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1

Development and validation of an operational fast time ship manoeuvring solver to increase navigation efficiency in horizontally restricted waterways

Kazerooni M. F., Rahimian M., Tree M., Womersley T., Jensen B.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2023

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Vol. 17 No. 1

71--76

EN

Growth of demand for containerized cargo shipping has put more ports into pressure to accommodate larger vessels. Considering the limitations on dimensions of navigation channels, this is not feasible unless aiming for significant capital dredging or alternatively creating high precision predictions of vessel motions subjected to environmental forcing and interaction with shallow and restricted waterway. NCOS ONLINE (Nonlinear Channel Optimisation Simulator) is a state of the art navigation support tool which combines DHI’s high level forecast of environmental conditions with mathematical model of ship motions to add an extra level of accuracy in predicting the under-keel clearance and vessel swept path to boost the efficiency of navigation and pilotage within restricted channels. NCOS Manoeuvring Module utilizes an autopilot scheme based on PID (Proportional / Integral / Derivative) controller and Line of Sight Algorithm to FORCE Technology’s SimFlex4 manoeuvring solver for prediction of manoeuvring ship swept path and response, which will effectively bring the accuracy of real time full bridge simulator to fast time operation support tool. In this paper, the result of mathematical model is validated against fullscale measurements of containership transits through Port of Auckland Navigation channel by comparing pilot commands, leeway drift and swept path through output of portable pilotage unit. According to the results the model is found promising to predict the behaviour of human pilots with precision required in operational use. Finally, the swept path and manoeuvring performance of a sample transit is assessed on different environmental conditions and tide stages to evaluate the safe transit windows in operation.

2

Flotation of copper-bearing shale at different pH values of solutions and sodium chloride concentrations

Sajewicz Jakub, Ratajczak Tomasz

Physicochemical Problems of Mineral Processing

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2023

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Vol. 59, iss. 6

art. no. 176242

EN

Flotation of copper-bearing shale in aqueous solutions of NaCl at their different pH values was investigated. The tests were carried out in a laboratory flotation machine. The pH range was between 5 and 10 while NaCl concentrations were 0.5M, 1.0M and 2.0M. It was observed that the flotation recovery of the copper shale was increasing with the increase of pH and concentration of the salt solution. On the basis of thermodynamic and hydrodynamic considerations it was postulated that the increasing surface tension was responsible for better shale flotation observed with increasing salt concentration. The observed improved shale flotation caused by increasing pH is most likely due to changes in the properties of the thin film between particle and bubble including mosaic structure of water on the surface of shale. It was shown that the zeta potential of shale particles, zeta potential of air bubbles, solution surface tension, and shale hydrophobicity were not responsible for the increasing with pH recoveries.

3

Control of capillary instability under hydrodynamic impact on the reservoir

Panahov Geylani M., Abbasov Eldar M., Sultanov Babek N.

Nafta-Gaz

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2023

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R. 79, nr 2

71--83

EN

The paper presents the results of studies on optimisation of water impact on a reservoir by means of sequential periodic increase in hydrodynamic pressure in order to extract capillary trapped oil. The method provides a coordinated account of both displacement conditions and capacitive-filtration characteristics of fluid-saturated reservoirs. The results of experimental, theoretical and field studies of mass transfer processes in the presence of hydrodynamic nonequilibrium in heterogeneous porous media are presented. This paper considers a case where capillary forces are the determining factor for the displacement of immiscible liquids. Laboratory test results have shown that the formation of CO2 in the reaction of an alkaline solution with naphthenic components can make an additional contribution to the control of surface tension in porous media. A series of experimental studies were carried out on a core sample model to simulate the oil displacement by in-situ generated CO2 gas-liquid system. The article offers an analytical and technological solution to the problem of ensuring the value of “capillary number” and capillary penetration corresponding to the most complete extraction of trapped oil by regulating the “rate” of filtration (hydrodynamic injection pressure). The paper presents the field cases of implementing the new reservoir stimulation techniques to increase sweep efficiency. For effective residual oil recovery in fluid flow direction, conditions of stepwise (staged) maintenance of specified hydrodynamic water pressure at the boundary of injection contour are considered. Estimated calculations allow to determine time duration and stage-by-stage control of injection pressure as a requirement for reaching the expected increase in oil recovery.

