adamiec-Wójcik, I.
Brzozowska, L.
Wojciech, S.
Powiązania:
https://bibliotekanauki.pl/articles/140334.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
slender links
rigid finite element method
risers
hydrodynamic forces
internal flow
Opis:
The paper presents an application of the modified rigid finite element method to analysis of the dynamics of slender structures. The equations of motion are formulated for a system discretized by means of the method, and discussion is limited to planar systems and large deformations. Slender elements can be found in offshore engineering as lines, cables and risers. In these cases the hydrostatic influence of water and sea currents has to be taken into account. While analyzing dynamics of risers it may also be necessary to consider the flow of fluid inside the riser. The influence of hydrodynamic coefficients and the velocity of the internal flow of fluid on displacements and forces is presented.
W pracy przedstawiono zastosowanie zmodyfikowanej metody elementów skończonych do analizy dynamiki wiotkich struktur. Sformułowano równania ruchu układu dyskretyzowanego prezentowaną metodą, przy ograniczeniu rozważań do płaskich układów i uwzględnieniu dużych ugięć. Elementy wiotkie spotykane są często w technice offshore’owej jako liny, kable i risery. Analizę dynamiki tych elementów trzeba jednak wówczas uzupełnić o hydrostatyczne oddziaływania wody i prądów morskich. W przypadku riserów, należy też uwzględnić możliwość przepływu płynu w ich wnętrzu. Na przykładzie risera pokazano wpływ współczynników hydrodynamicznych i prędkości przepływu płynu we wnętrzu risera na przemieszczenia i siły.
Źródło:
Archive of Mechanical Engineering; 2013, LX, 3; 409-429
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Two-dimensional and dynamic method of visualization of the flow characteristics in a convection boundary layer using infrared thermography
Autorzy:
Patorski, J. A.
Bauer, G. S.
Dementjev, S.
Powiązania:
https://bibliotekanauki.pl/articles/279681.pdf
Data publikacji:
2001
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
IR-thermography measurement
visualization of internal flow within convection boundary layer
heat transfer visualization
Opis:
The paper presents a two-dimensional and dynamic (2DD) method of using infrared thermography (IRT) for visualization of the cooling efficiency of a heated wall, as this method was applied in an experimental investigation. The 2DD method allows the outer surface temperature measured by an IRT device to be worked out relative to the bulk coolant-fluid temperature. This way the 2DD method makes visible the qualitative and quantitative flow characteristics within the thin contact layer at the inner surface of the wall. These flow characteristics, and more specifically, the pattern of the flow (similar to streamlines useful for the detection of dead zones) and the distribution of the temperature differences between the temperature on the wall outer surface and the bulk temperature of the coolant, determine the cooling efficiency. Finally, animated IR thermogram sequences could be generated, allowing observation of the spatial and temporal behavior of the flow/cooling behind the wall, for an example see animations in internet page (Patorski, 2000). The study of the cooling of the proton beam entry window described in this paper is a part of the development program of neutron spallation sources with liquid metal targets. The basic idea of the experiments was to use the real interacting materials (mercury as the liquid metal and steel as the window wall) and observe the cooling effects of the mercury flow on the heated wall of the hemispherical shell of the mockup window. Different geometrical configurations of the inner flow guide tubes of the flow and different pumping velocities were examined in view of finding the optimal cooling solution.
Dwuwymiarowa dynamiczna metoda wizualizacji charakterystycznych właściwości przepływu w konwekcyjnej warstwie granicznej przy użyciu termowizji. Artykuł przedstawia, na przykładzie zastosowania w badaniach doświadczalnych, dwuwymiarową dynamiczną (2DD) metodę użycia termowizji (IRT) wizualizującą efektywność chłodzenia przepływem cieczy silnie ogrzewanej ścianki zbiornika. Wykorzystanie zsynchronizowanych pomiarów: temperatury zewnętrznej powierzchni ścianki zbiornika (za pomocą IRT) oraz temperatury masy płynącej cieczy (za pomocą termoelementów (TC)), pozwoliło na wizualizację jakościowych i ilościowych zjawisk przepływu cieczy charakteryzujących efektywność chłodzenia ścianki. Do zjawisk jakościowych zaliczono tu wizualizację obrazów przepływu; w przybliżeniu obrazów lini przepływu w pobliżu ścianki, ponieważ pola temperatur w dominującym stopniu zależą od rozkładu prędkości przepływu. Obrazy takie dają możliwość wykrycia zawirowań czy tzw. "marwych" stref przepływu występujących po niewidocznej stronie nieprzeźroczystej ścianki. Do zjawisk ilościowych zaliczono wizualizację pola rozkładu wartości różnicy temperatur pomiędzy ścianką a masą płynącej cieczy; mniejsze wartości tej różnicy wskazują lepszą lokalną efektywność chłodzenia. Wartość tej różnicy temperatur może być bezpośrednio skorelowana z konwekcyjnym współczynnikiem przekazywania ciepła. Pokazanie animacji w postaci sekwencji tak specyficznie zdefiniowanych pól temperatur pozwala na geometryczno-czasową (dynamiczną) ocenę efektywności chłodzenia ścianki zbiornika dla różnych konfiguracji wewnętrznego przepływu cieczy. Dla przykładu, na stronie internetu (Patorski,2000) pokazano dwie animacje dotyczące eksperymentów omawianych w artykule. Przedstawione badania doświadczalne służą wyborowi optymalnej konfiguracji przepływu rtęci dla chłodzenia ścianki stalowego zbiornika źródła neutronów, tzw. "okna" wejścia wiązki protonów, podczas wytwarzania neutronów z jąder atomów ciężkich metali w procesie spallacji. W omawianym przypadku rtęć będzie jednocześnie wykorzystywana do wytwarzania neutronów, jak i do chłodzenia stalowej ścianki naczynia źródła neutronów. Z punktu widzenia analizy naprężeń termo-mechanicznych w ściance "okna" zbiornika źródła neutronów było koniecznym doświadczalne zbadanie charakterystyki konwekcyjnego przekazywania ciepła z użyciem przewidywanych do zastosowania materiałów (stal i rtęć), z zastosowaniem realnych kształtów i wymiarów zbiornika źródła neutronów (cylinder zakończony półkulą) oraz wewnętrznych geometrycznych i hydraulicznych warunków przepływu rtęci.
