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Home>Products>Journal and Reviews>I.RE.M.E.>Latest issue
International Review of Mechanical Engineering - March 2009 - Papers
International Review of Mechanical Engineering - Papers
Vol. 3. n. 2, pp. 133-138
Abstract - This paper provides an overview of how CFD technology is currently being used in the heat transfer approach of muffle furnaces. The overview is achieved by taking into consideration of five influencing factors: 1) effect of computing technology, 2) model building and mesh generation, 3) relevant physical models, 4) validation and 5) post-processing and data extraction. Incompressible forced convection heat transfer problems normally admit an extremely important simplification: the fluid flow problem can be solved without reference to the temperature distribution in the fluid. Thus, it can first find the velocity distribution and then put it in the energy equation as known information and solve for the temperature distribution. In this paper it is intended to expand the theoretic researches concerning heat processes intensification and their use in industrial practice. In conclusion the fundamental research with concrete technical applications represents a significant contribution to the development of knowledge in domain.In conclusion, changing the working space by introducing some radiant panels inside the furnace leads to important energy savings in the heating process, by increasing the heating rate of charge and by decreasing its residence time in the thermal equipment. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Simulation, Convection, Fluid Flow, Applications, Furnace.
Vol. 3. n. 2, pp. 139-146
Abstract - A heat and mass transfer problem of for micropolar fluid flow with magnetic and radiation effects micropolar fluids past through a stretching sheet has been studied. Governing equations for heat convection equation of a stretching sheet, and continuity equation, momentum equation and energy equation of a micropolar fluid have been analyzed by a combination of the similarity transformation and a second-order accurate finite-difference method. These solutions are used to obtain distributions of the local convective heat transfer coefficient and the stretching sheet temperature. The dimensionless parameters, the Prandtl number Pr, the magnetic parameter M, the material parameter K, the Eckert number Ec, the radiation number F and the Schmidt number Sc use to analysis one by one, respectively. The numerical results indicate that, an increase in the magnetic parameter gives a decrease in the values of the velocities and Nusselt number, or an increase in the values of the shear stress, couple stress at the surface, temperature and concentration. The material parameter has the opposite effect of magnetic field parameter on the values of the velocities, temperature, concentration, shear stress, Nusselt number and Schmidt number. The temperature decreases as the Prandtl number increases or increases as the Eckert number increases. The concentration decreases as Schmidt number increases. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved Keywords: Finite difference method, Heat and mass transfer, Magnetic field, Radiation effect, Micropolar fluid, Stretching sheet.
Vol. 3. n. 2, pp. 147-155
Abstract - The scope of this paper is to present a correlation between the homogeneous flow theory and the drift-flux model through experimental data from two-phase air-lift pump installations. Homogeneous flow theory is used for a first prediction of the air-lift pump performance and a first calculation of the void fraction is achieved. By using the drift-flux model a void fraction calculation follows from the available experimental data. The ratio of these two void fraction calculations, called here correction factor CoSM, is used for the precise prediction of the liquid superficial velocity and the air-lift pump operation curve. The good agreement between corrected values and experimental data leads to the conclusion that the proposed expressions of the correction factor CoSM constitute a very good tool for a more precise prediction of the operational behaviour of an air-lift pump installation. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Fluid Mechanics, Mass Transfer, Multiphase Flow, Voidage, Drift-flux Model, Air-lift Pump.
Vol. 3. n. 2, pp. 156-161
Abstract - Heat transfer to Bingham plastic fluids in an agitated vessel is a commonly used in chemical and food industry processes. However, little is known about the effects of mixing system geometry and the influence of rheological properties of the liquids on the heat transfer phenomenon. The hydrodynamic and thermal behaviours induced by anchor agitators, in a closed, unbaffled, batch stirred vessel is predicted numerically by means of a Computational Fluid Dynamic (CFD) model. Heat transfer is applied on the jacketed wall of the stirred vessel. Solutions of the time-averaged Navier–Stokes and energy equations are developed using a control volume discretization method. Streamlines and isotherm represent the corresponding flow, field and the global distributions of Nusselt number are also presented. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Agitated vessel, 2D modeling, Bingham Fluid, Heat transfer, Finite volume, CFD.
