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1
Content available Projekt specjalnych wkładów tłumiących tłumików broni strzeleckiej wytwarzanych przyrostowo. Część I - analiza wybranych konstrukcji
Żelichowska Maja, Bogajczyk Mikołaj, Grygoruk Roman
Problemy Techniki Uzbrojenia
|
2025
|
R. 54, z. 174
77--96
PL
W ramach tego projektu przeprowadzono kompleksowe badania przepływów dla różnych zaproponowanych wariantów konstrukcyjnych, uwzględniając przy tym zdefiniowane para metry towarzyszące zjawisku wystrzału. Badania miały na celu zbieranie danych dotyczących zachowania przepływów wewnątrz wkładów tłumiących w warunkach związanych z procesem strzelania. Parametry takie jak ciśnienie, temperatura, prędkość i właściwości poszczególnych geometrii były systematycznie rejestrowane i analizowane. Otrzymane wyniki stanowiły podstawę do przeprowadzenia analizy, pozwalając na porównanie różnych wariantów konstrukcyjnych i ocenę ich skuteczności. Dodatkowo wykonane zostało porównanie zaprojektowanych wkładów dedykowanych pod wytwarzanie przyrostowe z wkładem porównawczym, którego otrzymanie możliwe jest przez dotychczasową technologię, obróbkę ubytkową. W części I zawarto analizę wybranych konstrukcji tłumików do broni strzeleckiej oraz technologii wytwarzania przyrostowego i materiałów możliwych do zastosowania w konstrukcji elementów tłumiących.
EN
As part of this project, comprehensive studies of flows were conducted for various proposed design variants, taking into account defined parameters accompanying the firing phenomenon. The research was aimed at collecting data on the behavior of flows inside suppressor cartridges under conditions associated with the firing process. Parameters such as pressure, temperature, velocity and proper ties of individual geometries were systematically recorded and analyzed. Obtained results formed the basis for the analysis, allowing the comparison of different design variants and evaluation of their effectiveness. In addition, a comparison was made between the designed inserts dedicated to incremental manufacturing and the comparative inserts fabricated by the existing technology of cavity machining. Part I contains an analysis of selected designs of silencers for small arms, and technologies of additive manufacturing, and materials which can be used in construction of silencer components.
2
Content available Projekt specjalnych wkładów tłumiących tłumików broni strzeleckiej wytwarzanych przyrostowo. Część II – projekty kompletnych wkładów tłumiących
Żelichowska Maja, Bogajczyk Mikołaj, Grygoruk Roman
Problemy Techniki Uzbrojenia
|
2025
|
R. 54, z. 175
21--36
PL
W ramach tego projektu przeprowadzono kompleksowe badania przepływów dla różnych zaproponowanych wariantów konstrukcyjnych, uwzględniając przy tym zdefiniowane para metry towarzyszące zjawisku wystrzału. Badania miały na celu zbieranie danych dotyczących zachowania przepływów wewnątrz wkładów tłumiących w warunkach związanych z procesem strzelania. Parametry takie jak ciśnienie, temperatura, prędkość i właściwości poszczególnych geometrii były systematycznie rejestrowane i analizowane. Otrzymane wyniki były podstawą do przeprowadzenia analizy, pozwalając na porównanie różnych wariantów konstrukcyjnych i ocenę ich skuteczności. Dodatkowo wykonane zostało porównanie zaprojektowanych wkładów dedykowanych pod wytwarzanie przyrostowe z wkładem porównawczym, którego otrzymanie możliwe jest przez dotychczasową technologię, obróbkę ubytkową. W części II zawarto projekty kompletnych wkładów tłumiących.
EN
As part of this project, comprehensive flow studies were conducted for various proposed design variants, taking into account the defined parameters accompanyying the firing phenomenon. The research was aimed at collecting data on the behavior of flows inside suppressor cartridges under conditions associated with the firing process. Parameters such as pressure, temperature, velocity and properties of individual geometries were systematically recorded and analyzed. The obtained results formed the basis for the analysis, allowing the comparison of different design variants and evaluation of their effectiveness. In addition, a comparison was made between the designed inserts dedicated to incremental manufacturing and the comparative inserts made with the existing technology of cavity machining. Part II contains the complete damping insert designs.
