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Wyszukujesz frazę "Seals" wg kryterium: Temat


Wyświetlanie 1-11 z 11
Tytuł:
An attempt to determine the digestibility of natural food in Antarctic seals using tracer method. A preliminary study
Autorzy:
Weiner, January
Woyciechowski, Michał
Zieliński, Jan
Powiązania:
https://bibliotekanauki.pl/articles/2058103.pdf
Data publikacji:
1981
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Antarctic seals
digestibility
mineral elements
Źródło:
Polish Polar Research; 1981, 2, 1-2; 153-163
0138-0338
2081-8262
Pojawia się w:
Polish Polar Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Moulting southern elephant seals, Mirounga leonina (L.) and local weather conditions, on Livingston Island, South Shetland
Autorzy:
Cruwys, Elizabeth
Davis, Pamela B.
Powiązania:
https://bibliotekanauki.pl/articles/2052696.pdf
Data publikacji:
1994
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Antarctica
moult
southern elephant seals
Źródło:
Polish Polar Research; 1994, 15, 3-4; 135-146
0138-0338
2081-8262
Pojawia się w:
Polish Polar Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effects of variable operational parameters on an aero engine labyrinth seals performance
Autorzy:
Szymański, A.
Dykas, S.
Majkut, M.
Strozik, M.
Powiązania:
https://bibliotekanauki.pl/articles/175364.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
labyrinth seals
experiment
turbomachinery
gas turbine
validation
Opis:
The paper presents the accurate assessment of the amount of gas flowing through three types of aero-engine expander sealing. Structures consisting of straight-through labyrinth seals – with one, two and three fins are considered. The study deploys two independent approaches. The first one focuses on the experimental research using high-precision test section with non-rotating labyrinth seals specimen connected to a high capacity vacuum installation. Experimentally tested seals are of actual size (model to engine scale is 1:1). High accuracy hot-wire anemometry probes, and orifice plate are deployed to evaluate the flow indicators accurately, allowing for comparison of different sealing structures. The second approach uses quasi-two-dimensional axissymmetric, steady-state Reynolds averaged Navier Stokes (RANS) computations to simulate the flow field. Various meshes and turbulence models were tested, presenting capabilities as well as limitations of specific computational approaches. The experimental and computational results were compared with literature data, showing a good agreement regarding overall trends, yet underlining some local discrepancies. This paper brings two significant findings. The 2D RANS methods tend to overestimate the leakage when compared with experimental results, and the difference is more significant for advanced arrangements. There is a notable difference between the performance of labyrinth seal with one fin and structure with two and three fins. In some operational areas, one-finned seal performs better than more advanced ones, reducing the leakage more effectively. This feature of one finned seal is not intuitive, as one would expect it to perform worse than a seal with two or three fins.
Źródło:
Transactions of the Institute of Fluid-Flow Machinery; 2018, 140; 83-104
0079-3205
Pojawia się w:
Transactions of the Institute of Fluid-Flow Machinery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
CFD analysis of fluid flow through the labyrinth seal
Autorzy:
Kaszowski, P.
Dzida, M.
Powiązania:
https://bibliotekanauki.pl/articles/175521.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
labyrinth seals
k-ǫ model
CFD calculations
fliud-flow machines
modeling
Opis:
Steam and gas turbines are essential to produce electricity. Since the launch of the first turbine in the world, there become a tendency to constantly achieve higher efficiency. There are many solutions to overcome losses in the working steam turbine. One of such methods is the use of seals. To determine thermodynamic parameters of steam, which prevail in the seal, we could use experimental methods or numerical calculations. Experimental researchs are too expensive and time consuming. Therefore, computational fluid dynamics (CFD) is increasingly used in the analysis of fluid flow through the labyrinth seal. The paper describes the results using CFD simulation software with the help of contained a computational k-ε model.
Źródło:
Transactions of the Institute of Fluid-Flow Machinery; 2015, 130; 57-69
0079-3205
Pojawia się w:
Transactions of the Institute of Fluid-Flow Machinery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The assessment of the calculation method for determining characteristics of one straight fin labyrinth sea
Autorzy:
Szymański, A.
