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1

Environmental Assessment of Energy Dissipation over Submerged Dams Using MATLAB Simulation

Shehab Fatin M.

Ecological Engineering & Environmental Technology

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2024

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Vol. 25, iss. 3

1--8

EN

In this study, a MATLAB simulation model was developed for the purpose of calculating the energy dissipation of runoff over submersible dams. A laboratory model of a submersible dam with standard dimensions was used, and two angles of inclination of the dam surface 16° and 24.5° were used downstream. In the laboratory work, the discharge and water depth were measured, in addition to the length of the hydraulic jump and the distance from the source, and by using the basic flow equations, the percentage of flow energy dissipation was calculated for both models, and the discharges were counted. The values of the Froude number ranged from 3.612 to 10.784. A simulation model was built in the MATLAB program using the basic equations of flow, finding the values of energy dissipation percentage and comparing them with the laboratory results. Then drawing the relationships between each of the discharge (Q), energy dissipation percentage (E%), Froude number (Fr), hydraulic jump length (Lj), and the distance of the hydraulic jump from the submerged dam (Dj). The numerical and experimental data have been compared, and it has been determined that there is an acceptable agreement between them. The results also showed the efficiency of using the MATLAB simulation method to obtain accurate and fast results.

2

Experimental study of dam-break-like tsunami bore impact mechanism on a container model

Chen Cheng, Chen Jun, Lin Peng, Chen Chiwei, Chen Haozhe

Polish Maritime Research

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2020

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nr 1

53--59

EN

Tsunami disasters have frequently occurred in recent years. More and more researchers are focusing on this topic. To investi-gate the tsunami bore impact mechanism on a container model, a multi-functional slope-changing tsunami flume is built in this study. To simulate a tsunami bore, a dam-break wave was generated by a free-falling gate in a reservoir. A needle water level gauge and a high-speed camera were used to measure the tsunami wave heights and velocities for different storage water levels in the test flume, and the corresponding Froude numbers of tsunami waves were also calculated. The factors af-fecting the movement distance of the tsunami wave impacting the container model are explored in this experiment, and the results show that the movement distance is positively correlated with the storage water level, and negatively correlated with the container density and the coast slope.

3

Physical modeling of a fire with the use of the Froude number

Zimny Mateusz

Budownictwo i Architektura

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2019

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Vol. 18, nr 1

71--80

PL

Testy pożarowe w małej skali (skali modelowej) od samego początku istnienia dziedziny Inżynierii Bezpieczeństwa Pożarowego były źródłem wielu cennych informacji na temat zjawisk zachodzących podczas spalania. Przez lata wykształciło się kilka metod obliczeniowych pozwalających wyznaczyć kryteria podobieństwa pożarów w rzeczywistej i małej skali geometrycznej. Celem niniejszego artykułu jest przedstawienie metody wykonywania testów pożarowych w skali modelowej z wykorzystaniem liczby Froude’a. Omówione zostały podstawy skalowania, warunki podobieństwa, jakie muszą zostać zachowane, sposoby opisywania zjawisk pożarowych, a także metody przeliczania parametrów pożaru ze skali rzeczywistej i modelowej. Przedstawiono również przykładowe badania fizykalne z wykorzystaniem pomniejszonych modeli badawczych. W sposób szczególny podkreślono, jak ważne są tego typu eksperymenty oraz jaka odpowiedzialność spoczywa na osobach, które je przeprowadzają. Motywacją do przeprowadzenia badań jest bowiem bezpieczeństwo ludzi, którzy przebywają w budynkach z zabezpieczeniami przeciwpożarowymi opartymi na testach w skali modelowej.

EN

Ever since the field of Fire Safety Engineering first came into existence, small-scale (model scale) fire tests were the source of much valuable information about the phenomena occurring during combustion. Over the years, several computational methods to determine the criteria for the similarity of fires on both a real and small geometric scale have been developed. The purpose of this article is to present a method of performing fire tests on a model scale using the Froude number. The basics of scaling, similarity conditions that must be preserved, ways of describing fire phenomena, as well as methods of calculating fire parameters from the real and model scale have been discussed. An example of physical tests with the use of reduced research models is also presented. What is particularly emphasized is how important these types of experiments are and what responsibility rests with the people who carry them ouvol. The motivation to conduct research is the safety of people who reside in buildings with fire protection based on model scale test.

4

Experimental investigation of moonpool shapes on a ship with forward speed

Sajjan Sharanabasappa C., Surendran S.