3
Content available A new approach to modelling the average interannual streamflow in the watersheds of Northern Algeria
Adjissi Omar, Ghodbane Messaoud, Ladjel Mahmoud, Madani Khodir
Journal of Water and Land Development
|
2025
|
no. 65
24--35
EN
The estimation and potential exploitation of water resources in arid and semi-arid regions, especially in the watersheds of Northern Algeria, where climatic variability affects the transformation of precipitation into river flow, needs to be based on effective management of these resources depends on understanding hydrological relationships. This must be grounded in knowledge and probable mastery of the phenomena governing their formation under local physico-geographical conditions, particularly in ungauged watershed areas. The objective of this approach is to develop a general and regional model for estimating interannual average flow (IAF) at the level of ungauged basins. This model is based on the analysing and identifying the influence of local factors such as the surface area of the watershed, relief, geology, soils, and plant cover. Its development relies on statistical and grapho-analytical methods. The results demonstrate that the watershed area and climatic flow are key parameters, which indicate the dependency of the climatic coefficient kobs on these two factors and give good correlations, which vary from 0.615 to 0.92. Hence, the model was established based on these two parameters and found to perform well in estimating IAF, according to the performance criteria.
4
Content available A novel approach for measuring the void fraction in stratified air-water systems utilizing an 8-blade capacitance-based sensor, sinogram, and a deep neural network
Mayet Abdulilah Mohammad, Shahsavari Mohammad Hossein, Alizadeh Sayed Mehdi, Hanus Robert, Parayangat Muneer, Raja Ramkumar M., Muqeet Mohammed Abdul, Salman Mohammed Arafath, Kubiszyn Piotr
Advances in Science and Technology. Research Journal
|
2025
|
Vol. 19, no. 1
269--283
EN
Measuring Void Fraction (VF) in a pipeline is crucial for ensuring operational efficiency, safety, and environmental responsibility in various engineering applications. There are several methods commonly used to measure VF in multiphase flow systems. Capacitance sensors are a dependable and practical option for measuring VF, providing benefits such as versatility, sensitivity, cost-effectiveness, and ease of use. In this study, simulations were performed to produce different VF levels of an air-water stratified two-phase flow, ranging across 31 distinct VF values from completely full to entirely empty. Moreover, an 8-blade concave capacitive sensor was designed and utilized for VF measurements. In order to use the power of the Finite Element Method (FEM), COMSOL Multiphysics was employed to produce the desired void fractions and measure the capacitance value of each pair of electrodes. The capacitance values of these electrode pairs were measured, resulting in the creation of sinograms corresponding to different VF. These sinograms were utilized as inputs for a Deep Neural Network (DNN) developed in Python, specifically a Multilayer Perceptron model, to estimate VFs. Furthermore, to enhance user understanding, sinograms were employed to reconstruct fluid images using the back-projection method. The results demonstrated an accuracy of 0.002, a significant improvement over previous methodologies in VF measurement.
5
Content available Investigation of flow features and acoustic radiation of a set of rectangular cavities in a channel
Łojek Paweł, Suder-Dębska Katarzyna
Vibrations in Physical Systems
|
2024
|
Vol. 35, nr 1
art. no. 2024110
EN
This article focuses on a noise of aerodynamic origin, generated by the flow over single and multiple rectangular cavities. The paper presents the methodology and results of the conducted numerical simulations of the air flow in a channel with a set of rectangular cavities. The aeroacoustic wave equation was used to determine the acoustic pressure generated by the flow. Various configurations of the cavities made it possible to study the influence of their reciprocal location on the generated sound. The research showed that as the distance between the cavities decreased, the acoustic pressure levels increased. They were several decibels higher than for the single-cavity case.