Dykas, S.
Majkut, M.
Strozik, M.
Powiązania:
https://bibliotekanauki.pl/articles/175271.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
labyrinth seals
Computational Flow Dynamics (CFD)
seal
smooth
turbomachinery
leakage flow rate
Opis:
The method for the selection of a calculation scheme for the evaluation of the flow behaviour of labyrinth seal with one straight fin, against smooth wall, was presented. Experimental results were obtained from measurement data carried out on the in house, vacuum test section. The advantage of the test rig is a circular shape of the labyrinth specimen, providing similar shape to configuration operated in practise. In computational fluid dynamics study different types of mesh resolution were tested, with variable volume discretization in the area of a labyrinth fin tip. Moreover, a wide range of turbulence models basing on k-ε and k-ω, exploiting the (Reynolds Average Navier Stokes) scheme, for the flow pattern evaluation, were examined. All obtained results were compared with literature data, covering research conducted on similar configurations. The presented study shows challenges as well as the possibilities of calculation simplification and compares results obtained by means of simulations and experiment. The proposed method is characterised by excellent agreement of computational results with experiment data.
Źródło:
Transactions of the Institute of Fluid-Flow Machinery; 2016, 134; 89-107
0079-3205
Pojawia się w:
Transactions of the Institute of Fluid-Flow Machinery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of results of experimental research with numerical calculations of a model one-sided seal
Autorzy:
Joachimiak, D.
Krzyślak, P.
Powiązania:
https://bibliotekanauki.pl/articles/239985.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
labyrinth seals
turbomachines
fluid-flow machines
uszczelnienia labiryntowe
maszyny wirnikowe
maszyny przepływowe
Opis:
Paper presents the results of experimental and numerical research of a model segment of a labyrinth seal for a different wear level. The analysis covers the extent of leakage and distribution of static pressure in the seal chambers and the planes upstream and downstream of the segment. The measurement data have been compared with the results of numerical calculations obtained using commercial software. Based on the flow conditions occurring in the area subjected to calculations, the size of the mesh defined by parameter y+ has been analyzed and the selection of the turbulence model has been described. The numerical calculations were based on the measurable thermodynamic parameters in the seal segments of steam turbines. The work contains a comparison of the mass flow and distribution of static pressure in the seal chambers obtained during the measurement and calculated numerically in a model segment of the seal of different level of wear.
Źródło:
Archives of Thermodynamics; 2015, 36, 2; 61-74
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effects of friction on the performance of a concrete block mine seal with pressurized grout bags
Wpływ tarcia na zachowanie tamy uszczelniającej wykonanej z bloków betonowych ze sprasowanymi workami zaczynu
Autorzy:
Perry, K. A.
Powiązania:
https://bibliotekanauki.pl/articles/219549.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
górnictwo węgla
tamy uszczelniające
wybuch
metoda elementów skończonych
coal mining
mine seals
explosions
finite element modeling
Opis:
Mine seals are necessary in nearly every underground coal mine to isolate mined-out areas from the ventilation network. Many seals are already in place in active mines and more need to be constructed to keep up with the development of underground coal reserves. The accidents involving seal failures at Sago and Darby prompted MSHA to create and implement new regulations regarding the strength of the seals. These regulations require the design and construction of seals that are larger and stronger than ever before. Structural seals capable of withstanding the new required design loads are now designed by an engineer and no longer approved through explosion testing. Prior to the seal failure accidents, a solid-block wall with pressurized grout bags at the wall/ribs and wall/roof interfaces was a popular design which met the 137.9 kPa (20 psi) requirement. After implementation of the new 344.7 kPa (50 psi) or 827.4 kPa (120 psi) design regulations depending on whether the atmosphere is kept inert in by the seal, a re-design of the seal was necessary. This paper discusses the quantification of the coefficients of friction which are then implemented into finite element modeling.