Vol. 3. n. 2, pp. 162-170
Abstract -
In an
industrial context, the real-time simulation of a mechanical assembly is
a powerful tool for the design phase. However this kind of problem
presents geometric, material and boundary conditions non-linearities, so
the resolution is impossible in real-time for industrial model. A
methodology, divided into a learning phase then a real time phase, is
proposed. Only the first phase is exposed in this paper. In order to
obtain quickly a reduced response, model reduction methods are used. We
focus on two formulations to solve the system: Galerkin method and
residual minimisation method. Comparisons of these two formulations are
realised with three reduction levels: Adaptive method, adaptive method
combined with Karhunen-Loeve Expansion, and hyperreduction combined with
Karhunen-Loeve Expansion.
Keywords: Adaptive method, Galerkin method, Hyperreduction, Karhunen-Loeve Expansion, Residual minimisation.
Vol. 3. n. 2, pp. 171-174
Abstract -
In the
polluted region such as the Sahara, the mining careers, the wear of the
machine elements moving remains important and the problem of abrasive
wear arises with acuity. This research highlights the impact of the
pollutants on the operation of the bearings. With this intention, a
device experimental representing a system of crankshaft and rod was
developed. Different type of lubricants was used with a fine sand
addition to simulate reality. A vibrotest standard CM 400 was used to
measure the evolution of the vibrations according to the various
lubricants.
Keywords: Smooth bearings, Wear, Pollutants, Vibrations, Viscosity.
Vol. 3. n. 2, pp. 175-181
Abstract -
In this work
a smart cantilever beam, having piezoelectric sensor and actuator
patches that are symmetrically bonded on the top and bottom surfaces of
the beam and integrated with a classical control strategy is simulated
by ANSYS. The integration of the control actions with the ANSYS finite
element model is done using APDL. At first the scheme is tested on
controlling the free vibrations of the smart beam. The control gain is
increased until it reaches the maximum possible value which depends on
instrumental restrictions. Despite the simplicity of the control scheme,
it has desired accuracy and the numerical results are in good agreement
with the results reported by former researchers for the structure
integrated with more complicated classical or optimal controllers. The
proposed scheme is also capable of simulating the active vibration
control of the smart structures subjected to different loading patterns.
The study is developed to simulate the active control of forced
vibrations of the same structure subjected to different loads including
impulsive, step, sine and moving excitations and the efficiency of the
controller on attenuating the structural vibrations of the beam is
investigated.
Keywords: Smart Structure, Piezoelectric, Active Vibration Control, Finite Element, ANSYS.
by A. Benhamou, P. Maspeyrot, A. Bounif Vol. 3. n. 2, pp. 182-187
Abstract - The measurement of lubricating film thickness separating the piston and the cylinder walls during the function of an internal combustion engine is a difficult experimental procedure to set in practice. The setting in position of the film transmitter’s thickness constitutes the major difficulty of the problem. Other difficulties are to be surmounted like the choice of the sensor and the data acquisition system. These elements influence the precision whose value must be less than the lubricating film thickness. This article brings the brief replies to the problems mentioned above to lead to the performance of the experimental model of measurement of the profile of lubricating film. The followed method is based mainly on the experimental methods obtained on the revolving bearings where the adaptation is made on the model of piston of direct fuel injection engine type F8L413 Deutz. A test bench for the measurement thickness of oil film of lubrication is proposed. The measurement technique will use capacitive sensors. The results obtained on the test bench will be employed to validate a numerical model, which predicts the characteristics and the oil consumption in the cylinders of the engines. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Piston, Hydrodynamic lubrication, Thickness of oil film.