PL

W artykule przedstawiono wyniki badań nad optymalizacją oddziaływania wody na złoże poprzez sekwencyjne, okresowe zwiększanie ciśnienia hydrodynamicznego w celu wydobycia kapilarnie zatrzymanej ropy. Metoda ta pozwala w sposób skoordynowany uwzględnić zarówno warunki wyporu, jak i charakterystykę kapilarno-filtracyjną złóż nasyconych cieczą. Przedstawiono wyniki badań doświadczalnych, teoretycznych i praktycznych procesów przenoszenia masy w obecności braku równowagi hydrodynamicznej w heterogenicznych ośrodkach porowatych. W artykule rozpatrywany jest przypadek, w którym siły kapilarne są czynnikiem decydującym o wypieraniu niemieszalnych cieczy. Wyniki badań laboratoryjnych wykazały, że powstawanie CO2 w reakcji roztworu zasadowego ze składnikami naftenowymi może mieć dodatkowy udział w kontroli napięcia powierzchniowego w ośrodkach porowatych. Przeprowadzono serię badań eksperymentalnych na modelu próbki rdzeniowej w celu symulacji wypierania ropy przez generowany in-situ układ gazowo-cieczowy CO2. W artykule zaproponowano analityczne i technologiczne rozwiązanie problemu zapewnienia wartości „liczby kapilarnej” i przenikania kapilarnego odpowiadających najbardziej pełnemu wydobyciu zatrzymanej ropy, poprzez regulację „szybkości” filtracji (ciśnienia zatłaczania hydrodynamicznego). W artykule przedstawiono przykłady praktycznego zastosowania nowych technik stymulacji złoża w celu zwiększenia efektywności wydobycia. W celu osiągnięcia efektywnego wydobycia ropy resztkowej w kierunku przepływu cieczy rozważono warunki stopniowego (podzielonego na etapy) utrzymywania określonego ciśnienia hydrodynamicznego wody na granicy konturu zatłaczania. Przeprowadzone obliczenia szacunkowe pozwalają na określenie czasu trwania i etapowego kontrolowania ciśnienia zatłaczania jako warunku osiągnięcia oczekiwanego wzrostu odzysku ropy.

4

A review of the state of research on bridge pier scour under combined action of waves and current

Kumar Lalit, Afzal Mohammad Saud

Acta Geophysica

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2023

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Vol. 71, no. 5

2359--2379

EN

This article presents a review of the state of research on bridge pier scour under combined wave–current flow. The hydrodynamics and scour around the bridge pier under combined wave–current flow have been explained in detail based on the information available in the literature. The impact of relative flow velocity (Ucw), Keulegan–Carpenter number (KC), absolute Reynolds number (Rea), and sediment characteristics on bridge pier scour under combined wave–current flow is presented. This study includes physical modelling of scour with various formulations to predict scour depth and calculation procedures related to scour under combined wave–current flow in the coastal environment. In addition, this study also provides the development of numerical models to investigate bridge pier scour in detail. In the end, future prospects of hydrodynamics and scour around the bridge pier under combined wave–current flow are delineated.

5

Simulation study of hydrodynamic cavitation in the orifice flow

Pietrykowski Konrad, Karpiński Paweł

Applied Computer Science

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2022

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Vol. 18, no 3

31--41

EN

Hydrodynamic cavitation is a phenomenon that can be used in the water treatment process. For this purpose, venturis or orifices varying in geometry are used. Studying this phenomenon under experimental conditions is challenging due to its high dynamics and difficulties in measuring and observing the phase transition of the liquid. For this reason, the CFD method was used to study the phenomenon of hydrodynamic cavitation occurring in water flow through the orifice and then analyze flow parameters for different boundary conditions. The research was performed for four different orifice geometries and two defined fluid pressure values at the inlet, based on a computational 2D model of the research object created in Ansys Fluent software. As a result of the numerical simulation, the distribution of fluid velocity and pressure and volume fraction of the gas phase were obtained. A qualitative and quantitative analysis of the phenomenon of hydrodynamic cavitation under the considered flow conditions was conducted for the defined orifice geometries. The largest cavitation zone and thus the largest volume fraction of the gas phase was obtained for the orifice diameter of 2 mm with a sharp increase in diameter. However, the geometry with a linear change in diameter provided the largest volume fraction of the gas phase per power unit.