Tamy uszczelniające niezbędne są prawie w każdej kopalni podziemnej do oddzielenia obszarów wybranych od sieci wentylacyjnej. W kopalniach aktywnych znajdują się już liczne tamy a coraz większa ich ilość zostanie zbudowana w miarę udostępniania kolejnych złóż węgla. Wypadki spowodowane przez awarie tamy w kopalni Sago i Darby stanowiły bodziec dla urzędu górniczego MSHA do stworzenia i wdrożenia nowych regulacji odnośnie wytrzymałości tam. Przepisy te wymagają projektowania i budowania tam większych i bardziej wytrzymałych niż kiedykolwiek w przeszłości. Tamy strukturalne zdolne do przenoszenia na nowo określanych obciążeń obliczeniowych muszą być obecnie projektowane przez inżynierów a procedura ich odbioru nie obejmuje badań w warunkach wybuchu. Przed wypadkami spowodowanymi przez awarie tam, popularnym rozwiązaniem były ściany z jednolitych bloków ze sprasowanymi workami zaprawy umieszczanymi na styku pomiędzy ścianą, żebrami oraz stropem. Rozwiązanie to było szeroko stosowane i zapewniało spełnianie kryterium przenoszenia obciążeń na poziomie 137.9 kPa (20 psi). Po wdrożeniu nowych wymogów określających obciążenia obliczeniowe: 344.7 kPa (50 psi) lub 827.4 (120 psi) w zależności od tego, czy atmosfera w rejonie zamkniętym tamą uszczelniająca ma pozostawać obojętna czy też nie, niezbędne okazało się przeprojektowanie tamy. W pracy tej zbadano w ujęciu ilościowym współczynniki tarcia, a wyniki badania zaimplementowano z wykorzystaniem metody elementów skończonych.
Źródło:
Archives of Mining Sciences; 2014, 59, 3; 793-805
0860-7001
Pojawia się w:
Archives of Mining Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A model of gas flow with friction in a slotted seal
Autorzy:
Joachimiak, D.
Krzyślak, P.
Powiązania:
https://bibliotekanauki.pl/articles/239930.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
slotted seals
annular slot
friction coefficient
gas flow
uszczelki szczelinowe
szczelina pierścieniowa
współczynnik tarcia
przepływ gazu
Opis:
The paper discusses thermodynamic phenomena accompanying the flow of gas in a slotted seal. The analysis of the gas flow has been described based on an irreversible adiabatic transformation. A model based on the equation of total enthalpy balance has been proposed. The iterative process of the model aims at obtaining such a gas temperature distribution that will fulfill the continuity equation. The model allows for dissipation of the kinetic energy into friction heat by making use of the Blasius equation to determine the friction coefficient. Within the works, experimental research has been performed of the gas flow in a slotted seal of slot height 2 mm. Based on the experimental data, the equation of local friction coefficient was modified with a correction parameter. This parameter was described with the function of pressure ratio to obtain a mass flow of the value from the experiment. The reason for taking up of this problem is the absence of high accuracy models for calculating the gas flow in slotted seals. The proposed model allows an accurate determination of the mass flow in a slotted seal based on the geometry and gas initial and final parameters.
Źródło:
Archives of Thermodynamics; 2016, 37, 3; 95-108
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Illustrating Polish Coins, Medals, and Seals in the Graphic Arts Techniques in the Second Half of the 19th Century. The Period of the Outstanding Numismatic Publications
Autorzy:
Podniesińska, Katarzyna
Powiązania:
https://bibliotekanauki.pl/articles/2089988.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
illustrations of coins
medals and seals
numismatic iconography (in graphic art)
graphic art XIX c.
engravers and illustrators XIX c.