6
Content available Solving the prevention of the formation of traffic jams in pipelines in the transportation of gases by the autoejection process
Gurbanov Abdulaga, Sardarova Ijabika
Nafta-Gaz
|
2024
|
R. 80, nr 4
252--256
EN
The article presents the application of autoejection process to ensure efficient operation of pipeline systems and gas separation installations when it is impossible to remove and utilize the condensate from the pipelines. Thus, in the suggested ejector, a single common stream is separated into two streams, i.e., an active and a passive stream, as opposed to two separate independent streams in existing ejection devices. As a result, we refer to such an ejection process as autoejection, or a self-ejection process. Such a procedure is run in the pipeline with the goal of blowing and dusting the liquid phase through the central high-velocity nozzle in circumstances of mass blocking and coating rather than expelling the liquid from the pipes. On the cross-sectional area of the belts, the velocity profiles of flows in laminar and turbulent regimes are known to differ greatly from one another. The adhesion forces acting from the tube's central axis outwards, towards its walls cause the flow rate to decrease. There is a cross-sectional interaction of flows in this mode, according to experimental studies of turbulent flows. As a result, compared to the laminar domain, the flow velocities in this regime are more equally distributed across the cross-section of the flow, and their values are roughly equal to the flow's average value. In this case, based on the dependences of the flow ∆p = f(W), it is known from the calculations and the table that at such velocity limits of the flows, the “braking” pressure (p0) of the liquid coating on the pipe walls corresponds to the maximum velocity of the central gas flow. The autoejection process can occur due to the difference between the static pressures. Unsaturated absorbent coatings can be blasted off the tube absorber's walls using this technique and blended back into the main gas stream. Gas-liquid autoejectors installed along the pipe absorber's length make it possible to use this method. The purpose and principles of autoejectors’ operation are considered and a perspective of their application in tube absorbers is noted.
PL
Artykuł prezentuje zastosowanie procesu automatycznego strumieniowania w celu zapewnienia efektywnej pracy systemów rurociągowych i instalacji separacji gazu, gdy niemożliwe jest usunięcie i wykorzystanie kondensatu z rurociągów. W związku z tym w sugerowanej strumienicy automatycznej pojedynczy wspólny strumień jest rozdzielany na dwa strumienie, czyli aktywny i pasywny, w przeciwieństwie do dwóch oddzielnych, niezależnych strumieni w istniejących urządzeniach strumieniowych. Taki proces strumieniowania nazywany jest automatycznym strumieniowaniem lub procesem samostrumieniowania. Procedura ta uruchamiana jest w rurociągu w celu przedmuchiwania i odpylania fazy ciekłej przez centralną dyszę o wysokiej prędkości w warunkach masowego blokowania i usuwania, a nie wypierania cieczy z rur. Wiadomo, że profile prędkości przepływów w reżimach laminarnym i turbulentnym w przekroju poprzecznym stref znacznie się od siebie różnią. Siły adhezji działające od centralnej osi rury na zewnątrz w kierunku jej ścian powodują spadek prędkości przepływu. Zgodnie z wynikami badań eksperymentalnych przepływów turbulentnych w tym trybie występuje interakcja przepływów w przekroju poprzecznym. W rezultacie, w porównaniu do domeny laminarnej, prędkości przepływu w tym reżimie są bardziej równomiernie rozłożone w przekroju przepływu, a ich wartości są mniej więcej równe średniej wartości przepływu. W tym przypadku, na podstawie zależności przepływu ∆p = f(W), wiadomo z obliczeń i tabeli, że przy takich granicach prędkości przepływów, „hamujące” ciśnienie (p0) powłoki cieczy na ścianach rurociągu odpowiada maksymalnej prędkości centralnego przepływu gazu. Proces automatycznego strumieniowania może zaistnieć dzięki różnicy między ciśnieniami statycznymi. Nienasycone powłoki absorbujące mogą być zdmuchiwane ze ścian absorbera rurociągu przy użyciu tej techniki i ponownie mieszane z głównym strumieniem gazu. Wykorzystanie tej metody jest możliwe dzięki zastosowaniu automatycznej strumienicy gazowo-cieczowej zainstalowanej wzdłuż absorbera rurociągu. Artykuł zawiera również rozważania dotyczące celu stosowania i zasad działania strumienic automatycznych, zwracając uwagę na ich zastosowania w absorberach rurociągowych.