6

Analiza efektywności mieszadeł turbinowych z łopatkami pochylonymi w zależności od wysokości zawieszenia mieszadła

Stelmach Jacek, Musoski Radosław, Mysakowski Tymoteusz

Przemysł Chemiczny

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2021

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T. 100, nr 8

762--766

PL

Przeanalizowano warunki hydrodynamiczne w mieszalniku do wytwarzania zawiesin w zależności od odległości mieszadła od dna zbiornika. Ustalono, że posadowienie mieszadła bliżej dna jest korzystne, gdyż umożliwia unoszenie większych ziaren z dna. Jednak prędkość przepływu cieczy przy ściance praktycznie nie zależy od wysokości zawieszenia mieszadła, a to ona determinuje warunki wytwarzania jednorodnej zawiesiny. Stwierdzono również, że niższe umieszczenie mieszadła wpływa negatywnie na efektywność jego pracy.

EN

The mixing power was calcd. for different distances of the stirrer from the bottom of the tank filled with water and for the set rotational frequencies. Liq. velocity measurements were detd. with a laser imaging system by adding 10 μm tracer particles to the water. Placing the impeller closer to the bottom was beneficial as it allowed larger grains to be lifted off the bottom. The velocity of liq. flow at the wall, which dets. the conditions for the formation of a homogeneous suspension, practically did not depend on the impeller clearance. The lower position of the impeller had a negative effect on the efficiency of its work.

7

Microphytobenthic primary production on exposed coastal sandy sediments of the Southern Baltic Sea using ex situ sediment cores and oxygen optodes

Kuriyama Kana, Gründling-Pfaff Sigrid, Diehl Nora, Woelfel Jana, Karsten Ulf

Oceanologia

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2021

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No. 63 (2)

247--260

EN

The shallow coastal water zone of the tide-less southern Baltic Sea is dominated by exposed sandy sediments which are typically inhabited by microphytobenthic communities, but their primary production is poorly studied, and hence four stations between 3.0 and 6.2 m depth were investigated. Sediment cores were carefully taken to keep the natural layering and exposed in a controlled self-constructed incubator. Respiratory oxygen consumption and photosynthetic oxygen production were recorded applying planar oxygen optode sensors. We hypothesized that with increasing water depths the effects of wind- and wave-induced erosion and mixing of the upper sediment layer are dampened and expected higher microphytobenthic biomass and primary production in the incubated cores. Our data partly confirm this hypothesis, as cores sampled at the most exposed stations contained only 50% chlorophyll a m−2 compared to the deeper stations. However, primary production was highly variable, probably due to fluctuating sediment-disturbing conditions before the cores were taken. Due to these physical forces sand grains were highly mobile and rounded, and small epipsamic benthic diatoms dominated, which preferentially occurred in some cracks and crevices as visualized by scanning electron microscopy. The data fill an important gap in reliable production data for sandy sediments of the southern Baltic Sea, and point to the ecological importance and relevant contribution of microphytobenthic communities to the total primary production of this marine ecosystem. Oxygen planar optode sensor spots proved to be a reliable, sensitive and fast detection system for ex situ oxygen exchange measurements in the overlying water of intact sediment cores.

8

Numerical study of a cone mill for emulsion preparation: Hydrodynamics and population balance modelling

Lupieri Guido, Bagkeris Ioannis, Janssen Jo J.M., Kowalski Adam J.