graphic techniques
Źródło:
Wiadomości Numizmatyczne; 2020, 64; 157-186
0043-5155
Pojawia się w:
Wiadomości Numizmatyczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on mine seal stability under explosion load and ground pressure in underground coal mines
Autorzy:
Cheng, Jianwei
Song, Wanting
Jing, Yi
Zhang, Xixi
Korzec, Marek
Borowski, Marek
Wang, Yue
Powiązania:
https://bibliotekanauki.pl/articles/218944.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
kopalnia węgla
symulacja numeryczna
dłutowanie
seals in underground coal mines
numerical simulation
slotting
ground pressure
roof to floor moving convergence
damage level
Opis:
The mine seals in coal mines with a good impact resistance and air tightness are mainly used to isolate abandoned mining areas from active workings. For one thing, it can prevent the leakage of harmful gases, such as toxic gas from abandoned areas. For another, once an underground mine explosion happens, it can effectively block the spread of the explosion between the abandoned mining areas and the active workings. Hence, it is of great significance to study the explosion-proof performance and mechanical properties of the mine seals. First of all, the effect of slotting on the stability of the seals in coal mines under explosion load was explored in this study. By numerical simulations, the mechanical response characteristics of the seals with or without cutting a slot under the explosion load were compared in detail. The results show that slotting improved the stress concentration at the contact surface of surrounding rock by transferring partial impact received by mine seals to the surrounding rocks, thus, to achieve the effect of buffering explosion impact. Besides, such effect will be enhanced with increasing cutting depth into rock, and will stabilize when the depth is 20 cm. On this basis, the mechanical properties and damage of the seals constructed by different materials (standard brick and #C40 concrete) under the explosion load were compared. It was found that once a slot was set, the maximum deformation of the concrete seal was reduced, while the maximum deformation of the brick seal increased. Since the non-deformability of the concrete seal is obviously stronger than that of the brick seal, with the impact resistance stronger than that of the brick seal, the concrete seal is more suitable for slotting. Moreover, the damage of the seals in underground coal mines under the strata ground pressure was studied; the results of which show that the damage state under the ground pressure can be divided into 3 levels, i.e. no damage, minor damage and rapid development of damage. Meanwhile, it was found that the prestressed structure fordem by the ground pressure at the level of no damage can enhance the protective effect of the seals in coal mines. However, when the ground pressure was further developed, the seal itself was destroyed and the protective effect was lost. In addition, the influence of roof to floor moving convergence, a deformation parameter of the roadway, on the seals was also investigated. The results show that the ground pressure and roof-to-floor convergence act on the seals in coal mines in the same way, thus roof to floor moving convergence can replace the ground pressure to analyze other related mechanical properties of the seals in coal mines in the future researches.
Źródło:
Archives of Mining Sciences; 2020, 65, 1; 71-87
0860-7001
Pojawia się w:
Archives of Mining Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The surface texture of hardened 18CrMo4 steel after turning with plunge feed
Struktura geometryczna powierzchni stali 18CrMo4 w stanie zahartowanym po toczeniu z posuwem wgłębnym
Autorzy:
Pytlak, B.
Powiązania:
https://bibliotekanauki.pl/articles/175837.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
hard turning with plunge feed
plunge grinding
surface texture
radial shaft seals
toczenie na twardo z posuwem wgłębnym
szlifowanie wgłębne
tekstura powierzchni
wargowe pierścienie uszczelniające
Opis:
A research results of surface texture after finish turning operation with plunge feed of hardened 18CrMo4 steel with use of cubical boron nitride (CBN) inserts having Wiper geometry are presented in this paper. The research was conducted according to Taguchi methodology, especially for mating of the machined surface with radial shaft seals. Next, the surface after finish turning with plunge feed was compared with the surface after plunge grinding, while assessment indicators used to this purpose testify a substantial similarity of the two surfaces.
W pracy przedstawiono wyniki badań struktury geometrycznej powierzchni po operacji toczenia wykończeniowego z posuwem wgłębnym stali 18CrMo4 w stanie zahartowanym płytkami z regularnego azotku boru (CBN) o geometrii typu Wiper. W badaniach stosowano metodykę Taguchi’ego. Uwzględniono współpracę obrobionej powierzchni z wargowymi pierścieniami uszczelniającymi. Porównano stan powierzchni po toczeniu wykończeniowym z posuwem wgłębnym i powierzchni po szlifowaniu wgłębnym. Wartości przyjętych wskaźników oceny świadczą o znacznym podobieństwie obu powierzchni.
Źródło:
Advances in Manufacturing Science and Technology; 2014, 38, 1; 53-62
0137-4478
Pojawia się w:
Advances in Manufacturing Science and Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-11 z 11

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