Wyniki wyszukiwania - BazTech

1

Analiza stateczności pontonu w zależności od konstrukcji budynku pływającego

Trzcińska Klaudia, Szymczak-Graczyk Anna, Ksit Barbara

Materiały Budowlane

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2024

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nr 2

86--88

2

Wielokryterialna analiza doboru typów konstrukcji pomostów pływających

Spychalski Konrad, Szymczak-Graczyk Anna

Materiały Budowlane

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2020

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nr 2

2--4

PL

W artykule przedstawiono analizę czterech typów pomostów pływających. Trzy z nich są ogólnie dostępne na rynku, natomiast rozwiązanie czwarte stanowi projekt autorski. Komfortowe użytkowanie pomostu związane jest z wyborem właściwego rozwiązania zależnie od panujących warunków i potrzeb użytkownika. W tabeli przedstawiono wszystkie konstrukcje tak, aby potencjalny nabywca z łatwością mógł dobrać najodpowiedniejsze rozwiązanie.

EN

The article presents an analysis of four types of floating platforms. Three of them are generally available on the market, while the fourth solution is an original project. Comfortable use of the platform is connected with the selection of the right solution depending on the prevailing conditions and the user's needs. In table all constructions were collected so that a potential buyer could easily choose the most suitable solution.

3

Effect of slip condition on vertical channel flow in the presence of radiation

Guria M.

International Journal of Applied Mechanics and Engineering

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2016

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Vol. 21, no. 2

341--358

EN

An analysis is made on the three dimensional flow of a viscous incompressible fluid through a vertical channel in the presence of radiation in slip flow regime. The right plate is subjected to an uniform injection and the left plate to a periodic suction velocity distribution. The velocity and temperature fields have been derived using the perturbation technique. It is found that the velocity decreases with the increase of the slip parameter. It is also found that the velocity decreases with the increase of the radiation parameter but near the right plate it increases. For cooling of the plate, the velocity increases with the increase of the Grashoff number and decreases near the right plate but the reverse effect is observed for heating the plate.

4

Analiza pływalności i stateczności pojazdu ratownictwa wodnego do prowadzenia akcji na akwenach śródlądowych i wodach przybrzeżnych oraz pokrytych lodem

Cwojdziński L., Gerigk M. K., Szulczewski P.

TTS Technika Transportu Szynowego

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2015

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R. 22, nr 12

331--335, CD

PL

W artykule przedstawiono wyzwania związane z zastosowaniem małego pojazdu ratownictwa wodnego do prowadzenia akcji na akwenach śródlądowych i wodach przybrzeżnych oraz pokrytych lodem. Przedstawiono koncepcję małego pojazdu ratownictwa wodnego. Opisano wybrane elementy modelowania pływalności i stateczności pojazdu. Przedstawiono podstawowe elementy związane z modelowaniem ruchu i oceną zachowania się obiektu w warunkach operacyjnych. Podano wnioski końcowe dotyczące prowadzonych badań.

EN

In the paper the basic problems associated with development the concept of an inland water rescue vehicle PRWL which is devoted to perform the rescue activities on the inland waters covered by ice is presented. The research objective, PRWL vehicle, research method and some elements of the research directed towards development of the PRWL vehicle technology demonstrator has been described. Some elements asso-ciated with assessment of the vehicle floatability, stability and performance in the water have been presented. Some information on a possible application of the PRWL vehicle have been given. The information presented in the paper are the results of work of the authors and results of research investigations conducted at the Gdańsk University of Technology, Faculty of Ocean Engineering and Ship Technology between 2014 and 2015.

5

Experimental and numerical buoyancy analysis of tracked military vehicle

Kotowski M., Barnat W., Grygorowicz M., Panowicz R., Dybcio P.

Journal of KONES

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2012

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Vol. 19, No. 4

321-324

EN

The paper presents experimental validation of numerical flow analysis around tracked amphibious military vehicle. The aim of the study was to validate the simulation results and visualize the flow around optimized geometry To perform numerical simulations, a Computational Fluid Dynamics code FLUENT was used. The software is dedicated to model flow, turbulence, heat transfer, and reactions. The area was divided into two domains – air and water. During the simulation, water was moving with speed specified in standardization. However the numerical techniques are constantly developed and improved there is still a strong need for verification especially in buoyancy analysis and water performance evaluation. Results showed quite good agreement with literature after some modifications of the model. Then the flow was numerically visualized. That allowed in-depth analysis of the flow around each of vehicle's parts and some major and minor modifications were proposed. Modified geometry was analyzed and obtained results will be compared with previous ones. Additional stability and manoeuvrability tests were conducted. The results will be used to modify the geometry of vehicle and conduct experimental tests to verify the numerical code performance and check the actual change in vehicle's water performance. Future work will also consider propeller influence on results.

6

Buoyancy and Soret effect on unsteady MHD mixed convective slip flow in a permeable vertical plate

Rashi Kumar B., Sivaraj R.