Źródło:
Journal of Theoretical and Applied Mechanics; 2001, 39, 2; 353-376
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Interior Perforation Flow Field Study of Partially Cut 7-Perforated Stick Propellants
Autorzy:
Zhao, Xiaoliang
Zhang, Xiaobing
Powiązania:
https://bibliotekanauki.pl/articles/358092.pdf
Data publikacji:
2019
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
partially cut
7-perforation stick propellants
internal perforation flow field
pressure difference
gas velocity
Opis:
Partially cut 7-perforated propellants are used in gun charges because of their good flame spreading, high progressivity and loading density. To investigate the complex flow field in a partially cut multi-perforation stick propellant, a steady three-dimensional model for compressible viscid internal perforation and the vent gas region flow field was established and simulated by ANSYS Fluent. The results illustrate that the cut vent can decrease the internal perforation pressure and end face gas velocity. Moreover, the mass that escaped through the vent to the outside was 85.3% of the whole internal burning propellant gas. When the width of the cut slot was larger than half the diameter, the internal pressure decreased weakly and the progressive intensity decreased slightly as the cut slot was increased. As the same side intervals were increased or the perforation diameters were decreased, the end face gas velocity and the internal and external perforation pressure differences increased, and the propellant combustion area progressive intensity increased. As the web thickness increased, the internal pressure increased, and gas velocity exhibited an upward tendency and reached peak values when 2e1 = 0.84 mm, whilst the progressive intensity increased slightly.
Źródło:
Central European Journal of Energetic Materials; 2019, 16, 4; 564-582
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical simulations of linearly stratified flow past submerged bodies
Autorzy:
Ma, W.
Li, Y.
Ding, Y.
Hu, K.
Lan, L.
Powiązania:
https://bibliotekanauki.pl/articles/259150.pdf
Data publikacji:
2018
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
stratified flow
circular cylinder
internal wave
Suboff
equation of state
Opis:
In this study, a methodology was presented to predict density stratified flows in the near-field of submerged bodies. The energy equation in temperature form was solved coupled with momentum and mass conservation equations. Linear stratification was achieved by the definition of the density as a function of temperature. At first, verifications were performed for the stratified flows passing a submerged horizontal circular cylinder, showing excellent agreement with available experimental data. The ability of the method to cope with variable density was demonstrated. Different turbulence models were used for different Re numbers and flow states. Based on the numerical methods proposed in this paper, the stratified flow was studied for the real scale benchmark DAPRA Suboff submarine. The approach used the VOF method for tracing the free surface. Turbulence was implemented with a k − ω based Detached Eddy Simulation (DES) approach. The effects of submarine speed, depth and density gradient on the free surface wave pattern were quantitatively analyzed. It was shown that, with the increasing of the speed of the submarine, the wavelength and wave height of the free surface wave were gradually increasing. The wave height of the free surface wave was gradually reduced as the submarine’s depth increased. Relative to the speed and submarine depth, the changes of the gradient density gradient have negligible effects on the free surface wave field.