by Semin, Rosli A. Bakar, Abdul R. Ismail Vol. 3. n. 2, pp. 188-195
Abstract - The natural gas is a promising alternative fuel which fulfills the strict engine emission regulations in many countries. In a compressed form, known as CNG (compressed natural gas) has long been used in stationary engines, but the application of CNG as a transport engines fuel has been considerably advanced over the last decade by the development of lightweight high-pressure storage cylinders. This is equipped with the engine conversion technology which is well established and the availability of the conversion equipment. For spark ignition engines there are two options, a bi-fuel conversion and a dedicated to CNG engine. For compression ignition engines converted to run on natural gas, there are two main options discussed; dual-fuel engines and normal ignition. Natural gas engines can operate at lean burn and stoichiometric conditions with different combustion and emission characteristics. In this paper, the CNG engines research and the development of CNG as fuel used are highlighted to keep the output power, torque and emissions of natural gas engines comparable to their gasoline or diesel counterparts. The high activities for future CNG engines research and development to meet future CNG engines is recorded in the paper. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Alternative Fuel, CNG Engine, Compressed Natural Gas.
by M. Abbasi, A. Karami Mohammadi Vol. 3. n. 2, pp. 196-202
Abstract - The characteristic equation of the flexural vibration of an AFM cantilever with different contact position is derived. Because the tip is not exactly located at one end of the cantilever, the cantilever is modeled as two beams. The effects of tip length, effective mass, contact position and normal contact stiffness on the resonant frequency of the flexural vibration of the cantilever for the first four modes has been analyzed. The results shows that to increase the effective mass or tip length, the resonant frequency of the cantilever is decreased, but effect of effective mass on the resonant frequency of the cantilever is opposite of the effect of tip length. The resonant frequency is free resonant frequency for very low values of normal contact stiffness. Whatever the degree of modes exceeded, the resonant frequency is free resonant frequency for more low values of normal contact stiffness and effect of normal contact stiffness on the resonant frequency of the cantilever happened in higher value of normal contact stiffness. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Atomic Force Microscope, Contact Position, Contact Stiffness.
Vol. 3. n. 2, pp. 203-208
Abstract - The paper presents the results of numerical simulation of crack of mild steel under compression load. The work is performed with the use of CASCA and FRANC2D/L for modeling and simulating the stress distribution of crack under compression radial load. The aims were to develop a finite element model and to simulate the crack propagation in steel plate under compression load. The simulation results were compared with experimental results for verification. The obtained results will provide a prediction of physical behaviour of the structure with failure direction of the crack path. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
FEM, CASCA,
FRANC2D/L, Crack, Compression radial load.
Vol. 3. n. 2, pp. 209-215 Abstract -
A novel
separator consisting of two volutes (inlet and outlet) connected with a
cylindrical chamber is proposed as an alternative to conventional
separators. The separator has a wide range of applications in the oil
and gas industry. It has the advantages of being compact, free of the
effect of motion on floating platforms, and can be modularised in series
to remove liquid or gas carry-over. In order to have a first insight in
the separator performance, a series of CFD simulations has been
performed as the first stage of the research program. The flow
simulations using FLUENT showed that the design has a clear potential
for phase separation applications without any alterations in the basic
geometry design. As a next step, a purpose built test rig has been used
to perform a series of phase separation tests. Various runs of
liquid-gas separation experiments have been performed. Using a suitable
mixture inflow velocity range, the phase volume fraction has been
altered and the results have been monitored. The results have been
processed in order to indicate the areas of best performance of the
initial separator design and to find any suitable alterations in the
initial design, which would increase the separation efficiency. The
experiments, results and conclusions for future work, are presented and
analyzed in the present paper. Copyright © 2009 Praise Worthy Prize S.r.l. -
All rights reserved Keywords:
Phase
separator, Experiments, Performance analysis, Optimization.
Vol. 3. n. 2, pp. 216-221 Abstract -
In the
present work, results of tests conducted on thin welded rectangular
steel-concrete stubs are presented. The stub section was made from two U
shaped cold formed steel plates welded to form box whose dimensions
were: 100x70x2mm. The main parameters studied were: stub height
(50-500mm), effect of the concrete infill and the weld fillet location.