7
Content available Identification of roughness coefficients based on recycled steel pipes using various mathematical models
Mańko Robert
Materiały Budowlane
|
2024
|
nr 10
84--94
EN
This paper presents the results of a detailed comparative analysis of the inverse problem, focusing on the identification of surface roughness coefficients for steel pipes. Various formulas were utilized and discussed to calculate the linear resistance coefficient. Among these formulas, only about half could be transformed into an explicit form, enabling direct application in engineering practice. The results obtained from the calculations were then compared with the outcomes derived from the widely used and recommended Colebrook-White equation in technical literature. The analysis demonstrated that the obtained results show a high degree of agreement with those obtained using the Colebrook-White equation. For some research models, the difference was less than 0.1%, indicating very high accuracy and consistency with this standard computational tool.
PL
W artykule przedstawiono wyniki szczegółowej analizy porównawczej problemu odwrotnego, koncentrując się na identyfikacji współczynników chropowatości powierzchni rur stalowych. W celu przeprowadzenia tej analizy wykorzystano i omówiono różne formuły obliczania wartości współczynnika oporów liniowych. Spośród tych formuł, większość mogła zostać przekształcona do postaci jawnej, co umożliwia bezpośrednie zastosowanie w praktyce inżynierskiej. Wyniki uzyskane z przeprowadzonych obliczeń zostały następnie porównane z rezultatami pochodzącymi z powszechnie stosowanego i rekomendowanego w literaturze technicznej równania Colebrooka-White’a. Analiza wykazała, że uzyskane wyniki charakteryzują się dużą zgodnością z wynikami otrzymywanymi przy użyciu równania Colebrooka-White’a. W przypadku niektórych modeli różnica była mniejsza niż 0,1%, co wskazuje na bardzo dużą zgodność z tym narzędziem obliczeniowym.
8
Odra - funkcjonowanie w czasach konfliktów społecznych i gospodarczych na tle kryzysu klimatycznego
Czerniawski Robert, Horska-Schwarz Sylwia, Grygoruk Mateusz, Sługocki Łukasz, Szklarek Sebastian, Kobos Justyna, Maciej Humiczewski
Gospodarka Wodna
|
2024
|
Nr 2
18--27
PL
Odra, będąca z jednej strony rzeką wykorzystywaną do celów gospodarczych, jest jednym z najważniejszych ekosystemów wodnych Polski. Dotychczasowe publikacje branżowe poświęcone katastrofie odrzańskiej (zdarzeniu z lipca i sierpnia 2022 r., w którym w warunkach wysokiego zasolenia wód rzeki towarzyszącemu głębokiej niżówce doszło do intensywnego rozwoju glonów Prymnesium parvum oraz do śmierci ryb i makrobezkręgowców wodnych) dotyczyły hipotetycznych przyczyn tego zdarzenia, pomijając podmiotowość Odry jako złożonego ekosystemu wodnego, którego odporność na niekorzystne zdarzenia ekohydrologiczne została znacząco zmniejszona w wyniku destrukcyjnej dla tego ekosystemu, wieloletniej działalności człowieka. W niniejszej pracy dokonano szerokiego opisu elementów środowiska ekosystemu wodnego Odry. Uwzględniono jej stan hydromorfologiczny, sytuację hydrologiczną oraz wybrane wyniki pomiarów jakości wody ocenione w czasie trwania katastrofy odrzańskiej. Przeanalizowano typową dynamikę gęstości populacji, składników odżywczych i aktywności toksycznej podczas zakwitów Prymnesium parvum w okresach występowania śnięć ryb. W podsumowaniu wskazano elementy struktur abiotycznych i biotycznych Odry, które - jako jedne z najważniejszych wskaźników zmian i prognoz jej stanu - powinny być brane pod uwagę w dyskusjach o możliwościach dalszego korzystania z Odry jako jednej z najbardziej zmienionych, a przede wszystkim najbardziej przez ścieki zdegradowanych dużych rzek Europy.