Chemical and Process Engineering

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2021

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Vol. 42, nr 4

295–-320

EN

The work concerns numerical simulations of a cone mill used for emulsion preparation. Hydrodynamics, power consumption and population balance are investigated for various operating conditions at high phase volume emulsions and for different rheologies. Cone mills are usually simplified as a simple gap between rotor and stator but by increasing the complexity of the geometry till it represents the commercial device identifies a wealth of additional features such as recirculation zones above (which enhance breakage) and below (which allow for coalescence) the rotor-stator gap. Two separate sets of population balance modelling constants are required to capture all the experiment results – even with the most complex geometries. Some suggestions are made for improvements and further studies will consider other rotor-stator devices.

9

Fluidized bed in gravitational shelf dryers: optimization calculation

Artyukhova Nadiia, Krmela Jan, Krmelová Vladimíra, Artyukhov Artem, Gavendová Mária

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 3

art. no. e137388

EN

The article deals with studying the hydrodynamic characteristics of the fluidized bed in gravitation shelf dryers. The algorithm to calculate hydrodynamic characteristics of the fluidized bed in the dryer’s workspace is described. Every block of the algorithm has a primary hydrodynamic characteristics theoretical model of calculation. Principles of disperse phase motion in various areas in the gravitation shelf dryer are established. The software realization of the author’s mathematic model to calculate disperse phase motion trajectory in a free and constrained regime, disperse phase residence time in the dryers’ workspace, polydisperse systems classification is proposed in the study. Calculations of disperse phase motion hydrodynamic characteristics using the software product ANSYS CFX, based on the author’s mathematic model, are presented in the article. The software product enables automating calculation simultaneously by several optimization criteria and visualizing calculation results in the form of 3D images. The disperse phase flow velocity fields are obtained; principles of a wide fraction of the disperse phase distribution in the workspace of the shelf dryer are fixed. The way to define disperse phase residence time91 in the workspace of the shelf dryer in free (without consideration of cooperation with other particles and dryer’s elements) and con-strained motion regimes is proposed in the research. The calculation results make a base for the optimal choice of the gravitation shelf dryer working chamber sizes.

10

Analysis of dynamical behaviour of full-floating disk thrust bearings

Nitzschke Steffen, Ziese Christian, Woschke Elmar

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 6

art. no. e139001

EN

Full-floating ring bearings are state of the art at high speed turbomachinery shafts like in turbochargers. Their main feature is an additional ring between shaft and housing leading to two fluid films in serial arrangement. Analogously, a thrust bearing with an additional separating disk between journal collar and housing can be designed. The disk is allowed to rotate freely only driven by drag torques, while it is radially supported by a short bearing against the journal. This paper addresses this kind of thrust bearing and its implementation into a transient rotor dynamic simulation by solving the Reynolds PDE online during time integration. Special attention is given to the coupling between the different fluid films of this bearing type. Finally, the differences between a coupled and an uncoupled solution are discussed.

11

Cząstki Janusa, syntetyczne pływaki i materia aktywna w mikroskali

Lisicki Maciej

Postępy Fizyki

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2020

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T. 71, z. 3

3--11

PL

Materia aktywna to układy złożone z wielu elementów, które poruszają się czerpiąc energię z otoczenia. Jednym z przykładów są orzęski – jednokomórkowe mikroorganizmy, poruszające się poprzez wytworzenie na swojej powierzchni przepływu za pomocą setek drobnych rzęsek pokrywających ich komórki. Mechanizm ten zainspirował prace nad sztucznymi mikropływakami, które poruszają się wykorzystując wytwarzane przez siebie gradienty odpowiednich wielkości fizycznych, takich jak temperatura, stężenie produktów reakcji chemicznej albo pole elektryczne. W poniższym artykule omawiam krótko mechanizmy fizyczne rządzące ruchem syntetycznych mikropływaków i podsumowuję dotychczasowe próby wykorzystania wspominanych zjawisk do napędzania aktywnych mikrocząstek. Wskazuję niektóre kierunki rozwoju i wyzwania stojące przed bionaśladowczą mikroinżynierią, takie jak kontrola ruchu cząstek przy użyciu zewnętrznych bodźców, i prezentuję potencjalne rozwiązania.