The tests were carried out 28 days after the date of casting the
concrete infill under axial compression up to failure. A total of 28
stubs were tested, 14 were empty and 14 filled with concrete made with
crushed crystallized slag aggregate. The object of the study was to
investigate the failure load of composite sections and the use of
crushed slag instead of conventional aggregate. From test results it was
confirmed that the length of stubs had a drastic effect on the failure
load and resulted from local buckling. It appeared that the location of
weld fillets had only a slight effect on the failure load for empty
steel stubs and was insignificant for composite stubs. Copyright © 2009 Praise Worthy Prize S.r.l. -
All rights reserved Keywords:
Composite
Structure, Concrete Filled Steel Stubs, Crystallized Slag, Failure Load.
by K. Harrat, A.
Boumekik, M. Queneudec.t’ Kint
Vol. 3. n. 2, pp. 222-229 Abstract
-
The use of
lignocellulosic residues in the composite materials manufacture, based
on hydraulic binder, as fiber, has shown to improve the mechanical
behaviour of the material, preserve the environment and develop a
growing need for degradable plant products exploitation. Moreover, this
may certainly offer alternative traditional materials. The aim of the
present work is to characterize a cement palm date fibre composite to be
used in the manufacture of new structural materials and isolation. The
study focuses on the fiber dimensional stability which is sensitive to
water. The presence of organic matter has been proved to be detrimental
to the durability of untreated fiber-reinforced composite. The fibers
were treated with boiling water to extract organic matter and then
coated with several kind of product. The heat treatment associated with
the cement coating in particular, has led to considerable improvement in
the fiber water sensitivity and the mechanical behaviour of composite
ductility. Copyright © 2009 Praise Worthy Prize S.r.l. -
All rights reserved Keywords:
Absorption,
Cement composite, Date palm fiber, Ductility, Strength, Treatment. by T. Descamps, J.
Noël
Vol. 3. n. 2, pp. 230-238 Abstract
-
Timber
frameworks are one of the most important and widespread patrimonial
structures. Because old timber framings are most of the time very
complex structures, quick and efficient techniques are required for
their study. This work focuses on the assessment of the stiffness of old
carpentry joints. As pegged mortise and tenon joints are widespread
joints used in most of old timber frames, our study essentially focused
on them. Semi-rigid studies are generally reduced to the study of the
rotational stiffness and its influence on the structural response. The
component method is here presented for the assessment of the rotational,
axial and shear stiffness. 3D finite elements models and
experimentations have been also performed for the validation of the
proposed method. Finally, an application to the framings of the
Ecaussines-Lalaing castle in Belgium is presented. This clearly
highlights the efficiency of the method and the importance of such a
semi-rigid approach for old timber structures. Copyright © 2009 Praise Worthy Prize S.r.l. -
All rights reserved Keywords:
Component
method, Finite elements, Semi-rigid joints, Timber.
by Ahmed Moustafa
Farag
Vol. 3. n. 2, pp. 239-246 Abstract
-
The main
objective of the present study is to achieve a semi analytical solution
based on a modified strip method to visualize the vibration and buckling
effect on the mode shape of a plate subjected to in- plane forces. On
the present method the plate domain is divided into a limited number of
wide strips (panels) which are solved by the power series expansion on
the matrix exponential technique. The accuracy is improved by increasing
the number of terms of the expanded series which allow applying a low
number of strips. The present study investigated plates of classical
edges and plates of edges elastically restrained against rotation. The
effect of the unaxial and biaxial in-plane forces on the natural
frequency parameters and mode shapes of retrained plate is studied. The
critical buckling of rectangular plate under compressive inplane forces
is included. The convergence and efficiency of the present technique is
demonstrated by several numerical examples compared with those available
in the published literature. The results show a fast convergence and
stability with good agreement in compressions. The present study is
demonstrated by means of a several cases of mode shapes represented by
2D and 3D graphs. Copyright © 2009 Praise Worthy Prize S.r.l. -
All rights reserved Keywords:
Power Series,
Strip, Surface Mode, Buckling, Vibration, Frequency.