EN
The Oder River, largely used for economic purposes, is also one of the most important aquatic ecosystems in Poland. The hitherto published studies devoted to the Oder environmental disaster (which happened in July and August 2022 in conditions of high salinity of the river waters accompanying a very low water level that led to an intensive growth of the Prymnesium parvum algae and death of fish and aquatic macroinvertebrates) focused on hypothetical reasons of this catastrophe, forgetting to see the Oder River as a complex water ecosystem whose resistance to adverse ecohydrological incidents has been significantly reduced by the long-term destructive human activity. This article contains a detailed description of the Oder River aquatic ecosystem environment. It includes its hydromorphological status, hydrological situation and selected results of water quality measurements assessed during the Oder disaster. The authors analyse the typical dynamics of the population density, nutrients and toxic activity during the Prymnesium parvum algae bloom in the periods of fish die-offs. In the summary, the authors indicate the abiotic and biotic structure components of the Oder River - being one of the most important indicators of change and a forecast of the river status - that should be taken into account in discussions on the possibility to continue the exploitation Oder as one of the most transformed and, in particular, one of the most sewage-degraded large European rivers.
9
Content available Fractional order transient free-convection flow in a channel: application of the optimal homotopy asymptotic method
Irshad Sadia, Jahan Shah, Jan Ahmed Zubair, Kędzia Krzysztof, Majeed Afraz Hussain, Khan Fiza
Archives of Thermodynamics
|
2024
|
Vol. 45, no. 2
139--144
EN
In this study, a new physical model has been created to look into the behaviour of transient incompressible unsteady flow between two infinite parallel plates exposed to high temperatures. The model takes into consideration thermal radiation flux, chemical reaction, and mass diffusion at the boundaries. To handle non-integer behaviour, the model incorporates the Caputo notion of time fractional derivative. To solve this complex physical fractional order fluid model, a novel optimal homotopy asymptotic method and semi-analytical methodology is extended and utilized successfully. This method provides a third-order highly approximate solution, offering valuable insights into the behaviour within the system. The study comprehensively examines the effects of varied flow characteristics and fractional order on the dynamics of the system. The results are visually presented through graphs, offering a clear understanding of the system's response under different conditions. The effectiveness and ease of use of the optimal homotopy asymptotic method make it a valuable tool for solving boundary value fractional order problems encountered in scientific fields. The developed physical model and its fractional extension contribute significantly to the understanding of unsteady flow phenomena with thermal and chemical effects, advancing knowledge in this area of research.
10
Content available remote Hospital Patient Distribution After Earthquake
Fidanova Stefka, Kirilov Leoneed, Ivanov Veselin, Ganzha Maria
Annals of Computer Science and Information Systems
|
2024
|
Vol. 39
597--601
EN
The correct organization of medical assistance after the occurrence of a major disaster is very important for saving the lives of the victims. Earthquakes are natural phenomena/disasters in which there are many victims. The timely provision of medical assistance to the injured is an important element of their service. It is good to divide them into types of injuries and severity of injuries. Thus, the medical teams will be prepared for how many people need outpatient treatment and how many need hospital treatment. Rapid distribution of victims to hospitals according to their injuries can reduce the number of deaths and people with serious consequences. In this article, we present a breakdown of the injured by hospitals and medical facilities near the earthquake site. The type of injuries and the capacity and equipment of hospital facilities are taken into account.
11
Mechanizm adaptacyjnego zarządzania czasami życia przepływów w sieciach SDN
Radamski Krystian, Wójcik Robert
Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne
|
2023
|
nr 4
411--414
PL
Sieci sterowane programowo pozwalają na dynamiczne sterowanie ruchem w sieci. Do sprawnego działania konieczne jest odpowiednie zarządzanie tablicami przepływów w węzłach. W artykule proponujemy mechanizm zarządzania czasami życia przepływów, który wykorzystuje ustawienia parametrów idle timeout oraz hard timeout. W celu wyliczenia odpowiednich wartości parametrów mechanizm analizuje czas przybycia kolejnych pakietów przepływu. Dodatkowo, działanie algorytmu uwzględnia aktualny poziom wypełnienia tablicy wpisów.