EN

Active matter are systems comprising of many elements which move by drawing the energy from their environment. An example are ciliates – unicellular microorganisms which move by generating flow on their surfaces using hundreds of tiny cilia covering their cell bodies. his mechanism has inspired works on artificial microswimmers which move in response to self-generated gradients of various physical quantities, such as temperature, concentration of chemical species, or electric field. In this article, I briefly review the basic physical mechanisms governing the motion of synthetic microswimmers and summarise previous implementations using the above mentioned phenomena to propel microparticles. I highlight possible developments and challenges of biomimetic microengineering, such as the control of motion of particles using external stimuli, and present potential solutions.

12

Hydrodynamic model of the new waterway through the Vistula Spit

Szydłowski Michał, Kolerski Tomasz

Polish Maritime Research

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2020

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nr 3

159--167

EN

The decision to build a new waterway (strait) in the Polish part of the Vistula Spit was made in 2017. The new connection between the Gulf of Gdańsk and the Vistula Lagoon is planned as an artificial navigable channel with a lock and a small port. During storm surges and wind tides in the gulf or in the lagoon, sluicing will be required for vessels to tackle the Vistula Spit. This procedure does not require significant water flow through the channel in normal conditions. However, in the case of a lock failure or in the case of controlled opening of the gate to increase water exchange in the lagoon or to reduce flood risk in the Vistula Lagoon, high flow rates may occur in the navigable channel and in the neighboring port basin. In order to inves-tigate the hydraulic conditions in such extraordinary situations, numerical modeling of the hydrodynamics during water damming in the gulf or in the lagoon is performed. To analyze the hydrodynamics of the artificial connection between the sea and the lagoon during periods of high water stages, mathematical modeling is required. This paper presents the shallow water equations (SWE) model adapted to simulate the flow through the port basin and the navigable channel. The calcula-tions allowed the relation between the water head and the capacity of the navigable channel to be found, as well as to analyze circulations which may occur in the port basin.

13

Seepage process on weathered crust elution-deposited rare earth ores with ammonium carboxylate solution

Zou Hualiang, Zhang Zhenyue, Chen Zhuo, Liu Defeng, Chai Xiuwei, Zhang Han, Chi Ru-an

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 1

89--101

EN

In order to reveal the seepage law of ammonium carboxylate solution in the in-situ leaching process of weathered crust elution-deposited rare earth ores, the effects of concentration, pH, temperature, particle size and porosity on permeability were discussed in this paper. The results shown that the seepage of the leaching agent solutions in the rare earth ore follows Darcy's law and displays a laminar flow under the conditions of this experiment and seepage velocity can be increased by changing leaching conditions. The permeability coefficients are inversely proportional to concentrations of ammonium acetate, ammonium tartrate and ammonium citrate whose concentration is greater than 0.7wt%, because the insoluble complexes formed by the reaction of ammonium citrate with RE3+ at lower concentration n decrease the permeability coefficient. The permeability coefficients of ammonium carboxylate solutions increase firstly and then decrease with the pH increased. The maximum of permeability coefficients of ammonium acetate, ammonium tartrate and ammonium citrate solution were 2.92, 1.91 and 2.70, respectively, while the pH of solution were 5, 6 and 7, respectively. Increasing temperature is beneficial for the seepage of ammonium carboxylate solution in orebody, therefore, it is helpful for leaching operation in summer. Moreover, clay minerals particle size and porosity are the key factors affecting the permeability of ammonium carboxylate solution in orebody. The permeability coefficients of ammonium acetate, ammonium tartrate and ammonium citrate solutions are 2.92×104cm/s,1.90×10-4cm/s and 2.69×10-4cm/s, respectively, at the same temperature of 293K, original particle size and porosity of the ore. Ammonium acetate solution has the best permeability in orebody.