Annual of Navigation

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2019

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No. 26

151--162

EN

A moonpool is a feature of marine drilling platforms, drillships and diving support vessels, some marine research and underwater exploration or research vessels, and underwater habitats, in which it is also known as a wet porch. A floating platform with a moonpool is subjected to different forces due to sloshing and movement of the entrapped fluid in it, while the body is subjected to environmental loads like waves, winds, currents etc.,. Inside a moonpool considerable relative motions may occur, depending on shape and depth of the moonpool and the frequency range of the waves to which it is exposed. The vessel responses are entirely different in zero and non-zero Froude numbers. Later situation is paid attention in this study. There will be different water column elevations in the moonpool depending on the shapes. Two modes of responses are possible based on the shape of the moonpool viz., piston mode for square and sloshing mode for rectangular shape. An aspect ratio of 1:1 for square, 1:1.5 and 1:2 in case of rectangular shapes is considered during experimentation. Circular shaped moonpool is also tested for finding the response. The vessel is initially tested in a towing tank with different drafts and speeds based on Froude scaling. The different modes of oscillations of water column are measured using wave gauge and the vessel resistance is also studied, with and without moonpool. The water column elevation in moonpool may provide better insight to the designer to consider operational and safety parameters.

5

Shapes of an air Taylor bubble in stagnant liquids influenced by different surface tensions

Lertnuwat B.

International Journal of Applied Mechanics and Engineering

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2018

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Vol. 23, no. 1

79--90

EN

The aim of this work is to propose an empirical model for predicting shapes of a Taylor bubble, which is a part of slug flows, under different values of the surface tension in stagnant liquids by employing numerical simulations. The k - turbulence model was used in the framework of finite volume method for simulating flow fields in a unit of slug flow and also the pressure distribution on a Taylor bubble surface. Assuming that an air pressure distribution inside the Taylor bubble must be uniform, a grid search method was exploited to find an appropriate shape of a Taylor bubble for six values of surface tension. It was found that the shape of a Taylor bubble would be blunter if the surface tension was increased. This was because the surface tension affected the Froude number, controlling the flow around a Taylor bubble. The simulation results were also compared with the Taylor bubble shape, created by the Dumitrescu-and-Taylor model and former studies in order to ensure that they were consistent. Finally, the empirical model was presented from the simulation results.

6

O zapasie bezpieczeństwa podczas kroczenia dwunożnego antropomorficznego robota typu DAR

Głębocki M., Jaworek K.

Pomiary Automatyka Robotyka

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2009

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R. 13, nr 2

267-273

PL

W pracy opisano sposób regulacji prędkości robota typu DAR i wyznaczenie dla niego krytycznej prędkości kroczenia za pomocą (nigdzie dotychczas niepublikowanego) wskaźnika bezpieczeństwa chodu (ang. gait safety faktory - GSF). Wskaźnik GSF będzie wyznaczany w robocie DAR, w trybie on-line (tzn. na bieżąco) podczas kroczenia robota. W tym celu stosowana będzie metoda funkcji regresji - zwanej w metodach identyfikacji metodą MFR. W pracy podano równanie zmiennej zespolonej "kroczenia" robota typu DAR na płaszczyźnie Gaussa. "Kroczenie" robota DAR na płaszczyźnie Gaussa umożliwia wyznaczenie (w trybie on-line) wskaźnika bezpieczeństwa kroczenia i prędkość krytyczna chodu robota typu DAR, co zapobiegnie jego np. przewracania się podczas kroczenia w płaszczyźnie strzałkowej ruchu, po względnie płaskiej i utwardzonej powierzchni.

EN

In this paper was described how to build two legged machine (robot), in domestic circumstances, called by authors two legged machine - DAR. The construction of robot has eight degrees of freedom and consists of trunk and two legs equipped with two big feet. Kinematics pairs of machine - DAR are propelled by DC motors, with regulated instantaneous power (similar from "servomotors" of human legs developed by a man muscles). Model of instantaneous power developed at three main "joints" at real the machine - DAR "were taken" from instantaneous power developed from normal of human walk, in sagittal plane, under laboratory condition. In machine - DAR is provided regulation of it’s speed and is calculated maximal speed by means of (nowhere published) Gait Safety Factor - GSF. Coefficient GSF will be calculated in the machine - DAR on-line by the (MFR) method well known from identification methods during "gait" of the two legged machine - DAR, on complex plane, named Gauss plane.

7

O kroczeniu dwunożnego antropomorficznego robota - typu DAR

Jaworek K., Głębocki M.

Pomiary Automatyka Robotyka

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2009

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R. 13, nr 2

259-266

PL

W pracy opisano sposób wykonania, w warunkach krajowych, pierwszego dwunożnego antropomorficznego robota zwanego przez autorów pracy dwunożną maszyną - DAR. Zaprezentowana konstrukcja robota ma osiem stopni swobody i składa się z dwóch nóg wyposażonych w duże stopy i korpus. Pary kinematyczne maszyny - DAR napędzane są silnikami prądu stałego, o regulowanej mocy chwilowej (tak jak to jest w "siłownikach" mięśniowych nóg człowieka). Wzorce przebiegów mocy chwilowych, w trzech głównych "stawach" nóg rzeczywistej maszyny - DAR, "pobrano" z normalnego chodu człowieka, podczas kroczenia, w płaszczyźnie strzałkowej ruchu, po względnie płaskiej i utwardzonej powierzchni, w warunkach laboratoryjnych. Zastosowano liczbę Froude’a do zaprojektowania jej wymiarów geometrycznych, znalezienia podobieństwa dynamicznego między kroczeniem robota typu DAR a człowiekiem. Rzeczywista maszyna dwunożna typu DAR pod względem geometrycznym i masowym będzie e razy mniejsza od wielkości ciała człowieka, gdzie: e - liczba Eulera.