EN
Software-Defined Networking allows dynamic control of network traffic. For efficient operation, proper flow table management is necessary. In this paper, we propose a mechanism to manage flow timeout values, which uses idle timeout and hard timeout parameters. To calculate the appropriate values of the parameters, the mechanism analyses the packet interarrival times. The algorithm also takes into account the current occupancy of the flow table.
12
Content available Effect of soil consolidation on the fractality of the filtration law
Panahov Geylani, Museibli Parviz, Sultanov Babek
International Journal of Applied Mechanics and Engineering
|
2023
|
Vol. 28, no. 1
84--94
EN
In this paper, the effect of consolidation of the soil structure on the fractality of the fluid flow was evaluated. The equation of fractal law of flow in the porous medium under consolidation of two-phase, fully fluid-saturated soil was determined. Given all the simplifications, as well as the undoubted importance of the nature of the porous medium, which primarily determine the possible processes of both consolidation and fractal flow based on the results of the studies, we can conclude that a homogeneous porous reservoir at given parameters under the effect of groundwater pressure will expand its fractal structure.
13
Content available Characterization of Climatic Drought Sequences in the Upper Moulouya Watershed, Morocco
Hachem Abdelaaziz, Mili El-Mostafa, Benbella Bouchra, El Ouardi Hmidou, Mehdaoui Radouan
Ecological Engineering & Environmental Technology
|
2023
|
Vol. 24, iss. 2
162--179
EN
Like most of the countries of the African continent and the MENA, Morocco has experienced alternating wet and dry periods for several decades and is still confronted with the effects of unstable climate change due to the specificities conferred by its geographical position and the diversity of its ecosystems. It is one of the countries most affected by desertification, with an arid and semi-arid climate covering more than 93% of its territory. Indeed, the Upper Moulouya watershed has been exposed to severe droughts several times in recent decades. The spatial and temporal distribution of drought episodes in this watershed is studied over a 91-year period between 1931 and 2022. In order to characterize and evaluate the severity and sustainability of drought in this watershed, four indices were used and applied in this study, as they have advantages in terms of statistical consistency and have the capacity to describe, through different time scales (short, medium and long) the impacts of the climatic drought in question. These are the Standardized Precipitation Index SPI, RDI, RI and DI. The annual rainfall series at the eight meteorological stations of the said watershed show irregularities and very marked spatial and temporal variability with a generally decreasing trend. The SPI calculation results obtained show a heterogeneous distribution of SPI values throughout the watershed area. The analysis of the graphical illustrations of this index allowed to highlight an important fluctuation of the dry and wet periods with a strong dominance and tendency to drought with the order of 51% in the stations of Midelt, and Ansegmir, 52% in the station of Zaida, 59% in the stations of Tabouazant, Barrage (Dam) Enjil and El Aouia, 58% in the station of Louggagh, 47% in the station of Anzar Oufounes. The analysis of the results of the of the drought indices RDI, RI and DI at the level of this watershed also made it possible to highlight the existence of numerous drought sequences alternating with other wet sequences and indicates a dominance of dry years, perfectly remarkable during the period 1976-93. The most important dry episode, in number of successive years, was recorded at the Ansegmir station from 1976-89 and the most important rainy episode was recorded at the Midelt station from 1966-76. The years of the 2015-2022 series show an overall persistent decrease in rainfall, thus allowing the installation of a severe drought episode. The trend in the entire watershed is a decrease in rainfall and the installation of mild, moderate and severe drought episodes of varying length and duration.