International Journal of Applied Mechanics and Engineering

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2012

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Vol. 17, no. 1

179-190

EN

This paper is focused on the study of heat and mass transfer in the unsteady MHD mixed convective flow of a viscous incompressible fluid bounded by a permeable vertical plate subject to the influence of buoyancy, viscous dissipation, ohmic heating and the Soret effect embedded with slip condition at the boundary layer. In order to obtain a better insight into this problem, we make use of the perturbation method. The results for velocity, temperature, concentration, skin friction, the Nusselt number as well as the Sherwood number are examined analytically and the effects of various significant parameters entering into this problem are displayed graphically.

7

Device supporting military vehicles buoyancy and ballistic resistance

Derewońko A., Sławiński G., Niezgoda T.

Journal of KONES

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2011

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Vol. 18, No. 1

129-134

EN

A deep modernization of equipment due to its assembling to the modern requirements of a battlefield and getting full compatibility to NATO structures caused that some military vehicles equipment with additional staff lose their buoyancy or are at the edge of losing it. The solution to this problem can be setting an additional device which helps to increase mass that allows to keep buoyancy of a military vehicle. The panels are fixed as the outer elements of the container which is simultaneously used for storing the elastic air cushions. Before the water crossing, the air cushions are filled with gas and additional buoyancy force is generated. The paper presents a structure and usage of a multipurpose ballistic protection which, in the passive state, is an additional armour and in the unfolded state increases buoyancy lost in the case of setting additional devices or armament. In the paper, initial simulations developed with the use of Ls-Dyna software are described. The influence of modules number of the air cushion on the buoyancy of the multi-purpose ballistic protection is considered. The advantage of the solution is possibility of the chamber volume change which causes the increase of device volume of the whole module of the chambers is dependent on the vehicle buoyancy which results from its current weight.

8

Three dimensional MHD free convection flow and heat transfer through a vertical channel

Guria M., Ghara N., Jana R. N.

International Journal of Applied Mechanics and Engineering

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2010

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Vol. 15, no 4

1047-1063

EN

An analysis is made on the three dimensional MHD flow of a viscous incompressible fluid through a vertical channel in the presence of a uniform injection on the right plate and the left plate is subject to a periodic suction. The velocity and temperature fields are derived using the perturbation technique. It is observed that the primary velocity increases near the left plate and decreases near the right plate with an increase in the Reynolds number while it decreases with an increase in the magnetic parameter. It is seen that with an increase in the Prandtl number the primary velocity decreases whereas it increases with an increase in the Grashof number. It is seen that the magnitude of the secondary velocity increases in the range […] and thereafter decreases with an increase in the Reynolds number. It is also seen that the shear stress due to primary flow increases with an increase in either the Grashof number or Reynolds number but decreases with an increase in the Prandtl number. It is seen that the shear stress […] at the plate […] decreases with an increase in the magnetic parameter. Also, the magnitude of the shear stress due to cross flow increases with an increase in the Reynolds number. It is seen that the temperature at any point decreases with an increase in either the Prandtl number or Reynolds number. The rate of heat transfer in terms of the Nusselt number is also studied. Dimensional variables are indicated by dropping the asterisk and are defined in Eq.(2.8).

9

Radiation effect on three dimensional vertical channel flow

Guria M., Ghara N., Jana R. N.

International Journal of Applied Mechanics and Engineering

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2010

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Vol. 15, no 4

1065-1081

EN

An analysis is made of the three dimensional flow of viscous incompressible fluid through a vertical channel in the presence of a uniform injection on the right plate and a periodic suction velocity distribution on the left plate with radiation effect. The velocity and temperature fields are derived using the perturbation technique. It is found that the primary velocity decreases with an increase in the radiation parameter. It is seen that the shear stress due to primary flow increases with an increase in the Reynolds number but decreases with an increase in the radiation parameter. It is also seen that the temperature decreases with an increase in the radiation parameter. The rate of heat transfer in terms of the Nusselt number is also studied.

10

Finite element solutions for two-phase magneto-heat transfer in a particle-suspension through a non-Darcian porous channel with heat source and buoyancy effects

Bhargava R., Rawat S., Takhar H. S., Beg T. A., Anwar Beg o.