14

Identification and evolution of the Turonian aquifer case study: Cretaceous basin of Béchar, southwestern Algeria

Sadat Sonia, Mansour Hamidi, Mekkaoui Abderrahmane, Merzougui Touhami

Journal of Water and Land Development

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2020

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no. 46

190--199

EN

Faced with the challenges of sustainable groundwater resource management in the arid zone, the identification of reserves and their monitoring have become vital. This paper aims to identify the Turonian aquifer in the Cretaceous Béchar basin, and calculate its transmissivity, permeability and storage coefficient, as well as its evolution over time. This Turonian aquifer is characterized by marine limestones (gentle dip shelters 45° to the North and 5° to 10° to the South). Pumping tests revealed a transmissivity T of 10–4 to 10–2 m2·s–1, a permeability K of 10–6 to 10–4 m·s–1 and a storage coefficient S of approximately 10–3. Two piezometric campaigns, carried out between (1976–2018), show a converging and constant flow direction from the North–East to the South–West and from the North–West to the South–East towards the outlet of the basin. Decreased values were observed in the North and South–West borders due to isopiezometric lines. However, this water table is not in a stationary state, it shows seasonal and interannual fluctuations in relation to the variable rainfall and the exploitation rate. In terms of facies, the projection of the two hydrochemical campaigns, during 1976 and 2018 on the Piper diagram, did not show any significant evolution, they are concentrated in the chlorinated and sulphated calcium and magnesium facies.

15

Variable rotational speed control system of sewage pumping station

Szychta E., Szychta L.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2019

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Vol. 13, no. 2

343--346

EN

Cascade and variable rotational speed control systems of sewage pumping stations are compared in this article. The range of pump efficiency variations and potential for breakdowns are adopted as criteria. A pumping station including two or three pumps is analysed. A control system at a variable rotational speed and maximum sewage level is presented. Properties of a cascade control system and a system at a maximum head of sewage are compared using the example of any pump performance chart.

16

Is full-autonomy the way to go towards maximizing the ocean potentials?

Zghyer R., Ostnes R., Halse K. H.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2019

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Vol. 13, no. 1

33--42

EN

Growth prospects for ocean economy are promising because ocean industries are addressing challenges such as food security, energy security and climate change. However, safety and efficiency are the general challenges of ocean operations. Increased automation is believed to solve these problems. This paper discusses the impact of automation on safety and efficiency. A literature review of ‘Human factors’ mainly from the aviation and maritime industries is presented to untangle the human-machine relationship characteristics when increased automation is introduced to operators. A literature review of Hydrodynamics, Guidance, Navigation and Control (GNC) technologies is presented to introduce the state-of-art and associated limitations. It is concluded that, if the industry’s drive is safety and efficiency, then full-autonomy is, at present, not the way to go. Remote control, instead, could facilitate a feasible future, while focused research and development are in need.

17

Hydrodynamics of DARPA SUBOFF submarine at shallowly immersion conditions

Efremov D. V., Milanov E. M.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2019

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Vol. 13, no. 2

337--342

EN

Recently, the submarine missions are often evolving into operating to littoral areas, which require operating in shallow water. Such shallow water operations strongly contrast with the traditional ones due to the effect of a close to free water surface expressed mainly by surface suction force. This influence is particularly important for submarine maneuverability accounting for restricted area available. The prediction of submarine behavior in similar conditions requires adequate mathematical model and understanding of the additional hydrodynamic load generated near the surface region. The paper is aimed for better understanding of these issues and relating to development of a submarine simulation model, the experimental program of towing and PMM captive tests of DARPA Suboff submarine model were conducted at a towing tank. The influence of phenomenon such as effect of a close to free surface and Froude number at hydrodynamic forces and moments including control surfaces effectiveness were investigated and also was estimated directional stability of motion in horizontal plane.

18

Fluid Mud and Nautical Bottom – Concept and Application in Itajaí Port Complex (Brazil)