14
Content available Influence of the disturbance created in the measuring channel on the readings of the hot-wire anemometric sensor
Nitkiewicz Szymon, Al-Jumaily Ahmed
Diagnostyka
|
2023
|
Vol. 24, No. 3
art. no. 2023315
EN
The research presents issues related to fluid mechanics, thermodynamics, and statistics. In the first sections, the authors review methods and parameters of fluid measurements. The work mainly emphasizes measurements concerning the parameters of air flows during human breathing. In the following section, the test bench for the analysis is described, and the methodology of data acquisition is described. Finally, the authors present a numerical model of the measurement channel and its calculations compared to measurements from an actual test stand. The data acquirement was performed with LabVIEW, modeling with COMSOL Multiphysics®, and calculations with MATLAB software.
15
Content available 3D simulation of incompressible flow around a rotating turbulator: Effect of rotational and direction speed
Zoubai Elhadi, Laidoudi Houssem, Tlanbout Ismail, Makinde Oluwole Daniel
Archives of Thermodynamics
|
2023
|
Vol. 44, no. 2
139--157
EN
This paper presents new results for the dynamic behaviour of fluid around a rotating turbulator in a channel. The turbulator has a propeller form which is placed inside a flat channel. The research was carried out using 3D numerical simulation. The rationale of the experiment was as follows: we put a propeller-turbulator inside a flat channel, and then we insert a water flow inside the channel. The turbulator rotates at a constant and uniform speed. The main points studied here are the effect of the presence of turbulator and its rotational direction on the flow behaviour behind the turbulator. The results showed that the behaviour of flow behind the turbulator is mainly related to the direction of turbulator rotating. Also, the studied parameters affect coefficients of drag force and power number. For example, when the turbulator rotates in the positive direction, the drag coefficient decreases in terms of rotational speed of the turbulator, while the drag coefficient increases in terms of rotational speed when the turbulator rotates in the negative direction.
16
Content available Numerical modelling of SS316L powder flowability for laser powder-bed fusion
Bouabbou A., Vaudreuil S.
Archives of Materials Science and Engineering
|
2023
|
Vol. 120, nr 1
22--29
EN
Purpose: This work aims to improve the powder-bed spreading process for laser powder bed fusion additive manufacturing by gaining a greater understanding of metal powder flowability through numerical modelling and in-situ experimentation. Design/methodology/approach: Using the Discrete Element Method (DEM) to study the flowability of the powder and its intrinsic properties. A high-fidelity particle-scale model was developed to capture the dynamics of metal particle interactions in a virtual Hall flow meter based on a modified Beverloo law. The results are validated experimentally using the Hall flow static powder characterisation technique. Findings: For SS316L powder alloy with the hall-value of 29s/50g and with an angle of repose (AOR) of 32°, the modelled powder that exhibited the same flow behaviour was found using 0.5 for both rolling and sliding coefficients resulting in simulated Hall value of 28.55s/50g with a simulated flow rate of 0.571 g/s, which is validated by AOR of the simulated powder [31.2°- 32.6°]. However, rolling friction had minimal effect on the mass flow rate but increased the angle of repose. Sliding friction significantly decreased the mass flow rate and increased AOR. Research limitations/implications: DEM is an ideal method to study flowability. However, there are certain constraints imposed on the computational power by a number of simulated particles and simulation time-step. Future research may involve investigating other dynamic flowability characterisation techniques. Practical implications: Enabling a better understanding of powder particle flow at a micro-scale by modelling powder flowability. This leads to simulating a more realistic powder bed and improving the powder spreading process, leading to better AM parts quality. Originality/value: This paper provides a unique approach for modelling the flowability of SS316L powder using a Beverloo law-based design of the Hall flow meter. This will improve the modelling of the spreading process needed for metal 3D printing.