EN

In this paper was described how to build two legged machine (robot) named DAR. The construction of this robot has eight degrees of freedom and consists: trunk and two legs equipped with two relativity big two feet. Kinematics pairs of robot - DAR are propelled by DC motors, with regulated instantaneous power (similar from "servomotors" e.m. produced by group of muscles of human legs during walking). Model of instantaneous power was taken from shape of instantaneous power developed by group of muscles of a man, during walking in sagittal plane, over relatively flat surface - in laboratory condition. Proposed robot - DAR is e-time smaller then a man (where: e - is Euler number). Model of instantaneous power developed by DC control motor of artificial joints of a robot - DAR was elaborated by using Froude number Fr.

8

A mathematicaI model for turbulent bubble plume

Poria S.

International Journal of Applied Mechanics and Engineering

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2007

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Vol. 12, no 1

135-152

EN

A mathematical model for the underwater turbulent bubble plume has been constructed, assuming that slip velocity occurs between the gaseous and liquid phases. Such two-phase turbulent plume may be studied with the help of continuity equation and any one of governing equations e.g., momentum equation and the equation of energy. The present model has been constructed using the continuity equation and the equation of energy. In contrast to existing assumptions e.g., constant entrainment coefficient and constant spreading rate of the width it is assumed in the present model that the width of the plume spreads exponentially with the distance from the exit level of the plume. The distribution of the centerline velocity, relative entrainment coefficient and the relative Froude number are computed in a straight forward manner and discussed thoroughly.

9

Bed dynamics during drum granulation

Heim A., Gluba T., Obraniak A.

Physicochemical Problems of Mineral Processing

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2004

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Vol. 38

167--176

EN

Results of investigations of a granulated bed dynamics during agglomeration in rotating drums were discussed. The investigations were carried out in granulators with continuous wetting of the bed with water, thus making no difference whether the wetting time or bed moisture content was assumed as an independent variable. The variable parameters were: drum diameter D ranging from 0.25 to 0.4 m, drum filling with raw material k in the range from 5 to 20% of inner drum volume and rotational speed of the drum n = 10 to 32 rpm. During granulation the torque value was measured on the granulator shaft. Every minute a sample was taken from the drum, the angle of natural repose of the product, and its bulk density were determined. A dimensionless equation describing the bed dynamics during granulation process was proposed.

PL

W pracy przedstawiono wyniki badań dotyczących dynamiki granulowanego złoża podczas prowadzenia procesu aglomeracji w bębnach obrotowych. Badania prowadzono w granulatorach przy ciągłym nawilżaniu złoża wodą, co powodowało, że przyjęcie jako zmiennej niezależnej czasu nawilżania bądź wilgotności złoża było tożsame. Jako parametry zmienne stosowano: średnicę bębna D od 0.25 do 0.4 m, stopień wypełnienia bębna surowcem k w zakresie 5-20% objętości wewnętrznej bębna, prędkość obrotową bębna w zakresie n=10-32 obr/min. Podczas granulacji mierzono wartości momentu obrotowego na wale aparatu. W stałych odstępach czasowych równych 1 min. pobierano z bębna próbki, na podstawie których określano kąt naturalnego usypu uzyskanego produktu, a także jego gęstość nasypową. W pracy zaproponowano równanie kryterialne opisujące dynamikę złoża w trakcie procesu granulacji.

10

Zmiana warunków hydrodynamicznych wzdłuż koryta potoku górskiego w zróżnicowanej zabudową techniczną małej zlewni karpackiej

Radecki-Pawlik A.

Inżynieria Rolnicza

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2004

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R. 8, nr 2

21--33

PL

W pracy przedstawiono, w jaki sposób regulacja potoku górskiego wpływa na zmianę zasadniczych parametrów hydrodynamicznych przepływu, takich jak: prędkość dynamiczna, naprężenia styczne, liczba Froude’a i Reynoldsa, opory ruchu, moc strumienia oraz jednostkowa moc strumienia. Wykazano, że zabudowa bystrotokiem części koryta potoku górskiego znacznie zaburzyła warunki hydrodynamiczne cieku. Badaniami objęty został potok Młynne w Gorcach o częściowo zabudowanym korycie, a częściowo pozostającym w stanie naturalnym.

EN

The paper describes the way in which the river training influences such hydrodynamics stream conditions as shear velocity, shear stresses, stream power, unit stream power, Froude and Reynolds numbers and resistant coefficient. It was shown that after river training the hydrodynamics parameters in the trained part of the stream increased their value. The work is set up in the Młynne stream catchment in Polish Carpathians in Gorce Mountains.