Vol. 3. n. 2, pp. 247-251 Abstract
-
The aim of
this paper is to a comparative study between the modelling of a slow
landslide with the continuous medium approach and that of a
discontinuous medium. We used the PLAXIS and GEO4 Codes for the
modelling of the continuous medium. Whereas for the modelling of the
discontinuous medium, we used the two dimensional UDEC code of Itasca.
The mechanical model used the PLAXIS code is the elastoplastic
SOFT-SOIL-model. While that used for the modelling by the GEO4-FEM code
is the elastoplastic MOHR-COULOMB model. Thus, an analysis of slope
stability is used by the GEO4-stability of slopes- code, based on the
methods of BISHOP, PETTERSON and SARMA. As for as the modelling by
element distinct is concerned, we used an elastoplastic model of
Mohr-Coulomb for all the deformable blocks in contact one another
through discontinuity joints. The zone subject to this study is
BOUSSOUF'S city. It is located at 2 km of the city centre of
Constantine. The area affected by this landslide is about 21000 m². The
soil of this city is characterized by a marly clay formation with a
presence of a shallow water table. The analysis of the results obtained
showed a clear divergence between the calculations using continuous
model and that of the discontinuous model; is this reason the following
question can be given: Which of the two approaches is more efficient to
present the landslide behaviour? By this communication we try to answer
this question. Copyright © 2009 Praise Worthy Prize S.r.l. -
All rights reserved Keywords:
Finite
element, Discontinuous element, Stability, Landslide.
Abstract
-
The objective
of this paper is to help preserve Medinas against seismic risk. Medinas
are historical urban tissues that are frequently found in cities of
Morocco and northern Africa. They are made mostly of masonry buildings
that are constructed from stones, lime mortar and wood. In this article,
we work on typical building as a sample of the Médina of Salé buildings.
This building is eight centuries old, and we undertake several tests
aiming to characterize its soil, foundations, material features and its
constructional details. We also survey and assess the specific damages
to the building. For the structural identification, we undertake a
structural survey of this building, a seismic survey and in situ tests
to characterize the soil as well as laboratory tests. Thus, we undertook
experimental tests for the characterization of the Salé-stone, the
cedar-wood used and the behavior of a sample of lime-mortar as well as a
numerical characterization on the Salé-stone wall. For the structural
modeling of this building, we define the actions, and undertake an
analysis of the gravity and seismic loads. We use both a dynamic
approach to model the behavior of this building. The analyses show that
due to the stockiness of the walls and their low heights, the
displacements generated on the level of the walls do not present a
danger from a seismic point of view. However, these analyses show
weaknesses on the level of the joints between the walls and between the
walls and the floors. We recommend measures for the seismic
rehabilitation and strengthening of the existing structure, based on the
modeling results. Copyright © 2009 Praise Worthy Prize S.r.l. -
All rights reserved Keywords:
Medina,
Seismic vulnerability, Salé-stone, Lime-mortar, Rehabilitation, Cedar
wood, Seismic load, Numerical modeling.
Vol. 3. n. 2, pp. 258-264 Abstract
-
This paper
presents the numerical modeling of an elementary urban space (street
canyon). The proposed models allow us to determine the thermal response
of buildings and ambient air and then to simulate the microclimate
generated by the urban system. In summer period, the metro pole has
confronted microclimates problems related to heat bloc urban phenomena.
For example thermal stress, pollution and electrical consumption pick
for conditioning climate. Infact, the urban climate is dependant on the
geographic situation, the agglomeration and the regional meteorology.
Thus air circulation and the temperatures distribution in the canyon
streets has significant importance for the consumption of energy
building. The proposed model is based on numerical systems resolution of
partial’s derivatives equations, which describe the phenomena transfer
quantity movement, energy and mass. Considering the turbulence and using
computational fluid dynamic code, the object of this study is to define
the air circulation simulation and the interaction urban microclimate in
the case of Canyon Street situated in Bechar town (south Algeria).
The results are
presented by velocities and thermal distributions. Copyright © 2009 Praise Worthy Prize S.r.l. -
All rights reserved Keywords:
Street
canyon, Air distribution, Thermal effects, Numerical simulation,
Microclimate of south West Algeria. |
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