Źródło:
Polish Maritime Research; 2018, S 3; 68-77
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rural areas as the origin and destination of permanent internal migrations between 2002 and 2017 in poland. A local-level analysis (nuts 5)
Autorzy:
Ilnicki, Dariusz
Powiązania:
https://bibliotekanauki.pl/articles/1050816.pdf
Data publikacji:
2020-03-31
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
internal migration
rural areas
suburbanisation
origins and destinations of migration
the highest flow
Opis:
The main aim of the study is to identify the main streams of permanent migration and determine their reach. Special attention has been paid to rural areas (a rural commune, the rural area of an urban–rural commune) as the origin and destination of migration. The study has been conducted at the lowest level of territorial division in Poland (NUTS 5 – cities and communes). The analysed data cover the period between 2002 and 2017 and come from the online database Demografia GUS [Demography, Statistics Poland]. While presenting the volume and directions of migrations, the total and maximum values of migration have been considered. This approach allowed identifying the catchment areas as well as the areas of migratory attractiveness. These areas are highly similar in terms of their spatial extent. However, they differ significantly in terms of magnitude and reach of the main migration streams. Permanent internal migrations within rural areas are the least significant among all migration directions. One of their characteristics is the fact that they are short–distance migrations, occurring between neighbouring units. Permanent internal migrations appear to be a good indicator of urbanisation of suburban zones and the shaping of functional urban–rural–urban connections.
Źródło:
Quaestiones Geographicae; 2020, 39, 2; 15-30
0137-477X
2081-6383
Pojawia się w:
Quaestiones Geographicae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Catalytic reactor as a resistance element of ICE exhaust system
Autorzy:
Postrzednik, S.
Żmudka, Z.
Powiązania:
https://bibliotekanauki.pl/articles/242786.pdf
Data publikacji:
2007
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
internal combustion engine
catalytic converter
pressure drop
local and linear flow resistance
resistance number
Opis:
Selected problems connected with operation of catalytic reactors are presented. Conversion rate of harmful substances is the principal parameter of catalyst work in respect of ecology. However, resistance of exhaust gas flow through the catalytic converter is also essential problem, apart from its chemical efficiency because fitting the catalyst in exhaust system alters flow characteristic of this system significantly. Catalytic converter can be treated as local or linear resistance element of exhaust system. The first model, in which flow resistance generated by a catalyst is treated as local resistance, is more simplified. Resistance number of the converter was calculated using Darcy model. In the second case, exhaust gas flow resistance through catalyst is treated as linear resistance with energy dissipation (linear frictional resistance) distributed linearly along way of exhaust gas flow. Friction number for the tested converter was calculated and analysed. The problem has been illustrated by results of experimental researches of three-way catalytic converter installed in exhaust system of spark ignition engine and its basic analysis.
Źródło:
Journal of KONES; 2007, 14, 4; 351-356
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Migracje wewnętrzne na pobyt stały w makroregionie południowo-zachodnim w latach 2002–2017
Internal permanent migrations in the south-western macro-region in the years 2002–2017
Autorzy:
Ilnicki, Dariusz
Szczyrba, Zdeněk
Powiązania:
https://bibliotekanauki.pl/articles/1836106.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Opolski
Tematy:
internal migration
South–Western Macro–Region
suburbanization
origins and destinations of migration
the highest flow
Opis:
Głównym celem opracowania koncentruje się będzie na rozpoznaniu wartości interpretacyjnej i wnioskowej migracji wewnętrznych na pobyt stały z uwzględnieniem ich kierunku. Analizowane dane obejmują okres 2002–2017 a pochodzą z internetowej bazy danych Demografia GUS. W opracowaniu dokonano rozpoznania zjawiska migracji wychodząc od ujęcia ogółem, przez ujęcie klasyczne, ostatecznie do ukazania wielkości i kierunków przemieszczeń. Ukazując wielkość i kierunki przemieszczeń posługiwano się sumaryczną, wartością migracji w badanym okresie. Podejście to określono mianem „agregatowego”. Pozwoliło ono na identyfikację zlewni i obszarów atrakcyjności migracyjnej. Jakkolwiek obszary te są silnie zbliżone co do ich rozciągłości przestrzennej to zróżnicowane ze względu na wielkość i zasięg głównych strumieni migracji. Migracje wewnętrzne na pobyt stały jawią się jako dobry identyfikator urbanizacji stref podmiejskich i kształtowania powiązań funkcjonalnych miasto–obszar wiejski–miasto.
The main aim of the study is to identify the interpretative and conclusive value of internal migrations including their direction. The analysed data covers the period between 2002–2017 and comes from the online database Demografia GUS [Demography, Central Statistical Office]. The paper analyses the phenomenon of migration starting with a general overview, via a classical approach to finally present the volume and directions of movements. While presenting the volume and directions of migrations total values of migration have been considered for the given period. The approach has been called “the aggregate approach”. It allowed to identify the catchment areas as well as areas of migratory attractiveness. These areas are highly similar in terms of their spatial extent. However, they differ significantly in terms of magnitude and reach of the main migration streams. Permanent internal migrations appear to be a good indicator of urbanisation of suburban zones and the shaping of functional urban–rural–urban connections.
Źródło:
Studia Miejskie; 2019, 36; 25-44
2543-5302
2082-4793
Pojawia się w:
Studia Miejskie
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 23

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