17
Content available Osuwiska spływowe w Paśmie Bukowicy (Beskid Niski)
Walicka Anna
Przegląd Geologiczny
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2022
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Vol. 70, nr 9
651--660
EN
The study area is located in the tectonized area - the Dukla Nappe thrust zone. Rocks in this region are highly fractured and disintegrated, which predisposes it to the development of landslides. The movement occurs as a combination of slide (mainly rotational) and flow (mainly debris flow). Landslide initiation takes place in the upper part of the slope, in the spring area, as a slide. Flow is mobilized within the landslide body as a result of high precipitation and intensive water infiltration. Flow-like landslides often “use” existing channel of the catchment to transport material downslope. To show differentiation of flow-like landslides, the author selected six forms observed in the Bukowica Range. The character of flow depends mainly on liquefaction and volume of transported material, as well as on land relief. Keywords: flow, slide, complex landslides, Bukowica Range, flow-like landslides.
18
Content available Curve Flow-duration-Frequency. The flood modelling regime of the Wadi Mazafran catchment in the north of Algeria
Kourat Sofiane, Touaibia Bénina, Yahiaoui Abdelhalim
Journal of Water and Land Development
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2022
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no. 54
121--130
EN
Synthetic modelling of the flood regime is based on the overall knowledge of the hydrological regime in a catchment. The Flow-duration-Frequency (QdF) modelling is used to combine three parameters characterising flood with its mean or exceeded flow, its characteristic duration, and occurrence frequency. Which of these can be established locally at the extreme mean volume flow rates of a catchment reference hydrometric station? The determination of the reference QdF model in mean (volume) and exceeded flows requires two characteristics reflecting the flood regime in a catchment. The first is the characteristic flood duration and the second is the 10-year quantile of the annual maximum instantaneous flow. The comparison of the local situation to the reference QdF models enables to develop the final QdF model of the catchment and therefore the baseline QdF for exceeded and synthetic mono-frequency hydrographs. These are essential components in the study of flood risk mapping and the estimation of the instantaneous peak distribution from mean daily streamflow series.
19
Content available Monitoring of Water Flow in the Springs of the Golesh Massif, Kosovo
Çadraku Hazir S.
Ecological Engineering & Environmental Technology
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2022
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Vol. 23, iss. 5
109--123
EN
Water spring are vital to all human activities. The integration of hydrological, geological, hydrogeological and ecological characteristics of resource ecosystems provides a much needed tool for recognizing the characteristics and their distribution. The objective of this study was to identify springs in the study area, in order to evaluate their hydrogeological characteristics and parameters. Eight springs have been identified in the Golesh Massif area. They are mainly of lithological contact. Water flow ranging from 0.03 to 5 l/s, the temperature, pH and total hardness in the water of spring Curreli range within 11.1 to 15.7 °C, 5.51 to 8.03 °C and 18.8 to 21.67 °dH, respectively. Their recharge mainly depends on the amount of precipitations that falls in the area.
20
Content available Novel model for emptying of a self-pressurised nitrous oxide tank
Szymborski Jakub, Kardaś Dariusz
Archives of Thermodynamics
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2022
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Vol. 43, no. 3
141--173
EN
Nitrous oxide is often used in the space industry, as an oxidiser or monopropellant, mostly in self-pressurised configurations. It has potential for growth in use due to the recent rising interest in green propellants. At the same time, modelling the behaviour of a self-pressurising nitrous oxide tank is a challenging task, and few accurate numerical models are currently available. Two-phase flow, heat transfer and rapid changes of mass and temperature in the investigated system all increase the difficulty of accurately predicting this process. To get a get better understanding of the emptying of a self-pressurised nitrous oxide tank, two models were developed: a phase equilibrium model (single node equilibrium), treating the control volume as a single node in equilibrium state, and a phase interface model, featuring a moving interface between parts of the investigated medium. The single node equilibrium model is a variation of equilibrium model previously described in the literature, while the phase interface model involves a novel approach. The results show that the models are able to capture general trends in the main parameters, such as pressure or temperature. The phase interface model predicts nitrous oxide as a liquid, a two-phase mixture, and vapour in the lower part of the tank, which is reflected in the dynamics of changes in pressure and mass flow rate. The models developed for self-pressurisation, while created for predicting nitrous oxide behaviour, could be adapted for other media in conditions near vapour– liquid equilibrium by adding appropriate state equations.
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