Pion L.M., Alfredini P.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2019

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Vol. 13, no. 2

445--452

EN

Considering the demand for mooring larger ships at Brazilian port terminals, both private and public, in a scenario of growing exports, engineering interventions that can provide improvements in the vessel’s maximum allowed dimensions can represent significant profits. Hence, this work presents an approach of Nautical Bottom, defined as the minimum depth in which ships can navigate without significant adverse effects in ship control and maneuverability without physical damage, with the goal of raising the maximum ship draft allowed in nautical spaces with fluid mud beds. Due to its rheological properties, fluid mud, in general, allows for vessels navigate with low or negative under keel clearance, respecting the established Nautical Bottom concepts. In addition, fluid mud layer thickness at port areas can possibly vary according to hydrodynamics and sedimentologic variations. This article presents an analysis of fluid mud thickness variations within the Itajaí Port Complex (Santa Catarina, Brazil) turning basin, where fluid mud layers are up to 2.5 meters thick, by means of analyses of bathymetric surveys and numerical modeling. The Itajaí Port Complex is located at the Itajaí-açu river estuary, which presents high variability of river discharge and suspended sediments. From bathymetric surveys, it is possible to observe fluid mud thickness from 0.5 to 2.5 meters. Numerical simulation results indicate suspended sediment load as a main environmental aspect for fluid mud thickness variations in the study area.

19

A hybrid model of flooding of the ro-ro ships in damaged conditions

Gerigk M. K., Jachowski J., Sargun J.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2019

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Vol. 13, no. 2

347--354

EN

The paper presents some results on investigations concerning development of a hybrid model for assessment of performance of the ro-ro ships in damaged conditions. The model is devoted towards assessing the performance of the damaged ro-ro ships at the preliminary stage of design. The key problems associated with preparing of such the model are associated with working out a method of assessment of the damaged ro-ro ships performance, investigating all the phenomena which associated with the flooding process of the damaged ro-ro ships and preparing the model itself. Introducing the method of assessment of the damaged ro-ro ships performance it has been assumed that there is a dependence between the arrangement of internal spaces of a ro-ro ship and flooding process. The major phenomena which have been decided to take into account when considering flooding of the ro-ro ships are the flooding understood as the flow of external water into the data damaged compartment, impact of the flooding water on the ship structure and damaged ro-ro ship motion. Knowing the damaged ro-ro ship motion characteristics in time domain it is relatively easy to assess the damaged ro-ro ship performance according to the heeling angle and assess the ro-ro ship design according to the data arrangement of internal spaces. The last research issue is to investigate if the proposed model may be appropriate tool for assessing the performance of the ro-ro ships in damaged conditions at the preliminary stage of design. The aim of this paper is to show how to incorporate the dynamics of the damaged ro-ro ships when assessing the ship performance and safety at the preliminary stage of design. The basic information on the model for estimation of the damaged ro-ro ship behavior during the flooding process is presented. The complexity of this model is shown depending on the approach applied to consider the flooding process itself. The model is devoted towards assessment of performance of the damaged ro-ro ships and it is still under the development according to a Ph.D. research at the Faculty of Mechanical Engineering Gdańsk University of Technology.

20

The hydrodynamics of a fluidised bed reactor

Rybak Anna, Jankowski Dawid

Technical Transactions

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2019

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Vol. 116, iss. 5

55--70

EN

This article presents results concerning the hydrodynamics of a reactor with a porous fluidised bed (group D according to Geldart). Pressure drops were experimentally determined by gas flow through the bed and empty column. Using equations from literature flow resistance on the bed and gas distributor, critical velocity and terminal velocity were calculated and the obtained results were compared with experimental data. The equation which best described the work of the tested fluidised bed was identified through a process of trial and error. The influence of sieve being operated on pressure drops occurring during the process was determined and its applicability in the other conditions was verified.

PL

W pracy zaprezentowano wyniki dotyczące hydrodynamiki reaktora z porolitową warstwą fluidalną (grupa D wg Geldarta). Eksperymentalnie wyznaczono spadki ciśnienia przy przepływie gazu przez złoże i pustą kolumnę. Korzystając z równań literaturowych, obliczono opory przepływu na złożu, dystrybutorze gazu, prędkość krytyczną i prędkość wywiewania oraz porównano otrzymane wyniki z danymi doświadczalnymi. Metodą prób i błędów znaleziono równanie najlepiej przedstawiające pracę badanego układu fluidalnego, określono wpływ eksploatowanego sita na spadki ciśnienia występujące w trakcie procesu oraz zweryfikowano jego stosowalność w innych warunkach.