International Journal of Applied Mechanics and Engineering

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2008

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Vol. 13, no 2

325-357

EN

We consider the steady, laminar natural convection heat transfer of a particulate suspension in an electrically-conducting fluid through a two-dimensional channel containing a non-Darcian porous material in the presence of a transverse magnetic field. The transport equations for both fluid and particle phases are formulated using a two-phase continuum model and a heat source term is included which simulates either absorption or generation. A set of transformations are implemented to reduce the partial differential equations for momentum and energy conservation (for both phases) from a two-dimensional coordinate system to a one-dimensional system. Finite element solutions are obtained for the transformed model. A comprehensive parametric study of the effects of the heat source parameter (E), Prandtl number (Pr), Grashof number (Gr), momentum inverse Stokes number (Skm), Darcy number (Da), Forchheimer number (Fs), particle loading parameter (PL), buoyancy parameter (B), Hartmann number (Ha), temperature inverse Stokes number (SkT), viscosity ratio [...], specific heat ratio [...], dimensionless particle-phase wall slip parameter [...] on the dimensionless fluid phase velocity (U), dimensionless particle phase velocity ( ), dimensionless fluid phase temperature [...] and the dimensionless temperature of particle phase [...] are presented graphically. In addition, we also describe numerical solutions for several special cases of the model, for example, the inviscid hydromagnetic two phase non-Darcian free convection, heat transfer [...], forced convection case (GrŽ0) etc. Fluid phase velocities are found to be strongly reduced by the magnetic field, Darcian drag and also Forchheimer drag; a lesser reduction is observed for the particle phase velocity field. The Prandtl number is shown to depress both the fluid temperature and particle phase temperature in the left hand side of the channel but to boost both temperatures at the right hand side of the channel [...]. The inverse momentum Stokes number is seen to reduce fluid phase velocities and increase particle phase velocities. The influence of other thermophysical parameters is discussed in detail and computations compared with previous studies. The model finds applications in MHD plasma accelerators, astrophysical flows, geophysics, geothermics and industrial materials processing.

11

An asymptotic analysis of convection in boundary layer flows in the presence of a chemical reaction

Shateyi S., Sibanda P., Motsa S. S.

Archives of Mechanics

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2005

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Vol. 57, nr 1

25--41

EN

In this study we investigate the stability of two-dimensional disturbances imposed on a boundary layer flow over a semi-infinite flat plate in the presence of a reacting chemical species. Species concentration levels are assumed to be small, what is typical for many processes in water and in atmospheric air. We exploit the multi-deck structure of the flow in the limit of large Reynolds numbers to analyze asymptotically the perturbed flow. The neutral eigenrelations are obtained implicitly and limiting cases for large buoyancy and reaction kinematics are investigated. The results show some interesting effects of the Damkohler number on the wave number and wave speed of the disturbed flow.

12

Unsteady free convection flow in the stagnation-point region of a rotating sphere embedded in a porous medium

Hassanien I. A., Ibrahim F. S., Omer G. M.

Mechanics and Mechanical Engineering

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2004

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Vol. 7, nr 2

89-98

EN

The problem of the unsteady free convection flow in a fluid saturated porous medium of a rotating sphere in the presence of a solid matrix exerting first and second resistance is studied. Numerical solutions are obtained for the cases of constant wall temperature (CWT) and constant heat flux (CHF). The non-linear coupled partial differential equations governing the flow have been solved numerically using finite difference. The effects of the first resistance parameter ξ, the buoyancy parameter λ, the Prandtl number Pr, the variation of the angular velocity with time (ε > 0) on the skin friction and heat transfer rate ue discussed, is shown the figures. It is found that the buoyancy force enhanced both the skin fraction and the heat transfer rate. The effect of the presence of the first resistance decreases the skin friction and the heat transfer rate.

13

Effect of the magnetic field on forced convection flow along a wedge with variable viscosity

Dimian M. F.

Mechanics and Mechanical Engineering

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2004

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Vol. 7, nr 1

107-117

EN

This paper presents a study of the flow of a viscous incompressible fluid along a heated wedge, taking into account the variation of the viscosity with temperature. The flow is under the influence of a magnetic field B(x) along y direction applied perpendicular to the surface of the boundary layer along x direction and an electric field E(x) along z direction. The boundary layer equations are transformed to nonlinear ordinary differential equations and are solved numerically. The effects of the magnetic field on the velocity and the temperature and the shear stress on the surface (Tw) are studied. It is found that the velocity of the fluid increases with increasing the magnetic field parameter M, with the other parameters kept constant. It is also established that the temperature of the wedge decreases with increasing M value. The value of the skin friction increases whereas the rate of heat transfer decreases owing to increasing the magnetic field parameter and also according to decreasing the viscosity.

14

Effects of buoyancy and heterogeneous chemical reaction on unsteady convective diffusion of solute in a Boussinesq fluid flow

Siddheshwar P. G., Manjunath S.

Applied Mechanics and Engineering

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1999

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Vol. 4, no 4

739-757

EN

A closed - form solution is obtained for the problem concerning buoyancy - affected dispersion of solute in a Boussinesq fluid flow with wall - catalysed reaction. The long time Taylor (1953) and Aris (1956) regimes of dispersion for the present problem are obtained as limiting cases. The analytical result on dispersion of solute with wall catalysed reaction at long times is compared with the analytical solution when reaction is absent. The results have applications in heat exchangers, sediment - laden flows and extra - corporeal biomechanical situations.